Plug your nose; live a little longer. That's the take-home message from a study showing that mere whiffs of food can shorten a fly's life.
Studies in worms, flies, mice and monkeys have shown that aging can be slowed by cutting way back on calories consumed. Loosely organized experiments in humans are ongoing.
But is it food itself that shortens life? Or might it be the mere perception of food – the biochemical stimulation that occurs when food odors tickle olfactory nerves?
Scott Pletcher, a geneticist at the Huffington Center on Aging at Baylor College of Medicine in Houston, knew that the mere scent of food could block some of the life-extending effects of caloric restriction in tiny, soil-dwelling worms. So he and his colleagues conducted similar tests in flies.
Sure enough, when calorie-restricted flies – which tend to live about 50 percent longer than normal – were housed in containers with the smell of fresh yeast (a favorite food of flies) wafting in, the life-extending benefits of their diet were reduced by about 20 percent.
In separate tests, mutant flies with defective senses of smell lived 56 percent longer than their smell-enabled counterparts, even though they ate all they wanted.
Because odor has the same effect in worms and flies, it may affect people the same way, Pletcher said. He noted that food smells alone trigger a raft of biochemical and hormonal changes in people that, while not as intense as those that occur during eating, nonetheless appear to be implicated in the aging process.
Pletcher doubts that people can do much about the life-shortening effects of being well-fed by blocking their sense of smell alone. But exposure to food smells might blunt the life-extending effects of limiting calories, he speculated.
Further work may reveal the mechanisms that link olfaction and longevity, he said, and point the way to effective anti-aging drugs.
