A new study warns older people against taking growth hormone supplements to reverse the effects of aging. The research shows that the health drawbacks outweigh the marginal physical benefits.
Human growth hormone is a natural substance important for normal growth and maintenance of tissues and organs. Together with the sex hormones estrogen in girls and testosterone in boys, it promotes sexual maturation during adolescence.
The U.S. government authorizes synthetic human growth hormone supplements to treat severe deficiencies of it in children and adults and physical wasting in AIDS patients. But countless thousands in the United States and other western countries are taking it to fend off some of the ravages of aging.
"The usage is increasing substantially," said Dr. Marc Blackman, who is with the U.S. government's National Center on Complementary and Alternative Medicine. "The usage is increasing not only in persons beyond the age of 65 or so, but actually it's increasing in persons in their 40s and 50s, who believe that growth hormone may be helpful to them to attenuate or prevent changes of aging," he said.
A new study by Dr. Blackman shows that synthetic growth hormone does significantly transform older bodies to a more youthful profile. As he and his colleagues report in the Journal of the American Medical Association, it decreased fat and increased muscle in elderly men and women who took it for 26 weeks, whether by itself or with the appropriate sex hormones. The biggest changes were among men taking both growth hormone and testosterone.
"The magnitude of this fat mass decrease was about 10.5 pounds. That's noteworthy because in these men, as in all of the other participants, they were counseled not to change their diet or physical activity patterns during the course of the study," he said.
But despite more muscles, growth hormone takers did not increase their strength or exercise capacity, although the researchers say the study period may have been too short for those benefits to appear.
Worse, adverse side effects eclipsed the physical benefits. Diabetes, joint pain, and carpal tunnel syndrome increased markedly in many of the treated men, as did arm and leg swelling in women. Removing them from the supplements eliminated the side effects.
"The message here is that the benefits are at the moment more cosmetic than they are functionally relevant, and the adverse effects are worrisome because if they persist and worsen, they could lead to serious unwanted health consequences," Dr. Blackman said.
He said the best way to alter body composition is with exercise. He concedes that many elderly adults cannot do this because of frailty or dementia. He therefore calls for further study on the benefits of growth hormone on these people.