Diabetes is the most common cause of morbidity and mortality. According to figures issued by the 2012 German Health Survey, 7.2% of the population in Germany suffers from diabetes. The risk of cardiovascular mortality is three to five times higher in men and women suffering from type 2 diabetes.
The study by Ma et al. (2010) aimed to examine the effect of daily walnut consumption in type 2 diabetes patients. A total of 24 subjects participated in the randomised controlled crossover study over a study period of 20 weeks (14 women, 10 men - average age: 58 years). Preparation for the study spanned a period of four weeks, during which all subjects had to refrain from consuming walnuts. The study participants were randomly allocated to one of the two groups: the first group received an ad libitum (discretionary) diet incorporating the daily consumption of 56 g of walnuts (366 kcal). The second group also followed an ad libitum diet, refraining, however, from consuming walnuts. After eight weeks, the groups were interchanged (crossover). The effects arising from walnut consumption were measured on the basis of the vascular endothelial function using flow mediated dilatation (FMD) and further cardiovascular biomarkers. In total, there were five days of measurement during the entire study period.
The results show that endothelial function was significantly improved following consumption of the walnut-rich diet in comparison with the ad libitum diet, which precluded walnut consumption. The endothelial cells effect important physiological processes and are responsible for the elasticity of the blood vessels. Furthermore, in relation to the values recorded at the time of measurement upon commencement of the study, total cholesterol levels and LDL (low density lipoprotein) were lowered; nevertheless, these results were not significant when compared with those in the test group (without walnuts). Consequently, in summary it may be stated that a walnut-rich diet increases endothelial-dependent vasodilation (vascular dilation) in patients presenting with type 2 diabetes. This suggests that walnuts may contribute to a reduction in cardiovascular diseases. Nevertheless, further long-term studies are needed in order to achieve more definitive results.
Ma Y, Njike VY, Millet J, Dutta S, Doughty K, Treu JA, Katz DL (2010): Effects of walnut consumption on endothelial function in type 2 diabetic subjects: a randomized controlled crossover trial. Diabetes Care, 227-232.