Fontana and colleagues previously have found that people on the very low-calorie diet have low blood levels of cholesterol and triglycerides, blood pressure scores equivalent to those of much younger individuals, a lower risk of developing diabetes and reduced body fat. These markers indicate less secondary aging.
In this study, Fontana's team found that markers of inflammation indicative of primary aging were much lower in the caloric restriction group. Their serum levels of a pro-inflammatory molecule called tumor necrosis factor-alpha (TNFa) were significantly lower. They also had less C-reactive protein (CRP).
In addition, they had lower amounts of a substance called transforming growth factor-beta (TGFb), a molecule that both helps reverse inflammation and activates cells called fibroblasts to produce collagen. If, for example, you cut yourself, your body will work to repair the damage by activating fibroblasts to produce collagen and make scar tissue to heal the wound.
Fontana says the low levels of TNFa, CRP and TGFb, combined with evidence of "younger" hearts in people on caloric restriction, has led his research team to hypothesize that inflammation may play a key role in the aging process.
"Our hypothesis is that low-grade, chronic inflammation is mediating primary aging," he says. "It's not the only factor, of course -- aging is a complex process. But we found less inflammation in these people -- less TNFa, C-reactive protein and TGFb -- as well as a more flexible ventricle in their hearts."
Overweight and obese people also tend to have higher levels of inflammation than lean people. In this study, those on caloric restriction had about 7 percent total body fat. The control group had abo
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Contact: Jim Dryden
jdryden@wustl.edu
314-286-0110
Washington University School of Medicine
12-Jan-2006