Gut microbiomes linked to fertility as dietary tweaks urged for couples conceiving after 30

A growing body of research suggests that differences in gut microbiomes between women and men may influence fertility, and that couples conceiving after 30 could benefit from attention to diet and nutrients. Dr Emily Leeming notes that puberty and hormones shape gut bacteria, and that these microbes may subtly influence hormone production and reproductive health. A 2022 study in Human Reproduction Update found that men's sperm counts have halved over the past 45 years, a development that complicates family planning as people start families later.

Experts say the period before trying to conceive is a key window for building a fertility friendly body. For men, sperm take about two to three months to mature, so healthy habits during that window can matter. For women, eggs complete their final development in the three months before ovulation, so prenatal planning matters too. Dr Leeming and other clinicians advise many couples to start taking prenatal supplements with folic acid and to look for products that also include selenium, vitamin C and vitamin E to support egg health and protect against oxidative stress. They also highlight the role of omega 3 fatty acids, ideally from fish or supplements, as part of a balanced diet.

Dietary patterns play a crucial role once people start trying to conceive. The overall pattern matters more than any single food: a balance of fruits and vegetables, whole grains and healthy fats provides nutrients that support fertility. The NHS suggests at least one weekly portion of oily fish for those trying to conceive, but it also cautions against excessive intake during pregnancy because of pollutant concerns; other adults are typically advised that four portions per week is safe. If you are not routinely eating oily fish, a carefully chosen omega 3 supplement may help bridge the gap. For women in their late 30s or early 40s, fertility specialists sometimes recommend Coenzyme Q10, a powerful antioxidant, as egg quality tends to decline with age; some studies have shown higher pregnancy rates among women undergoing fertility treatment who took CoQ10.

For men, a balanced diet rich in zinc (found in shellfish, meat, nuts and whole grains), selenium (Brazil nuts) and omega 3s supports sperm count and quality. The science is complex, and the goal is not to promise a pregnancy, but to support overall health—habits that may also bolster fertility.

Evidence about probiotics and the microbiome is evolving. In the vaginal ecosystem, healthy bacteria such as Lactobacillus help create a mildly acidic environment that protects against infection. When this balance is disrupted, infections such as bacterial vaginosis can occur and may be linked to higher risks during pregnancy; a 2023 review found BV in pregnancy is associated with an increased risk of preterm birth, affecting about one in five infected women.

Early studies suggest certain probiotics or prebiotics may help support the vaginal microbiome and, in some cases, improve pregnancy outcomes, but findings are not uniform. A 2024 review in Reproductive Biomedicine Online concluded that some probiotic strategies may help restore healthy bacteria and reduce miscarriage risk or improve IVF success in women with an imbalanced vaginal or womb microbiome, though the evidence is not definitive. If you are considering a probiotic, talk to your GP, gynaecologist or fertility specialist first and choose a product that has been tested in clinical studies for women's health rather than an over the counter supplement marketed for general digestion or wellness.

Diet should be viewed as an overall pattern rather than a single item. A diet rich in fruit and vegetables, wholegrains and healthy fats—such as those from oily fish, nuts and seeds—helps provide a broad range of nutrients that support fertility. Omega 3 intake, in particular, has been linked in some reviews with higher pregnancy odds; the 2024 Heliyon review found women with higher omega 3 intake were more likely to become pregnant. If you are not meeting these guidelines, an omega 3 supplement can be considered after discussing it with a health professional.

For couples conceiving after 30, a practical approach is to focus on small, sustainable changes. Eggs remain a central piece of female fertility, and the time before trying to conceive—about three months for women and roughly two to three months for men—offers a window to carry out these adjustments. The goal is to optimize body reserves and gut health, which may in turn influence reproductive health.

Tip of the week: desserts can be made to support fibre and protein intake. A tablespoon of honey stirred into plain yogurt helps feed beneficial gut bacteria, and desserts can be reimagined to boost fibre and protein. Chia puddings, made with milk and a touch of honey, offer fibre and omega 3s; chocolate dipped fruit, peanut butter stuffed dates, and baked fruit with yogurt or ricotta provide a satisfying way to end a meal without sacrificing nutrition.