In this episode, Dr. Michael Greger continues his series on NAD+ by examining nicotinamide (NAM), a form of vitamin B3 widely used in supplements. He discusses its potential benefits, side effects, and why its role in healthy aging may be more complicated than supplement marketers suggest.

Key Points:

Nicotinamide plays vital roles in human biology, but high-dose supplementation carries real risks and lacks solid evidence for longevity benefits. For now, lifestyle and diet remain far more reliable tools for supporting healthy aging than pills.

• What Nicotinamide Can Do: NAM has shown benefits in specific contexts—such as skin health and skin cancer prevention—but it has failed to extend lifespan in animal studies and does not consistently raise NAD+ or improve muscle function in humans.
• Potential Risks and Side Effects: High doses of NAM can cause gastrointestinal issues, liver toxicity, and methylation problems. Excess NAM produces methylnicotinamide, a neurotoxic compound linked to Parkinson’s-like and Alzheimer’s-related changes.
• Impact on Aging Pathways: Unlike other NAD+ boosters, NAM may actually inhibit sirtuin activity, key enzymes that protect healthspan. This feedback effect could explain its lack of longevity benefits in lab studies.
• Supplements vs. Reality: While NAM and related compounds are marketed as anti-aging solutions, clinical trials in humans show minimal to no improvement in metabolic, cardiovascular, or muscular health outcomes.