Researchers report this week in the journal Nature that they have discovered a gene in yeast that could regulate how long organisms live. Since the 1930s, researchers have observed that fasting appears to increase the life span of a variety of animals, including mice. Eating less also seems to make humans live longer, healthier lives. But the precise mechanism that controls longevity has been a mystery.
Cell damage is known to promote aging. And it is believed that calorie restriction is less damaging to cells because they do not have to work as hard as well-nourished cells to process food.
Researchers at Harvard University in Boston, Massachusetts discovered that yeast, the kind used to bake bread, lives longer when deprived of vitamin B-3 from its food source, sugar.
Scientists found that a gene, known as PNC-1, regulates the amount of vitamin B-3, or nicotinamide within cells. They report in Nature that calorically-restricted yeast cells, containing less nicotinamide, lived nearly twice as long as yeast living under normal conditions.
Professor David Sinclair headed the study involving the tiny fungi, but says he does not know whether the same mechanism is at work in humans.
"I would love to know if this is true for humans," he said. "This is such a fun and exciting finding in yeast. I think if even a little bit of is true for humans, it would still be a pretty big deal."
More interesting still was the team's finding that yeast cells deprived of sugar and mildly stressed by some change in their environment, such as a slight increase in temperature, lived 70 percent longer than yeast fed normal amounts of sugar.
Professor Sinclair says the discovery raises the possibility that eventually people could survive longer without fasting.
"Perhaps one day we will have molecules that can mimic calorie restriction and turn on similar genes in humans, and extend life span that way," said Professor Sinclair.
David Finkelstein of the U.S. National Institute on Aging says the yeast finding is intriguing. But he cautions there may be other mechanisms by which calorie restriction promotes long life, especially in humans.
"It is sort of like saying we know we need gas to run our car, OK? And gasoline is very important for a car running," he said. "But exactly how the gasoline works is still open to question. It may be that tuning your carburetor would have a profound impact."
Harvard University's David Sinclair does not want people to get the wrong idea about and change their dietary habits to exclude vitamin B-3.
"I would also like to say that we do not claim that your average vitamin pill is going to be dangerous," he warned. "You would have to take significant amounts of, perhaps in the gram quantities, to have an effect presumably on aging."
Professor Sinclair say he and his colleagues are now trying to find out whether the amount of nicotinamide effects how long human cells are able to survive.