Trust score 5 of 5:Established Natural supplements
Soluble fibre
Psyllium husk makes the stool firmer and is recommended for IBS. Start slowly, otherwise bloating increases.
Evidence map
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.
28 tips
Opportunistic pathogens · Clear selection
Opportunistic pathogens
28 tips – expand
Trust score 4 of 5:Well supported Natural supplements
Saccharomyces boulardii
This yeast reduces the risk of antibiotic-associated diarrhoea. Against C. difficile, a meta-analysis found a statistically clear effect only in children, not in adults. The US specialist society nevertheless suggests it for adults at high risk of C. difficile while on antibiotics, as a weak recommendation, because the trend points the same way. Not with a central venous catheter, serious illness or severe immune weakness: the yeast can then, rarely, enter the blood and cause a serious infection.
After antibiotics: C. difficile and faecal transplants 2 sources
Trust score 4 of 5:Well supported Natural supplements
Saccharomyces boulardii during antibiotics
In meta-analyses, this probiotic yeast roughly halves the risk of diarrhoea during antibiotic treatment. Against C. difficile, a meta-analysis found clear protection only in children; the US specialist society nevertheless suggests it for adults at high risk too, as a weak recommendation. Not with a central venous catheter, serious illness or severe immune weakness: in those cases the yeast can rarely enter the blood.
Opportunistic pathogens 3 sources
Trust score 4 of 5:Well supported Natural supplements
During antibiotic treatment
Start on the first day of the antibiotic and continue until about a week after the end. Studies mostly used 250 to 500 mg once or twice a day. As antibiotics do not attack the yeast, no time gap is needed. Not with a central venous catheter, serious illness or severe immune weakness: the yeast can then, rarely, enter the blood and cause a serious infection.
Trust score 3 of 5:Promising Natural supplements
Yeast probiotics not in severe illness
Yeast probiotics such as Saccharomyces boulardii are well studied in healthy adults. In severely ill people, people with a venous catheter or very weak defences, however, yeast infections of the blood have been described. In those cases, clarify with a doctor first.
Trust score 3 of 5:Promising Natural supplements
Be careful with "detox" binders
Clay, zeolite or activated charcoal are often recommended against "die-off". There is no evidence, products can be contaminated, and activated charcoal can stop medicines from working.
Herxheimer reaction, die-off and toxins 2 sources
Trust score 3 of 5:Promising Natural supplements
Saccharomyces boulardii as an add-on
Small studies tested the probiotic yeast on top of standard treatment: with Giardia, fewer people still had cysts in their stool afterwards, and with amoebic dysentery the diarrhoea stopped sooner. In children with Blastocystis and symptoms, the yeast alone worked about as well as metronidazole. Each finding comes from a single small study, and the yeast does not replace targeted treatment. Do not take it at the same time as antifungal medicines, or if you are seriously ill, severely immunocompromised or have a central venous catheter, because the yeast can then, rarely, enter the blood; more in the chapter on Saccharomyces boulardii.
Parasites in the gut: worms, protozoa and Blastocystis 3 sources
Trust score 3 of 5:Promising Natural supplements
Check nutrients instead of a cleanse
Anyone who has had worms or spent a long time in warm countries can have iron or B12 deficiency. A blood test shows this; measure first, then make up the shortfall in a targeted way.
Parasites in the gut: worms, protozoa and Blastocystis 1 sources
Trust score 3 of 5:Promising Natural supplements
During Helicobacter treatment
Taken in addition, it reduces diarrhoea as a side effect and can help you complete the treatment. Here too, not with a central venous catheter, serious illness or severe immune weakness.
Trust score 3 of 5:Promising Natural supplements
Not together with antifungals
Antifungal medicines make the yeast ineffective. During such treatment, choose a bacterial probiotic with studies or do without.
Saccharomyces boulardii: the probiotic yeast no source of its own, score based on judgement
Trust score 3 of 5:Promising Natural supplements
Pay attention to the strain
Most studies used strain CNCM I-745. A product that only says “Saccharomyces boulardii” is not automatically the same. A product with a named strain and germ count is easier to judge.
Trust score 3 of 5:Promising Natural supplements
Glutamine
The only randomised trial so far studied exactly this group: IBS with diarrhoea after an infection. The result was clear but has not yet been confirmed.
Trust score 3 of 5:Promising Natural supplements
Peppermint oil
Enteric-coated capsules with peppermint oil relax the gut muscles and improved IBS symptoms in a meta-analysis. A possible side effect is heartburn.
Trust score 2 of 5:Plausible Natural supplements
Not probiotics by default
In a small study, probiotics after antibiotics delayed the return of the body's own gut microbiota. More probiotics are therefore not always better.
After antibiotics: C. difficile and faecal transplants 1 sources
Trust score 2 of 5:Plausible Natural supplements
Probiotics during immunotherapy only after discussion
In the same study, over-the-counter probiotics tended to go along with a poorer response, and in mice they weakened the effect. That is not proof, but a reason not to take probiotics on your own during immunotherapy.
Trust score 2 of 5:Plausible Natural supplements
Probiotics against diarrhoea during chemo and radiation: uncertain
A Cochrane review of 12 studies found signs that probiotics might reduce diarrhoea during radiation and chemotherapy, but the evidence was weak. With a weakened immune system, live germs can themselves cause infections. So only after consulting your care team.
Trust score 2 of 5:Plausible Natural supplements
Synbiotic: a first positive trial
In a double-blind trial of 463 people in Hong Kong, a mix of bacteria and fibre (SIM01) taken for six months improved fatigue, memory and concentration problems, gut symptoms and general unwellness more often than placebo. The product was developed by the research group itself, independent confirmation is lacking, and the results cannot be transferred to other products.
Long COVID and the gut: when your stomach won't settle after COVID 1 sources
Trust score 2 of 5:Plausible Natural supplements
Iron only with a proven deficiency
Many gut germs need iron to grow, and part of the iron taken stays unused in the gut. There are indications that high iron doses can favour unfavourable bacteria. So take iron not on suspicion but based on blood tests and after talking to a doctor.
Opportunistic pathogens no source of its own, score based on judgement
Trust score 1 of 5:Experimental Natural supplements
Prebiotics after antibiotics
Fibre powders and prebiotics might help recovery. For the time after antibiotics there are hardly any studies, though, and with acute diarrhoea they can make symptoms worse. Try slowly, at the earliest once symptoms have eased.
After antibiotics: C. difficile and faecal transplants no source of its own, score based on judgement
Trust score 1 of 5:Experimental Natural supplements
N-acetylcysteine (NAC)
NAC has not been studied against biofilms in the gut. As an add-on to Helicobacter treatment the benefit is uncertain. Gut symptoms are possible.
Trust score 1 of 5:Experimental Natural supplements
Serrapeptase and nattokinase: not recommended
No proven benefit in the gut, but a bleeding risk, especially together with aspirin, anticoagulants or before surgery.
Trust score 1 of 5:Experimental Natural supplements
EDTA: not recommended
EDTA binds minerals such as calcium. Safety data for longer use as a gut remedy are lacking.
Trust score 1 of 5:Experimental Natural supplements
Biofilm blends with herbal protocols
The only analysis covers 13 medical records and found no difference in clearance rates. A herbal protocol against SIBO does not need this add-on.
Trust score 1 of 5:Experimental Natural supplements
Herbal antifungals
Caprylic acid, oregano oil and similar products are marketed against gut fungi. In a test tube some inhibit yeasts, which says little about the gut: the substances are largely absorbed or broken down before they get there. Human studies are lacking.
Fungi in the gut: what is true about Candida no source of its own, score based on judgement
Trust score 1 of 5:Experimental Natural supplements
Chlorella, coriander and “heavy-metal chelation”
Algae and herbs said to “draw out” heavy metals rest on a few, mostly animal or very small studies. For people without a proven poisoning, this is not supported. Anyone who suspects heavy-metal exposure should have it measured by a doctor.
Herxheimer reaction, die-off and toxins 1 sources
Trust score 1 of 5:Experimental Natural supplements
Oil pulling, tongue scrapers and oral probiotics
There is no good evidence that oil pulling protects the gums or the gut. A tongue scraper can reduce bad breath; nothing more has been shown. Probiotic lozenges for the mouth have hardly been studied. None of these replaces brushing your teeth and seeing a dentist.
Mouth and gut: how teeth, gums and mouthwash touch the gut flora no source of its own, score based on judgement
Trust score 1 of 5:Experimental Natural supplements
Herbal antimicrobials
Oregano oil, berberine and similar products are often used against “dysbiosis”. There are hardly any human studies on specific pathobionts. They do not act selectively and also hit the beneficial bacteria.
Opportunistic pathogens no source of its own, score based on judgement
Trust score 1 of 5:Experimental Natural supplements
Herbal “parasite cleanses”
Wormwood, black walnut or cloves are often offered. Good human studies are lacking, and they do not replace targeted treatment. Wormwood contains thujone, which in larger amounts can damage nerves.
Parasites in the gut: worms, protozoa and Blastocystis no source of its own, score based on judgement