Walnuts are unique as a nutrient-dense whole food source of alpha linolenic acid (ALA), an essential omega-3 polyunsaturated fatty acid. An ever-growing body of research has shown that walnuts play a significant role in a healthy lifestyle. Numerous studies suggest that omega-3s may help reduce the risk for heart disease. More recent health studies are further exploring the benefits of walnuts in relation to cardiovascular health, diabetes and weight management. Following are some highlights of the most recent studies.

Endothelial Cell Function

Dr. Paul Davis, a professor in the nutrition department at the University of California, researched whether walnuts could reduce the effects of endothelin, a substance that promotes arterial inflammation and plaque development. The study was published in the January edition of the Journal of Nutrition. His research involved feeding male hamsters high-fat, hyperlipidemic diets supplemented with either walnuts; alpha-tocopherol, a form of vitamin E; walnut oil; or gamma-tocopherol, the form of vitamin E found in walnuts. Hamsters fed the walnut supplemented diet had the greatest reduction in endothelin activity, which means their arteries likely developed the least amount of plaque on the diet specifically designed to cause heart disease. This study helped explain the mechanisms behind the endothelial cell benefits of walnuts seen in human intervention trials.

Melatonin

Research conducted at the University of Texas Health Science Center in San Antonio has proven walnuts are a natural source of melatonin, and that when walnuts are eaten the melatonin gets absorbed in the bloodstream where it exerts antioxidant activity. According to Russel J. Reiter, Ph.D., Professor of Neuroendocrinology at the University of Texas Health Science Center at San Antonio, “The ingredients in walnuts would be expected to reduce the incidence of cancer, delay or make less severe neurodegenerative diseases of aging, including Parkinsonism, Alzheimer’s disease and reduce the severity of cardiovascular disease.” Published in the September 2005 issue of Nutrition: The International Journal of Applied and Basic Nutritional Sciences, the study is titled “Melatonin in walnuts: Influence on levels of melatonin and total antioxidant capacity of blood.”

Weight Management

Recent research from Loma Linda University suggests that adding walnuts to the diet does not have a detrimental effect on weight. The research was published in the November issue of the British Journal of Nutrition. The randomized cross-over field trial included two six-month diet periods, a control diet and a walnut-supplemented diet, with 90 participants (50 females; 40
males) aged 30-72 years. During the walnut phase, study participants were simply asked to eat
1-1.5 ounces of walnuts each day. The average weight change during the walnut phase was insignificant at only 0.4 kg over six months. .Study participants were not told this was a weight study. They were only instructed to add walnuts to their diet. Researchers think the participants intuitively adjusted their food and caloric intake to compensate for the walnut calories. Other studies have proven that walnuts aid in satiety, and may benefit consumers trying to lose weight or maintain weight.

Diabetes
A study published in the July 2005 issue of the Journal of the American Dietetic Association (JADA) shows that eating a handful of walnuts every day can help patients with type 2 diabetes achieve recommended intakes for polyunsaturated fatty acids (such as omega-3s), critical to protecting the heart. These findings build on a study published in the December 2004 issue of Diabetes Care, a journal of the American Diabetes Association (ADA), which shows that, for patients with type 2 diabetes, a whole foods diet including walnuts can reduce LDL cholesterol by as much as 10 percent.

Future Studies
Other studies in progress or scheduled to be published include studies on walnuts with relation to: bone health; prostate cancer; vitamin E; cytokines/heart health; postprandial arterial function; blood pressure; breast cancer; antioxidant status; walnuts, blueberries and aging; walnuts vs. fish; walnuts and diabetes; fatty acid balance; satiety and diabetes.

back to site