Japanese scientists find that NMN reduces blood vessel stiffness in middle-aged adults with higher-than-average weight and blood glucose levels.
Nicotinamide mononucleotide (NMN) is a promising anti-aging therapeutic, as it promotes the synthesis of nicotinamide adenine dinucleotide (NAD+), a molecule that declines with aging. NMN’s anti-aging potential stems from model organism studies showing that it prolongs lifespan and mitigates age-related disease. However, the degree to which NMN slows the aging process in humans remains unclear.
In a preprint article (not yet peer-reviewed) shared on Research Square, Katayoshi and colleagues from the DHC, a corporation in Japan that sells skincare products, report the findings of a clinical trial testing the effects of NMN on humans. The results showed that NMN tends to reduce arterial stiffness in healthy middle-aged adults but without statistical significance. However, statistically significant reductions in arterial stiffness were observed in individuals with above-average weight and blood glucose levels. Furthermore, NMN was calculated to reverse blood vessel aging by two years.
When young, our blood vessels are highly elastic, able to modulate blood flow to active organs. However, with age, our blood vessels lose elasticity and become stiff, making our hearts work harder. To test the effects of NMN on blood vessel aging, Katayoshi and colleagues measured blood vessel (artery) stiffness from thirty-four healthy adults aged 40-59 years who took 250 mg of NMN for twelve weeks. They assessed blood vessel stiffness by measuring how fast blood moves through an artery near the ankle. The researchers found that, while not statistically significant, NMN reduced blood vessel stiffness.
Since high blood pressure, obesity, and high blood glucose levels are cardiovascular disease risk factors, Katayoshi and colleagues separated participants based on their blood pressure, body mass index (BMI), or blood glucose level. Participants with above-average BMI or blood glucose levels had reduced blood vessel stiffness after NMN treatment, suggesting that NMN improves vascular health in those with high BMI and blood glucose.
Scientists have been able to calculate the age of our organs and tissues using various indicators, such as blood vessel stiffness. Using such calculations, Katayoshi and colleagues estimated that NMN makes blood vessels approximately two years younger in middle-aged adults. The precise process by which NMN improves blood vessel aging, however, remains unclear.
Since reduced blood vessel stiffness is associated with an increased risk of cardiovascular disease, the findings from Katayoshi and colleagues suggest that NMN supplementation could reduce cardiovascular disease risk. Only one other study has tested the effects of boosting NAD+ on blood vessel stiffness. In the study, 1000 mg of nicotinamide riboside (NR) was given to middle-aged adults for 6 weeks, resulting in a tendency to reduce blood vessel stiffness. Thus, these two studies have similar results, and it may be that a larger study could result in statistically significant findings.
Clinical trials testing the effects of NMN on human aging have only begun in the last few years. So far, NMN has been shown to increase insulin sensitivity, improve sleep and physical performance, enhance exercise endurance, improve skin health, increase walking speed, and increase strength in middle-aged and older adults. These clinical trials suggest that much of the research demonstrating the anti-aging effects of NMN on animals is translatable to humans. Still, more long-term studies are needed to assess adverse effects that may occur with chronic NMM supplementation. If NMN proves to be safe in the long-term, larger studies may even show more significant anti-aging effects.
Model: Human older adult
Dosage (oral): 250 mg/day of NMN for 12 weeks