Long-term Calorie Restriction Improves Cardiovascular Risk

Laurie Barclay, MD

April 20, 2004

April 20, 2004 -- Long-term calorie restriction improves cardiovascular risk factors, according to the results of a study published in the April 27 issue of the Proceedings of the National Academy of Sciences. Compared with control subjects, 18 individuals on calorie restriction for six years had a 40% reduction in carotid intima media thickness (IMT) and improved lipid profile, fasting glucose and insulin levels, and other markers of cardiovascular risk. Some risk factors were comparable to those typically seen in individuals decades younger.

"It's very clear from these findings that calorie restriction has a powerful, protective effect against diseases associated with aging," senior author John O. Holloszy, MD, from Washington University School of Medicine in St. Louis, Missouri, says in a news release. "We don't know how long each individual actually will end up living, but they certainly have a much longer life expectancy than average because they're most likely not going to die from a heart attack, stroke, or diabetes."

In mouse and rat models, stringent and consistent calorie restriction increases maximum lifespan by about 30% and has a protective effect against cancer. This study is the first to examine the effects of long-term calorie restriction in humans.

In an attempt to slow the aging process, members of The Caloric Restriction Optimal Nutrition Society eat small amounts of nutrient-dense foods to consume 10% to 25% fewer calories than the average American while still maintaining balanced nutrition. The 18 individuals who participated in the study were recruited from this national organization and had voluntarily followed this restricted calorie diet for three to 15 years. Age range was from 35 to 82 years.

Compared with 18 age- and sex-matched control subjects who followed a typical Western diet, individuals in the calorie restriction group consumed fewer calories (1,100 to 1,950 calories per day vs. 1,975 to 3,550 calories per day), relatively more protein (26% vs. 18% of caloric intake), less fat (28% vs. 32%), and fewer complex carbohydrates (46% vs. 50%).

Subjects in the calorie restriction group had total and low-density lipoprotein (LDL) cholesterol levels comparable to the lowest 10% of the population in their respective age groups; high-density lipoprotein (HDL) cholesterol levels in the 85th to 90th percentile for middle-aged men; and triglyceride levels lower than more than 95% of Americans in their twenties.

In the control group, cholesterol and triglyceride levels were in the 50th percentile for average middle-aged Americans. In 12 individuals in the calorie restriction group who had medical records before they began the diet, cholesterol and triglyceride levels were near the 50th percentile for middle-aged Americans, and levels decreased the most markedly during the first year of calorie restriction.

The calorie-restricted group also fared much better than the control group in terms of average blood pressure (100/60 vs. 130/80 mm Hg), fasting glucose, fasting insulin (65% reduction), body mass index (19.6 ± 1.9 vs. 25.9 ± 3.2 kg/m 2), body fat percentage (8.7% ± 7% vs. 24% ± 8%), C-reactive protein, carotid IMT (40% reduction), and platelet-derived growth factor AB.

"These effects are all pretty dramatic," says first author Luigi Fontana, MD, PhD, also from Washington University. "For the first time, we've shown that calorie restriction is feasible and has a tremendous [effect] on the risk for atherosclerosis and diabetes."

Dr. Holloszy's group is now conducting a controlled, long-term prospective study to compare the effects of calorie restriction and of the typical American diet on biological markers of aging.

The National Institutes of Health supported this study.

Proc Natl Acad Sci. 2004;101:6659-6663

Reviewed by Gary D. Vogin, MD



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