16 May 2016

How vitamin B3 protects against aging

Traditional approaches to stem cell therapy involve the transplantation of cells into the body to eliminate or alleviate the symptoms of the disease. Canadian researchers from the University of Ottawa, working under the leadership of Dr. Keir Menzies, together with Swiss colleagues from Lausanne and Zurich, identified a biological mechanism that allows increasing energy production in the body's own stem cells without transplantation of donor material.

This mechanism makes it possible to influence the mitochondria – the energy centers of the cell – during aging and diseases by adding the precursor NAD+ nicotinamidriboside, which is a special form of vitamin B3, which is part of milk and other foods. (NAD+ is the main energy carrier in the cell and a sufficient amount of it is necessary for the effective functioning of mitochondria.) The described intervention increases the viability and functionality of the body's stem cells, contributing to the restoration of organs damaged by the disease and increasing life expectancy.

Based on the results of the work, the authors also concluded that the hypothesis that stem cells avoid oxidative stress by using glycolysis as the main method of energy production may not cover all functional aspects. The new data demonstrate the importance of oxidative mitochondrial respiration for various types of adult stem cells in the aging process, as well as the fact that a decrease in the NAD+ cell pool complicates the adaptive mitochondrial response of unstructured proteins. Ultimately, this leads to the loss of mitochondrial homeostasis with a simultaneous decrease in the number of muscle stem cells and their ability to self-renew. An increase in the concentration of NAD+ in muscle stem cells can increase resistance to proteotoxic stress (toxicity from proteins, usually unstructured) by activating the mitochondrial response of unstructured proteins, stimulating proteins of the prohibitin family, which are sensors and effectors of mitochondrial stress. This, in turn, improves mitochondrial homeostasis, preventing muscle stem cells from entering the phase of physiological aging and protecting the muscle function of aging mice.

The analysis also showed that the positive effect of increasing intracellular NAD+ reserves extends not only to muscle stem cells. Nicotinamide riboside also delayed the physiological aging of nerve stem cells and melanocyte stem cells, which ultimately contributed to an increase in the lifespan of mice.

It should be noted that the increase in life expectancy was insignificant compared to the total life expectancy of animals. However, when comparing the duration of the remainder of life after the start of taking nicotinamide riboside at the advanced age of 24 months for mice, this difference increases and reaches 20%.

During the experiments, mice received nicotinamide riboside at a dose of 400 mg per kilogram of body weight per day for 6-8 weeks. The equivalent dose for humans, calculated according to the guidelines of the US Food and Drug Administration (FDA), is approximately 32 mg per kg of body weight per day, or approximately 2.1 g per day for a person with a body weight of 70 kg. Commercially available supplements usually contain nicotinamide triboside at a dose of 250 mg. Although there were no side effects from the use of nicotinamide triboside even in high doses, the authors note that its use can increase the functionality of not only useful, but also harmful (for example, malignant) cells and it will be possible to recommend "miracle vitamin" for use only after full-fledged clinical studies.

Article by Hongbo Zhang et al. NAD+ replication improves mitochondrial and stem cell function and enhances life span in mice published in the journal Science.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on EPFL materials: A vitamin that stops the aging process of organs..


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