Can We Extend Our Lifespan the Easy Way?
It’s been known for a long time that when animals drastically decrease their calorie intake, they can avoid many age-related health problems and live for a much longer time. But, using this approach to extend human lives is questionable. For one thing, scientists still have not proven the benefits of calorie restriction in humans and other primates. For another, even if this approach does work, people have a very difficult time drastically cutting their calorie intake enough to make a difference. “The problem is that requirement is so stringent that almost nobody can make it,” says Jin Huang of the University of California, Los Angeles.
Because of this, researchers have been looking for alternatives to calorie reduction as a way to slow down aging. Huang and her team thought that because aging is linked to metabolism, that metabolites, which are compounds produced by metabolic reactions, might increase lifespan. They tested their idea on nematodes (millimeter-long worms). The first molecule they tried, a-ketoglutarate (a-KG), which helps a cell extract energy from food, yielded some very impressive results. The worms that had a-KG added to their culture dishes survived 70% longer than normal and carried about 50% more a-KG in their cells than the control worms.
The researchers wondered how a-KG helped to slow the aging process. They found that a-KG attaches to ATP synthase, an enzyme that makes ATP, the cell’s main energy-carrying molecule. By blocking ATP synthase, it slows down the cell’s metabolism. Further investigation showed that a-KG indirectly inhibits TOR, a protein that gauges nutrient supplies and helps determine the rate of aging.
Of course, the scientists still can’t be sure that a-KG will have as dramatic an effect on aging in humans as it does in worms. The next step would be to see if the compound extends the lifespan of other organisms such as flies and mice. Still, this research brings us a step closer to finding molecules that will allow people to extend their lives without starving themselves.