Nicotinamide, also known as niacinamide, is a form of vitamin B3 that has gained attention in aging research primarily due to its role in cellular energy metabolism and DNA repair. Scientific interest is largely based on its function as a precursor to nicotinamide adenine dinucleotide (NAD+), a crucial coenzyme involved in numerous biological processes, including mitochondrial function and cellular repair mechanisms. NAD+ levels naturally decline with age, and this decline is thought to contribute to age-associated physiological changes and reduced cellular function.

Preclinical studies in animal models have shown that supplementation with nicotinamide or related compounds can increase NAD+ levels, improve cellular health, and in some cases, extend lifespan or delay aging phenotypes. However, direct evidence in humans is limited. Some small clinical trials suggest nicotinamide can improve skin barrier function and may reduce formation of some types of skin cancers, which are more prevalent with aging. However, robust evidence supporting its use for systemic anti-aging effects in humans is lacking. Large-scale, long-term clinical trials in humans are needed to better establish efficacy and safety for aging prevention specifically.

In summary, the rationale for nicotinamide in aging prevention is scientifically grounded, but current human evidence is limited and does not justify strong claims. The overall quality of evidence for its anti-aging effects in humans rates as low to moderate.