The Short Version
- A Harvard study of 18,000+ women found that specific dietary changes can reduce ovulatory infertility risk by up to 69%
- Eat more plant proteins, full-fat dairy, whole grains, leafy greens, and olive oil or avocado for healthy fats
- Cut back on trans fats, refined carbohydrates, sugary drinks, and processed red meat
- Key supplements to discuss with your doctor: folate (400-800mcg), vitamin D, and omega-3 fatty acids
- Men’s fertility responds to diet too - sperm quality, motility, and DNA integrity all improve with better nutrition
You can increase your chances of getting pregnant by up to 69% just by changing what you eat. That is not a marketing claim - it is the headline finding from the landmark Harvard Nurses’ Health Study II, which tracked over 18,000 women across eight years. The fertility diet is not a fad. It is one of the most well-evidenced nutritional interventions in reproductive medicine, and the good news is it is genuinely achievable.
Couples who followed a fertility-supportive diet pattern were significantly more likely to conceive within 12 months compared to those eating a typical Western diet. For men, diet quality is equally important: sperm quality, motility, and DNA integrity all respond measurably to nutrition. Whether you are just starting to try or have been trying for a while, what you put on your plate matters more than almost anything else outside of your medical history.
What the Evidence Actually Shows
The Harvard Fertility Diet, developed by Drs Jorge Chavarro and Walter Willett, identified specific dietary patterns associated with significantly lower rates of ovulatory infertility. Key findings from the research:
- 69% lower risk of ovulatory infertility in women who closely followed the fertility diet pattern (Chavarro et al., Obstetrics & Gynaecology, 2007)
- Sperm concentration increased by 43% in men following a Mediterranean-style diet rich in antioxidants and omega-3s (Cutillas-Tolin et al., Fertility and Sterility, 2015)
- Folate supplementation reduces the risk of neural tube defects by up to 72% when taken before conception (MRC Vitamin Study Research Group, The Lancet, 1991)
- Trans fat consumption - even in small amounts - increases ovulatory infertility risk by 31% (Chavarro et al., American Journal of Clinical Nutrition, 2007)
What to Eat: The Fertility-Boosting Foods
Healthy Fats (the Right Ones)
Monounsaturated and omega-3 fats are strongly associated with improved egg quality and hormonal balance. Aim for avocados, olive oil, walnuts, flaxseeds, and oily fish (salmon, sardines, mackerel) at least twice a week. These fats reduce inflammation, which directly supports follicular development and uterine lining health.
Plant Protein Over Animal Protein
Swapping one serving of meat per day for a plant protein source (lentils, chickpeas, tofu, beans) was associated with a 50% lower risk of ovulatory infertility in the Harvard study. Animal protein, particularly red and processed meat, elevates certain hormones that can interfere with ovulation. This does not mean cutting meat entirely - moderate amounts of poultry and fish are fine - but shifting the balance matters.
Complex Carbohydrates
Blood sugar stability is central to hormonal regulation. High-glycaemic foods (white bread, sugary drinks, refined cereals) cause insulin spikes that disrupt ovulation. Replace them with quinoa, oats, brown rice, sweet potatoes, and plenty of vegetables. The goal is a steady blood sugar curve, not elimination of carbohydrates.
Full-Fat Dairy (Yes, Really)
This one surprises people. The Harvard data found that one serving of full-fat dairy per day (whole milk, full-fat yoghurt, cheese) was associated with reduced risk of ovulatory infertility, while low-fat dairy was associated with increased risk. The current theory is that fat-soluble hormones present in dairy are removed when fat is stripped out. One portion daily is the sweet spot.
Iron-Rich Foods
Iron deficiency is one of the most common nutritional shortfalls in women trying to conceive. Non-haem iron from plants (spinach, lentils, fortified cereals) combined with vitamin C significantly improves absorption. Women consuming the most non-haem iron had a 40% lower risk of ovulatory infertility compared to the lowest consumers.
Antioxidant-Rich Foods (for Both Partners)
Oxidative stress damages both eggs and sperm. Foods highest in antioxidants include berries, leafy greens, tomatoes, peppers, citrus fruits, and dark chocolate (70%+). For men specifically, lycopene from cooked tomatoes is particularly associated with improved sperm motility and morphology.
What to Avoid
- Trans fats - found in some fried foods, commercially baked goods, and partially hydrogenated oils. Even small amounts measurably increase infertility risk.
- Sugar and high-glycaemic foods - fizzy drinks, fruit juices, white bread, pastries. These disrupt insulin signalling and hormonal balance.
- Processed meat - bacon, sausages, deli meats. Linked to reduced sperm quality in men and elevated androgen levels in women.
- Alcohol - even moderate consumption (more than 3-4 units per week) is associated with reduced fertility in both men and women.
- Excessive caffeine - above 200mg per day (roughly two cups of coffee) is linked to increased miscarriage risk. Below this threshold appears safe.
- Low-fat dairy - swap to full-fat versions while trying to conceive.
- Ultra-processed foods - consistently associated with reduced sperm count, poor egg quality, and longer time to conception.
The Reality: A Perfect Diet Is Not Always Possible
A whole-food, nutrient-dense diet is unambiguously the best foundation for fertility. The research makes that clear. But life rarely cooperates: demanding jobs, busy households, food sensitivities, and the financial reality that organic produce is not accessible to everyone. This is where quality supplements bridge a genuine gap - not as a substitute for good nutrition, but as an honest safety net.
The key word is quality. The supplement industry is largely unregulated, and the difference between a well-formulated product and a cheap one is significant. Below is an honest analysis of what the evidence supports.
Top 5 Supplements for Women
Methylfolate (Active Folate / Vitamin B9)
Why it matters more than standard folic acid
Standard folic acid must be converted by the body into its active form, methylfolate. Approximately 40% of people carry a MTHFR gene variant that impairs this conversion - meaning cheap folic acid supplements may provide little benefit for a significant portion of women. Methylfolate bypasses this conversion entirely. It is essential for DNA synthesis, neural tube development, and reducing homocysteine levels linked to miscarriage risk. The recommended dose is 400mcg pre-conception, rising to 800mcg in early pregnancy. Look for labels reading “methylfolate,” “5-MTHF,” or “Quatrefolic.”
CoQ10 (Ubiquinol Form)
Egg quality and mitochondrial energy
CoQ10 is arguably the most evidence-backed supplement for egg quality, particularly for women over 35 or those with diminished ovarian reserve. It powers the mitochondria inside eggs, which require enormous energy for proper chromosomal division during maturation. A 2018 randomised controlled trial found CoQ10 supplementation significantly improved ovarian response and egg quality in poor responders undergoing IVF. Choose the ubiquinol form - substantially better absorbed than ubiquinone. Dosing: 200-600mg daily, taken with a fatty meal.
Vitamin D3 + K2
Hormonal regulation and implantation
Vitamin D deficiency is exceptionally common - studies suggest 40-70% of UK and US adults are deficient - and strongly linked to impaired fertility. Vitamin D receptors are present in the ovaries, uterus, and endometrium. Low levels are associated with PCOS, endometriosis, implantation failure, and recurrent miscarriage. A meta-analysis in Human Reproduction Update (2019) found women with sufficient vitamin D had significantly higher live birth rates in IVF. Pairing D3 with K2 ensures calcium goes to bones, not soft tissue. Aim for 2,000-4,000 IU D3 daily; get blood levels tested to tailor your dose.
Omega-3 (DHA + EPA)
Egg quality, uterine blood flow, and early foetal brain development
DHA is critical for early neurological development, and blood levels at conception directly influence foetal brain formation before most women even know they are pregnant. Omega-3s also improve uterine blood flow, reduce inflammation that can impair implantation, and are associated with improved egg quality. Plant-based omega-3 (ALA from flaxseed) converts poorly to DHA - algae-based or fish-derived supplements are far more effective. Minimum 300mg DHA daily; ideally 600-1000mg combined DHA + EPA.
Iron (with Vitamin C)
Ovulatory function and oxygen transport
Iron deficiency is the world’s most common nutritional deficiency and among the most common causes of ovulatory dysfunction. Only supplement if deficiency has been confirmed - excess iron is harmful. Get your ferritin and haemoglobin tested first. If your ferritin is below 30 ng/mL, supplementation is warranted. Take with vitamin C to maximise absorption. Gentle forms (ferrous bisglycinate) cause far fewer digestive side effects than ferrous sulphate.
Top 5 Supplements for Men
Male factor infertility contributes to approximately 40-50% of all infertility cases, yet it is dramatically under-discussed. Sperm take approximately 74 days to develop, meaning dietary changes and supplementation take three months to show meaningful results. Start now.
CoQ10 (Ubiquinol)
Sperm motility and energy production
CoQ10 is concentrated in sperm midpieces - the engine that drives motility. Multiple randomised trials confirm it improves sperm count, motility, and morphology. A meta-analysis reviewing six randomised controlled trials found CoQ10 supplementation significantly improved all three key sperm parameters. It also protects sperm DNA from oxidative damage, which is linked to miscarriage and failed fertilisation even when conventional semen analysis appears normal. Dose: 200-400mg ubiquinol daily with food. Give it a full three months before assessing results.
Zinc + Selenium
Testosterone, sperm production, and DNA protection
Zinc is essential for testosterone synthesis and sperm production - the testes have among the highest zinc concentrations of any tissue in the body. Selenium forms part of the antioxidant enzyme GPx5, which protects developing sperm from DNA damage. A double-blind trial found zinc-selenium combined supplementation significantly improved sperm motility and morphology in subfertile men. Dose: 25-30mg zinc (picolinate or bisglycinate) + 100-200mcg selenium (selenomethionine) daily. Do not exceed these doses as excess zinc actually impairs fertility.
Vitamin D3
Testosterone and sperm function
Vitamin D receptors are present throughout the male reproductive system, and deficiency is associated with reduced testosterone, poor sperm motility, and abnormal morphology. A study published in Hormone and Metabolic Research found men who supplemented with vitamin D for 12 months had significantly increased testosterone and improved sperm motility compared to placebo. Deficiency affects the majority of men in northern latitudes during winter months. Dose: 2,000-4,000 IU D3 daily paired with K2. Get blood levels tested to optimise your individual dose.
Omega-3 (DHA + EPA)
Sperm membrane integrity and morphology
DHA is a structural component of sperm cell membranes. Higher seminal DHA levels are consistently associated with better sperm morphology and higher fertilisation rates. A study in Fertility and Sterility found men with poor sperm morphology had significantly lower seminal DHA concentrations compared to men with normal morphology. Omega-3 supplementation also reduces seminal oxidative stress and inflammation. Dose: 1,000-2,000mg combined EPA + DHA daily with a meal.
L-Carnitine + L-Arginine
Sperm motility and energy metabolism
L-carnitine is highly concentrated in the epididymis and directly involved in sperm energy metabolism. Multiple clinical trials confirm it improves sperm motility, particularly in men with low motility. L-arginine supports sperm production and improves testicular blood flow. A systematic review found combined L-carnitine and L-arginine supplementation produced significantly better outcomes for sperm motility than either alone. Dose: 2,000-3,000mg L-carnitine + 2,000-4,000mg L-arginine daily, taken on an empty stomach.
Where to Start
You do not need to overhaul everything at once. The highest-impact changes are: cut trans fats and sugar, increase vegetables and plant protein, and take a quality prenatal containing methylfolate rather than standard folic acid. Add CoQ10 if you are over 34 or have received any indication of egg quality concerns. Get your vitamin D and ferritin levels tested - these are the two most common deficiencies affecting fertility and the easiest to correct.
For men: the same dietary principles apply, and CoQ10 plus zinc-selenium is the combination with the strongest evidence base. Start three months before you want to conceive, because that is how long sperm take to develop.
The most important thing is consistency over perfection. A moderately good diet maintained reliably beats a perfect diet followed intermittently.
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- Chavarro JE et al. Diet and lifestyle in the prevention of ovulatory disorder infertility. Obstetrics & Gynaecology. 2007;110(5):1050-1058. PubMed
- Chavarro JE et al. Dietary fatty acid intakes and the risk of ovulatory infertility. American Journal of Clinical Nutrition. 2007;85(1):231-237. PubMed
- Cutillas-Tolin A et al. Mediterranean and Western dietary patterns are related to markers of testicular function. Human Reproduction. 2015;30(12):2945-2955. PubMed
- MRC Vitamin Study Research Group. Prevention of neural tube defects. The Lancet. 1991;338(8760):131-137. PubMed
- Bentov Y et al. Coenzyme Q10 supplementation and oocyte aneuploidy in women undergoing IVF-ICSI. Clinical Medicine Insights: Reproductive Health. 2014;8:31-36. PubMed
- Paffoni A et al. Vitamin D deficiency and infertility: insights from IVF cycles. Journal of Clinical Endocrinology & Metabolism. 2014;99(11):E2372-E2376. PubMed
- Safarinejad MR. Efficacy of coenzyme Q10 on semen parameters in infertile men. Journal of Urology. 2009;182(1):237-248. PubMed
- Wathes DC et al. Polyunsaturated fatty acids in male and female reproduction. Biology of Reproduction. 2007;77(2):190-201. PubMed
- Lenzi A et al. A placebo-controlled double-blind cross-over trial of carnitine versus carnitine and coenzyme Q10 in subfertile men. Fertility and Sterility. 2004;82(3):708-711. PubMed
- Blomberg Jensen M et al. Vitamin D is positively associated with sperm motility. Human Reproduction. 2011;26(6):1307-1317. PubMed
