All 885 tips from all chapters, sorted by topic and confidence score. See what is well supported and what is still experimental.
| Topic | Established | Well supported | Promising | Plausible | Experimental |
|---|---|---|---|---|---|
| Gut barrier | 3 | 14 | 5 | ||
| Opportunistic pathogens | 1 | 3 | 9 | 5 | 10 |
| Bacteriophages | 2 | 2 | |||
| Microbial diversity | 2 | 4 | 12 | 13 | 5 |
| Gut-brain axis | 3 | 5 | 7 | 2 | |
| Digestive function | 1 | 8 | 14 | 10 | 9 |
| Small intestine colonisation | 1 | 1 | 2 | 7 | 3 |
| Immune system and inflammation | 1 | 5 | 14 | 7 | |
| Total | 5 | 20 | 50 | 72 | 43 |
Tap a number to see the tips below. Darker cells contain more tips.
Microbial diversity · Clear selection
Trust score 5 of 5:Established Natural supplements
Soluble fibre such as psyllium husk is recommended in the American guideline for IBS and helps with constipation and loose stools. Start with a teaspoon a day and drink enough with it. More in the chapter on slowly fermenting prebiotics.
Big effect, small budget: low-cost measures for your gut 2 sources
Trust score 5 of 5:Established Natural supplements
They can help if your diet provides too little fibre. For IBS, the guideline recommends soluble fibre, but not bran. Increase slowly and drink plenty.
Your gut in ten minutes 1 sources
Trust score 4 of 5:Well supported Natural supplements
Because your own flora fends off foreign species and the benefit is unproven, money spent on fibre and plant variety does more than money spent on anaerobe capsules. The US professional body AGA sees insufficient evidence for most uses of probiotics.
Anaerobic gut bacteria: why the good ones do not fit in a capsule 2 sources
Trust score 4 of 5:Well supported Natural supplements
Soluble fibres such as psyllium are fermented slowly and produce little gas. Guidelines recommend them for IBS. Start with a teaspoon and drink plenty.
Trust score 4 of 5:Well supported Natural supplements
Green tea extracts are not proven to help the gut flora. EFSA could not set a safe amount of EGCG; in studies, liver values rose from about 800 mg a day. With liver disease or medication, avoid them or discuss with a doctor first.
Prebiotics beyond inulin: HMOs, arabinogalactan, polyphenols 1 sources
Trust score 4 of 5:Well supported Natural supplements
A meta-analysis using raw data from four studies found that the strain L. reuteri DSM 17938 clearly shortened crying in breastfed babies with colic. In formula-fed babies no effect could be shown. First have it checked that no other cause is behind the crying.
The first microbiome: birth, breastfeeding, antibiotics and what remains 1 sources
Trust score 3 of 5:Promising Natural supplements
It is authorised in the EU as a novel food, in killed form, with an upper limit and not for pregnant or breastfeeding women. The evidence is a feasibility study with 32 analysed participants over three months. Defensible as an experiment, not as an established treatment. Other countries have different rules, so ask locally.
Anaerobic gut bacteria: why the good ones do not fit in a capsule 2 sources
Trust score 3 of 5:Promising Natural supplements
Enteric-coated peppermint oil capsules eased abdominal pain in IBS in a meta-analysis. They are much cheaper than many specialty products. They can worsen heartburn.
Big effect, small budget: low-cost measures for your gut 1 sources
Trust score 3 of 5:Promising Natural supplements
The effect depends strongly on the strain. The US society AGA only recommends certain strains to protect against C. difficile during antibiotics and sees insufficient evidence for IBS. After antibiotics, probiotics even delayed the return of the body's own gut microbiota in a small study.
Building microbial diversity 2 sources
Trust score 3 of 5:Promising Natural supplements
Psyllium husk or inulin can increase fibre intake. Inulin causes a lot of bloating in some people.
Building microbial diversity 1 sources
Trust score 3 of 5:Promising Natural supplements
Recommendations derived from commercial microbiome analyses are based on unreliable measurements.
Trust score 3 of 5:Promising Natural supplements
There are no proven products that offset the effect of medications on the gut microbiota. Probiotics are only useful in certain situations.
Medications that change the gut 1 sources
Trust score 3 of 5:Promising Natural supplements
During a course of antibiotics, certain probiotics may lower diarrhoea and the risk of C. difficile infection, but the guideline gives only a cautious recommendation for strains tested in studies. For acid blockers, metformin or painkillers no benefit is proven. Details are in the chapter on antibiotics and C. difficile.
Medications that change the gut 1 sources
Trust score 3 of 5:Promising Natural supplements
GOS are also strongly bifidogenic. In a study in IBS they increased bifidobacteria and eased symptoms. They are FODMAPs, so start small.
Prebiotics beyond inulin: HMOs, arabinogalactan, polyphenols 1 sources
Trust score 3 of 5:Promising Natural supplements
If you want to try it, choose a strain tested in studies, such as Bacillus coagulans Unique IS2 or MTCC 5856. Test for four to eight weeks, note your symptoms and stop again if there is no clear improvement.
Spore-forming bacteria: Bacillus and co. as probiotics 1 sources
Trust score 3 of 5:Promising Natural supplements
Spores do not settle permanently. Their effect ends shortly after stopping. Fibre and plant variety feed your own gut flora more lastingly.
Spore-forming bacteria: Bacillus and co. as probiotics 1 sources
Trust score 3 of 5:Promising Natural supplements
Fermented foods vary from batch to batch, capsules are consistent. If you try capsules, choose by strain and intended use, and decide after four to eight weeks whether it does anything. More in the chapters on probiotics and Saccharomyces boulardii.
Using fermented foods well 1 sources
Trust score 3 of 5:Promising Natural supplements
What demonstrably helps everyone in a household is fibre and plant variety: meta-analyses show less bowel cancer, less heart disease and more regular bowel movements. A shared shopping trip changes something for everyone who eats at the table; a capsule for one person does not.
What a household shares: microbes between people, dogs and cats 2 sources
Trust score 2 of 5:Plausible Natural supplements
Some products combine several anaerobes with inulin. The best known study only narrowly reached its main goal in 76 people with type 2 diabetes and came from the manufacturer. If you try it: set a fixed period, note your symptoms and stop without a clear improvement.
Anaerobic gut bacteria: why the good ones do not fit in a capsule 1 sources
Trust score 2 of 5:Plausible Natural supplements
Raw potato starch is one of the cheapest sources of resistant starch. In studies with a branded product made from raw potato starch, bifidobacteria increased, and in people aged 70 and over butyrate rose slightly. In healthy people it had no measurable effect on symptoms such as bloating or constipation. Important: don’t heat it, stir it cold into yoghurt, water or a smoothie. Start with a teaspoon and increase slowly, otherwise it causes bloating.
Big effect, small budget: low-cost measures for your gut 3 sources
Trust score 2 of 5:Plausible Natural supplements
In small studies, inulin and other prebiotics raised GLP-1 and fullness. The propionate-inulin ester from the British study is not a freely available standard product. Prebiotics can cause bloating; dose them carefully with IBS.
GLP-1 from the gut: what bacteria do and what “natural Ozempic” cannot do 1 sources
Trust score 2 of 5:Plausible Natural supplements
It is often marketed as a natural GLP-1 remedy. Weight loss in studies averaged less than one kilogram, and the quality of the studies was mixed. Berberine interacts with medications and can irritate the gastrointestinal tract; not during pregnancy and breastfeeding.
GLP-1 from the gut: what bacteria do and what “natural Ozempic” cannot do 1 sources
Trust score 2 of 5:Plausible Natural supplements
The GLP-1-stimulating protein has been shown in mice. In humans there is one small study with pasteurised Akkermansia showing an effect on insulin sensitivity, but without clear weight loss. It is not a replacement for GLP-1 drugs.
GLP-1 from the gut: what bacteria do and what “natural Ozempic” cannot do 2 sources
Trust score 2 of 5:Plausible Natural supplements
Some products, such as probiotics, change stool and breath tests. Before a test, ask whether you should pause them for a few days, but never stop prescribed medicines on your own.
Gut tests: what they show and what they do not no source of its own, score based on judgement
Trust score 2 of 5:Plausible Natural supplements
Reliably promote bifidobacteria. Studies used 5 to 10 g a day, without worsening even in IBS. A benefit for symptoms has not been shown in controlled trials, and the effect only lasts while you take them. Relatively expensive.
Prebiotics beyond inulin: HMOs, arabinogalactan, polyphenols 3 sources
Trust score 2 of 5:Plausible Natural supplements
In studies it was well tolerated at up to 15 g a day. It shifts the gut flora and lowers by-products of protein fermentation. Studies on symptoms are lacking.
Prebiotics beyond inulin: HMOs, arabinogalactan, polyphenols 2 sources
Trust score 2 of 5:Plausible Natural supplements
Bacillus clausii can shorten diarrhoea by a few hours. Drinking and salts matter more. Professional societies disagree about probiotics for children.
Spore-forming bacteria: Bacillus and co. as probiotics 2 sources
Trust score 2 of 5:Plausible Natural supplements
A usable product names genus, species and strain, the germ count at the end of shelf life and the duration for which it was tested. Without the strain you cannot look up whether it was ever studied. Be wary of miracle claims.
Spore-forming bacteria: Bacillus and co. as probiotics no source of its own, score based on judgement
Trust score 2 of 5:Plausible Natural supplements
In a study of 10 healthy people, 30 g of resistant starch a day for four weeks improved insulin sensitivity. Powders made from potato or banana starch are one option, but foods are just as good and bring more with them. Increase slowly, otherwise bloating is likely.
The second-meal effect: why dinner helps decide your blood sugar in the morning 2 sources
Trust score 2 of 5:Plausible Natural supplements
Probiotics contain a few selected strains, fermented foods a broad mixture. The study results cannot be transferred. Guidelines recommend probiotics only for certain strains and uses, not across the board.
Using fermented foods well 1 sources
Trust score 2 of 5:Plausible Natural supplements
The idea of improving the shared gut flora with one product for everybody has not been studied. Even in individuals, purchased strains often fail to settle at all, and after antibiotics they delayed the return of a person’s own flora in one study. There is no reason to buy a pack for the family.
What a household shares: microbes between people, dogs and cats 1 sources
Trust score 1 of 5:Experimental Natural supplements
It is no substitute for the capsules, for example during antibiotics, because the amount of live yeast is unknown. There are neither studies nor tested instructions. Not suitable with a central venous catheter, a weakened immune system, during pregnancy or for children.
Fermenting at home: milk kefir, water kefir and S. boulardii soda 1 sources
Trust score 1 of 5:Experimental Natural supplements
Probiotics or powders meant to improve the ratio have no proven effect on weight.
Firmicutes, Bacteroidetes and body weight no source of its own, score based on judgement
Trust score 1 of 5:Experimental Natural supplements
Whether a prebiotic preserves the changes in the gut microbiota after fasting is only now being studied. There are no results yet.
Intermittent fasting and meal timing: 16:8, 5:2 and Ramadan 1 sources
Trust score 1 of 5:Experimental Natural supplements
There is no supplement that offsets the effect of sweeteners on the gut microbiota.
Sweeteners and sugar alcohols no source of its own, score based on judgement
Trust score 1 of 5:Experimental Natural supplements
In breastfed babies, B. infantis given as a supplement settled and dampened inflammatory messengers. Whether this prevents allergies later has not been shown. Healthy babies don’t need probiotics; if you are considering it, discuss it with your paediatrician.
The first microbiome: birth, breastfeeding, antibiotics and what remains 1 sources