Walnuts may support sperm health, according to new animal research

February 28, 2017, California Walnut Commission
Consuming walnuts may improve factors of sperm quality, key predictors of male fertility. Credit: California Walnut Commission

New animal research suggests eating a walnut-enriched diet may improve sperm quality by reducing lipid peroxidation, a process that can damage sperm cells. This form of cell damage harms sperm membranes, which are primarily made up of polyunsaturated fatty acids (PUFAs).1 Walnuts are the only tree nut that are predominantly comprised of PUFAs (one ounce contains 13 grams of PUFAs out of 18 grams of total fat). Research on the health benefits of PUFAs has advanced and most recently the 2015-2020 Dietary Guidelines for Americans has emphasized this type of fat as a replacement for saturated fats. As this is an animal study, there is no direct correlation to processes that occur in the human body. However, the findings support previous research suggesting that walnuts provide key nutrients that may be essential for sperm function.

Specifically, researchers found significant improvements in and morphology in mice that consumed a diet containing 19.6% of calories from (equivalent to about 2.5 ounces per day in humans) compared to mice that did not consume walnuts. Sperm motility (movement) and morphology (form) are markers of semen quality, which is a predictor of male fertility.3

"What's fascinating is we found that eating walnuts can actually help improve quality, likely by reducing peroxidative damage in ," says lead researcher, Patricia A. Martin-DeLeon, PhD of the University of Delaware. "More research is needed to understand the specific nutrients in walnuts that may contribute to this improvement, but the findings suggest that walnuts may be beneficial for sperm health."

This study supports findings from a published randomized control trial, which showed that eating 75 grams of walnuts per day (about 2.5 ounces) improved sperm vitality, motility and morphology in men who added walnuts to their diet compared to men who did not add walnuts.2 Healthy young men (117 total subjects) consumed their usual Western-style diet throughout the study and participated in monthly calls to share their dietary intake with the researchers. This research, led by Wendie A. Robbins, PhD, RN, FAAN of the UCLA Fielding School of Public Health and School of Nursing, established the potential role of walnuts in male fertility.

Intrigued by these findings, published in 2012 in Biology of Reproduction, Martin-DeLeon set out to understand the mechanism involved in improved sperm quality with a walnut-enriched diet. Healthy male mice as well as mice that were genetically predetermined to be infertile (Pmca4-/- gene deletion) were randomly assigned to a walnut-enriched diet or a control diet without walnuts that was followed for 9-11 weeks. Among the mice that consumed walnuts, fertile mice experienced a significant improvement in sperm motility and morphology and the infertile mice had a significant improvement in . Both groups experienced a significant reduction in peroxidative damage. However, investigators were unable to reverse the adverse effects on sperm motility in the infertile mice because of the genetic deletion in this group.

"This sheds light on how walnuts may improve sperm quality and is a great follow up to our human study that showed what effect walnuts may have," says Dr. Robbins. "Studies that look at the factors underlying sperm quality improvements are very valuable for advancing research on this important topic."

As with any research, study limitations should be considered. Animal research is provided as background and used to inform future studies needed to understand the effect on humans. Larger and longer-term studies, as well as studies in more diverse male populations, are needed to confirm the mechanism involved in improved with a walnut-enriched diet. Additionally, the impact on birth outcomes is still unknown and will require more investigation.

Explore further: A pack of walnuts a day keeps the fertility specialist away?

More information: 1. Lauren S. Coffua et al, Effectiveness of a walnut-enriched diet on murine sperm: involvement of reduced peroxidative damage, Heliyon (2017). DOI: 10.1016/j.heliyon.2017.e00250

2. Robbins WA, Xun L, FitzGerald LZ, et al. Walnuts improve semen quality in men consuming a Western-style diet: randomized control dietary intervention trial. Biol Reprod. 2012;87(4):101.

3. World Health Organization. Laboratory Manual for the Examination and Processing of Human Semen, 5th ed. Cambridge, UK: Cambridge University Press; 2010.

The study was funded by The California Walnut Commission.

Related Stories

A pack of walnuts a day keeps the fertility specialist away?

August 15, 2012
A paper published 15 August 2012 in Biology of Reproduction's Papers-in-Press reveals that eating 75 grams of walnuts a day improves the vitality, motility, and morphology of sperm in healthy men aged 21 to 35.

'Tis the season to indulge in walnuts

November 13, 2014
Researchers at UC Davis and other institutions have found that diets rich in whole walnuts or walnut oil slowed prostate cancer growth in mice. In addition, both walnuts and walnut oil reduced cholesterol and increased insulin ...

Prostate cancers are fewer, smaller on walnut-enriched diet

July 16, 2013
New research from the School of Medicine at The University of Texas Health Science Center San Antonio indicates that eating a modest amount of walnuts can protect against prostate cancer.

Walnuts may improve your colon health

June 2, 2016
Eating walnuts may change gut bacteria in a way that suppresses colon cancer, researchers led by UConn Health report in the journal Cancer Prevention Research.

Daily handful of walnuts linked to better diet and improvements in some health risk factors

November 23, 2015
Eating a daily handful of walnuts is linked to better overall diet quality and an improvement in certain risk factors among people at high risk of diabetes, finds research published in the online journal BMJ Open Diabetes ...

Animal study reveals potential brain-health benefits of a walnut-enriched diet

October 21, 2014
A new animal study published in the Journal of Alzheimer's Disease indicates that a diet including walnuts may have a beneficial effect in reducing the risk, delaying the onset, slowing the progression of, or preventing Alzheimer's ...

Recommended for you

Japanese team creates human oogonia using human stem cells in artificial mouse ovaries

September 21, 2018
A team of researchers with members from several institutions in Japan has successfully generated human oogonia inside of artificial mouse ovaries using human stem cells. In their paper published in the journal Science, the ...

A new approach to developing a vaccine against vivax malaria

September 21, 2018
A novel study reports an innovative approach for developing a vaccine against Plasmodium vivax, the most prevalent human malaria parasite outside sub-Saharan Africa. The study led by Hernando A. del Portillo and Carmen Fernandez-Becerra, ...

A Trojan Horse delivery for treating a rare, potentially deadly, blood-clotting disorder

September 21, 2018
In proof-of-concept experiments, University of Alabama at Birmingham researchers have highlighted a potential therapy for a rare but potentially deadly blood-clotting disorder, TTP. The researchers deliver this therapeutic ...

Researchers explore how changes in diet alter microbiome in artificial intestine

September 21, 2018
Using an artificial intestine they created, researchers have shown that the microbiome can quickly adapt from the bacterial equivalent of a typical western diet to one composed exclusively of dietary fats. That adaptation ...

Study identifies stem cell that gives rise to new bone and cartilage in humans

September 20, 2018
A decade-long effort led by Stanford University School of Medicine scientists has been rewarded with the identification of the human skeletal stem cell.

Scientists grow human esophagus in lab

September 20, 2018
Scientists working to bioengineer the entire human gastrointestinal system in a laboratory now report using pluripotent stem cells to grow human esophageal organoids.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.