High-carb diet linked to higher blood pressure

Carbohydrate-rich diets are associated with slightly higher blood pressure than diets rich in monounsaturated fats, according to the findings published in the American Journal of Clinical Nutrition.

However, the difference is not enough to justify making recommendations to change the carbohydrate and monounsaturated fat content of the diets to control blood pressure, Dr. Meena Shah and colleagues from the University of Texas Southwestern Medical Center at Dallas, report

The researchers conducted a review of 10 published studies, also referred to as a "meta-analysis," that compared high-carbohydrate and high-monounsaturated fat diets to better understand their effects on blood pressure.
The results of the authors' mathematical model revealed that the carbohydrate-rich diets led to a significantly higher blood pressure compared with the diets rich in monounsaturated fat.

When the analysis was restricted to studies in which the subjects were randomly assigned to one diet and then switch over to the other diet, the blood pressure readings were higher for the carbohydrate-rich diets than the monounsaturated fat diets, but the difference was not statistically significant.

The slight increase in blood pressure of subjects in the high-carbohydrate diet may be cause by elevated insulin levels, or "hyperinsulinemia," Shah's team suggests.

It has been suggested that hyperinsulinemia enhances the activity of the sympathetic nervous system, "which increases heart rate, cardiac output, vascular resistance, and sodium retention and thus blood pressure."

SOURCE: American Journal of Clinical Nutrition, May 2007.