Calorie restriction promises long and healthy life. Do sirtuins have a role to play?
There’s always another miracle cure or next-level health fad around the corner. And when it comes to finding that elusive fountain of youth, people are always curious and even excited at the new possibilities. In this context, calorie restriction (CR) is one such strategy proven to be highly effective in slowing down the aging process.
We eat so that we can provide our body with nutrition and energy to carry out day-to-day functions. However, over eating is one sure fire way to force the body to dash towards pre-mature aging and chronic diseases. Enter calorie restriction. It is a dietary plan where a person would consume restricted calories but without the risk of malnutrition.
CR has long been studied as a robust mechanism to extend human life and improve health – minimizing the risks of various diseases and basically achieving a better overall health. A 2015 study even showed CR may help improve metabolism in the aging of muscles and increase muscle mass in the middle age .
Now, how can simply restricting your calorie consumption slow down aging? What exactly goes on within the body that produces an anti-aging outcome? CR, with adequate nutrition, seems to trigger some precise biochemical pathways that promote longevity and delay the start of age-associated health conditions. Some of these mechanisms involve reduced production of free radicals in the body, and specific changes in the body’s bio-chemistry and energy metabolism .
But it looks like there is another key driver behind the CR promise of longevity. CR activates Sirtuins, regulatory proteins that have garnered tremendous attention and popularity in scientific circles for their possible role in anti-aging and in preventing many chronic, age related diseases. Studies show that Sirtuins are involved in mediating CR’s anti-aging and disease reversing benefits.
Sirtuins as metabolic sensors
Sirtuins can sense changes in the bioenergy status of the cells (NAD+ availability) and trigger very targeted responses aimed to help cells survive better in the backdrop of fluctuating metabolic needs. In scientific terms, CR increases the production of NAD+, which activate Sirtuins. The tight coupling of NAD+ and sirtuins is necessary for many important functions in the body, for example to improve mitochondrial health (that translates into better energy metabolism), reduce oxidative stress in tissues, lower inflammation, and repair damaged DNA, among many others.
Sirtuins regulate the expression of certain genes that are:
- Linked with aging
- Associated with energy metabolism, immune and inflammatory responses, cellular growth and survival
This study summarises that “an emerging consensus from these recent studies is that sirtuins may act as metabolic sensors, using intracellular metabolites such as NAD and short-chain carbon fragments such as acetyl coenzyme A to modulate mitochondrial function to match nutrient supply.” 
In other words, sirtuins allow the body to continue functioning optimally and maintain balance while responding to stressful times, increased oxidative damage and less availability of nutrients for example during calorie restriction.
- CJ Chen et al. Late-onset Caloric Restriction Alters Skeletal Muscle Metabolism by Modulating Pyruvate Metabolism. American Journal of Physiology – Endocrinology and Metabolism, 2015.
- Wu etal. Metabolomics Insights into the Modulatory Effects of Long-Term Low Calorie Intake in Mice. Journal of Proteome Research. 2016
- Sack eta al. Sirtuins, aging, and metabolism. Cold Spring Harb Perspect Biol. 2012 Dec; 4(12): a013102.