Nicotinamide adenine dinucleotide, or NAD, is a helper molecule that cells use for energy, DNA repair, and body clock control. Its level falls with age. NAD supplements do not provide NAD itself, they provide precursors, most often nicotinamide riboside, NR, or nicotinamide mononucleotide, NMN. These precursors can raise NAD in blood, but proof of broad, long term health benefits in people is still limited.
Early human trials suggest two patterns. First, raising NAD with NR looks safe for short periods in adults, and it reliably lifts blood NAD. Second, some signs of lower inflammation appear in select groups, for example a small trial in chronic lung disease found reduced airway inflammation after six weeks of NR. Clear gains in symptoms or long term outcomes were not shown.
For heart health, a pilot study in patients with heart failure showed NR increased blood NAD and was well tolerated, with lab signals of better cell energy, but it did not prove clinical benefit. Larger outcome trials are needed.
For muscle and strength, results are mixed. One trial in older men reported small improvements in grip strength and walking speed with NMN, while more recent evidence pooling trials finds no consistent benefit for muscle mass or function in older adults.
For brain aging, early studies in people with mild cognitive impairment show NR is safe and can change some brain measures, yet clear memory improvement has not been demonstrated. Research is ongoing.
Safety and who should avoid it: NR has formal safety opinions in the EU for adults at typical supplement doses, but not for children, pregnancy, or breastfeeding. NMN’s legal status as a supplement in the United States remains unsettled due to the FDA’s “drug preclusion” process. People with current or past cancer should be cautious, since some mouse studies suggest NAD precursors could, in some settings, fuel tumor spread, while other models show the opposite. This uncertainty supports medical advice before use.
NAD precursors can raise NAD, and may lower some inflammation in specific conditions, but proven, durable health gains in humans are not yet established. If you decide to try them, prefer products with clear quality control, avoid use in pregnancy, breastfeeding, and childhood, and discuss risks if you have a cancer history. For most people, habits that support healthy NAD, regular exercise, good sleep, and a balanced diet, are likely to deliver more certain benefits today.
Nature Aging – Effect of nicotinamide riboside on airway inflammation in COPD: a randomized, placebo controlled trial – 2024
In older adults with chronic obstructive pulmonary disease, six weeks of NR raised blood NAD and reduced a key airway inflammation marker. The study was small and did not show symptom gains.
JACC: Basic to Translational Science – Safety and tolerability of nicotinamide riboside in heart failure with reduced ejection fraction – 2022
In a pilot trial, NR doubled blood NAD in stable heart failure patients and was well tolerated, with signals of improved mitochondrial function, but no proven clinical outcome benefit.
npj Aging – Chronic nicotinamide mononucleotide supplementation elevates NAD and partially improves physical performance in healthy older men – 2022
NMN raised NAD and showed small improvements in walking speed and grip strength in older men. Findings are preliminary and short term.
Nutrients – The effect of nicotinamide mononucleotide and riboside supplementation on muscle in adults: a systematic review of randomized controlled trials – 2025
Across randomized trials in older adults, current evidence does not support NMN or NR to preserve muscle mass or function.
EFSA Journal – Safety of nicotinamide riboside chloride as a novel food – 2019
The EU safety panel concluded NR chloride is safe for the healthy adult population under specified uses, excluding pregnant and lactating women from the approval.
EFSA Journal – Extension of use of nicotinamide riboside chloride as a novel food – 2021
Confirmed NR as safe as a source of niacin for specific foods under set limits, with adult focused conditions of use.
Nutraceuticals World – FDA delays response to citizen petition on NMN – 2025
NMN remains under FDA drug preclusion review in the U.S., leaving its supplement status unresolved as of mid 2025.
European Journal of Cell Biology – Acute exercise boosts NAD metabolism in human immune cells – 2025
A controlled study shows a single bout of exercise upregulates enzymes of NAD metabolism in human blood cells, supporting exercise as a practical way to support healthy NAD.
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