NMN and NR

In people, both raise NAD+. In a six-week crossover trial in healthy middle-aged and older adults, NR was well tolerated and raised NAD+ metabolism in blood [1]. In a 10-week trial, NMN improved muscle insulin sensitivity in postmenopausal women with prediabetes and excess weight [2]. A 12-week trial of a high dose of NR in men with obesity found no change in insulin sensitivity or body composition [3].

Pooled results are modest. A 2024 meta-analysis of 19 trials found that NAD+ precursors lowered total cholesterol and triglycerides but had no clear effect on other metabolic measures [4], and a 2025 meta-analysis found no benefit for muscle mass or strength in adults over 60 [5]. A 2026 systematic review of 33 human studies concluded that the supplements reliably raise NAD+ markers, while effects on health are mixed and often absent [6].

The striking results are in mice. A year of NMN in normally aging mice limited weight gain and improved energy use, insulin sensitivity and eye function [7]. When the Interventions Testing Program fed NR to genetically mixed mice, it did not extend lifespan [8]. No study has tested whether NMN or NR extends life in people. Neither is an approved drug for any condition; both are sold as supplements.

• NMN and NR are sold as dietary supplements, not approved drugs. In September 2025 the FDA said NMN may be sold as a supplement in the US, reversing its 2022 position.
• Trials lasting weeks to a few months found both well tolerated. Safety over years of use is unknown.
• The FDA does not check supplements for purity or dose before they are sold, so products vary.
• Whether raising NAD+ for years changes cancer risk has not been studied in people.
• People who are pregnant, breastfeeding or being treated for cancer should talk with a physician before taking them.