The Benefits of Eating Walnuts on Overall Health

Multiple new research abstracts suggest walnuts may have the potential to positively affect several important health factors. From their impact on colon cancer and certain aspects of cognitive aging, to their positive effect on both gut health and vascular health, the research findings presented at Experimental Biology 2015 (EB) detail our latest understanding of walnuts’ inner workings. Running March 28 through April 1 in Boston, this annual meeting attracts an international audience of over 14,000 leading research scientists and exhibitors.

«These findings help advance the understanding of the many advantages of eating walnuts as part of a healthy diet, and add to the more than 159 published papers over 20 years that have shown how walnuts affect heart health, diabetes, cancer, cognition, fertility and weight management», said Dennis A. Balint, CEO, California Walnut Commission.

There are numerous possible active ingredients in walnuts that may be contributing factors in providing these health benefits. One component that differentiates walnuts is alpha-linolenic acid (ALA), the plant-based omega-3 fatty acid. Walnuts are the only nut that contain a significant amount of alpha-linolenic acid (ALA) with 2.5 grams per one ounce serving.

While scientific conclusions cannot yet be drawn from the abstracts presented at EB 2015, the following summaries share the latest findings:

• Colon Cancer: For the first time, researchers looked at whether components of walnuts have an effect on colon cancer cells. This cell study 1 was conducted by the Department of Nutritional Science and Food Management at the Ewha Womans University in Korea, and showed that walnut extract significantly slowed the survival of the cancer stem cells as well as reduced the stemness of colon cancer stem cells. Given the results, researchers state there is reason to further explore the role of walnut consumption in colon cancer therapies targeting cancer stem cells.

•  Gut Health: The gut microbiome is an ecosystem of bacteria that helps our bodies digest and use the food we eat; changes in the gut microbiome are linked to chronic diseases. A recent animal study 2 conducted by the Department of Physiology School of Medicine at Louisiana State University Health Sciences Center looked at the effect of walnuts on two major gut bacteria communities. A diet with walnuts (approximately 2 ounce human diet equivalent) significantly altered the ratio of the two communities, therefore suggesting «a new mechanism, changing the gut microbial environment, by which walnuts may exert their beneficial health effects.» As this study was performed on animals, however, findings cannot yet be implied for humans.
• Aging/Brain Health: This animal study 3 from the Human Nutrition Research Center on Aging at Tufts University looked at healthy rats, both young and old, and the impact of walnuts – a source of polyunsaturated fatty acids and nutrients such as folate, selenium, magnesium and polyphenols – on mechanisms in critical regions of the brain. Animals were segmented into three groups – one, the control group, who ate no walnuts at all (0%); a second that had 6% of their diet comprised of walnuts; and a third that had 9% of their diet comprised of walnuts (equivalent to one ounce and 1.5 ounces respectively in a human diet). The groups were monitored for ten weeks. According to the researchers, incorporating walnuts into one’s diet may have protective effects on the aging brain. As this study was performed on animals, however, findings cannot yet be implied for humans.

•  Vascular Health: Microvascular function refers to the health of our smallest blood vessels, such as capillaries. A study 4 from the Departments of Nutrition and Internal Medicine at the University of California, Davis of postmenopausal women with high cholesterol looked at the short-term impact of walnut consumption. The group that ate 40 grams, or 1.5 ounces, of walnuts per day saw improved vascular function. The study concludes this improvement is due to the effects from the walnut-derived fatty acids, alpha-linolenic acid (ALA) and linoleic acid (LA).

Resources:

1. Kim YS, Choi SW, Min SJ, Lee J, Kim Y. Walnut Phenol Extracts Inhibit Stemness of Colon Cancer Stem Cells in Vitro. FASEB J April 2015 29:752.10.
2. Byerley L, Ponder M, Lorenzo B, Banks S, Taylor C, Luo M, Blanchard E, Welsh D. Walnut Consumption Changes the Relative Abundance of Bacteroidetes and Firmicutes in the Gut. FASEB J April 201529:1006.1.
3. Poulose S, Bielinski D, Crott J, Roe A, Thangthaeng N, Shukitt-Hale B. Effects of Aging and Walnut-Rich Diet on DNA Methylation and Expression of Immediate-Early Genes in Critical Brain Regions. FASEB J April 2015 29:749.7.
4. Holt R, Yim  SJ, Shearer G, Keen C, Djurica D, Newman J, Hackman R. The Change in Human Microvascular Function and its Relationship to Plasma Epoxide Content After Short-Term Walnut Intake. FASEB J April 2015 29:923.9.