"But six of them agreed to lower their protein intake," Fontana explains, "and after three weeks their circulating IGF-1 declined dramatically."
Previous research from Fontana's group had found that a diet lower in protein might protect against some cancers. These more recent findings suggest lowering protein also might be important to longevity. Fontana admits his evidence is preliminary, but the findings suggest that when people adjust their diets to improve health and lengthen life, they should control not only calories and fat but also keep an eye on protein.
Fontana isn't proposing radical low-protein diets. Instead, he is suggesting the current recommended daily allowance (RDA) for protein, which is 0.82 grams of protein per kilogram of body weight, or about 56 grams of protein for an average, adult man and 46 grams for an average, adult woman. Most people, including CRONies, consume much more protein than the RDA recommendation.
"It's much easier to restrict protein than to restrict calories," he says. "If our research is on the right track, maybe humans don't need to be so calorie restricted. Limiting protein intake to .7 or .8 grams per kilogram per day might be more effective. That's just a hypothesis. We have to confirm it in future studies."
Until then, Fontana suggests people might want to look at protein consumption and tailor it to RDA recommendations. Traditionally, he says, nutritionists have not worried about people eating too much protein, but these findings suggest perhaps they should.
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| Contact: Jim Dryden jdryden@wustl.edu 314-286-0110 Washington University School of Medicine Source:Eurekalert |