Gut bacteria
How to improve your gut microbiome
The most reliable way to improve your gut microbiome is to eat a wide variety of plant foods and some fermented food every day, and to keep doing it. Gut bacteria respond to diet within days, but the change lasts only as long as the habit does. Sleep, physical activity and careful use of antibiotics and acid-blockers matter too. Supplements and short “gut reset” programmes add little to these.
In short
- Variety matters more than any single food. A useful target is 30 different plant foods a week.
- Increase fibre in steps over two to four weeks, to avoid gas.
- In a ten-week trial, a diet high in fermented foods increased the diversity of gut bacteria.
- The benefit lasts as long as the habit does.
What improves gut bacteria?
- 30 different plant foods a week is a useful target
- 2 to 4 weeks to increase fibre, in steps, to avoid gas
- 10 weeks on a diet high in fermented foods increased the diversity of gut bacteria in a trial
Eat more kinds of plants
In a large citizen-science study, people who ate more than 30 different plant foods a week had more varied gut bacteria than those who ate 10 or fewer. Vegetables, fruit, dals and pulses, whole grains and millets, nuts, seeds, herbs and spices all count.
Raise fibre in steps
Fibre is what gut bacteria live on. Large studies link an intake of 25 to 29 grams a day with lower rates of heart disease, diabetes and bowel cancer, and most adults eat less. Add one extra serving every few days. See what fibre is.
Include fermented foods
Curd, buttermilk, kanji and overnight-fermented rice contain live microbes. See fermented foods.
Include prebiotic foods
Onion, garlic, banana, oats, barley and pulses contain fibres that beneficial bacteria favour. See prebiotics.
Eat less ultra-processed food and sugar
Packaged snacks, sweets and sweetened drinks displace the plant foods that gut bacteria need. See sugar and gut health.
Sleep regular hours
Gut bacteria follow a daily rhythm. See how sleep affects the gut.
Move every day
Regular activity keeps the bowel moving. In a randomised trial, it improved gut symptoms in people with irritable bowel syndrome.
Use antibiotics and acid-blockers only when needed
Both change gut bacteria. Take them when they are prescribed, and ask at review whether a long-term acid-blocker is still required. Do not stop a prescribed medicine on your own.
How long does it take to improve gut bacteria?
Gut bacteria begin to shift within days of a change in diet. In the study that showed this, they also returned to their earlier state within days of going back to the old diet.
In practice, most people who feel a difference in bloating and bowel habit notice it over a few weeks. Lasting change depends on habits that are kept for months.
What adds little?
Short “gut reset” programmes
Three or seven days is too short. Whatever changes, changes back when the old diet returns.
Laxative teas and flush drinks
These empty the bowel. They do not feed gut bacteria or add to them.
A probiotic without a reason
A probiotic adds a few strains for a while. The evidence supports specific uses, not general improvement. See what probiotics are.
Cutting out many foods
Long exclusion diets remove the variety that gut bacteria need. Even the low FODMAP diet is meant for a limited period.
Supplements chosen from a test report alone
What does a good day of eating look like?
| Meal | Example |
|---|---|
| Breakfast | Idli or dosa with sambar and chutney, or ragi or oats porridge with nuts and a banana |
| Lunch | Rice or millet, dal, two vegetables, curd and a small salad |
| Evening | A fruit, a handful of peanuts or roasted chana, and buttermilk |
| Dinner | Roti, a vegetable dish, and dal, rajma, chana, egg or fish |
A day like this includes 15 or more different plant foods. See an Indian diet for the gut microbiome.
When should I see a doctor?
See a doctor if bloating, pain or a changed bowel habit lasts more than three to four weeks, or if more fibre makes you clearly worse. Bacterial overgrowth, IBS and food intolerances need a diagnosis and a different plan. Blood in the stool, weight loss or fever need attention promptly.
Questions patients ask me
How can I improve my gut microbiome naturally?
Through food and daily habits: many kinds of plant foods, fermented foods, regular sleep and movement. For most people these do more than any supplement.
How long does it take to improve gut health?
Gut bacteria shift within days of a change in diet. Symptoms such as bloating usually take a few weeks to improve, and the change lasts only if the habits do.
How will I know my gut bacteria are improving?
There is no home test. In practice, people report more regular, well-formed stools, less bloating, and better tolerance of fibre-rich foods.
Do I need a gut cleanse or a detox?
No. The liver, kidneys and gut clear waste continuously, and no juice, tea or kit has been shown to improve on this. Gut bacteria are improved by feeding them.
Should I take a probiotic every day?
For general health, no. Fermented foods and fibre do more. A probiotic is useful for specific purposes and a limited time.
Sources
This page is written for patients and is based on the guidelines and studies below. It is for education and does not replace a consultation.
- American Gut citizen-science study of diet and the microbiome. McDonald D et al. mSystems. 2018. PubMed 29795809
- Systematic reviews of carbohydrate quality and human health. Reynolds A et al. Lancet. 2019. PubMed 30638909
- Trial of high-fibre and fermented-food diets and immune status. Wastyk HC et al. Cell. 2021. PubMed 34256014
- International consensus statement on the definition of prebiotics. Gibson GR et al. Nat Rev Gastroenterol Hepatol. 2017. PubMed 28611480
- Study of how quickly diet changes the gut microbiome. David LA et al. Nature. 2014. PubMed 24336217
- Study of gut bacteria recovery in healthy adults after antibiotics. Palleja A et al. Nat Microbiol. 2018. PubMed 30349083
- Study of acid-blocking medicines and the gut microbiome. Imhann F et al. Gut. 2016. PubMed 26657899
- Trial of physical activity for irritable bowel syndrome. Johannesson E et al. Am J Gastroenterol. 2011. PubMed 21206488
- Study of gut microbiome diversity and sleep physiology. Smith RP et al. PLoS One. 2019. PubMed 31589627