NAD+-Precursor Supplementation With L-Tryptophan, Nicotinic Acid, and Nicotinamide Does Not Affect Mitochondrial...

Area of Science:

• Gerontology and Exercise Physiology
• Mitochondrial Biology
• Nutritional Biochemistry

Background:

• Nicotinamide adenine dinucleotide (NAD+) is crucial for cellular energy metabolism and healthy aging.
• NAD+ levels decline with age, potentially contributing to muscle mass and function loss.
• Supplementation with NAD+ precursors is explored as a strategy to counteract age-related decline.

Purpose of the Study:

• To evaluate the effectiveness of NAD+-precursor supplementation on skeletal muscle mitochondrial function in older adults with physical impairments.
• To assess the impact of NAD+ precursors on mitochondrial oxidative capacity and exercise efficiency.

Main Methods:

• A 32-day randomized, double-blind, controlled trial involving 14 older adults (age ~73 years) with impaired physical function.
• Participants received daily niacin equivalents (207.5 mg) or a placebo.
• Primary outcomes included mitochondrial oxidative capacity and exercise efficiency; secondary outcomes included NAD+ concentrations.

Main Results:

• Skeletal muscle NAD+ concentrations did not differ significantly between groups.
• Methyl-nicotinamide levels were significantly higher in the supplementation group, indicating increased NAD+ metabolism (P=0.001).
• No significant improvements were observed in ADP-stimulated or maximal mitochondrial respiration, nor in net exercise efficiency.

Conclusions:

• NAD+-precursor supplementation (tryptophan, nicotinic acid, nicotinamide) did not enhance skeletal muscle mitochondrial function or physical performance in older adults with impaired function.
• Findings suggest that NAD+ precursor supplementation may not be an effective strategy for improving muscle health in this demographic.
• Further research is needed to understand NAD+ metabolism and its role in age-related muscle decline.