A new study published in Cell Metabolism in May 2025 challenges the widely held belief that declining levels of nicotinamide adenine dinucleotide (NAD+) in muscles are a primary driver of aging. Researchers at the University of Copenhagen found that drastically reducing NAD+ levels in the skeletal muscle of mice did not accelerate aging or impair metabolism as expected.
The scientists reduced NAD+ levels in the mice's skeletal muscle by 85%. Surprisingly, the mice maintained normal muscle size, strength, and exercise performance. This suggests that healthy muscle function may not be as reliant on high NAD+ levels as previously thought.
While energetic stress increased during exercise, the overall muscle and body health of the mice remained similar to that of regular mice. These findings question the prevailing view that NAD+ decline is a primary cause of muscle aging and frailty, suggesting that the benefits claimed by supplement companies may be overstated. Associate Professor Jonas Treebak, the corresponding author of the study, stated that their results indicate that skeletal muscle can tolerate substantial NAD+ depletion without loss of function or accelerated aging.