Life Extension by Calorie Restriction in Humans

Abstract

Long-term reduction in energy intake in the diet (calorie restriction [CR]) extends the life of the laboratory rat by about 25%. However, in humans there are no life-long studies of CR, but only short-term trials which indicate that 20% CR acting over periods of 2-6 years is associated with reduced body weight, blood pressure, blood cholesterol, and blood glucose--risk factors for the major killer diseases of cardiovascular disease and diabetes. In addition, recent research has shown that CR for 6 months is able to improve biomarkers for longevity (deep body temperature and plasma insulin) and thus should increase life expectancy. The magnitude of the life-extension effect of CR in humans can only be estimated. The Okinawans, the longest-lived people on earth, consume 40% fewer calories than the Americans and live only 4 years longer. Similarly, women in United States consume 25% fewer calories than men and live 5 years longer. From the survival studies of overweight and obese people, it is estimated that long-term CR to prevent excessive weight gain could add only 3-13 years to life expectancy. Thus the effects of CR on human life extension are probably much smaller than those achieved by medical and public health interventions, which have extended life by about 30 years in developed countries in the 20th century, by greatly reducing deaths from infections, accidents, and cardiovascular disease.

Caloric Restriction and Antiaging Effects

“…CR is widely used as a novel model for aging research. The latest research report indicated that dietary restriction can increase longevity in humans [89,90]. CR changes the endocrine and neuroendocrine systems in humans.…”

“…The Nrf proteins can induce expression of phase II detoxification enzymes in the liver and digestive tract in response to oxidative stress and xenobiotics [86,87,88]. During adulthood, SKN-1 involves resistance to damage induced by oxidative stress [89]. Therefore, SKN-1 could be a key regulator of the response to CR [76].…”

Should animal fats be back on the table? A critical review of the human health effects of animal fat

“…Calorie restriction, not lipid restriction, has been shown to affect longevity in a wide range of species (Fontana et al 2010) but longevity studies of humans by humans are obviously impractical (Hursting et al 2010), the benefits are questioned relative to sanitation and modern medicine (Everitt and LeCouteur 2007), and a recent trial in primates failed to find an effect (Mattison et al 2012). It is well known that a low fat, low protein wholeplant diet, when supplemented with the essential nutrients vitamin B 12 and long-chain n-3 PUFA, has been associated with reduction of the thickness of cardiac arteries (Ornish et al 1998).…”

Mechanisms of reproductive aging in the females

“…mTOR1 is a master regulator of cell growth and metabolism and many pathways can converge to mTOR1 signaling, such as growth factors, which stimulate mTORC1 through the activation of the canonical insulin and Ras signaling pathways, energy status, oxygen levels, amino acids and other cellular conditions and signals [61,65]. Numerous studies have shown that reducing the mTOR signaling and energy metabolism can extend lifespan in many species [66,67]. Studies in mice also show that inhibition of the mTOR signaling pathway by rapamycin increases lifespan in genetically heterogeneous mice [68].…”