Nicotinamide Mononucleotide (NMN) is a prominent focus in anti-aging research due to its role in cellular metabolism. The compound is widely available as a dietary supplement and is often discussed for its potential to combat various signs of aging, including cognitive decline and physical fatigue. Determining if NMN’s cellular benefits extend to reversing grey hair requires examining its mechanism against the root cause of lost hair pigment.
The Biological Root Cause of Hair Greying
Hair greying is caused by the loss of pigment in new hair growth. Hair color is determined by melanocytes, specialized pigment-producing cells located in the hair follicle bulb. These melanocytes produce melanin, which is transferred to the keratinocytes that form the hair shaft.
The process of greying begins with a decline in the function and number of melanocytes and their stem cells (McSCs). Oxidative stress is a major contributor, damaging melanocytes and impairing the enzymatic machinery needed for melanin production. This cellular damage is exacerbated by environmental factors, genetic predisposition, and aging.
When a hair follicle enters a new growth cycle, McSCs migrate and differentiate into mature melanocytes. Hair becomes grey or white when this stem cell reservoir is depleted, or when differentiated melanocytes fail to produce pigment effectively. Once the stem cell pool is exhausted, the greying process is considered largely irreversible.
NMN’s Influence on Cellular Energy and Aging
Nicotinamide Mononucleotide is a direct precursor to Nicotinamide Adenine Dinucleotide (NAD+). NAD+ is a coenzyme present in all living cells and is fundamental to over 300 metabolic processes, including energy production and DNA repair. It plays a central role in mitochondrial function.
As organisms age, NAD+ levels in tissues naturally decline, sometimes plummeting by half by middle age. This age-related decrease is linked to a decline in cellular function, contributing to various aspects of aging. Supplementing with NMN is a strategy to boost NAD+ levels, thereby supporting cellular health and potentially mitigating some effects of aging.
The increased NAD+ levels activate sirtuins, a family of proteins that regulate cellular longevity and protect against stress. Sirtuins rely on NAD+ to function, and their activity is tied to DNA repair and maintaining genomic stability. By supporting these repair mechanisms and enhancing mitochondrial energy production, NMN is hypothesized to restore cellular vitality.
Current Scientific Findings on NMN and Hair Repigmentation
The direct evidence for NMN reversing existing grey hair in humans is currently limited and inconclusive, with most research focusing on hair growth and density. However, the connection between NMN and hair color is based on its ability to counteract the underlying causes of greying, particularly oxidative stress and stem cell decline. Boosting NAD+ with NMN may help protect pigment-producing cells from oxidative damage, which is a primary driver of premature greying.
Preclinical and laboratory studies have provided some initial, promising data concerning the NMN-NAD+ pathway and hair health. Animal studies have suggested that NMN may mitigate some age-related symptoms, including hair greying, and increase the size and number of hair follicles. Furthermore, NMN has been shown in laboratory settings to enhance the viability and proliferation of hair dermal papilla cells, which are essential for hair regeneration.
While NMN is effective in improving hair quality, increasing hair diameter, and enhancing hair density in human clinical trials, these studies have focused predominantly on hair growth rather than repigmentation. The few studies that have addressed pigmentation hint at NMN’s ability to influence melanin pathways in aging melanocytes, but the results are varied and require more extensive investigation. NMN is currently considered a potential tool to slow the future occurrence of grey hairs by protecting the melanocyte stem cell reservoir, rather than a proven method for repigmenting already grey hair strands.