Aug. 18, 2000 -- HMB is a common dietary supplement found on most health food store shelves and on the Internet. Many people haven't heard of HMB, but researchers wading through data on the supplement are finding that it apparently does some amazing things.
It has traditionally been used to increase gains in muscle size and strength when combined with exercise and maintain muscle mass in AIDS patients. As with many supplements, few scientific studies have looked at whether it is safe.
An article in the August issue of the Journal of Nutrition reports on the results of nine studies and suggests that HMB is indeed safe. In addition, they found some extra benefits they were not expecting. The supplement was shown to reduce both blood pressure and cholesterol in those taking it, possibly leading to a decreased risk of heart disease and stroke.
"While we were studying if there was a benefit to using HMB during exercise, it was important to us to collect safety data," says study author Steven L. Nissen, PhD, a professor of animal nutrition at Iowa State University in Ames. "This is something that is a little unusual in this day and age in the nutrition supplement business. We wanted to make sure there were no negative effects of using HMB."
HMB, technically known as Beta-hydroxy-beta-methylbutyrate, is formed naturally when the body breaks down the amino acid leucine, a component of protein. Small amounts of HMB are present in many kinds of animal and plants, especially alfalfa and catfish.
Dietary supplements of HMB are available in many drug and health food stores. Although the price can vary, a month's supply would probably run around $90. A common dose is around 3 grams a day.
"Other studies we have done show that HMB burns fat and builds lean muscle tissue," Nissen says. "If you lift weights or do other kinds of exercise, you basically double the response if you use HMB, too."
To look at the safety of the supplement, Nissen and his team got blood samples from participants in nine different HMB studies. They found no changes in the function of the liver, kidneys, other vital organs, or the muscles in general.
"We were able to establish that HMB is a safe compound to take," Nissen says. "Although it wasn't an objective [analysis] of the studies, we're also able to show some additional health benefits."
Specifically, they found a significant reduction in average cholesterol and blood pressure. When compared with a placebo, those taking HMB had an almost 6% decrease in total cholesterol, and their LDL, or "bad" cholesterol, was reduced by over 7%. In addition, average blood pressures in those taking the supplement decreased by over four points.
"The data pretty clearly show that there is a drop in cholesterol and a reduction in blood pressure," Nissen says. "It is hard to tell what the clinical significance of these changes are in a person's risk for heart disease. However, if you put the numbers we found into the risk factor equations, the risk of heart disease is decreased around 20%. These figures are just about what you would see by taking medications for hypertension or lowering cholesterol."
The key, according to Nissen, is that HMB effects both blood pressure and cholesterol. He notes that there are not many interventions that can impact both those risk factors.
"I usually tell people that if you are exercising and trying to get maximum effects, HMB will magnify burning of fat and building lean muscle," Nissen says. "It gives you a bigger bang for the buck. If you are out exercising to improve your health, HMB is a good addition."
However, taking the supplement to reduce your cholesterol is "premature," according to Philippe Szapary, MD, a professor from the University of Pittsburgh School of Medicine. He viewed the results as being interesting.
"If someone thinks they are taking HMB to reduce cholesterol, they may be deceiving themselves," he said. "I don't think they will be doing themselves any harm, but we are not yet sure if there really is any benefit. Personally, if I had high cholesterol, I would not be taking HMB yet."