Scientists have known since the 1930s that mice and other animals live 30 to 50 percent longer when placed on a diet that's low in calories yet nutritionally complete. The unanswered question has been whether calorie restriction has the same life-extending effect on people.
Direct proof of a payoff for human longevity would take decades. But scientists have now shown that people on a calorie-restricted diet experience many of the cellular changes reported in mouse studies.
"The experimental results [in mice] mirror the results we found," says Anthony E. Civitarese of the Pennington Biomedical Research Center in Baton Rouge, La. Whether those changes would extend a person's life remains uncertain, he notes.
As people get older, energy-converting organelles called mitochondria decrease in number and generate greater amounts of harmful by-products called free radicals. Many scientists hypothesize that DNA damage from these by-products can cause chronic diseases of ol