It's no secret that nuts are good for your heart. We know that consuming nuts can dramatically reduce cardiovascular disease risk, but scientists are just beginning to figure out how this works. A recent study found that almonds have a potent antioxidant effect, leading to decreases in circulating oxidized LDL, helping to keep the arteries clear of atherosclerotic plaque.1
Like all nuts, walnuts are rich in fiber, minerals, micronutrients, phytosterols, antioxidants, and monounsaturated fats, but walnuts stand out because of their distinctively high levels of ALA, an omega-3 fatty acid and precursor to EPA and DHA.
Researchers at Yale University wondered whether walnuts would have beneficial effects on blood vessel function in individuals at risk for cardiovascular disease - those with type 2 diabetes.
Twenty-four subjects with type 2 diabetes were included in the study. Half were assigned to supplement their diets with 2 ounces of walnuts per day for 8 weeks.
The researchers tested flow-mediated dilatation (FMD), which is a measure of how well the endothelial cells, the cells that line all blood vessels, are working to keep blood pressure in a favorable range. One of the endothelial cells' most important jobs is to produce nitric oxide, which regulates blood pressure by relaxing the muscle in the walls of the arteries.
After 8 weeks of daily walnut consumption, flow-mediated dilatation was improved - the blood vessels were able to dilate more in the subjects who ate walnuts.2 This is good news for overall cardiovascular disease risk since loss of endothelial function is one of the initiating events in atherosclerotic plaque development.
Want another reason to eat some walnuts? Fascinatingly, nuts and seeds also promote weight loss. Research on the issue shows when an equal number of carbohydrate calories are replaced with nuts and seeds weight loss increases. Scientists from Purdue University did a thorough review of all the research studies that looked at nut intake and weight loss. Not only did they find nuts were a rich source of nutrients and protect the heart and blood vessels, but they found a surprising inverse association between nut intake and Body Mass Index. Most studies explained this as being due to the appetite suppressing effect of nuts, but like beans all the calories may not be bio-accessible, meaning that not all of the calories in nuts are absorbed. Plus, they enhance the absorbtion of nutrients in vegetables when consumed in the same meal.3
We can apply this information by following including a variety of nuts and seeds in our diets. As time goes on, we can be sure that scientists will continue to reveal many more health-promoting properties of nuts and seeds.
by Joel Fuhrman, M.D. and Deana Ferreri, Ph.D.
1. Jenkins DJ, Kendall CW, Marchie A, et al. Almonds Reduce Biomarkers of Lipid Peroxidation in Older Hyperlipidemic Subjects. J. Nutr. 138: 908-913, 2008.
USDA/Agricultural Research Service (2008, November 4). Antioxidant Effects From Eating Almonds. ScienceDaily. Retrieved February 25, 2010, from http://www.sciencedaily.com /releases/2008/10/081031213057.htm
2. Ma Y, Njike VY, Millet J, et al. Effects of walnut consumption on endothelial function in type 2 diabetic subjects: a randomized controlled crossover trial. Diabetes Care. 2010 Feb;33(2):227-32. Epub 2009 Oct 30.
Medscape Medical News: Walnuts Shown to Improve Endothelial Function in Diabetics
3. Mattes RD et al. Impact of peanuts and tree nuts on body weight and healthy weight loss in adults. J Nutr. 2008 Sep;138(9):1741S-1745S.