• NMN increases the lifespan of female mice by 8.5% but does not increase the lifespan of male mice, perhaps because NMN metabolism is increased in females. 
  • NMN improves the health of both male and female mice but in a sex-dependent manner. 
  • NMN increases the abundance of beneficial gut bacteria, which are also abundant in people who live to be 100 years old. 

Last year, Professor David Sinclair teased new findings from his Harvard University lab showing that NMN extends the life of mice. Now, a preprint of Sinclair’s latest study reveals the details, demonstrating that NMN increases the lifespan of female but not male mice. 

In the yet-to-be peer-reviewed study, male and female mice were given ~550 mg/kg/day of NMN in their drinking water from 13 months of age. For their experiments, Sinclair’s team used C57BL/6 mice, a strain of mouse widely used by scientists. Interestingly, female C57BL/6 mice are known to have shorter lifespans than male C57BL/6 mice. Still, NMN treatment increased the median lifespan of female mice by 8.5% and maximal lifespan by 7.9%. 

Additionally, while NMN did not increase tumor burden, female mice exhibited more tumors than male mice. The authors note that increased tumor incidence could contribute to the shorter lifespans of C57BL/6 females. Moreover, the researchers found that NMN metabolism was greater in females than males, which could account for NMN increasing the lifespan of females but not males. 

NMN Improves Healthspan 

When it comes to healthspan — time lived in good health, especially during the final stage — both males and females reaped the benefits of NMN. Improvements from NMN observed in males include: 

  • Reduced vision loss
  • Less distended abdomen
  • Maintained fur color
  • Better breathing rate 

Improvements from NMN observed in females include:

  • Greater fur color maintenance 
  • Better coat condition
  • Less hunched posture 
  • Less tail stiffening

Additionally, in middle-aged (18 and 24 months) male mice, NMN prevented weight gain by reducing fat mass and increasing lean mass, as measured by DEXA imaging — used to measure bone density and fat accumulation. However, upon analyzing 17 tissues for disease burden, NMN-treated female mice were found to have inflamed kidneys. NMN also did not significantly change the grip strength of either males or females.

NMN Improves Gut Bacteria 

NMN has previously been shown to reduce harmful gut bacteria and increase beneficial gut bacteria in C57BL/6 mice. Now, Sinclair’s team has found that the beneficial bacterial species Anaerotruncus colihominis is increased in the gut of NMN-treated mice. Gut A. colihominis has been shown to suppress brain inflammation in mice and is also increased in centenarians — humans that live to 100 years and beyond. These findings suggest that NMN may improve healthspan, and possibly lifespan by increasing the abundance of A. colihominis in the gut.

Can NMN Restore the Healthspan of 88% of Americans? 

NMN supplementation appears to have healthspan effects in nearly every organ system. For example, NMN counteracts bone loss in a mouse model for osteoporosis, reverses cardiovascular dysfunction in aged mice and middle-aged adults, improves the metabolism of overweight middle-aged adults, and alleviates signs of dementia in mouse models for Alzheimer’s disease. Considering that NMN improves the metabolism of cells, and only 12% of Americans are metabolically healthy, it could be that NMN supplementation could improve the health of 88% of the population who are unhealthy. However, more studies are needed to confirm this speculation.