Old cells, free radicals, and no breakfast
It used to be that food merely made us fat. Now science tells us that food can't be converted into energy without creating rogue molecules, which bash into once youthful cells and make them old and haggard.
Through a microscope, old cells actually can look old. "They get kind of big and raggedy," says Huber Warner, an associate director at the National Institute on Aging (NIA). "Young cells look like little torpedoes and pack together nicely."
Cells begin to age quickly once they stop dividing. A human skin cell divides about 50 times in a lifetimemaybe 60 or 70. This cycle is regulated, in part, by telomeres. These are sequences of DNA that mark the ends of chromosomes, a bit like the plastic caps on the tips of shoelaces. Each cell division slowly whittles away a tiny bit of the telomeres. When they get too short, cell division ceases.
Telomeres protect us from cancer, explains cell biologist Judith Campisi, because tumors can develop if cells divide forever. But when they stop dividing, our bodies soon become hosts to millions of decrepit cells.
So how do the old cells get so beat up? One way is from free radicalsmolecules that break through cell membranes and damage proteins and DNA. Free radicals are a normal by-product of metabolism and our bodies have built-in defenses against them: enzymes that convert them to water, for instance. Antioxidants like vitamin E, vitamin C, selenium, and beta carotene may help the counterattack.
But might it be possible to produce fewer free radicals to begin with? Sure. Cut back on food. Way, way back. This unorthodox practice is proposed by Mark Mattson, a neurobiologist at NIA. He says that in mice, restricting calories adds at least a year to their average three-year life spans. Their ability to regulate blood sugar levels improves, and their cells become better able to respond to stress.
It's unclear whether humans can benefit from an ultra-low-cal diet, but the NIA is supporting three exploratory studies over the next few years. In the meantime, Mattson has been using himself as a test subject. He's been eating a third fewer calories than the average person for more than a decade. At five feet nine inches tall (175 centimeters), he weighs a scant 120 pounds (50 kilograms). In lieu of breakfast, he exercises. He doesn't touch ice cream. His one indulgence: For a bedtime snack he'll have a bowl of oatmeal. With raisins. Can he convince others to adopt the same unappealing diet? It might take a while, he admits. And since he's only 45, it's impossible to know if his antiaging scheme even works. We'll check back in 50 years.
Joel Achenbach Washington Post