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7 Things You Can Do to Improve Gut Health, With the Trial Evidence
In this article
Seven things improve gut health with a study behind each: eat a wide variety of plants, reach 30 g of fibre a day, include live fermented foods, move most days, sleep and manage stress, keep alcohol within the NHS limit, and take antibiotics only when prescribed. None is quick and none is a product; the evidence is strongest for fibre and plant variety and thinnest for sleep, where no trial has measured the gut as the outcome. One spoke of the Wellgard probiotics guide: the seven, each with its trial, and the questions people ask around them.
Evidence at a glance
- Trials: 5 pooled analyses and 6 single studies, among them 16 fibre trials in 1,251 adults and a citizen-science cohort of more than 10,000 people.1, 2
- Longest single trial: 36 healthy adults for 17 weeks, the only randomised fermented-food diet trial.3
- Strongest measured outcome: fibre supplements above 10 g a day, 66% of constipated adults responding against 41% on control.2
- Not tested: sleep, stress or cutting alcohol with the gut microbiome as the outcome; "30 plants a week" as a threshold.
Sources checked on 16 October 2026.
What are 7 things you can do to improve gut health?
The seven below are the habits that have been measured, in order of how much evidence sits behind them. "Improve" means what a study measured, usually bowel habit, microbial diversity or an inflammatory marker, not a feeling. And the gut changes back when the habit stops: six weeks after the exercise study's participants returned to sitting still, their gut bacteria had largely returned to where they started.4
| Habit | What the study found | Study |
|---|---|---|
| 1. Eat a wide variety of plants | The variety of plants people ate tracked their gut-microbe profile better than labels such as vegan, which had "little or no explanatory power"1 | More than 10,000 citizen-science samples, mainly US, UK and Australia |
| 2. Reach 30 g of fibre a day | Guidance is 30 g a day and most adults eat about 20 g; in fibre-supplement trials, 66% of constipated adults responded against 41% on control, only above 10 g a day and after four weeks or more, with more wind2, 5 | 16 randomised trials, 1,251 adults |
| 3. Include live fermented foods | A diet high in fermented foods "steadily increased microbiota diversity and decreased inflammatory markers"; a high-fibre diet in the same study did not change diversity3 | 36 healthy adults, 17 weeks, randomised |
| 4. Move most days | Six weeks of endurance exercise, three days a week, changed gut-microbe composition and raised short-chain fatty acids in lean but not obese participants; the changes largely reversed on stopping4 | 32 previously sedentary adults |
| 5. Sleep, and manage stress | No trial has tested sleep or stress with the gut as the outcome; the NHS lists stress, anxiety or depression among the common causes of constipation6 | NHS guidance only |
| 6. Keep alcohol within the NHS limit | The NHS limit is 14 units a week, spread over three or more days; no trial has tested cutting alcohol with the gut as the outcome, and in one 4-week trial alcoholic and alcohol-free beer both raised diversity7, 8 | 22 healthy men, 4 weeks |
| 7. Antibiotics only when prescribed | If you need a course, live cultures started within two days of the first dose cut C. difficile infection in hospital patients, risk ratio 0.32 against 0.70 when started later, and cut antibiotic diarrhoea in adults by 37%9, 10 | 19 studies, 6,261 inpatients; 42 trials, 11,305 adults |
Two notes. The "30 plants a week" target that circulates comes from the American Gut project's reporting categories; its abstract gives no number, so the finding is the variety itself, not a threshold.1 And the fermented-food result is one study of 36 people, the only randomised diet trial of its kind, which is why it is one line rather than a rule. A fermented food only carries live cultures if nothing killed them afterwards: live yoghurt, kefir, raw sauerkraut and kimchi do; sourdough, most jarred sauerkraut and pasteurised kombucha do not.11 Foods high in Lactobacillus has the list.
On antibiotics, one more finding belongs beside the table. In a 2018 study that sampled the gut lining directly, an 11-strain culture taken after a week of antibiotics delayed the return of the person's own bacteria compared with taking nothing.12 The diarrhoea trials dosed during the course; the lining study dosed afterwards. Live cultures with antibiotics reconciles the two.
What are the signs of a healthy gut?
A bowel habit that is regular for you and comfortable, and none of the symptoms the NHS says to see a GP about. The NHS defines constipation as not having a poo at least three times in the last week or less often than usual, poo that is dry, hard or lumpy, straining or pain, or feeling you have not fully emptied; a healthy gut is the absence of those most of the time.6 Occasional bloating tied to a meal is normal; the NHS says see a GP "if you feel very bloated, you're often bloated or it does not go away".13 Energy, skin and mood are not signs of gut health in any trial; the signs people read as an unhealthy gut takes each in turn. Blood in your poo, losing weight without trying or a lasting change in bowel habit are GP appointments, not habits to adjust.
How can a woman improve her gut health?
With the same seven habits, plus three things worth knowing. The NHS notes that some people feel bloated around the time of their period, and that constipation is common in pregnancy and after giving birth.6, 13 No trial has tested whether live cultures change when a period comes or how heavy it is; the small trials in women with PMS or painful periods are on do probiotics help with periods. Tiredness that does not lift is a GP question first, because the NHS lists iron-deficiency anaemia among its causes.14 Vaginal flora, thrush, BV and UTIs are a different community of bacteria, answered on what probiotics do for women.
Do you need a supplement to improve gut health?
The seven habits are food and behaviour, and supplements enter where the trials used them. Fibre supplements are the best-replicated: psyllium above 10 g a day for at least four weeks, with wind as the trade-off, and the GB register's authorised wording for chicory inulin, that it "contributes to normal bowel function by increasing stool frequency", applies at 12 g a day, the dose that moved 44 constipated adults from three to four stools a week in a supplier-funded four-week trial.2, 15, 16 A fibre supplement counts towards the 30 g by its grams; how much fibre you need a day does the arithmetic and what psyllium husk does covers the fluid rule. Live cultures have their own record by use: in 14 trials of 1,182 adults with constipation they added 1.3 bowel movements a week, and alongside antibiotics they cut diarrhoea by 37% in 42 trials.10, 17 In one of those situations, a product whose label matches what the trials used is a reasonable part of the plan, alongside the seven habits rather than instead of them.
What we don't know
- No randomised trial has tested the "30 plants a week" threshold; the plant-diversity finding is observational.1
- The fermented-food diet result rests on one study of 36 adults and has not been replicated.3
- No trial has measured the gut microbiome after improving sleep, lowering stress or cutting alcohol.
Frequently asked questions
What kills good bacteria in the gut?
Antibiotics are the best-documented cause in people, which is why the seventh habit is to use them only when prescribed and to start any live culture with the course.9, 12 No trial has shown that coffee, sugar, citrus or alcohol kills gut bacteria.8
How do I heal my gut naturally?
A healthy gut has nothing to heal. The seven habits are the natural version. Symptoms that persist, blood in your poo or unexplained weight loss are for a GP, not a reset.6
Is coffee good for gut health?
No trial in our sources has measured gut bacteria after coffee, so there is no figure either way. The NHS bloating page advises against lots of caffeine in coffee and tea while you are bloated; that is the only guidance on record.13
What are the 3 worst foods for gut health?
No trial has ranked foods by harm to the gut, so any list of three is opinion. The evidence runs the other way: variety and fibre help.1, 5 For bloating, the NHS names fizzy drinks, alcohol, caffeine and lots of gas-producing foods such as cabbage, beans and lentils as things to cut down on while it settles, not foods to avoid.13
What is the best breakfast for gut health?
One that gets fibre and a live fermented food into the first meal. The NHS example, two slices of wholemeal toast with peanut butter and an orange, gives around 8.3 g of fibre; porridge oats with live yoghurt or kefir add soluble fibre and live cultures.5 In trials of foods for constipation, kiwifruit and rye bread each raised stool frequency.18
Sources
- McDonald D, et al. Observational, citizen-science cohort, more than 10,000 samples. 2018. PubMed 29795809.
- van der Schoot A, et al. Pooled analysis, 16 randomised trials of fibre, 1,251 adults with constipation. 2022. PubMed 35816465.
- Wastyk HC, et al. Randomised diet study, 36 healthy adults, 17 weeks; university-funded. 2021. PubMed 34256014.
- Allen JM, et al. Exercise intervention study, 32 previously sedentary adults, 6 weeks plus 6 weeks washout; funding not checked. 2018. PubMed 29166320.
- NHS. How to get more fibre into your diet. Page last reviewed 2 March 2026. nhs.uk.
- NHS. Constipation. Page last reviewed 26 October 2023. nhs.uk.
- NHS. Alcohol units. Page last reviewed 27 August 2024. nhs.uk.
- Marques C, et al. Randomised trial, 22 healthy men, 4 weeks; publicly funded. 2022. PubMed 35834180.
- Shen NT, et al. Pooled analysis with meta-regression, 19 studies, 6,261 hospital inpatients. 2017. PubMed 28192108.
- Goodman C, et al. Pooled analysis, 42 randomised trials, 11,305 adults. 2021. PubMed 34385227.
- Marco ML, et al. Expert consensus statement on fermented foods. 2021. PubMed 33398112.
- Suez J, et al. Invasive sampling study, healthy volunteers after a week of antibiotics. 2018. PubMed 30193113.
- NHS. Bloating. Page last reviewed 21 January 2026. nhs.uk.
- NHS. Tiredness and fatigue. Page last reviewed 2 June 2023 (review overdue). nhs.uk.
- Micka A, et al. Randomised crossover trial, 44 adults with constipation, 4 weeks; supplier-funded. 2017. PubMed 27492975.
- Great Britain nutrition and health claims register. gov.uk.
- Dimidi E, et al. Pooled analysis, 14 randomised trials, 1,182 adults with constipation. 2014. PubMed 25099542.
- Van Der Schoot A, et al. Pooled analysis, 23 studies of foods and drinks, 1,714 adults with constipation. 2024. PubMed 37905980.
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