The pattern matters more than any single food. A 2017 systematic review of observational studies found diets rich in vegetables, fruit, fish and seafood, poultry, whole grains, nuts and low-fat dairy were associated with better semen quality, and diets high in processed meat, full-fat dairy, sweets, sugary drinks and alcohol with worse. A 2020 study of 2,935 young Danish men put numbers on it: men in the top fifth for a "prudent" pattern (fish, chicken, vegetables, fruit, water) had total sperm counts 43 million higher than men in the bottom fifth, and men in the top fifth for a Western pattern (pizza, chips, processed and red meat, snacks, sugary drinks) had counts 26 million lower. One randomized trial found 60 g of nuts a day for 14 weeks raised sperm count by about 16%. Diet is a slow lever: allow three months or more.
The pattern that keeps coming up
Salas-Huetos and colleagues reviewed every observational study to 2016 on food and semen quality. The same shape appears across countries and study designs: more vegetables, fruit, fish and shellfish, poultry, whole grains, nuts, legumes and low-fat dairy goes with better concentration, motility and morphology; more processed meat, full-fat dairy, sweets, sugary drinks and alcohol goes with worse. The nutrients that come up repeatedly are omega-3 fats, antioxidants such as vitamins C and E and lycopene, zinc, selenium and folate, all of them abundant in that first list of foods. Because the studies are observational, they cannot prove that changing your diet changes your sperm; they show that men who eat this way tend to have better results.
The numbers from 2,935 Danish men
Nassan and colleagues (JAMA Network Open, 2020) took 2,935 men aged around 19 being examined for military service in Denmark, an unselected group rather than fertility patients, and matched food questionnaires to semen samples. Men whose diet sat in the top fifth for the prudent pattern had a median total sperm count 43 million higher than men in the bottom fifth. Men in the top fifth for the Western pattern had counts 26 million lower than the bottom fifth. For scale, the WHO 2021 lower reference limit for total count is 39 million, so the gap between the two ends of the prudent pattern is larger than the whole reference limit. The Western pattern was also linked to lower levels of inhibin B, a hormone that tracks how hard the testes are working.
The one trial on a single food
Salas-Huetos and colleagues (American Journal of Clinical Nutrition, 2018) randomized 119 healthy men aged 18 to 35 to add 60 g a day of mixed almonds, hazelnuts and walnuts to their usual Western-style diet, or to change nothing, for 14 weeks. The nut group's sperm count rose about 16%, motility about 6%, vitality about 4% and normal morphology about 1%, and their sperm DNA fragmentation fell. Two caveats the authors made themselves: the men were healthy and apparently fertile, so the result may not carry to men with low counts, and the trial was funded by the International Nut and Dried Fruit Council. It is still the best randomized evidence for any single food.
Sugary drinks
Chiu and colleagues (Human Reproduction, 2014) studied 189 healthy men aged 18 to 22 in Rochester, New York. Men drinking 1.3 or more servings of sugar-sweetened drinks a day had progressive motility 9.8 percentage points lower than men drinking almost none, with the effect concentrated in lean men and absent in overweight men. Concentration and hormones were unaffected. A Danish study of 2,554 men found heavy cola drinkers (more than 14 half-liter bottles a week) had lower concentrations and counts, an effect the authors could not pin on caffeine; the caffeine guide has the details. Sugary drinks are the one item on the Western list with their own evidence.
Food versus supplements
The nutrients above are the same ones sold in fertility supplements, and the trial evidence for the pills is weaker than the observational evidence for the food. The 2022 Cochrane review of antioxidant supplements for male subfertility called the evidence inconclusive, and the two largest recent trials, of a combined antioxidant and of folic acid with zinc, found no improvement in semen quality or live birth. The supplements guide goes through each ingredient. Nobody has run the equivalent comparison for a diet, but a plate of oily fish, vegetables and nuts brings the nutrients with the fiber, the weight effect and the displacement of the Western foods, and none of the trials found harm in it.
How long until it shows
Diet works on the raw materials the early weeks of the 74-day cycle draw on, so it is slower than removing an acute insult such as heat. The nut trial ran 14 weeks; the observational studies reflect years of eating. Give a change three months before you test for it, and the timeline tool will give you the date.
What to do
- Push the share of whole, unprocessed food up. That is the single question Motily's nutrition check-in asks, because it tracks the pattern the studies found.
- Eat oily fish twice a week, vegetables and fruit daily, and a handful of nuts most days. Those are the foods with the most consistent signal.
- Swap sugary drinks for water. It is the one item in the Western pattern with its own evidence.
- Cut processed meat and takeaway food back rather than out; the studies compare fifths of a population, not saints and sinners.
- Skip the supplement aisle unless a doctor has found a deficiency. Get the nutrients from the plate.
Related guides
Sources
- Salas-Huetos A, et al. Dietary patterns, foods and nutrients in male fertility parameters and fecundability: a systematic review of observational studies. Human Reproduction Update, 2017.
- Nassan FL, et al. Association of dietary patterns with testicular function in young Danish men. JAMA Network Open, 2020.
- Salas-Huetos A, et al. Effect of nut consumption on semen quality and functionality in healthy men consuming a Western-style diet: a randomized controlled trial. American Journal of Clinical Nutrition, 2018. (Funded by the International Nut and Dried Fruit Council.)
- Chiu YH, et al. Sugar-sweetened beverage intake in relation to semen quality and reproductive hormone levels in young men. Human Reproduction, 2014.
- Jensen TK, et al. Caffeine intake and semen quality in a population of 2,554 young Danish men. American Journal of Epidemiology, 2010.
- de Ligny W, et al. Antioxidants for male subfertility. Cochrane Database of Systematic Reviews, 2022.
- Heller CG, Clermont Y. Spermatogenesis in man: an estimate of its duration. Science, 1963.