beta-hydroxy-beta-methylbutyrate (HMB) supplementation in humans is safe and may decrease cardiovascular risk factors

The leucine metabolite, beta-hydroxy-beta-methylbutyrate (HMB) enhances the effects of exercise on muscle size and strength. Although several reports in animals and humans indicate that HMB is safe, quantitative safety data i n humans have not been reported definitively. The objective of this work wa s to summarize safety data collected in nine studies in which humans were f ed 3 g HMB/d. The studies were from 3 to 8 wk in duration, included both ma les and females, young and old, exercising or nonexercising. Organ and tiss ue function was assessed by blood chemistry and hematology; subtle effects on emotional perception were measured with an emotional profile test (Circu mplex), and tolerance of HMB was assessed with a battery of 32 health-relat ed questions. HMB did not adversely affect any surrogate marker of tissue h ealth and function. The Circumplex emotion profile indicated that HMB signi ficantly decreased (improved) one indicator of negative mood (Unactivated U npleasant Affect category, P < 0.05). No untoward effects of HMB were indic ated. Compared with the placebo, HMB supplementation resulted in a net decr ease in total cholesterol (5.8%, P < 0.03), a decrease in LDL cholesterol ( 7.3%, P < 0.01) and a decrease in systolic blood pressure (4.4 mm Hg, P < 0 .05). These effects of HMB on surrogate markers of cardiovascular health co uld result in a decrease in the risk of heart attack and stroke. In conclus ion, the objective data collected across nine experiments indicate that HMB can be taken safely as an ergogenic aid for exercise and that objective me asures of health and perception of well-being are generally enhanced.