How to improve gut health: what the evidence says
The three things with real evidence behind them cost nothing: eat enough fiber, add it slowly with plenty of liquid, and eat fermented foods. [2][5] Most of what is sold as "gut health" has less behind it than that, including, for healthy people, probiotic supplements. [6]
What does "gut health" actually mean?
In plain terms: your digestive system doing its job without bothering you. The bacteria in your gut, which the NIH calls gut flora or the microbiome, help with digestion; bacteria in the small intestine make some of the enzymes needed to digest carbohydrates, and bacteria in the large intestine break down remaining nutrients and make vitamin K. [1] That is the settled part. Claims that a particular food or pill will "balance" or "reset" those bacteria go well past what the research shows, which is why this article sticks to the few things that have been tested.
How much fiber do you need, and how far short are most women?
Adults should get 22 to 34 grams of fiber a day depending on age and sex, according to the National Institute of Diabetes and Digestive and Kidney Diseases. [2] The 2020-2025 Dietary Guidelines set the target for women aged 31 to 50 at 25 grams and for women 51 and over at 22 grams, and reported that more than 90% of women do not meet it, which is why fiber is listed as a dietary component of public health concern. [3] The newer 2025-2030 edition does not publish a gram table and instead tells Americans to prioritize fiber-rich whole grains. [3]
Two details matter more than the number. Add fiber a little at a time so your body gets used to the change, and drink plenty of water and other liquids to help the fiber work. [2] People who ramp up fast often get more gas, not less: the NIH notes that some people have more gas symptoms when they consume too much fiber. [4] If you want a plan with the right amount for you, that is what a dietitian is for. [2]
Do fermented foods improve gut health?
This is the one popular gut-health idea with a randomized trial behind it. Stanford researchers ran a 17-week study in healthy adults, 18 per arm, comparing a high-fiber diet with a high-fermented-food diet. [5] The fermented-food group's microbiome diversity steadily increased and their inflammatory markers decreased; the high-fiber group's community diversity stayed stable, though their microbes gained more carbohydrate-digesting capacity. [5] It is a small study and it measured lab markers rather than how people felt, so treat it as a promising signal, not proof. The authors' own conclusion was that fermented foods "may be valuable," which is about the right strength. [5]
Do probiotics improve gut health?
Not in the general way the labels suggest. The American Gastroenterological Association's 2020 clinical guideline recommends probiotics for irritable bowel syndrome, Crohn's disease, ulcerative colitis and treating C. difficile only within a clinical trial; it suggests specific strains in a few situations, such as adults and children taking antibiotics to prevent C. difficile infection, and it suggests against probiotics for children with acute gastroenteritis. [6] The NIH's complementary-health center describes the evidence for antibiotic-associated diarrhea as promising: a 2017 review of 17 studies found about half the likelihood of diarrhea in people given probiotics with antibiotics, but called the conclusion tentative because study quality was only moderate. [7] For a healthy woman with no diagnosis and no antibiotics, there is no guideline recommending a probiotic. [6] A fuller account is in our article on gut health supplements.
Does menopause change the gut microbiome?
You will read that it does. The research says: not consistently, not yet. A 2026 systematic review and meta-analysis pooled seven studies covering 1,222 post-menopausal women, 45 women with premature ovarian insufficiency and 463 pre-menopausal controls, and found no significant differences in microbiome diversity or in the abundance of the two major bacterial groups, with very high variability between studies. [8] The authors said the findings should be interpreted with caution and called for better-controlled studies. [8] If digestion changes for you in these years, that is real; the explanation is simply not established.
What helps constipation?
Constipation is common: about 16 in 100 US adults have symptoms, rising to about 33 in 100 at age 60 and over, and it is more likely in women and in older adults. [9] The NIH's advice is the unglamorous kind: enough fiber, plenty of liquids, regular physical activity, and bowel training. [2][10] A health care professional may suggest a laxative for a short time and will say which type; if you have used laxatives so long that you cannot go without them, that is a conversation to have rather than something to push through alone. [10]
What to track for a week
Your fiber for one ordinary day, roughly; most women are surprised how far under 22 grams it lands. [3] Your liquids. [2] And, if bloating is your complaint, what you ate and drank before it: the NIH says a food-and-symptom diary is what helps a doctor or dietitian work out whether specific foods are the cause. [4]
What about reflux?
If reflux shows up at night or when you lie down, the NIH says eating meals at least 3 hours before lying down or going to bed may improve symptoms. [11] Foods and drinks commonly linked to symptoms are acidic foods such as citrus and tomatoes, alcohol, chocolate, coffee and other caffeine, high-fat foods, mint and spicy foods; the advice is to talk with your doctor about which seem to affect you rather than cut everything. [11]
When to talk to your clinician
Gas and bloating are normal; the NIH's threshold for an appointment is when symptoms bother you, when they change suddenly, or when they come with abdominal pain, constipation, diarrhea or weight loss. [12] Long-lasting constipation can need treatment, and any bleeding, unexplained weight loss or new symptoms after 50 belong in an appointment, not an article. [9]
Sources
- NIDDK, Your digestive system and how it works. Last reviewed December 2017. Retrieved 2026-10-18.
- NIDDK, Eating, diet and nutrition for constipation. Retrieved 2026-10-18.
- Dietary Guidelines for Americans 2020-2025, p. 124 and Appendix 1. Retrieved 2026-10-15. The 2025-2030 edition (PDF) publishes no fiber table; retrieved 2026-10-15.
- NIDDK, Eating, diet and nutrition for gas in the digestive tract. Last reviewed June 2021. Retrieved 2026-10-18.
- Wastyk HC et al. Gut-microbiota-targeted diets modulate human immune status. Cell, 2021;184(16):4137-4153. Abstract retrieved 2026-10-18.
- Su GL et al. AGA Clinical Practice Guidelines on the Role of Probiotics in the Management of Gastrointestinal Disorders. Gastroenterology, 2020;159(2):697-705. Recommendations verified 2026-10-15 against the published text.
- National Center for Complementary and Integrative Health, Probiotics: what you need to know. Last updated August 2019. Retrieved 2026-10-18.
- Saravinovska K et al. The impact of estrogen status on the gut microbiome: a systematic review and meta-analysis. Frontiers in Endocrinology, 2026;17:1780806. Abstract retrieved 2026-10-18.
- NIDDK, Definition and facts for constipation. Last reviewed May 2018. Retrieved 2026-10-18.
- NIDDK, Treatment for constipation. Retrieved 2026-10-18.
- NIDDK, Eating, diet and nutrition for GER and GERD. Last reviewed July 2020. Retrieved 2026-10-18.
- NIDDK, Symptoms and causes of gas in the digestive tract. Last reviewed June 2021. Retrieved 2026-10-18.
Every statement above was checked against the linked source on the date shown. This article is education, not individual medical advice. Related: What causes bloating · How to reduce bloating quickly · Gut health supplements: the evidence.