Calorie restriction keeps its followers young at heart
In research published in the January 17 2006 issue of the Journal of the American College of Cardiology, Luigi Fontana MD, PhD, and colleagues at Washington University School of Medicine in St. Louis, Missouri reported that individuals who have adopted a calorie restricted yet nutritionally balanced diet have the heart function of people much younger. "This is the first study to demonstrate that long-term calorie restriction with optimal nutrition has cardiac-specific effects that ameliorate age-associated declines in heart function," Dr Fontana announced.
The team studied 25 members of the Caloric Restriction Optimal Nutrition Society, who consume approximately 1,400 to 2,000 calories per day, which is 10 to 25 percent fewer calories than most Americans, while maintaining nutritionally adequate diets. Diastolic function of the heart, which is the ability of the organ to relax between beats and which, unlike systolic function, declines with age, was evaluated via ultrasound. Blood samples were evaluated for C-reactive protein, tumor necrosis factor-alpha, and transforming growth factor-beta 1, which are involved with inflammation.
The researchers found that the hearts of the subjects examined had greater elasticity than those of control subjects matched for age and gender, and that the organs relaxed between beats in a manner similar to that of younger people. Compared to the control subjects, blood pressure, serum C-reactive protein, tumor necrosis factor-alpha, and transforming growth factor-beta 1 levels were significantly lower in the calorie restricted group.
Dr Fontana, who is an assistant professor of medicine at Washington University School of Medicine as well as an investigator at the Istituto Superiore di Sanita, in Rome, believes that deaths from the most common causes in Western societies results from what scientists call secondary aging, a term that characterizes preventable adverse health conditions such as diabetes that contribute to premature aging. Consuming a nutritious diet and engaging in regular exercise help reduce risks resulting from secondary aging; however, calorie restriction could be an even more powerful measure.
Although the participants had been practicing calorie restriction for an average of 6.5 years, their diastolic function resembled that of people fifteen years younger, suggesting that the practice may not just prevent, but could reverse the decline that usually occurs with aging. The finding, combined with reduction in inflammatory markers observed in the calorie restricted group, has led the researchers to believe that inflammation could be an important factor in aging.
"Our hypothesis is that low-grade, chronic inflammation is mediating primary aging," Dr Fontana submitted. "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."
Study coauthor John O. Holloszy, MD, summarized, "It's very clear from these studies that caloric restriction has a powerful, protective effect against diseases associated with aging. We don't know how long each individual will end up living, but they certainly have a longer life expectancy than average because they're most likely not going to die from a heart attack, stroke or diabetes. And if, in fact, their hearts are aging more slowly, it's conceivable they'll live for a very long time."