Question 1

What is the difference between NMN, NR, and niacin for boosting NAD+?

Accepted Answer

All three are NAD+ precursors but enter the biosynthesis pathway at different points. NMN (Nicotinamide Mononucleotide) is one step away from NAD+ and requires the transporter SLC12A8 for cellular uptake. NR (Nicotinamide Riboside) enters cells via nucleoside transporters and is converted to NMN then NAD+. Niacin (vitamin B3) uses the Preiss-Handler pathway but causes flushing at effective doses. NR has the most published human clinical trial data. NMN has growing evidence and is favored by some researchers. Cost, bioavailability, and side effect profiles differ between them.

Question 2

Is IV NAD+ better than oral NMN or NR?

Accepted Answer

IV NAD+ infusion bypasses the digestive system and delivers NAD+ directly to the bloodstream, producing immediate and dramatic increases in blood NAD+ levels. However, NAD+ in the blood has a very short half-life (~30 minutes) and the extent to which IV NAD+ enters cells is debated. Oral precursors (NMN, NR) are converted to NAD+ inside cells where it is actually needed. The "best" approach likely depends on the goal: IV NAD+ is popular for acute applications (detox, energy boost), while oral precursors are more practical for sustained daily NAD+ elevation.

Question 3

What does David Sinclair say about NAD+ and aging?

Accepted Answer

Dr. David Sinclair, a Harvard genetics professor, has been a prominent advocate for NAD+ supplementation as an anti-aging strategy. His lab's research demonstrated that NMN can reverse aspects of aging in mice, including improved blood vessel growth, exercise endurance, and muscle function. Sinclair has publicly stated he takes NMN daily as part of his personal longevity regimen. While his research is respected, it is important to note that animal results do not always translate to humans, and large-scale human longevity trials with NMN are still ongoing.

Question 4

What is the optimal dose and timing for NAD+ supplementation?

Accepted Answer

There is no universally agreed-upon optimal dose. Human trials have used NR at 300–2000 mg/day and NMN at 250–1200 mg/day, generally showing safety and NAD+ elevation across this range. Many researchers and clinicians recommend starting at 250–500 mg NMN or 300 mg NR daily and adjusting based on response. Morning dosing is preferred as NAD+ is involved in circadian rhythm regulation. Taking precursors with food may reduce GI side effects. Some practitioners cycle NAD+ supplementation (5 days on, 2 days off) to prevent potential downregulation of salvage pathway enzymes.

Question 5

Is it too late to start NAD+ supplementation at age 60 or older?

Accepted Answer

No. In fact, the greatest NAD+ decline occurs between ages 40 and 70, making this the period where supplementation may have the most impact. Animal studies have shown benefits even when NAD+ boosting is initiated in old age — including improved mitochondrial function, reduced inflammation, and better metabolic markers. Some researchers argue that older individuals may benefit more because they have a larger NAD+ deficit to correct. The key concern is the theoretical cancer risk, which should be discussed with a physician, particularly for older individuals who have a higher baseline cancer risk.

Route	Dosage Range	Frequency	Notes
Oral (NMN)	250–1000 mg	Once daily, typically morning	Sublingual NMN may improve bioavailability; take with food to reduce GI effects
Oral (NR / Niagen)	300–1000 mg	Once or twice daily	NR (Nicotinamide Riboside) is the most clinically studied NAD+ precursor
Intravenous infusion (NAD+)	250–750 mg	Single session over 2–4 hours; series of 4–8 sessions	Infusion rate should be slow to minimize chest tightness; clinic-administered only

NAD+

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