CHICAGO, Nov. 16 (UPI) -- A drug now under development mimics the health benefits of long-term calorie restriction and may help ward off diseases of aging, like diabetes and heart disease.
Animals whose food intake was restricted to about a third less than they would eat given the opportunity are healthier and develop diabetes and heart disease later in life than do animals who could eat what they wanted, said researcher Barbara Hansen, director of the Obesity and Diabetes Research Center at Johns Hopkins University in Baltimore, Md.
A new agent, which mimics the function of a compound called PPAR-delta, seems to provide benefits similar to those of calorie restriction --at least in monkeys.
In the body, PPAR-delta is involved in the regulation of fat transport and insulin sensitivity, characteristics that made researchers interested in pursuing its possible health effects.
"Sixty percent of Americans are overweight and could certainly benefit from calorie restriction," Hansen said. However, she said, many Americans find dieting very hard to do. A drug to ward off some of the diseases linked to both aging and obesity might give these people real benefit, she said.
Hansen took six middle-aged male monkeys who had abnormally high levels of triglycerides, or fatty acids, in their blood, as well as abnormally low levels of high-density-lipoprotein, or the good cholesterol. Both these factors are known to increase a monkey's-and a person's-risk of developing heart disease. The monkeys also were resistant to insulin, the hormone that helps the body take sugar from the blood and use it to produce energy inside cells. Insulin resistance is an early sign of diabetes.
After four weeks on the PPAR-gamma mimic, the monkeys had HDL cholesterol levels 79 percent higher than when they started. They also had triglyceride concentrations 56 percent below the levels seen at the beginning of the study. And over the time period, the monkey's sensitivity to insulin increased, Hansen reported at a meeting of the Gerontological Society of America in Chicago. In the monkeys, no side effects were apparent after a month on the drug.
"Especially for HDL, I've never seen a more powerful agent," Hansen said. "In all these monkeys, ranges [of these disease markers] went from subnormal to better than normal."
Although the study is small, if it holds up in people "the public health impact could be enormous," said Andrezej Barthe of Southern Illinois University in Carbondale, Ill., who also does research on calorie-restricted animals. "Most people don't want to diet, much less reduce their calorie intake by up to 30 percent. These drugs could provide an important option" for people who are overweight, have abnormal blood cholesterol and triglyceride levels, or are resistant to insulin, he said.
The results from monkey studies often hold true for trials in people, and researchers are just beginning to test the effects of this PPAR-delta mimic in people at risk of developing diabetes and heart disease, Hansen said. It's not known whether the PPAR-delta mimic would lengthen lifespan by affecting insulin sensitivity and blood cholesterol concentrations in people who do not seem to be at risk of developing diabetes or heart disease, she said. Before such a drug could be used in healthy people not at risk of developing disease, it would have to be thoroughly tested in people and be very unlikely to cause side effects.
