NAD+ and hair regrowth: what does science say?

NAD+ for restoring hair growth: myth or reality?

NAD+ (nicotinamide adenine dinucleotide) is an essential coenzyme found in all living cells, playing a crucial role in cellular energy production and the regulation of numerous biological processes. Its potential impact on hair regrowth is an increasingly explored subject, although research is still in its early stages.

A recent study, primarily conducted on animal models, has shown that increasing levels of β-nicotinamide mononucleotide (NMN), a precursor of NAD+, could have a positive effect on hair growth. A study in vivo observed that the administration of NMN in mice post-hair removal helped to reduce signs of ageing in hair follicles. NMN not only helped to restore the size of hair follicles, but also to reduce hair thinning caused by a treatment with dihydrotestosterone (DHT), a factor commonly associated with hair loss. The observed effects were similar to those of minoxidil, a treatment commonly used to stimulate hair regrowth.

The underlying mechanisms of these results include the reduction of inflammation in the dermal cells of the hair papilla treated by DHT, as well as the protection against oxidative stress. Furthermore, hair growth markers, such as Vascular Endothelial Growth Factor (VEGF) and β-catenin, showed increased expression, while androgen receptors and inhibitors like DKK-1 were decreased, thus promoting hair regrowth.

Another study in vivo has also validated the effect of NAD+ on DNA repair, directly through the activation of PARP1 and by acting on hair growth cycles. In summary, it has been demonstrated that the activation of PARP1 under the control of NAD+ could reduce DNA losses from hair follicles and regulate the stages of hair growth.

However, although the studies are promising, large-scale human clinical trials are needed to confirm these effects, which are currently only hypothesised in humans. Ongoing studies indeed show that NAD+ could play a role in the regeneration of hair follicles, but there is still no proof that it is effective in a practical application against hair loss.

What are the mechanisms of NAD+ related to hair regrowth?

To understand the extent to which NAD+ could become a partner in hair regrowth, it is insightful to observe the biological mechanisms it regulates. Indeed, this molecule is fundamental in several cellular processes, including DNA repair systems, combating oxidative stress, and the activation of certain proteins. It is possible to associate these functions with its potential effects on the health and regeneration of hair follicles.

NAD+ in cellular and DNA repair: Hair follicles are constantly exposed to oxidative stress, particularly with age. NAD+ plays a crucial role in the repair of damaged DNA and the regulation of oxidative stress. By increasing NAD+ levels, it becomes possible to enhance the cells' ability to regenerate, including those involved in hair production.
The activation of sirtuins by NAD+: Sirtuins, proteins activated by NAD+, are involved in the regulation of cell lifespan and their resistance to stress. Research has shown that these sirtuins, particularly SIRT1, are crucial for the survival and regeneration of stem cells in hair follicles. Increasing the activity of sirtuins, particularly via a NAD+ supplement, could theoretically promote hair growth.
Reducing cellular ageing with NAD+: The ageing of hair follicle stem cells is a major factor in hair loss. NAD+, known for its beneficial effects on cellular vitality, could also play a role in the regeneration of hair follicles. Some research suggests that it has the ability to reverse certain aspects of hair ageing by regenerating the stem cells involved in hair growth.

Although the results are promising regarding the existing link between NAD+ and, therefore, hair, the research is in its infancy. Studies conducted on animals demonstrate that this molecule could be beneficial for hair follicles by playing a role in cellular renewal, as well as having a protective effect against oxidative stress, but there is no evidence to support its action on human hair in practice during clinical trials. It is important to highlight the interest in the underlying mechanisms of NAD+, but further studies are needed to demonstrate its potential role in a protocol aimed at stimulating hair regrowth.