Walk down the supplement aisle at your local drugstore and you’ll likely spot bottles of NAD (nicotinamide adenine dinucleotide) pills, powders, or liquids that promise to slow down aging.
The global market for these products hit $535.53 million in 2022. But do NAD supplements really work?
“I get asked about NAD supplements occasionally by patients,” says Dr. Nicholas Dragolea, a London-based GP with an interest in longevity and functional health at My Longevity Centre in the United Kingdom. “My answer usually is that there isn’t enough medical evidence to support taking it.”
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What is NAD and why the hype?
NAD is a molecule your body makes from nutrients in your diet like tryptophan and niacin. It’s involved in hundreds of different processes in the body—from metabolism, to brain health, to DNA repair—making it critical for overall human health, explains Daniel Craighead, an assistant professor in the School of Kinesiology at the University of Minnesota Twin Cities.
“NAD levels tend to go down as we get older,” he says. “Therefore, the thought is that if we can restore NAD through dietary supplements, we may be able to reverse a lot of the signs and symptoms of aging.”
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What do studies show?
In 2023, Craighead and his colleagues reviewed research on oral NAD precursors and their effects on healthy aging and age-related chronic diseases. (Rather than NAD itself, many supplements contain NAD precursors like nicotinamide riboside and nicotinamide mononucleotide, which are more stable and are converted to NAD by the body).
Lab studies in cells and mice showed promising results, supporting the theory that NAD promotes healthy aging and helps with DNA repair. But human studies paint a more mixed picture.
“So far, most of the studies in people are relatively short, lasting weeks to months, and done in small groups of only a couple dozen people,” says Craighead. “These human studies have shown that NAD+ precursors are safe and boost NAD+ levels, but significant improvements in health generally haven’t been observed.”
The best evidence we have is that these NAD precursors may decrease inflammation, adds Craighead. For example, a study published in 2019 found that three weeks of nicotinamide riboside supplementation reduced blood markers of inflammation by 50% to 70% in older men. Chronic inflammation is a hallmark of aging and age-related diseases, making this a promising result.
Another review, published in 2024, noted potential benefits for age-related and neurological conditions like Parkinson’s and Alzheimer’s disease, but cautioned that further clinical trials must be performed. One of the studies included in the review showed that oral nicotinamide riboside supplements increased brain NAD levels and altered brain metabolism in individuals with Parkinson’s disease. The supplements also reduced inflammatory cytokines—proteins that act as messengers in the immune system—in the blood and cerebrospinal fluid (a fluid that surrounds and protects the brain and spinal cord) of participants. In another 2004 study, patients with Alzheimer’s disease who took NAD supplements showed improvements in cognitive functions, such as verbal fluency and abstract reasoning.
What do doctors say?
Some clinicians report anecdotal benefits. “My patients see huge improvements in energy when I start them on injections of daily low dose NAD,” says Dr. Heather Hinshelwood, the co-owner and chief of medicine of Fraum Health, a provider of restorative medicine, chiropractic, and proactive wellness care on Hilton Head Island in South Carolina. “I have dementia patients who start having better cognition than their spouses,” she adds.
But many experts remain cautious.“There is no high-quality evidence that NAD supplementation has any health benefit,” says Dr. David S. Seres, a professor of medicine at the Institute of Human Nutrition at Columbia University Medical Center in New York. “Without strong evidence from well-done randomized trials, we recommend against taking any dietary supplements.”
Are they safe?
So far, human studies indicate that NAD supplements are generally safe. But Dr. Seres warns that safety assumptions based on weak evidence can be dangerous.
Take vitamin E and selenium: Early research showed that men with prostate cancer had low levels of vitamin E and selenium. But a clinical trial involving 35,000 men later found that men who took vitamin E were more likely to develop prostate cancer compared to men on placebo.
“You cannot assume that supplements are effective or safe based on the kind of evidence used to make claims such as ‘supports energy’ or ‘supports healthy aging,’” says Seres.
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Bottom line
For now, NAD supplements are not a proven tool for healthy aging. “Longer studies with more participants are needed,” says Craighead.
If you still want to try taking NAD, just note that not all supplements contain what their labels claim. A 2024 analysis found that many nicotinamide mononucleotide (NMN) products contained far less of the active ingredient than advertised, Craighead says, “so consumers may be wasting money on supplements that contain no NMN.”
This story is part of Popular Science’s Ask Us Anything series, where we answer your most outlandish, mind-burning questions, from the ordinary to the off-the-wall. Have something you’ve always wanted to know? Ask us.
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