Diet, as a major environmental factor, has been shown to have a profound effect on many aspects of health. Specifically caloric restriction (CR) has been shown to expand the maximal lifespan of many species. While CR has not been proven to increase lifespan in humans, CR has also been shown to delay a wide range of aging-associated diseases, such as cancer, diabetes, atherosclerosis, cardiovascular diseases and neurodegenerative diseases in higher mammals, such as nonhuman primates and humans. CR may therefore increase longevity by favorably influencing broad aspects of human health.
Although some define CR as a 30 to 40 percent reduction in calorie intake (as determined by daily energy expenditure) there is no “official” definition of caloric restriction, and investigations have revealed CR benefits can still occur with less-restrictive caloric intakes. The National Institute on Aging (NIA) sponsored a randomized, human clinical study to assess the safety and efficacy of CR in non-obese but overweight, healthy individuals. Researchers followed overweight, middle-aged (average age, 37) individuals for six months who reduced their daily caloric intake by 25 percent or by 12.5 percent with an additional 12.5 percent caloric expenditure from exercise. Both intervention groups demonstrated reduced body weight and abdominal fat, as well as reduced liver fat deposits and DNA damage. In addition, the participants were able to improve two markers of longevity (reduced body temperature and reduced fasting plasma insulin), as well as reduce cardiovascular risk factors (LDL, triglycerides, and blood pressure).
Similar results have also been observed from another study on slightly older 50-60-year-old non-obese, overweight volunteers after one year of CR. However, some of the older volunteers also experienced decrease in muscle mass, strength, and aerobic capacity. Exercise is therefore very important for this age group in order to minimize these consequences.
Ways CR may improve longevity
There are many hypotheses on how CR minimizes aging-associated diseases and improve longevity. Possible mechanisms include protection from oxidative damage, increased cellular and DNA repair, reduction in the inflammatory molecules and therefore inflammation that may be responsible for a wide range of conditions from cancer to cardiovascular diseases and neurodegenerative conditions such as Alzheimer’s.
Resveratrol may mimic CR
The significant impact of CR on delaying aging and preventing aging-related diseases has motivated efforts to identify natural or synthetic compounds that mimic the effects of CR. Resveratrol is such a compound that has garnered much research as a CR mimicker. Resveratrol is a compound found in the skin of red grapes and it is a potent antioxidant. Studies have revealed promising and universal effects of resveratrol by favorably increasing cellular detoxification, protecting DNA damage, modulating metabolic processes such as blood sugar and insulin regulation and inhibiting tumor formation and growth, all of which significantly improve human health and lead to increased human lifespan.
While there is no specific and definite composition of the CR diet, the potentially significant reduction in caloric intake requires the consumption of nutrient-dense foods, and the avoidance of “empty” calories from foods such as white flour and refined sugar. It is also important to mention that the focus of CR is on health and longevity and not merely weight loss. When adopted long-term, the CR lifestyle may be a simple way to prevent various potentially debilitating diseases and promote longevity.
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