A combination of HMB (a metabolite of leucine), glutamine and arginine may improve vascular function and blood flow in older people, says a new study.
Scientists from the University of Alabama report that a supplement containing HMB (beta-hydroxy-beta-methylbutyrate), glutamine and arginine (Juven by Abbott Nutrition) increased flow-mediated dilation (FMD – a measure of blood flow and vascular health) by 27%, whereas no changes were observed in the placebo group.
However, the researchers did not observe any changes to markers of inflammation, including high-sensitivity C-reactive protein (hsCRP) and tumor necrosis factor-alpha (TNF-alpha)
“Our results indicate that 6 months of dietary supplementation with HMB, glutamine and arginine had a positive impact on vascular endothelial function in older adults,” wrote the researchers, led by Dr Amy Ellis in the European Journal of Clinical Nutrition . “These results are clinically relevant because reduced endothelial-dependent vasodilation is a known risk factor for cardiovascular diseases.
“Further investigation is warranted to elucidate mechanisms and confirm benefits of foods rich in these amino acids on cardiovascular outcomes.”
The study supported financially by the National Center for Complementary and Alternative Medicine.
Study details
Dr Ellis and her co-workers recrtuited 31 community-dwelling men and women aged between 65 and 87 to participate in their randomized, placebo-controlled trial. The participants were randomly assigned to one of two groups: The first group received the active supplements providing 3 g HMB, 14 g glutamine and 14 g arginine per day; while the second group received a placebo.
After six months of intervention, the researchers found that FMD increased in the HMB + glutamine + arginine group, but no such increases were observed in the placebo group.
While no changes in CRP or TNF-alpha levels were observed in the active supplement group, a trend towards an increase in CRP levels was observed in the placebo group, but this did not reach statistical significance, they noted.
“Although no previous studies have examined this combination of amino acids on vascular function, we hypothesized that the active ingredients of the supplement would act synergistically to improve endothelial function by reducing oxidative stress and inflammation,” wrote the researchers. “However, although we observed a trend for increasing hsCRP among the placebo group (P=0.059), no significant changes in hsCRP or TNF-alpha were observed for either group.
“Possibly, the effects of the supplement on reducing oxidative stress and inflammation were subclinical, or the high variability in these biomarkers, particularly hsCRP, among our small sample could have precluded visible differences.”
The researchers also noted that an alternate mechanism may also be responsible, adding that arginine is a precursor of the potent vasodilator nitric oxide
“Although investigation of this mechanism was beyond the scope of this study, it is feasible that the arginine in the supplement improved endothelial-dependent vasodilation by providing additional substrate for nitric oxide synthesis,” they added.
ISSN position paper
The International Society of Sports Nutrition recently published a position paper on HMB in Journal of the International Society of Sports Nutrition as a nutritional supplement.
For more information, please click here .
Source: European Journal of Clinical Nutrition
Published online ahead of print, doi: 10.1038/ejcn.2015.137
“Effects of 6-month supplementation with beta-hydroxy-beta-methylbutyrate, glutamine and arginine on vascular endothelial function of older adults”
Authors: A.C. Ellis, et al.
