Nuts boost BP regulating reflex

Eating a diet rich in cashew nuts improves the sensitivity of a key reflex, for maintaining healthy blood pressure, known as the baroreflex. The baroreflex becomes less sensitive as heart disease develops. People with metabolic syndrome, a constellation of symptoms including obesity, high blood sugar and high cholesterol, have an increased risk of heart disease and diabetes, and also have impaired baroreflex sensitivity. Cashews are high in monounsaturated fatty acids (MUFA), while walnuts contain polyunsaturated fatty acids (PUFA). To investigate the effect of the nuts in people with the metabolic syndrome, researchers from the North-West University, Potchefstroom, South Africa, divided 62 people with the syndrome into three groups. One followed a normal diet, the second ate a diet with 20% of calories from walnuts, and the third got 20% of their calories from unsalted cashews. It was found that after eight weeks, there was no change in baroreflex sensitivity among people on the control diet. Those on the walnut-rich diet showed significant impairment in baroreflex sensitivity, while baroreflex sensitivity improved among those eating the cashew-rich diet. No other significant changes were seen in other components of the metabolic syndrome, and neither diet produced changes in levels of cholesterol and other blood fats. However, the people on the cashew diet showed higher blood sugar levels. The most obvious interpretation of the findings is to attribute them to differing effects of MUFA and PUFA on baroreflex sensitivity. However, the nuts also contain a wide variety of other ingredients that can benefit blood vessel function such as fibre and folic acid. An overwhelming body of evidence has demonstrated the beneficial effects of nuts, but the above study suggests that intake of large quantities of walnuts and cashews may have detrimental effects on the baroreflex sensitivity and glycaemia, respectively, at least in individuals with metabolic syndrome. Therefore, further research defining the potential benefits and harmful effects of nuts, especially when consumed in large quantities, is needed.