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Add Walnuts to Your Baby-Making Recipe
When trying to get pregnant, it may be helpful for men to go a little (wal)nuts for their … ahem … well, for their "nuts."
Researchers at the UCLA School of Nursing have found that the nutrient-rich walnut may improve men's fertility. Eating about two handfuls of walnuts a day improved sperm health in their study.
"Women are not the only ones who should be paying attention to what they eat when they are trying to get pregnant," says Wendie Robbins, a professor at the UCLA School of Nursing and UCLA's Fielding School of Public Health and lead author of the study. "This study shows that what men eat is important too."
"We’ve known for a long time that increased oxidative stress, measured in the laboratory as ‘Reactive Oxidative Species' or ‘ROS’ and more recently related to increased rates of DNA fragmentation, has an adverse effect on sperm function and sperm fertilizing capacity," says George M. Grunert, M.D., medical director of Fertility Specialists of Houston. "Reducing ROS and DNA fragmentation improves fertility. A number of anti-inflammatories and antioxidants have been found to be of value, specifically vitamins C, D and E and omega-3 fatty acids. Pharmacologic treatments have focused on non-steroidal anti-inflammatories. As this article points out, walnuts may be another good, natural source of antioxidants and omega-3 fatty acids."
The Nut Study
The study — "Walnuts Improve Semen Quality in Men Consuming a Western-Style Diet: Randomized Control Dietary Intervention Trial" — has been published in the journal Biology of Reproduction. The study set out to look at the effects of a plant source of omega-3 on sperm and involved 117 men between the ages of 21 and 35. The researchers divided the men into two groups. One group added 75 grams (around 2.5 ounces) of whole-shelled walnuts to their diet daily, and the other group continued their usual diet, but they avoided eating tree nuts.
Both groups of men ate a typical Western-style diet, but the researchers found significant improvements in sperm parameters in the men who ate the walnuts. The men who ate no tree nuts had no change in their sperm.
The researchers analyzed sperm before the study began and after 12 weeks. They found that eating the walnuts had improved sperm shape (morphology) and movement (motility) — and the sperm of the nut eaters had fewer chromosomal abnormalities. The men themselves had no significant changes in body mass index, weight or activity level.
"The study clearly showed that eating a handful of walnuts a day had a significant effect on increasing sperm health, including vitality, motility and morphology in healthy men," says Donald P. Evenson, Ph.D., HCLD, president and director of SCSA Diagnostics, the company that tests sperm DNA/chromatin for DNA damage. "Human life is dependent on an oxygen environment; however, a negative side of this fact is that oxidative (oxygen) stress can cause damage to cells, including sperm. Reactive oxygen species (ROS) damage sperm membranes, including mitochondrial — the sperm engine for motility — membranes. Consumption of walnuts, a rich nutritional source of the antioxidant omega-3, was related to the reducing of the damaging effects on sperm parameters.
"Besides the classical sperm parameters measured in a routine semen analysis, it would have been of great interest to have determined the effect of the walnut diet on sperm DNA integrity," Dr. Evenson says. " While the classical sperm parameters are important for fertilization of the egg, once the sperm has entered into the egg, the all-important factor for normal embryo growth is the integrity of the sperm DNA which, comprises one-half of the embryo’s genetic makeup."
Increasingly, research is showing that dietary factors are important to fertility. A recent study by the Harvard School of Public Health demonstrated that avocado and olive oil — good sources of monounsaturated fat — were linked to better odds of live birth during in vitro fertilization (IVF).
Walnuts are a good source of a-linolenic acid, a natural plant source of omega-3 fatty acids, and the researchers suspect this is what helped improve the men's sperm. Studies have shown that omega-3 fats play a role in sperm maturation and membrane function.
Walnuts are also rich in monunsaturated fats and are full of minerals, antioxidants and vitamins that are important for overall health. Regularly eating walnuts can also contribute to heart health by lowering levels of bad cholesterol and raising levels of good cholesterol.
So for whatever reason, walnuts reign supreme in the world of nuts. When you're trying to conceive, it may be helpful to add nuts, but always remember to talk to your doctor before undergoing any significant dietary change.
"Research studies have shown that nutrient antioxidants can reduce the extent of sperm DNA damage, thereby leading to a higher probability of a healthy pregnancy," Dr. Evenson says. "There is however, a new a cautionary note against the often stated phrase that 'a lot more of what may be good for you is not necessarily good for you.'"
This saying applies to sperm chromatin quality as noted in a 2007 study: "Antioxidants to reduced sperm DNA fragmentation: an unexpected adverse effect."
"What was observed was that while giving men a new antioxidant cocktail to bring down the level of sperm DNA fragmentation, it was noted that the other factor that the SCSA technique measures is the level of chromatin condensation," Dr. Evenson says. The level of sperm DNA fragmentation went down, but the level of sperm chromatin decondensation increased with negative results on pregnancy outcome.
"At this point we don't know the exact dose of walnuts, but we can say that regular consumption may be beneficial," Dr. Grunert says. "As with anything though, the advice has to also include common sense and moderation."