Walnuts seem to be making their way into the news with increasing frequency lately. A recent study, published in the journal BMJ Open Diabetes Research & Care showed that including walnuts into the diet significantly improved diet quality, endothelial functional (lining of the walls of blood vessels), total and LDL cholesterol (bad cholesterol).
This study was a randomized, controlled trial that included 112 participants ages 25 75 considered high-risk for developing diabetes. They were assigned to two separate treatment arms, dietary counseling or no dietary counseling to adjust calorie intake. The groups were further randomized within each treatment arm to receive 56 grams of walnuts per day or no walnuts. The outcomes assessed were diet quality, body composition, and cardiac risk measures (i.e. LDL levels, blood glucose, and blood pressure), body composition (percent body fat), and Body Mass Index (BMI).
The study, which lasted six months, found that whether or not dietary counseling was received to adjust calories, there were significant overall benefits. Diet quality assessed by the Healthy Eating Index 2010. Endothelial function was measured using the diameter of the brachial artery, one of the medium-sized blood vessels traversing down the arm. They measured the velocity of blood flow before and after the use of a blood pressure cuff. There would be a greater difference in velocity of blood flow if the arteries are more pliable and not subject to stiffening from plaque buildup. Lipid profile measured total cholesterol, LDL, HDL and triglycerides.
Our data suggest that inclusion of walnuts in the diet, with or without dietary counseling to adjust caloric intake, improved diet quality and may also improve endothelial function, and reduce total and LDL cholesterol in this sample of adults at risk for diabetes, according to the research team led by Dr, David Katz, Yale University Prevention Research Center.
Another study published in the American Journal of Clinical Nutrition recently, also found that by consuming tree nuts, such as walnuts, there was a reduction in total cholesterol, triglycerides, LDL cholesterol and ApoB (apolipoprotein B a main component of LDL cholesterol). The study was performed conducting a systematic review and meta-analysis of 61 controlled trials where nut consumption was used as an intervention, hence giving the studies more validity. This is important in that the data would be less credible if investigators had left it to the discretion of participants to consume nuts.
Our study results further support the growing body of research that tree nuts, such as walnuts, can reduce the risk of cardiovascular disease, stated Michael Falk, PhD, Life Sciences Research Organization, one of the authors of the study. Tree nuts contain important nutrients such as unsaturated fats, protein, vitamins and minerals. Walnuts are the only nut that provide a significant amount (2.5 grams per one ounce serving) of alpha-linolenic acid (ALA), the plant-based form of omega-3s. Omega-3 fatty acids are thought to slow down plaque growth in arteries.
Although this particular study was conducted with support from The International Tree Nut Council Nutrition Research and Education Foundation, it does not discount the fact that there are values to incorporating walnuts into the diet. Caution must be exercised as they are calorie-dense and can contribute to an increase in body fat, therefore, like any good thing in life, moderation is key.