Walnuts May Improve Sperm Quality in Healthy Men
Researchers Now Want to See Whether Walnuts Can Help Men With Fertility Issues Become Fathers
Aug. 15, 2012 -- If you aspire to fatherhood, it might not hurt to go a little nuts. Walnuts, that is.
Eating 2.5 ounces of walnuts a day -- a little more than half a cup -- for 12 weeks improved sperm quality in healthy young men, researchers report. Their study is part of a growing body of evidence that men’s dietary and lifestyle choices might affect their fertility.
The new study, funded in part by the California Walnut Commission, enrolled 117 men aged 21 to 35 who ate a typical Western diet.
Half the men were randomly assigned to eat 2.5 ounces of walnuts a day, along with their usual diet. The other men were told to continue their regular diet but not to eat any tree nuts.
Walnuts are the only nuts with appreciable levels of omega-3 fatty acids, which some studies of male infertility have linked to better sperm quality, says researcher Wendie Robbins, PhD, of the UCLA Fielding School of Public Health. Animal and human studies have shown that omega-3 fats and other polyunsaturated fatty acids “play critical roles in sperm maturation and membrane function,” Robbins’ team writes.
Previous research has shown that men with poor sperm counts saw improvement after taking fish oil supplements high in omega-3 fats, Robbins says. And a study of men attending a fertility clinic, published in May by the journal Human Reproduction, found that high intake of omega-3 fats was linked to more normal sperm size and shape, while high intake of saturated fats was related to lower sperm concentration.
In the new study, most of the walnut eaters snacked on the shelled whole nuts straight out of the package, Robbins says. Others mixed them with applesauce and cinnamon in a blender or chopped them up and added them to meatloaf, hamburger, and spaghetti sauce.
Before and after the experiment, the men’s semen quality was analyzed by a researcher who did not know which ones had eaten walnuts. The researcher looked at sperm concentration, vitality, ability to move, shape and size, and chromosome abnormalities, all thought to be related to fertility.