Friends and enemies of Fertility
Nourishing Life: How Nutrition Shapes Fertility in Women and Men
Fertility is rarely discussed through the lens of nutrition, yet the evidence is compelling. What we eat directly influences hormonal signalling, egg and sperm quality, implantation, and early embryonic development. An estimated one in seven couples in the UK experience difficulty conceiving, and while fertility is shaped by many factors, diet represents one of the most modifiable. This article examines the biological mechanisms through which nutrition affects reproductive function, the dietary patterns most strongly associated with improved fertility outcomes, and the supplements with the most robust clinical evidence.
The biological engine: why diet matters for fertility
Reproductive function depends on a precisely orchestrated hormonal cascade governed by the hypothalamic-pituitary-gonadal (HPG) axis. Nutritional status directly influences every level of this axis. Deficiencies in key micronutrients impair gonadotropin secretion, disrupt folliculogenesis, compromise oocyte maturation, and reduce sperm motility and morphology. Conversely, chronic dietary excess, particularly of refined carbohydrates and saturated fats, promotes insulin resistance and oxidative stress, both of which are independently associated with ovulatory dysfunction and poor embryo quality.
In women, nutrition affects the quality of the oocyte environment, the hormonal milieu of the follicular fluid, and the receptivity of the endometrium. In men, diet directly shapes sperm DNA integrity, motility, and count, all of which are increasingly recognised as critical determinants of conception success and early pregnancy outcomes.
Friends of Fertility: Foods and Nutrients That Support Conception
Folate and its food sources
Folate is perhaps the most well-established fertility nutrient. Beyond its role in preventing neural tube defects, folate is essential for DNA synthesis and methylation during oocyte maturation and early embryonic cell division. Low folate status has been associated with impaired oocyte quality and increased risk of chromosomal abnormalities. Food sources include dark leafy greens, lentils, chickpeas, asparagus, broccoli, and fortified cereals. Supplementation with 400mcg of folic acid daily is recommended from preconception through the first trimester, with some women requiring the active form (methylfolate) depending on MTHFR gene variants.
Omega-3 fatty acids
Omega-3 fatty acids, particularly EPA and DHA, are concentrated in the follicular fluid surrounding the developing egg. Higher omega-3 concentrations in follicular fluid have been associated with better oocyte quality and improved embryo development in IVF studies. In men, omega-3 supplementation has been shown to improve sperm morphology and motility. Food sources include oily fish such as salmon, sardines, mackerel, and anchovies, as well as flaxseeds, chia seeds, and walnuts. Two portions of oily fish per week is recommended for those trying to conceive, though high-mercury fish such as shark, swordfish, and marlin should be avoided.
Chiu YH, Karmon AE, Gaskins AJ, et al. Serum omega-3 fatty acids and treatment outcomes among women undergoing assisted reproduction. Hum Reprod. 2018;33(1):156-165.
Antioxidants: vitamin C, vitamin E, and CoQ10
Oxidative stress is a major driver of both male and female infertility. The ovarian follicle and developing sperm are particularly vulnerable to reactive oxygen species (ROS), which can damage DNA and impair function. Antioxidant-rich diets counteract this damage. Vitamin C supports progesterone production and corpus luteum function. Vitamin E protects cell membranes from lipid peroxidation. Coenzyme Q10 is concentrated in the inner mitochondrial membrane of oocytes and sperm, where it supports energy production essential for fertilisation. Clinical trials show CoQ10 supplementation improves ovarian response in poor responders and sperm parameters in men with idiopathic infertility.
Xu Y, Nisenblat V, Lu C, et al. Pretreatment with coenzyme Q10 improves ovarian response and embryo quality in low-prognosis young women with decreased ovarian reserve: a randomized controlled trial. Reprod Biol Endocrinol. 2018;16(1):29.
Food sources of antioxidants include: berries, citrus fruits, kiwi, peppers, tomatoes, spinach, almonds, sunflower seeds, avocado, and dark chocolate (70% cocoa and above).
Zinc
Zinc is essential for follicle development, ovulation, and fertilisation in women, and for testosterone synthesis and sperm production in men. Zinc deficiency is associated with reduced sperm count and motility, and impaired egg maturation. Food sources include red meat, shellfish (particularly oysters), pumpkin seeds, legumes, and dairy.
Iron
Non-haem iron from plant sources, rather than haem iron from red meat, has been more consistently associated with ovulatory fertility in prospective cohort studies, including the landmark Nurses Health Study. Iron supports folliculogenesis and is essential for DNA synthesis. Food sources include lentils, tofu, fortified cereals, spinach, and pumpkin seeds. Pairing these with vitamin C-rich foods enhances absorption significantly.
Chavarro JE, Rich-Edwards JW, Rosner BA, Willett WC. Iron intake and risk of ovulatory infertility. Obstet Gynecol. 2006;108(5):1145-1152.
The Mediterranean dietary pattern
The Mediterranean diet, characterised by high intake of vegetables, fruits, wholegrains, legumes, oily fish, olive oil, and moderate dairy, consistently emerges as the dietary pattern most associated with improved fertility outcomes in both natural conception and assisted reproduction. Its anti-inflammatory and insulin-sensitising properties support hormonal balance, egg quality, and endometrial receptivity.
Karayiannis D, Kontogianni MD, Mendorou C, Mastrominas M, Yiannakouris N. Adherence to the Mediterranean diet and IVF success rate among non-obese women attempting fertility. Hum Reprod. 2018;33(3):494-502.
Enemies of Fertility: Foods and Habits That Harm Conception
Ultra-processed foods and trans fats
Trans fatty acids, found in partially hydrogenated vegetable oils and many ultra-processed foods, are strongly associated with ovulatory infertility. They promote insulin resistance and systemic inflammation, disrupting the hormonal signals that govern ovulation. Every 2% increase in energy from trans fats has been associated with a more than doubled risk of ovulatory infertility in prospective studies.
Chavarro JE, Rich-Edwards JW, Rosner BA, Willett WC. Dietary fatty acid intakes and the risk of ovulatory infertility. Am J Clin Nutr. 2007;85(1):231-237.
Excess sugar and refined carbohydrates
High glycaemic load diets drive insulin resistance and elevate androgens, directly impairing ovulatory function. In men, high sugar intake is associated with reduced sperm motility and increased DNA fragmentation. Foods to minimise include white bread, pastries, sugary drinks, sweets, and breakfast cereals with added sugar.
Alcohol
Alcohol consumption, even at moderate levels, has been associated with reduced fertility in women and impaired sperm quality in men. It disrupts the HPG axis, reduces zinc absorption, increases oxidative stress, and in early pregnancy, poses serious developmental risks to the embryo. Current guidance recommends avoiding alcohol entirely when trying to conceive.
Excess caffeine
High caffeine intake, above 200-300mg per day, has been associated with delayed conception and increased risk of early pregnancy loss. One to two cups of coffee per day appears to be safe for most women, but high intake from multiple sources including tea, energy drinks, and chocolate should be monitored carefully, if not reduced.
Soy in excess
Soy contains phytoestrogens, plant compounds that weakly mimic oestrogen and can potentially interfere with hormonal signalling at high doses. Moderate consumption of whole soy foods such as edamame and tofu is likely safe for most women, but high-dose soy supplements or heavily processed soy products are best avoided when trying to conceive.
Endocrine-disrupting chemicals
While not a food per se, the packaging and preparation of food matters. Bisphenol A (BPA) found in some plastic containers and tin can linings, and pesticide residues on non-organic produce, act as endocrine disruptors that can interfere with oestrogen and progesterone signalling. Choosing organic where possible for the "dirty dozen" most pesticide-laden fruits and vegetables, and avoiding microwaving food in plastic, are practical steps to reduce exposure.
Evidence-based supplements for fertility
Folic acid or methylfolate (400-800mcg daily) First-line recommendation for all women trying to conceive. Essential for DNA synthesis and prevention of neural tube defects from the point of conception.
Coenzyme Q10 (200-600mg daily) Strongest evidence base for improving ovarian response in women over 35 or with diminished ovarian reserve. Also supports sperm parameters in men. Best taken with a meal containing fat for absorption.
Vitamin D (1,000-2,000 IU daily, depending on levels) Vitamin D receptors are present throughout the reproductive system. Deficiency is associated with impaired implantation, reduced IVF success rates, and poor sperm motility. Testing serum 25-OH vitamin D and correcting deficiency before conception is advisable.
Omega-3 (EPA and DHA, 1-2g daily) Supports oocyte quality, embryo development, and sperm morphology. Particularly important for those with low oily fish intake.
Inositol (myo-inositol 2-4g daily) Particularly relevant for women with PMOS or insulin resistance-related ovulatory dysfunction. Improves oocyte quality and menstrual regularity.
Zinc (for men, 25-50mg daily) Supports testosterone synthesis and sperm production. Particularly relevant in men with known deficiency or poor sperm parameters.
Beyond the plate: lifestyle factors that matter
Nutrition works in concert with lifestyle. Maintaining a healthy body weight is one of the most impactful steps, as both underweight and obesity are independently associated with impaired ovulation and reduced IVF success rates. Moderate exercise supports insulin sensitivity and hormonal balance, though excessive vigorous exercise can suppress ovulation in women with low body fat. Sleep quality governs cortisol and melatonin rhythms that directly influence reproductive hormones, and chronic psychological stress activates the HPA axis in ways that suppress the HPG axis and impair conception.
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice.
Written by Ines Jabir BSc RD MPH
The views expressed in this article are the author's own and do not necessarily reflect My Nutrition Balance's editorial stance. This blog should not be consulted as medical advice.