Eat Less and Live Longer

Scientists have known for about 70 years that cutting calories by 30-40% can extend the life of animals. However, it’s been difficult to determine the reasons for this phenomenon.

Researchers from Harvard Medical School have discovered two genes that determine cellular longevity. When cells are under stress, such as that caused by caloric restriction, these genes help protect cells from diseases associated with aging, such as cancer and diabetes.

The new genes are called SIRT3 and SIRT4. These genes help to keep the mitochondria (sometimes called “cellular power plants” because their main task is to convert nutrients to energy) alive in circumstances when it would normally die. When the cells undergo calorie restriction, a gene called NAMPT is activated. As the levels increase, a small molecule called NAD begins to form in the mitochondria, which in turn stimulated the activity of the enzymes created by SIRT3 and SIRT4. This results in the mitochondria growing stronger, increasing energy output, and slowing down the aging process of cells. This process is also activated by exercise.

Researchers conducted the study on rats. One group was fed sucrose, and the others fasted for 48 hours. The group that fasted had increased NAD levels in their livers.

David Sinclair, associate professor of pathology at Harvard Medical School and senior author of the study, said, “Theoretically, we can envision a small molecule that can increase levels of NAD, or SIRT3 and SIRT4 directly, in the mitochondria. Such a molecule could be used for many age-related diseases.”