Is there a beneficial effect of gamma-linolenic acid supplementation on body fat in postmenopausal hypertensive women? A prospective randomized double-blind placebo-controlled trial.

Abstract

Systemic arterial hypertension and obesity are major public health problems that increase risks of serious cardiovascular diseases and kidney failure as well as increase mortality. Substances that can alleviate these problems are desirable. We evaluated the beneficial effects of nutritional supplementation with gamma-linolenic acid in postmenopausal hypertensive women. This was a prospective, double-blind, placebo-controlled, randomized study involving 96 postmenopausal women. Participants were divided into two groups either receiving 1,000 mg of borage oil rich in gamma-linolenic acid + vitamin E (drug) or only vitamin E (placebo) capsules for 6 months. They were followed up monthly to assess the impact on systemic blood pressure and body composition. To verify group homogeneity, Fisher's exact and Student t tests were performed. To evaluate differences in various parameters between the two groups and at various times, repeated measures analysis of variance was performed, with Bonferroni correction. The power of the test was calculated based on the difference in the mean systolic blood pressure between baseline and after 6 months of treatment in the placebo group and in the drug group. A 92.9% test power was found with a 95% confidence interval. There was a significant reduction in the systolic and diastolic pressure as well as a significant change in waist-hip ratio (P < 0.01) in the drug group as compared with the placebo group. Supplementation with borage oil rich in gamma-linolenic acid had significant beneficial short-term effects without showing any adverse effect. There remains a need for further studies to evaluate long-term benefits.