This is the second in a three-part series on what scientific discoveries are revealing about the aging process and how the findings will change the way people age.
Not many folks can claim to be the oldest guinea pig. But Ernest Umberger can -- the 90-year-old retired pharmacologist has been participating in the country's longest-running study of human aging since it began in 1958.
Umberger is a living experiment, a testament to what scientists are saying is a combination of good genetics and advances in medicine that have enabled him to live so long and in great shape. Among his many activities, he starts the morning with a 30-minute walk, reserves every afternoon for golf and tops the day off with a 20-minute stroll.
Healthy Lifestyle, Healthy Aging
To track his progress, scientists at the Baltimore Longitudinal Study on Aging invite the Rockville, Maryland resident to the study center, at the National Institute on Aging in Baltimore, every two years to find out exactly what keeps him ticking.
But the study isn't likely to result in helping people live longer, said Jerome Fleg, interim director of the study. To these scientists, finding ways to help older people live more healthfully, not necessarily longer, is the more realistic goal.
"You can't prevent the aging process itself," Fleg said. "You can do things to not accelerate it."
Nearly 1,300 people like Umberger are helping researchers discover the keys to healthy aging. Every year or two the study participants, ranging in age from 18 to 90 years, complete a battery of tests that measure everything from how well their brains function to how fast their hearts beat.
Not surprisingly, the scientists are finding that a major key to healthy aging is lifestyle. Smokers, couch potatoes and people who subsist on fast food will age faster and fall ill sooner.
Hormones Could Be Players
However, what's interesting researchers are hormones and extremely altered diets, which may also be intimately involved with the aging process.
Dr. Marc Blackman, professor of medicine at the Johns Hopkins University School of Medicine, has been studying the human growth hormone for 20 years and is currently analyzing the data of a seven-year study he just completed.
Young people lacking the human growth hormone display premature signs of aging, which disappear once they take artificial growth hormone, Blackman said. On the other hand, previous studies found that older men who took the hormone had an increase in muscle mass and a decrease in fat.
To probe further, Blackman researched the sex hormones -- testosterone and estrogen -- that decline as the growth hormone starts decreasing at age 30 and may also play a role in the symptoms of aging.
When the researchers finish analyzing the data in the next year, they expect to uncover more about whether the growth hormone -- by itself or in combination with a sex hormone -- can increase muscle strength and aerobic fitness, and offset senior health problems like heart disease, osteoporosis and diabetes.
In the meantime, Blackman recommends that people abstain from taking growth hormone supplements until researchers find more convincing evidence. In addition, side effects including high blood pressure, headaches and carpal tunnel syndrome could result from taking the growth hormone.
The Longevity Diet
Another key to youth may simply be eating less, said Dr. Roy Walford, professor of pathology at the University of California, Los Angeles. Walford is a leading proponent and author of the caloric-restriction theory, which holds that people can live longer if they cut back on the number of calories they consume each day.
Walford himself has been part of the experiment. In 1991 he and other scientists entered Biosphere 2, a three-acre glass-domed space outside Tucson, Arizona, that contains several ecological climates and environments, such as a rain forest and a savanna, as well as scientific laboratories.
For two years the scientists put themselves on a diet of 1,800 calories a day -- consisting of fruits, vegetables, grains, beans and some meat -- and saw significant decreases in their blood pressure and cholesterol. Walford said these and other physiological signs showed that the aging process slowed by up to 50 percent.
Most of Walford's research focuses on mice. He has previously shown that mice that eat less can increase their life span from 39 months (110 human years) to 56 months (162 human years). Similar research in humans, such as the one Umberger participates in, has not yet been completed since the human life span is so long.
People may benefit from cutting their caloric intake by a mere 10 percent, Walford said. However, those restricting their calories must choose foods more wisely to ensure that the diets include enough nutrients. Pregnant women and children should not try the calorically restricted diet, he said.
Walford added that people who want to live longer don't have to wait for any more research and should just get started by cutting back on their calories now.
"It's already a fact," Walford said. "I am confident about it."