Monday, September 30, 2013

Walnuts in Diet Can Improve Endothelial Functions for Overweight Adults

Crazy for snacks, go nuts, walnuts to be exact.

Medical researchers from the Yale-Griffin Prevention Research Center in Connecticut have found evidence suggestive that adding walnuts to one's diet can protect against diabetes and heart disease in at-risk individuals.

The research found that daily intake of 56g* of walnuts improves endothelial function in overweight adults with visceral adiposity. The addition of walnuts to the diet does not lead to weight gain.

Walnuts are a uniquely rich source of a-linolenic acid (ALA), and epidemiological studies suggest that plant-derived ALA may confer particular cardiovascular benefits. A meta-analysis investigating the impact of walnut consumption on blood lipids showed that walnut-enriched diets significantly decreased total cholesterol and low-density lipoprotein cholesterol (LDL-C) when compared with control diets for the duration of the short-term trials. Furthermore, walnuts are also rich in tocopherol, phenolic antioxidants, folic acid, and magnesium, nutrients that have been shown to impact endothelial function favourably.

For the study, a sample of 46 adults aged 30-75 were selected. Participants had a Body Mass Index larger than 25, and a waist circumference exceeding 40 inches for men and 35 inches for women. They were also required to be non-smokers, and all exhibited one or more additional risk factors for metabolic syndrome, a precursor of diabetes and cardiovascular disease. The group was randomly assigned to two 8-week sequences of either a walnut-enriched ad libitum diet or an ad libitum diet without walnuts. Those chosen for the walnut diet were instructed to consume 56g of shelled, unroasted English walnuts per day as a snack or with a meal.

FMD or flow-mediated vasodilatation of the brachial artery improved significantly from baseline in subjects on the walnut-enriched diet as compared with the control diet. Beneficial trends in systolic blood pressure reduction were seen, and maintenance of the baseline anthropometric values was also observed. Secondary measures included serum lipid panel, fasting glucose and insulin, were unaltered.

"We know that improving diets tends to be hard, but adding a single food is easy," explained Dr. David Katz, Director of the Yale-Griffin Prevention Research Center and lead author of the research team. "Our theory is that if a highly nutritious, satiating food like walnuts is added to the diet, there are dual benefits: the benefits of that nutrient rich addition and removal of the less nutritious foods."


The above story is based on materials provided by Taylor & Francis, via AlphaGalileo.

The original research article is now available online in the Journal of the American College of Nutrition:

Katz DL, Davidhi A, Ma Y, Kavak Y, Bifulco L, Njike VY. Effects of walnuts on endothelial function in overweight adults with visceral obesity: a randomized, controlled, crossover trial. J Am Coll Nutr. 2012 Dec;31(6):415-23. 

Click HERE to read the full text.

* AUD1.30 (RM3.90) for 56g of Walnuts at Coles

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