HMB Powder, 3.2 oz (90 g), NOW FoodsNOW Sports HMB Powder Vegan Vegetarian. non GMO. Made w o Gluten. HMB (beta Hydroxy beta Methylbutyrate) is a clinically researched, naturally occurring metabolite of the branched chain amino acid leucine. HMB normally plays a role in the regulation of protein breakdown in the body, helping to preserve lean muscle tissue. HMB therefore can help to maintain muscle strength and mass when combined with regular exercise and a healthy diet. In addition, it