Gut barrier
The gut lining as the border between gut contents and the body. 7 chapters – expand
- Level:Beginner The gut barrier A layer of cells thinner than a hair separates the gut contents from the body. What keeps it tight. FibreAlcoholAdditivesCoeliac disease and glutenInflammationTests and diagnostics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate The mucus layer and additives Why the distance between bacteria and the gut wall matters and what emulsifiers have to do with it. AdditivesFibreInflammation Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Butyrate and other short-chain fatty acids What gut bacteria make from fibre and what the body needs these substances for. Short-chain fatty acidsFibreInflammationPlant diversity Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Mould: mycotoxins in food and damp in the home What mould toxins can do in the gut, which dangers are well established, and which tests and cures do not deliver what they promise. Toxins and mouldInflammationTests and diagnostics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Longer fasting: water fasting, therapeutic fasting and fasting-mimicking How several days without food remodel the gut microbiota, what studies on therapeutic fasting and fasting-mimicking diets show, and where the risks lie. FastingInflammationBody weight Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate The “leaky gut stack”: colostrum, zinc carnosine, aloe and co. What goes into the typical gut-lining blends, what studies show and where the risks lie. Vitamins and fatty acidsMedicationIBSInflammationExercise Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Gut and endurance sport: runner’s gut, cramps and what helps During long, hard sessions the gut gets less blood, briefly becomes leakier and digests less well. Why runners are hit more often, what heat and ibuprofen have to do with it, and why the gut can be trained. ExerciseDiarrhoeaFODMAPMedicationNutrientsBloating Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
Opportunistic pathogens
Germs that only become a problem when the balance is off. 11 chapters – expand
- Level:Intermediate Opportunistic pathogens Germs that are always there and only become a problem when the balance tips. AntibioticsAcid blockersMedicationProbioticsGut infectionsInflammationTests and diagnostics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate After antibiotics: C. difficile and faecal transplants A germ that can take over after antibiotics, and a treatment that works better than any drug. AntibioticsFaecal transplantProbioticsDiarrhoeaGut infectionsBile acidsToxins and mould Established How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate When the gut does not settle after an infection Stomach bug, food poisoning, traveller's diarrhoea: why symptoms sometimes stay. Gut infectionsIBSDiarrhoeaBile acids Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Fungi in the gut: what is true about Candida Yeasts are part of the normal gut microbiota. When they are a problem and when they are not. AntibioticsGut infectionsTests and diagnostics Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Parasites in the gut: worms, protozoa and Blastocystis Which parasites make you ill, which are probably harmless lodgers and how to detect them reliably. ParasitesGut infectionsDiarrhoeaTests and diagnostics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Herxheimer reaction, die-off and toxins When feeling worse at the start of treatment is real, and when "detox" is used to explain away harm. Toxins and mouldAntibioticsGut infectionsParasitesProbiotics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Saccharomyces boulardii: the probiotic yeast Why a yeast survives antibiotics, what it is proven to help with, and when it can become dangerous. ProbioticsAntibioticsDiarrhoeaGut infections Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Mouth and gut: how teeth, gums and mouthwash touch the gut flora Every day we swallow billions of mouth bacteria. Usually this is harmless, but with inflamed gums, acid blockers or a weakened gut flora, some of them settle in the gut. Mouth and teethAcid blockersInflammation Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Expert Biofilms in the gut and “biofilm busters” Bacteria often live in communities with a protective coat. On teeth this is well established, in the gut there are exciting new findings. The products meant to dissolve such films have not been studied there. IBSBile acidsMedicationMouth and teethInflammationAntibiotics Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Long COVID and the gut: when your stomach won't settle after COVID Diarrhoea, bloating and IBS after a COVID infection: what cohort studies show, what viral remnants in the gut might mean and which treatments have been tested so far. Gut infectionsIBSProbioticsInflammation Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Gut and cancer: what the gut microbiota protects against, what harms, and why it matters in cancer treatment Fibre and its bacteria protect against colorectal cancer, while some bacteria damage the genome. Why colorectal cancer is rising in people under 50, which germs travel along in tumours, what Helicobacter has to do with stomach cancer, and why the gut microbiota helps decide whether immunotherapy works. FibreInflammationAntibioticsProbioticsTests and diagnosticsMouth and teethFaecal transplantBile acids Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
Bacteriophages
Viruses that hunt bacteria and help steer the microbiome. 2 chapters – expand
- Level:Expert Bacteriophages: the hunters in the gut Viruses that only infect bacteria are among the most numerous entities in the gut. What they do there. AntibioticsAntibiotic resistanceFaecal transplantFermented foods Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Expert Phage therapy: viruses as medicine How phages are used against resistant germs and where the therapy stands today. Antibiotic resistanceGut infections Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
Microbial diversity
Why many different species keep the gut stable. 18 chapters – expand
- Level:Beginner For everyone Your gut in ten minutes Who lives there, what do they do, and why is balance more important than individual germs? FibrePlant diversityFermented foodsAntibioticsExerciseTests and diagnostics Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Beginner Building microbial diversity Why many different species keep the gut stable and how to rebuild them after antibiotics. Plant diversityFermented foodsProbioticsAntibioticsFibre Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Beginner Using fermented foods well Sauerkraut, kefir, kimchi: what the studies show and how to include them. Fermented foodsProbioticsHistamineInflammation Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Beginner Sweeteners and sugar alcohols Sugar-free does not mean without consequences: what each sweetener and sugar alcohol does to the gut microbiota and digestion. SweetenersAdditivesBloatingFODMAP Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Medications that change the gut Not just antibiotics: acid blockers, metformin, painkillers and others affect the gut microbiota. MedicationAcid blockersAntibioticsAntibiotic resistance Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Gut tests: what they show and what they do not Microbiome analysis, zonulin, IgG, breath test, calprotectin: which tests are worth it. Tests and diagnosticsCoeliac disease and glutenInflammation Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Expert Firmicutes, Bacteroidetes and body weight Does your gut microbiota make you fat? What is behind the much-quoted bacterial ratio. Body weightPlant diversityTests and diagnostics Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Expert Prebiotics beyond inulin: HMOs, arabinogalactan, polyphenols Lesser-known food for the gut flora: what studies show and which polyphenols are best researched. PrebioticsFibrePlant diversityShort-chain fatty acidsIBS Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Spore-forming bacteria: Bacillus and co. as probiotics How probiotics in spore form survive stomach acid, what they do in the gut and where the evidence ends. ProbioticsIBSDiarrhoea Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Fermenting at home: milk kefir, water kefir and S. boulardii soda What lives in the grains, what studies show about kefir, how to do it safely, and why S. boulardii soda is an experiment. Fermented foodsProbioticsHistamine Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Beginner Intermittent fasting and meal timing: 16:8, 5:2 and Ramadan What happens in the gut between meals, what studies on eating windows show, and why the time of day might matter. FastingSleepBody weight Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Expert Anaerobic gut bacteria: why the good ones do not fit in a capsule The most important gut bacteria cannot tolerate oxygen. What makes them thrive, and why you can barely swallow them. ProbioticsShort-chain fatty acidsFibreFaecal transplant Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Expert The second-meal effect: why dinner helps decide your blood sugar in the morning Lentils at breakfast lower blood sugar at lunch, whole barley kernels in the evening lower it at breakfast. How this works, and what role gut bacteria play. FibreShort-chain fatty acidsBlood sugarBody weight Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Expert GLP-1 from the gut: what bacteria do and what “natural Ozempic” cannot do Weight-loss injections mimic a hormone that your own gut wall also makes, stimulated among other things by bacteria. How this pathway works and why it does not have the same effect as the drug. Short-chain fatty acidsFibreBody weightBlood sugar Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Carnivore and keto: less gas, but at what cost? Why many people feel less bloated on an all-meat or ketogenic diet, what this does to gut bacteria, and why experts do not recommend it for gut health. FibreShort-chain fatty acidsPlant diversityBloatingBody weight Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Beginner The first microbiome: birth, breastfeeding, antibiotics and what remains In the first three years of life the gut microbiota forms, and the immune system learns from it. What birth mode, breastfeeding, antibiotics, siblings and pets have to do with it, what evens out later, and what parents can really do. AntibioticsProbioticsAllergiesAntibiotic resistanceFaecal transplant Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Beginner For everyone Big effect, small budget: low-cost measures for your gut What demonstrably helps the gut often costs almost nothing: slow breathing, cooled potatoes, potato starch from the supermarket, legumes, psyllium, kiwis, a stool in front of the toilet. An overview of how well each is supported, what it costs and where you can skip expensive detours. FibreExerciseStressPrebioticsFermented foodsConstipationBloatingShort-chain fatty acids Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate What a household shares: microbes between people, dogs and cats People who live together swap bacteria constantly: through hands, kitchen, bathroom, kisses and the animal on the sofa. What studies on shared bacterial strains show, what is useful about it, which pathogens and resistant bacteria really do get passed on, and why shared bacteria are not proof of transmission. Gut infectionsAntibiotic resistanceMouth and teethAllergiesAntibioticsBody weight Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
Gut-brain axis
How stress, sleep and nerves steer digestion. 10 chapters – expand
- Level:Beginner For everyone A gut-friendly everyday life Exercise, sleep, social contact and breaks: what your gut picks up from the rest of your life. StressSleepExercisePsychotherapyConstipation Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Beginner The gut-brain axis How stress hits the stomach and why psychotherapy works for IBS. StressIBSPsychotherapyExercise Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Beginner Stress, sleep and the gut What happens in your belly when your head cannot switch off. StressSleepPsychotherapy Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Hormones, the cycle and the gut Why gut symptoms change around your period, in pregnancy and at menopause, and when endometriosis or the thyroid may be behind them. IBSConstipationDiarrhoea Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate The vagus nerve: the data line between belly and head The longest cranial nerve tells the brain what is happening in the gut and dampens inflammation. What of this is proven, and what breathing exercises and devices can really do. StressIBSInflammation Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Fear of food: when your list of safe foods keeps shrinking How gut symptoms can tip into fear of eating, ARFID or orthorexia, why unintended weight loss is a warning sign, and how to find your way back to a varied diet. PsychotherapyBody weightIBSFODMAP Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Brain fog and fatigue: when your gut makes your head tired Many people with gut problems feel exhausted and foggy. What studies show, which causes can be checked and what is mere speculation. SleepVitamins and fatty acidsCoeliac disease and glutenInflammationProbioticsTests and diagnostics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Gut-directed hypnotherapy and psychological therapy: treatment via the gut-brain axis Why gut-directed hypnotherapy and CBT are among the best-proven treatments for IBS, how they work, what apps can do, and why "limbic retraining" is something else. PsychotherapyIBSStress Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Expert POTS and hypermobility: when circulation and connective tissue drag the gut along People with hypermobile joints (hEDS, hypermobility spectrum) or a racing heart on standing (POTS) have gut symptoms strikingly often. What studies show, what to make of the much-quoted "trifecta" with MCAS, and what helps. IBSConstipationExerciseHistamine Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Beginner Abdominal pain and cramps: where the pain comes from Cramp, fullness or stabbing: why the gut signals pain, when it is harmless and when it needs checking. IBSBloatingConstipationDiarrhoeaStressExercise Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
Digestive function
Stomach acid, bile and enzymes as groundwork for the gut. 20 chapters – expand
- Level:Intermediate Stomach acid, bile and enzymes The groundwork in the stomach and small intestine determines what reaches the large intestine. Acid blockersMedicationBile acidsAlcoholBloatingTests and diagnostics Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Bile acids: when bile causes diarrhoea Primary and secondary bile acids, the role of gut bacteria and why antibiotics can shift the balance. Bile acidsDiarrhoeaIBSTests and diagnostics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Beginner Constipation: more than too little fibre Kiwifruit, psyllium, pelvic floor and methane: what is behind sluggish digestion. ConstipationFibreExerciseMedication Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Beginner Lactose, fructose, gluten: making sense of intolerances What real intolerances are, which tests are worth anything and when cutting foods out does harm. Coeliac disease and glutenFODMAPBloatingTests and diagnostics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Beginner Heartburn and reflux When acid rises: what helps, when acid blockers make sense and when to stop them. Acid blockersMedicationSleep Established How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Pelvic floor: when stool won’t come out properly Why straining sometimes does not help, how a defecation disorder shows itself and why biofeedback works better than laxatives. ConstipationExerciseTests and diagnostics Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Sensitive stomach: fullness, upper abdominal pain and Helicobacter What is behind upper abdominal symptoms when the endoscopy is normal, why the Helicobacter test comes first and what else helps. BloatingIBSAcid blockersTests and diagnostics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Pressure under the right ribs: bile, liver and gallstones A feeling of pressure in the upper right abdomen makes many people think of the gallbladder. What makes a real biliary colic, what “thick bile” means medically, and which other causes are more common. Bile acidsTests and diagnosticsBody weightFasting Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Acid blockers (PPIs): what they change in the gut and how to stop them properly Proton pump inhibitors are among the most widely used medicines in the world. They are very effective for reflux and ulcers, but change the gut flora and nutrient absorption. What is established, what is not, and how to stop them. Acid blockersMedicationGut infectionsAllergies Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate The digestive chain: how stomach acid, bile and pancreas set each other off Digestion is a relay race: the head starts, the acid passes the signal to the duodenum, hormones call up bile and enzymes. Who sends which signal, and what happens when one link is weak. Bile acidsAcid blockers Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Digestive enzymes from mouth to colon: who breaks down what Saliva, stomach, pancreas, gut wall and bacteria each contribute their own enzymes. A map of where each enzyme works, and what happens when one is missing. FODMAPBloatingCoeliac disease and glutenTests and diagnostics Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Oxalate, salicylate, lectins: hidden culprits or internet myth? Where these plant compounds really cause problems, such as kidney stones, after bowel surgery or with raw beans, and why lists against "oxalate dumping" and lectins tend to harm the gut. Toxins and mouldPlant diversityFibreMedication Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Gastroparesis: when the stomach empties too slowly Nausea, vomiting, feeling full after a few bites: in gastroparesis, food stays in the stomach too long. Why it can hardly be separated from functional dyspepsia, what diabetes, viruses and weight-loss injections have to do with it, and what helps. BloatingMedicationBlood sugarTests and diagnostics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Life without a gallbladder: diarrhoea, fat and symptoms after surgery Gallbladder removal is one of the most common operations, and most people do well afterwards. Why some get diarrhoea, what lies behind post-cholecystectomy syndrome and why cutting the sphincter usually does not help. Bile acidsDiarrhoeaTests and diagnostics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Beginner Diverticula, haemorrhoids and fissures: what can go wrong at the end of the gut Three common problems in the lower gut that people rarely talk about. Why nuts and seeds are fine with diverticula, why mild diverticulitis often heals without antibiotics, and what your phone on the toilet has to do with haemorrhoids. FibreConstipationInflammationAntibiotics Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Beginner Bloating and fullness: gas that will not move on Why the belly distends even though there is rarely too much gas – and what really helps. BloatingIBSFODMAPSweetenersFibreExercise Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Beginner Diarrhoea: understand it, place it and react the right way Watery, urgent, acute or chronic: the four mechanisms, the most common causes and when it needs checking by a doctor. DiarrhoeaIBSFODMAPBile acidsGut infectionsTests and diagnosticsTravel Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Nutrient deficiency in gut problems: when food no longer arrives Why gut symptoms can leave you short of iron, vitamin B12, vitamin D, the fat-soluble vitamins and zinc, how to read blood results correctly and when supplements really help. NutrientsVitamins and fatty acidsDiarrhoeaTests and diagnosticsBody weight Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Expert Bile, lipase and lecithin: what fat digestion really needs Digesting fat takes more than bile: the enzyme lipase from the pancreas, bile as a washing-up liquid and an intact gut wall. What bile salt, TUDCA, ox bile and lecithin capsules actually show, and what choline is really needed for. Bile acidsNutrientsMedicationTests and diagnostics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Beginner When the supplement itself is the problem: iron, magnesium, excipients and more People struggling with their gut often take several supplements at once. Some of them trigger exactly the symptoms they are meant to relieve. Which products typically cause diarrhoea, constipation or bloating, what tablets contain besides the active ingredient, and how to find the culprit. MedicationVitamins and fatty acidsNutrientsProbioticsSweetenersBloatingDiarrhoeaConstipation Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
Small intestine colonisation
When bacteria grow where few belong. 7 chapters – expand
- Level:Intermediate When the small intestine is too densely colonised Bacteria in the wrong place: why fibre can then become a problem. BloatingFODMAPAntibioticsIBSConstipationBile acidsTests and diagnostics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Doing low-FODMAP right The best-studied diet for bloating, and why it is only meant to be temporary. FODMAPBloatingIBS Well supported How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Prebiotics that build up gently Why some fibres cause bloating and others feed the gut microbiota gently. FibreBloatingFODMAPShort-chain fatty acidsIBSPrebiotics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Expert Where the small intestine meets the colon: ileum, valve and caecum At the end of the small intestine, the gut switches from few to very many bacteria. What the last stretch of small intestine does, how the valve separates the two worlds, and how this transition can be disturbed. Bile acidsDiarrhoeaInflammationTests and diagnostics Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Expert Why SIBO comes back: the cleaning wave, underlying causes and prokinetics After successful treatment, small intestinal bacterial overgrowth returns in many people. What the small intestine’s cleaning wave has to do with it, which causes are worth looking for, and what drugs that stimulate gut movement can do. BloatingAntibioticsAcid blockersMedicationConstipation Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Expert SIBO treatments compared: rifaximin, herbs, elemental diet and faecal transplant Antibiotic or herbs, a liquid formula diet or a faecal transplant: what studies show for each option, where the evidence is thin and what people with SIBO report. AntibioticsBloatingProbioticsFaecal transplantTests and diagnostics Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Expert Hydrogen sulfide and methane: the other gases in the gut Methane is linked to constipation, hydrogen sulfide to diarrhoea. Which microbes produce them, what a three-gas breath test can and cannot show, and what to make of low-sulfur diets and bismuth. ConstipationDiarrhoeaBloatingTests and diagnosticsAntibiotics Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
Immune system and inflammation
The gut as the body's largest immune organ. 14 chapters – expand
- Level:Intermediate Immune system and inflammation The gut trains your defences and can also upset them unnecessarily. InflammationMediterranean dietFermented foodsSleepTests and diagnostics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Eating against silent inflammation What is on your plate influences how agitated your immune system is. InflammationMediterranean dietAdditives Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Histamine intolerance: much searched, little proven Headache after red wine, diarrhoea after cheese? What is known about histamine and what is not. HistamineFermented foodsAlcoholTests and diagnosticsDiarrhoea Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Expert DAO: the enzyme that intercepts histamine from food Where DAO is made, why it can be lacking, which medicines inhibit it, and what DAO capsules and sprouts can do. HistamineMedicationAlcoholFermented foods Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Expert IgA: the antibody that keeps the gut clean, and what vitamin A, D and omega-3 have to do with it The body makes more IgA than all other antibodies combined, most of it in the gut. How it is made, why vitamin A matters for it, and what vitamin D and omega-3 really contribute. InflammationVitamins and fatty acidsCoeliac disease and glutenTests and diagnostics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Expert Mast cells: alarm cells in the gut, histamine and the disputed MCAS Mast cells sit just beneath the gut lining and release histamine when alarmed. What they have to do with IBS and stress, and why mast cell activation syndrome is so often wrongly diagnosed. HistamineIBSStressAllergies Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Allergies and intolerances: how the gut learns to tolerate food Every day the gut has to tolerate foreign protein. How this tolerance develops, what role bacteria, stomach acid and skin play, and why many people feel allergic without being so. AllergiesProbioticsAcid blockersAntibioticsTests and diagnostics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate SCD, GAPS and the autoimmune protocol: what strict elimination diets can and cannot do Diets with long lists of forbidden foods promise to heal the gut. What studies show about SCD, GAPS and AIP, and why a short, structured test is different from months of avoidance. InflammationMediterranean dietFODMAPPlant diversity Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Expert Low-dose naltrexone (LDN): hope, studies and limits An addiction medicine at a very low dose is being tried for Crohn's disease, IBS, fibromyalgia and long COVID. What lies behind it, what studies show and why it belongs in medical hands. MedicationIBSInflammationSleep Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Skin and gut: what there is to the gut-skin axis Acne, rosacea, eczema, psoriasis: which links to the gut are proven, where a real disease is behind it, and where the hype begins. InflammationCoeliac disease and glutenProbioticsAllergiesAntibiotics Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Beginner Dogs and cats: what pets do to your gut, immune system and nerves Living with animals means sharing microbes, dust and daily life with them. What that means for gut bacteria, allergies, inflammation and the vagus nerve, which of it is only an association, and where pets bring germs along too. AllergiesInflammationStressExerciseGut infectionsAntibiotic resistance Promising How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate PEA (palmitoylethanolamide): the body's own inflammation brake in a capsule A fatty substance the body makes itself to calm mast cells and inflammation. As a supplement it is taken for gut and nerve pain. What studies show and where they are thin. IBSInflammationHistamineDiarrhoea Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.
- Level:Intermediate Autoimmune diseases and the gut: Hashimoto's, vitiligo, type 1 diabetes and more When the immune system attacks the body itself, the gut is often involved – as the place where the immune system learns, as a bystander that gets hit, and perhaps as a co-trigger. What is established, what has only been shown in mice, and what people affected can actually do. InflammationCoeliac disease and glutenVitamins and fatty acidsMedicationTests and diagnostics Plausible How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open. Community
- Level:Intermediate Crohn’s disease and ulcerative colitis: understanding inflammatory bowel disease In Crohn’s disease and ulcerative colitis, the immune system permanently attacks the gut wall. What distinguishes the two, what role genes, smoking, antibiotics and gut microbiota play, why early treatment matters, and what diet, probiotics and faecal transplants really achieve. InflammationDiarrhoeaTests and diagnosticsMedicationAntibioticsNutrientsProbioticsFaecal transplantMediterranean diet Established How we rate the evidence Established Recommended in medical guidelines or supported by several consistent meta-analyses of randomised human studies. Well supported Several randomised studies in humans with largely consistent results. Promising Single randomised or controlled studies in humans, not yet independently confirmed — or many consistent observational studies. Plausible Two cases: first observational or pilot studies with small samples — or a settled basis that is not in dispute, such as movement, sleep or meal pauses. But not tested in humans for symptoms. Experimental Barely studied in humans. Mainly lab and animal studies or theoretical reasoning; whether it helps is open.