NAD+

Nicotinamide adenine dinucleotide (NAD+) is a coenzyme essential for energy production and cellular health, often linked to anti-aging benefits. However, when it comes to taking pure NAD+ orally, the evidence leans toward it being ineffective due to challenges with absorption in the digestive system.
Pure NAD+ seems likely to be broken down in the stomach, reducing its ability to reach cells in an active form. This is why supplements often use precursors like NR and NMN, which the body can convert into NAD+ more efficiently.
If you're considering NAD+ for health benefits, oral supplements are typically in the form of precursors, not pure NAD+.
Nicotinamide adenine dinucleotide (NAD+) is a critical coenzyme found in all living cells, playing a central role in metabolism, particularly in redox reactions that generate energy. It exists in two forms: NAD+ (oxidized) and NADH (reduced), and is essential for processes like mitochondrial function, DNA repair, and sirtuin activation, which are linked to healthy aging. Given its importance, there has been growing interest in NAD+ supplementation, especially as levels decline with age, potentially contributing to age-related diseases.
To provide context, precursors like NR and NMN have been more extensively studied for oral use. Chronic supplementation with NR was well-tolerated and increased NAD+ levels in healthy middle-aged and older adults, with potential benefits for blood pressure and arterial stiffness Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults.

Study Focus	Form Administered	Findings	Human/Animal	Source URL
NAD+ precursors in aging	NR, NMN	Increased NAD+ levels, potential cardiovascular benefits	Human	Dietary Supplementation With NAD+-Boosting Compounds in Humans
Oral nicotinamide effects	Nicotinamide	500 mg increased blood NAD+ after 12 hours in small cohort	Human	A single oral supplementation of nicotinamide
Bioavailability of NADH	NADH	Increased brain levels in rats, limited human data	Animal	Bioavailability of reduced nicotinamide-adenine-dinucleotide
Clinical trials on NAD+	NAD+, precursors	Mixed results, more focus on precursors, 8 studies on oral NAD+	Human	Clinical Evidence for Targeting NAD Therapeutically