To study the effect of walnuts on semen quality, researchers randomly selected 117 young men to follow their usual diet, or their usual diet plus 75 grams of walnuts per day. For reference, 75 grams is 2.6 ounces, which translates into approximately two large handfuls of walnuts per day. The men were 21-to-35 years old, and their semen quality--sperm vitality, motility, and morphology--was measured before and after the 12-week study.
Vitality refers to the overall strength and health of sperm. Motility refers to how well the sperm move, or swim, and morphology refers to the structure of the sperm.
After 12 weeks, compared with men eating their usual diet, all three measures of semen quality--sperm vitality, motility, and morphology--improved in the men eating their usual diet plus walnuts.
Focus on fertility
This small study found that eating walnuts improves semen quality, however, more research is needed to confirm these findings. Fortunately, walnuts are loaded with healthful fats, vitamins, and minerals, so for most men there are no downsides to eating more walnuts. And as noted by lead study author Wendie Robbins, PhD, associate professor in the UCLA Program on Genomics and Nutrition, for couples looking to start a family, "This study shows that what men eat is important, too."
Our tips can help you make the most of your diet and lifestyle choices, for best total and reproductive health:
- Start with the experts. The study included healthy young men, with normal fertility. It does not tell us whether walnuts improve semen quality in men with underlying fertility issues. If you, as a couple, have tried to get pregnant without success, see your doctor for a complete health work up. Adding walnuts can't hurt, but you may need medical management to address other conditions that affect fertility.
- Adjust accordingly. At 185 calories per ounce, walnuts are caloric; however, the men in the walnut group did not gain weight, suggesting they adjusted their diets to account for the extra calories. When adding in healthy new foods, make sure you do the same to avoid weight gain.
- Tackle the total picture. Eating walnuts is a healthy choice, but for best health, which translates into better fertility, aim to reach a healthy body weight, exercise regularly, and improve total diet quality. This means eating less added sugar and fewer processed foods, and eating more vegetables, fruit, beans, lentils, nuts, seeds, and whole grains.
(Biol Reprod 2012;87:101, 1-8)