Juicing up with growth hormones may build muscles, but probably won't help you live to see 100 candles on your birthday cake, a new study suggests.
A study of 384 aged Ashkenazi Jews shows that a decrease in insulinlike growth factor 1 (IGF-1) activity is associated with long life, Nir Barzilai and his colleagues report in the March 4 Proceedings of the National Academy of Sciences.
For a decade, Barzilai has studied centenarians, a rare group of people who live to be 100 or older, looking for genes that contribute to longevity. But he never expected IGF-1, or growth hormone, would be involved, says Barzilai, director of the Institute for Aging at the Albert Einstein College of Medicine in New York City.
Practitioners of antiaging medicine tout IGF-1 as a youth-restoring treatment because it helps firm skin and build muscles. The substance is good for the heart, brain, and bones, stimulating stem cells to replace damaged cells, says Jan Vijg of the Buck I