High-Carbohydrate Diets Are Linked to Higher Blood Pressure

NEW YORK (Reuters Health) May 29 - Carbohydrate-rich diets are associated with slightly higher blood pressure than diets rich in cis-monounsaturated fat, according to findings published in the May issue of the American Journal of Clinical Nutrition.

However, the difference is not enough to justify making dietary recommendations to change the carbohydrate and cis-monounsaturated fat content of the diet in order to manage blood pressure, Dr. Meena Shah and colleagues from the University of Texas Southwestern Medical Center at Dallas, write.

The researchers conducted a meta-analysis of intervention studies that compared high-carbohydrate and high-cis-monounsaturated fat diets in order to better understand the effect on blood pressure of carbohydrate and cis-monounsaturated fat. Study diets had to be isoenergetic in order to be included in the analysis.

In addition, the patients' body weight had to remain stable. A total of 10 studies were included in the analysis, including six randomized crossover, one randomized parallel, and three nonrandomized.

Results of a random-effects model revealed that carbohydrate-rich diets led to significantly higher systolic blood pressure (difference: 2.6 mm Hg, p = 0.002) and diastolic blood pressure (difference: 1.8 mm Hg, p = 0.05) compared to diets rich in cis-monounsaturated fat. When the analysis was restricted to randomized crossover studies, systolic blood pressure (1.3 mm Hg, p = 0.11) and diastolic blood pressure (0.9 mm Hg, p = 0.11) were higher with carbohydrate-rich diets than with high cis-monounsaturated fat diets, but the difference was not significant.

"The slightly higher blood pressure of subjects following the high-carbohydrate diet may be due to accentuation of hyperinsulinemia," Dr. Shah's team suggests. "Hyperinsulinemia is suggested to enhance sympathetic nervous system activity, which increases heart rate, cardiac output, vascular resistance, and sodium retention and thus blood pressure."

Am J Clin Nutr 2007;85:1251-1256.

Source: http://www.medscape.com/viewarticle/557416?src=mp