Diet has a measurable impact on fertility for both women and men. The foods you eat influence hormone balance, ovulation, and sperm quality, and some dietary patterns have been linked to nearly doubled pregnancy rates in clinical studies. The effect isn’t subtle: specific choices around fats, protein sources, dairy, and carbohydrates can meaningfully shift your chances of conceiving.
The Mediterranean Diet and Pregnancy Rates
The strongest body of evidence connecting diet to fertility centers on the Mediterranean diet, which emphasizes vegetables, fruits, whole grains, legumes, fish, and olive oil. Among couples undergoing fertility treatment, those with the highest adherence to this pattern had a 50% clinical pregnancy rate compared to 29% for those with the lowest adherence. Live birth rates showed an even wider gap: 49% versus 27%.
These aren’t small differences. Across multiple studies, closely following a Mediterranean-style diet was associated with roughly 1.4 to 2.7 times the odds of achieving a clinical pregnancy. For live births specifically, the relative likelihood was about 2.5 times higher. While much of this research comes from couples using IVF, the underlying biology applies broadly: the nutrients in this dietary pattern support hormone production, reduce inflammation, and protect egg and sperm cells from oxidative damage.
How Carbohydrates and Blood Sugar Disrupt Ovulation
High-glycemic foods, those that cause rapid blood sugar spikes, can interfere with ovulation through a chain reaction that starts with insulin. When blood sugar rises sharply, your body releases more insulin. Elevated insulin increases levels of a growth factor called IGF-1 and alters sex hormone binding globulin, creating a hormonal environment that resembles what happens in polycystic ovary syndrome (PCOS). This hormonal shift can prevent the release of an egg during your cycle.
For women who already have PCOS, a condition marked by insulin resistance and irregular ovulation, diets with a lower glycemic load have been shown to improve menstrual cycle regularity and reduce insulin resistance. But the mechanism isn’t limited to PCOS. High blood sugar also generates reactive oxygen species, a form of cellular stress that damages both egg and sperm quality. Choosing whole grains, legumes, and fiber-rich carbohydrates over refined starches and sugary foods keeps insulin levels steadier and protects reproductive cells.
Trans Fats Carry Outsized Risk
Of all the dietary factors studied, trans fats show one of the sharpest connections to infertility. Replacing just 2% of daily calories from carbohydrates with trans fats was associated with a 73% greater risk of ovulatory infertility. Replacing monounsaturated fats (the type found in olive oil and avocados) with the same small amount of trans fat more than doubled the risk.
Trans fats are found in some fried foods, packaged baked goods, and products made with partially hydrogenated oils. While food manufacturers have reduced their use in recent years, they still appear in certain processed foods. Reading ingredient labels for “partially hydrogenated” oils is the most reliable way to identify them. Given how small an amount of trans fat it takes to shift fertility risk, this is one of the most actionable dietary changes you can make.
Plant Protein vs. Animal Protein
The source of your protein matters more than the total amount. In a large prospective study following over 18,000 women, those with the highest intake of animal protein had a 39% greater risk of ovulatory infertility compared to those with the lowest intake. Plant protein showed the opposite trend. Replacing 5% of total calories from animal protein with plant protein was associated with a greater than 50% lower risk of ovulatory infertility.
This doesn’t mean you need to eliminate meat entirely. The practical takeaway is that swapping some servings of red meat or chicken for beans, lentils, tofu, or nuts can make a meaningful difference. The effect likely comes from the different hormonal responses these protein sources trigger, along with the fiber, antioxidants, and other compounds that come packaged with plant-based foods.
Full-Fat Dairy May Be Better Than Low-Fat
A large study following more than 18,500 women over eight years found a surprising pattern with dairy. Women consuming two or more servings per day of low-fat dairy foods had an 85% higher risk of anovulatory infertility compared to women who ate one serving or fewer per week. Full-fat dairy showed the opposite effect: one or more daily servings of high-fat dairy foods was linked to a 27% lower risk.
Each additional daily serving of low-fat dairy increased anovulatory infertility risk by about 9%, while each additional serving of high-fat dairy decreased it by about 20%. The likely explanation involves how fat removal changes the hormonal content of dairy products. Skim and low-fat milk contain a higher ratio of certain hormones and growth factors relative to the fat-soluble compounds that would normally balance them out. If you’re trying to conceive and regularly eat dairy, consider choosing whole milk, full-fat yogurt, or cheese over their low-fat versions.
Diet and Male Fertility
Diet affects the male side of the equation just as directly. Sperm take roughly 70 to 90 days to mature, so what a man eats in the two to three months before conception attempts shapes the quality of those sperm cells. Oxidative stress is one of the primary drivers of poor sperm quality, and antioxidant-rich diets can counter it.
Several nutrients have been studied in clinical trials with measurable results. CoQ10, a compound found in organ meats, fatty fish, and whole grains, improved sperm motility (how well sperm swim) in multiple randomized trials at doses between 150 and 300 mg daily. In one study of 212 infertile men, CoQ10 supplementation improved both sperm concentration and motility after about six months. Zinc, found in shellfish, seeds, and legumes, has shown similar benefits. A combination of zinc and folic acid taken for 26 weeks produced a 74% increase in total sperm count among infertile men.
High blood sugar affects men too. Hyperglycemia generates oxidative stress that damages developing sperm cells and impairs the function of mature sperm. The same insulin pathway that disrupts ovulation in women can reduce semen quality in men, making blood sugar management a shared concern for couples trying to conceive.
Caffeine and Alcohol
Caffeine in moderate amounts appears to be compatible with conception, but the exact safe threshold is debated. The European Food Safety Authority recommends women trying to conceive stay below 200 mg per day (roughly one to two standard cups of coffee), while the World Health Organization sets the limit at 300 mg. However, a large dose-response meta-analysis suggested that even these limits may be too generous, and that lower intake is safer. If you’re a heavy coffee drinker, cutting back to one cup a day is a reasonable precaution.
Alcohol is more straightforward. There is no established safe level of alcohol consumption during pregnancy, and preconception guidelines recommend that both partners reduce or eliminate alcohol while trying to conceive. Alcohol contributes to oxidative stress in reproductive cells and can disrupt hormone levels in both women and men.
Putting It Into Practice
The dietary changes most consistently linked to better fertility outcomes cluster around a few core principles: eat more vegetables, fruits, whole grains, legumes, nuts, and fish. Choose plant proteins over animal proteins when you can. Use olive oil and other sources of unsaturated fat. Avoid trans fats. Opt for full-fat over low-fat dairy. Keep refined carbohydrates and added sugars low to maintain steady blood sugar.
These changes don’t need to happen overnight, but timing matters. Egg cells go through a critical maturation window in the three to four months before ovulation, and sperm take about three months to develop. Starting dietary changes at least three months before you plan to conceive gives your body time to produce healthier reproductive cells. For couples already undergoing fertility treatment, the evidence suggests that diet quality can meaningfully improve outcomes even in that context.