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, cereals 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, French fries, processed and red meat, snacks, sugary drinks) had counts 26 million lower. In a randomized trial, 60 g of mixed nuts a day for 14 weeks improved count, motility, vitality and morphology against a no-nuts control. Diet is a slow lever: allow three months or more.
The pattern that keeps coming up
Salas-Huetos and colleagues reviewed the observational studies published up to late 2016 on food and semen quality. The same shape appears across countries and study designs: more vegetables, fruit, fish and shellfish, poultry, cereals and low-fat dairy goes with better concentration, motility and morphology; more processed meat, full-fat dairy, soy foods, potatoes, sweets, sugary drinks, coffee 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.
Which foods have evidence behind them?
Most of what follows is observational: it shows that men who eat a certain way tend to have certain semen results, not that the food caused it. Only nuts, Mediterranean-style diets, soy protein and a lycopene supplement have been tested in randomized trials, and those trials were short, small and measured semen rather than pregnancies. "Moderate" here means at least one randomized trial that met its main measure, or a consistent signal across several studies; "weak" means a single study, small numbers, or results that disagree.
| Food | Evidence | What the studies found | Design and size |
|---|---|---|---|
| Nuts | Moderate | 60 to 75 g a day for 12 to 14 weeks improved vitality, motility and normal forms against a no-nuts control. Pooled, the two trials showed no significant effect on concentration [3][9][10] | 2 randomized trials, 223 healthy men pooled |
| Fish | Moderate | Men in the top quarter of fish intake had an average total count of 168 million, against 102 million in the bottom quarter, and more normal forms [11]. Fits the wider pattern in the review [1] | Cohort, 155 men at a fertility clinic |
| Mediterranean-style diet | Moderate | Six months on a Mediterranean diet raised concentration by about 2 million per mL and total count by about 8 million more than a low-fat diet [12]. A second trial combined the diet with exercise, so the two cannot be separated [13] | 2 randomized trials, 504 men randomized |
| Sugary drinks | Moderate | Danish men drinking the most (about 220 ml a day) had a median concentration 13 million per mL lower than non-drinkers [18]. US men drinking 1.3 or more servings a day had lower progressive motility [4] | Cross-sectional, 189 to 2,935 men |
| Fruit and vegetables | Mixed | Total intake was unrelated to semen quality in both studies that looked [14][15]. Where there is a signal, it is about pesticide residue rather than amount | Cohort 155, cross-sectional 189 |
| High-residue produce | Weak | Clinic patients eating the most high-residue produce had a 49% lower total count than those eating the least [14]. Residue was estimated from US surveillance data, not measured in the men, and the finding did not repeat in young healthy men [15] | Cohort, 155 men |
| Processed meat | Weak | The top quarter of intake had 1.7 percentage points fewer normal forms than the bottom quarter, with a confidence interval that nearly touches zero [11] | Cohort, 155 men |
| Dairy | Weak | Full-fat dairy was linked to fewer normal forms in young men [16]. In clinic patients, low-fat milk was linked to higher concentration and motility, and cheese to lower concentration only in men who had ever smoked [17] | Cross-sectional 189, cohort 155 |
| Soy | Weak | One clinic study found 41 million per mL lower concentration at the highest soy intake than at none, but a randomized crossover trial of soy protein found no effect on any semen measure [19][20] | Cross-sectional 99; crossover trial 32 |
| Tomatoes and lycopene | Weak | The one trial used a 14 mg lycopene supplement, not tomatoes. It missed its main measure (motile sperm concentration); fast-moving sperm and normal forms improved [21] | Randomized trial, 60 men |
Two notes on the table. In the larger nut trial, much of the gap in total count came from the control group's count falling (a median drop of about 15 million) rather than the nut group's rising (about 4 million), and the trial had links to the nut industry [3]. And no food or diet has been shown in a trial to increase pregnancies or live births. The largest trial in men with live birth as its outcome tested a supplement, folic acid with zinc, in 2,370 couples and found no difference (34% against 35%) [8], and a cohort of 245 men in fertility treatment found no link between any of eight healthy diet scores and either semen quality or live birth [22].
The nut trials
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 [3]. Against the control group, the nut group did better on total count, vitality, motility and morphology, and its sperm DNA fragmentation fell. The conference press release from ESHRE put the gains at about 16% for count, 6% for motility, 4% for vitality and 1% for morphology; the paper's own figures show much of the count gap came from the control group falling. One caveat the authors made themselves: the men were healthy and apparently fertile, so the result may not carry to men with low counts. The trial was also partly funded by the International Nut and Dried Fruit Council [3]. An earlier trial (Robbins and colleagues, Biology of Reproduction, 2012) randomized 117 healthy men to 75 g of walnuts a day for 12 weeks or no tree nuts: vitality, motility and morphology improved, and concentration did not [9]. That trial was funded in part by the California Walnut Commission. Together they are the best randomized evidence for any single food, and a 2024 meta-analysis of the two found no significant effect on concentration [10].
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. A later study of 2,935 young Danish men looked at sugary drinks directly: those drinking the most (a median of about 220 ml a day) had a median concentration 13 million per mL lower than men who drank none [18]. Sugary drinks are the item on the Western list with the most direct evidence of their own. Bottled water is a different question: it raises how many microplastic particles you swallow, but nobody has linked that to semen quality, and the microplastics guide explains why it stays a swap rather than a score.
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 trials ran 12 to 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 item in the Western pattern with the most direct evidence of its own.
- Cut processed meat and takeout 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. (Partly 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. Kinetics of the germinal epithelium in man. Recent Progress in Hormone Research, 1964.
- Schisterman EF, et al. Effect of folic acid and zinc supplementation in men on semen quality and live birth among couples undergoing infertility treatment: a randomized clinical trial. JAMA, 2020.
- Robbins WA, et al. Walnuts improve semen quality in men consuming a Western-style diet: randomized control dietary intervention trial. Biology of Reproduction, 2012. (Funded in part by the California Walnut Commission.)
- Cardoso BR, et al. Nut consumption and fertility: a systematic review and meta-analysis. Advances in Nutrition, 2024.
- Afeiche MC, et al. Processed meat intake is unfavorably and fish intake favorably associated with semen quality indicators among men attending a fertility clinic. Journal of Nutrition, 2014.
- Caruso P, et al. Effects of Mediterranean diet on semen parameters in healthy young adults: a randomized controlled trial. Minerva Endocrinologica, 2020.
- Montano L, et al. Effects of a lifestyle change intervention on semen quality in healthy young men living in highly polluted areas in Italy: the FASt randomized controlled trial. European Urology Focus, 2022 (online 2021).
- Chiu YH, et al. Fruit and vegetable intake and their pesticide residues in relation to semen quality among men from a fertility clinic. Human Reproduction, 2015.
- Chiu YH, et al. Intake of fruits and vegetables with low-to-moderate pesticide residues is positively associated with semen-quality parameters among young healthy men. Journal of Nutrition, 2016.
- Afeiche M, et al. Dairy food intake in relation to semen quality and reproductive hormone levels among physically active young men. Human Reproduction, 2013.
- Afeiche MC, et al. Dairy intake and semen quality among men attending a fertility clinic. Fertility and Sterility, 2014.
- Nassan FL, et al. Association between intake of soft drinks and testicular function in young men. Human Reproduction, 2021.
- Chavarro JE, et al. Soy food and isoflavone intake in relation to semen quality parameters among men from an infertility clinic. Human Reproduction, 2008.
- Beaton LK, et al. Soy protein isolates of varying isoflavone content do not adversely affect semen quality in healthy young men. Fertility and Sterility, 2010.
- Williams EA, et al. A randomized placebo-controlled trial to investigate the effect of lactolycopene on semen quality in healthy males. European Journal of Nutrition, 2020. (Part-funded by the supplement's maker.)
- Salas-Huetos A, et al. Paternal adherence to healthy dietary patterns in relation to sperm parameters and outcomes of assisted reproductive technologies. Fertility and Sterility, 2022.
Update, 5 October 2026. Added the food-by-food table, the walnut trial, the 2021 Danish soft drinks study and sources 8 to 22. Corrected: the 2017 review lists cereals, not whole grains, and does not list nuts or legumes among the foods linked to better semen quality; the percentage gains quoted for the nut trial are now attributed to its press release, since the paper reports them differently.
