Nutrition plays a significant role in the human lifecycle because it provides energy, prevents diseases and promotes growth. Scientists identified the role of dietary involvements in the aging process. The role of calorie restricted diets generates interest among scientists in the field of gerontology and they result in numerous research studies. Caloric restriction (CR) refers to a reduction of 10-40 percent intake of a healthy nutritious diet. Scientists identify it as the primary non-genetic mechanism that extends longevity (Mattison, et al., 2012). A study by McCay et al. in 1930 (Heilbronn & Ravussin, 2005) provided evidence that CR slows aging and extends human lifespan. Caloric restriction is applicable at any stage in the life cycle, but the goal should be to ensure consumption of a healthy diet. The physiological changes related to aging include cell damage and the appearance of cancerous cells. Low calorie diets in old age help to eliminate these cells (Spingler & Dhahbi, 2007). Consequently, studies on the impact of CR in rodents and primates show that it improves lifespan by up to 40 percent with a nutritious diet (Fight Aging, n.d.). Research studies also demonstrate that longevity increases with an increase in caloric restriction (refer to Figure 1). In addition, research studies have sought to establish the mechanism by which CR increases human lifespan. Caloric restriction improves lifespan by delaying and preventing chronic diseases, and through independent mechanisms. Researchers propose mechanisms such as reduced metabolic rates and slow sexual maturation. However, recent studies suggest that conserved stress response in most animals is the primary mechanism (Heilbronn & Ravussin, 2005).
Another research study proposes that CR slows the aging process by preventing peroxiredoxin from inactivation (Molin, et al., 2011). For CR to work efficiently, peroxiredoxin must remain active. Failure to this results in genetic disorders and cancer. These diseases are the main factors that accelerate aging. In addition, peroxiredoxin inhibits protein damage, which also contributes to aging because of age-related diseases such as Alzheimer’s and Parkinson’s.
Dietary interventions in mice and rats demonstrate the effect of CR in extending human lifespan. Studies also indicate that different nutrients contribute to improved health and increased lifespan. Inclusion of antioxidants, vitamins and proteins in the diet is essential in slowing the aging process. Moreover, a calorie restricted diet should not lead to malnutrition. Few studies show the effect of methionine and protein restriction in rats and primates. Other studies indicate that caloric restriction slows the onset of diseases and death in rhesus monkeys (Colman et. al, 2009).
Although extensive research indicates that CR increases lifespan, there are studies that oppose this view. A study by Phelan and Rose (2005) concludes that calorie restriction will not extend human...