Life Extension Update
Encouraging news for couch potatoes
The results of a study published online on May 23, 2006 in the Journal of Clinical Endocrinology and Metabolism revealed that calorie restriction (CR) is more effective than exercise at influencing factors associated with extended lifespan. Unfortunately for non-exercisers, the finding doesn’t negate exercises’ other health and disease prevention benefits.
For the current study, researchers at Washington University School of Medicine in St. Louis led by assistant professor of medicine Luigi Fontana, MD, PhD, compared 28 members of the Calorie Restriction Society, whose daily calorie intake averaged about 1,800 for the past six years, with 28 sedentary individuals and 28 endurance runners who consumed a standard Western diet consisting of approximately 2,700 calories per day. Body fat and trunk fat were similar among the calorie restricted and exercise groups, and lower than that of the non-restricted non-exercising group.
The research team found that the calorie restricted diet was associated with lower levels of the thyroid hormone T3 (which controls energy balance and cellular metabolism) compared to the other two groups, while T4 (the other thyroid hormone) as well as thyroid stimulating hormone remained normal, showing that the calorie restricted participants did not have clinical hypothyroidism. In addition, the restricted group had lower levels of an inflammatory molecule known as tumor necrosis factor alpha than the nonrestricted groups. When T3 levels of the exercising group on the Western diet were examined, they were found to be similar to those of the non-exercising Western diet group. The combination of reduced T3 and tumor necrosis factor alpha may retard the aging process by lowering the body’s metabolic rate and reducing oxidative damage to the tissues.
Study coauthor and Washington University School of Medicine professor of medicine John O. Holloszy, MD, found similar results in a study conducted with rats in 1997. "Sedentary rats who ate a standard diet had the shortest average life-spans," Dr Holloszy stated. "Those who exercised by running on a wheel lived longer, but animals on calorie restriction lived even longer."
Drs Fontana and Holloszy will be conducting a new investigation called the Comprehensive Assessment of the Long Term effects of Reducing Intake of Energy (CALERIE) study, which will find out whether calorie restriction will lower serum T3 and inflammation as well as improve heart function and other markers of aging among normal weight adults as it has among members of the Calorie Restriction Society. "We want to learn whether calorie restriction can reverse some of these markers of aging in healthy people," Dr Holloszy explained. "It's going to be many years before we know whether calorie restriction really lengthens life, but if we can demonstrate that it changes these markers of aging, such as oxidative damage and inflammation, we'll have a pretty good idea that it's influencing aging in the same way that CR slows aging in experimental animals."
It appears that caloric restriction works by slowing biological aging in many ways, including decreasing ROS damage to cells, limiting inflammation, enhancing insulin sensitivity, and repairing damaged cells. Certain nutrients have demonstrated similar effects, leading one group of researchers (Lemon JA et al 2005) to attempt to mimic CRON with a formula containing 31 ingredients that included a wide range of antioxidants and nutrients that have been extensively studied in humans (such as vitamin E, vitamin C, coenzyme Q10, glutathione precursors, and essential fatty acids).
This formula was given to normal mice and mice that over-expressed growth hormone. The mice that over-expressed growth hormone were larger and had a shorter life span than the normal ones, presumably because they aged faster.
The results were dramatic. Supplementation extended the life span of the growth hormone mice by 28 percent, to 431 days. In normal mice, supplementation extended life span by 11 percent on average, from 688 days to 765 days (Lemon JA et al 2005).
How does this 11 percent increase in longevity in normal mice compare to caloric restriction? Although a CRON group was not included in the study described above, other investigators have reported that 40 percent restriction in calories increased survival in the same strain of mice about 19 percent (Forster MJ et al 2003). Thus, supplementation yielded about half as much longevity as caloric restriction.
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