Does Caloric Restriction Slow Aging of the Human Immune System?

Marco Colonna, M.D.

Project Overview:
The proportion of individuals aged 60 years and older was ~10% of the total world population in year 2000 and is projected to reach ~20% in 2050. This increase in elderly individuals is an important consequence of advances in medicine and public health. However, advanced age is also accompanied by an increased frequency of age-related diseases that can affect the quality of life. Among other diseases, aging leads to a decline in immune system, increasing our susceptibility to bacteria and viral infections and reducing our capacity to respond to vaccines. Aging of the immune system contributes to death in elderly humans due to infections, inflammation, and possibly cancer.

Caloric restriction is an eating practice based on the reduction of daily calories without malnutrition. This rigorous diet has gained considerable attention over the years because it has been shown to delay aging and increase longevity in rodents and monkeys. However, the effects of caloric restriction on humans have not been carefully evaluated. We propose to address this issue by comparing individuals who have practiced caloric restriction for a long period of time with healthy controls who eat a typical U.S. diet, focusing on relevant aspects of the immune system. This study will clearly determine whether or not caloric restriction is beneficial for the human immune system and may also help us understand how to augment immune function in the elderly.