Fertility Diet: What to Eat When Trying to Conceive

Does diet actually affect fertility?

The evidence connecting diet to fertility is real but not simple. No randomized trial has proven that switching to a specific diet causes pregnancy — that would require controlling every variable in human reproduction. What observational and mechanistic research does show is that dietary patterns influence hormone balance, ovulation regularity, sperm quality, and the inflammatory environment in which conception and early implantation occur.

Anti-inflammatory dietary patterns, including Mediterranean-style eating, are associated with reduced markers of systemic inflammation 1Ref 1Koelman L, Egea Rodrigues C, Aleksandrova K (2022).Effects of Dietary Patterns on Biomarkers of Inflammation and Immune Responses: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.Anti-inflammatory effects of Mediterranean-style dietary patterns as a biological basis for diet-fertility connections. Chronic low-grade inflammation can affect ovarian function and endometrial receptivity, which may be one mechanism through which diet matters.

What eating pattern has the most evidence?

The Mediterranean-style pattern — emphasis on vegetables, fruits, whole grains, legumes, olive oil, nuts, and fish, with moderate dairy and limited red meat — has the broadest research base for general health and some reproductive health outcomes. This is not a proprietary program or a strict elimination diet; it is a flexible pattern of food choices.

Key features researchers have focused on:

• Plant-based protein sources (lentils, beans, tofu) in place of some red or processed meat
• Whole grains over refined carbohydrates — relevant for blood sugar stability, which matters especially for women with PCOS 2Ref 2Teede HJ, Tay CT, Laven JJE, Dokras A, et al. (2023).Recommendations From the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome.Diet and lifestyle as first-line interventions in PCOS management, relevance of carbohydrate quality and insulin resistance
• Fatty fish (salmon, sardines, mackerel) as a source of long-chain omega-3 fats
• Monounsaturated fats from olive oil and avocados in place of saturated fats
• Abundant vegetables and fruits, which provide folate, antioxidants, and fiber

What nutrients are most important before conception?

Folate is the most critical preconception nutrient. Adequate folate in the weeks before and immediately after conception reduces the risk of neural tube defects — a window when most people do not yet know they are pregnant. Food sources include dark leafy greens, lentils, fortified cereals, and avocado. A supplement is typically recommended in addition to food sources (see the separate article on folic acid dosing).

Iron — both heme iron from meat and non-heme iron from plant foods — supports egg quality and early fetal development. Iron deficiency is common and affects energy, which matters throughout trying to conceive.

Vitamin D — many people are insufficient. Vitamin D receptors are present in reproductive tissue, and very low levels have been associated in some studies with reduced IVF success, though supplementation trials have not been conclusive.

Iodine — important for thyroid function, which is closely tied to ovulation and pregnancy maintenance. Seafood and iodized salt are the main dietary sources.

What should I limit or avoid when trying to conceive?

Alcohol — there is no established safe level of alcohol in pregnancy. Current guidance from major obstetric organizations recommends avoiding alcohol entirely when trying to conceive, given that implantation and early development can occur before a missed period.

Trans fats — found in some processed and fried foods. Research has associated higher trans fat intake with higher risk of ovulatory infertility.

High-mercury fish — shark, swordfish, king mackerel, and tilefish should be limited during preconception and pregnancy. Low-mercury options (salmon, shrimp, canned light tuna, sardines) are fine.

Excessive caffeine — most guidelines suggest keeping caffeine under 200-300 mg per day during preconception and pregnancy (roughly one to two standard cups of coffee). The evidence at moderate intake is mixed; very high intake is more clearly associated with risk.

Ultra-processed foods — associated with poorer dietary quality overall and with inflammatory patterns that may be relevant to reproductive health.

Does the same advice apply for male partners?

Sperm quality — count, motility, and morphology — is influenced by diet and lifestyle as well. Anti-inflammatory eating patterns, adequate zinc and selenium, and avoiding excess alcohol and heat exposure (hot tubs, tight clothing) are relevant. Sperm take approximately 72 days to mature, so dietary changes in a male partner show up in semen analysis roughly three months later. Evaluation by a urologist or reproductive endocrinologist with a semen analysis is the starting point if male factor is a concern 3Ref 3Schlegel PN, Sigman M, Collura B, De Jonge CJ, Eisenberg ML, Lamb DJ, Mulhall JP, Niederberger C, Sandlow JI, Sokol RZ, Spandorfer SD, Tanrikut C, Treadwell JR, Oristaglio JT, Zini A (2021).Diagnosis and Treatment of Infertility in Men: AUA/ASRM Guideline Part I.Semen analysis as the initial evaluation for male factor infertility, lifestyle factors affecting sperm quality.

What about PCOS specifically?

For women with polycystic ovary syndrome, diet has a clearer and more studied role. PCOS frequently involves insulin resistance, and diets that moderate refined carbohydrate intake and support a healthy weight can improve ovulation regularity and menstrual cycle predictability. Fiber-rich whole foods, lower-glycemic carbohydrates, and adequate protein are particularly relevant. International PCOS guidelines note that diet and exercise are first-line interventions before or alongside medical treatment in women with overweight 2Ref 2Teede HJ, Tay CT, Laven JJE, Dokras A, et al. (2023).Recommendations From the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome.Diet and lifestyle as first-line interventions in PCOS management, relevance of carbohydrate quality and insulin resistance.