04 / results and their limits
NAD+ research shows blood changes, while lasting health gains are much less sure.
NAD+ assists cells with energy use and repairs. Here you'll find what happened in pill studies, mouse experiments, and early tests of drips.
The strongest NAD+ pill finding is a higher blood reading
NAD+ is part of the work that supplies energy and repairs cells. This page explains what researchers found and what those findings mean for you. Mouse studies produced many of the claims about slower aging. Vein-drip studies provide little strong proof of benefit. A 2025 review found lasting gains in human health still unproved. Human pill tests reliably found higher NAD+ in blood. The tested ingredients, NMN or NR, supplied material for cells to make NAD+. Tests of walking or muscle response also improved in some studies.
A change in one test doesn't tell you whether you'll gain extra years or feel a difference.
Cells pass energy along with NAD+ and spend NAD+ on repairs
NAD+ changes form as cells break food down and release energy. During those changes, NAD+ collects energy and carries the energy where cells can use it [5]. Other work spends NAD+ rather than returning NAD+ ready for reuse. Three groups of proteins depend on NAD+: some control food use and responses to stress, some repair DNA, and some control the response to injury or infection [5]. That immune response is called inflammation.
After NAD+ is spent, your cells have to replace the supply.
Much of the replacement comes from reusing parts left from spent NAD+ [5][14]. A protein controls how quickly cells can do that work. Researchers study that protein to understand aging and diseases that damage the brain [14]. In aging mice, another protein consumes more NAD+ [2]. More use can leave less for other cell work.
Your supply depends on how quickly cells replace NAD+ as well as how much they use.
A NAD+ supplement raises blood readings more reliably than health
A 2025 review found little firm proof that these supplements improve health with age. Few studies had measured NAD+ in different human tissues [15]. NAD+ has no FDA drug approval. Pills commonly contain ingredients that help make NAD+, since the whole substance isn't absorbed easily [5]. During eight weeks of NR, the participants' NAD+ blood readings rose by 22%, 51%, and 142% at 100, 300, and 1000 milligrams a day, respectively [4]. In a different study, NMN at 300-900 milligrams a day for 60 days gave larger blood rises at larger amounts [3].
Neither set of blood results establishes a lasting benefit for you.
One NMN study tested women whose blood sugar was above normal. They took 250 milligrams a day for 10 weeks. Their muscles took sugar in more readily in response to insulin, the hormone helping sugar enter cells, but their fat, muscle amount, and test of longer-term blood sugar were unchanged [1]. Another NMN study found people walked farther in a test and gave more favorable answers about their health [3].
The muscle finding is narrower than proof of better blood sugar control overall.
Nicotinamide riboside (NR) raised NAD+ during an eight-week test
These findings concern healthy overweight adults, rather than everyone who might take NR. The test lasted eight weeks, so long-term safety wasn't settled. At 100/300/1000 milligrams daily, participants' NAD+ blood readings rose by 22%/51%/142%, respectively. The rises lasted during the study. Nobody reported flushing, when skin turns red and feels hot. Tests found no rise in “bad” cholesterol. Side effects showed no clear difference between NR and placebo, a similar-looking pill containing no NR [4]. Lab studies explain how cells change NR to NMN ahead of the final step making NAD+ [13]. You can follow the NR findings while keeping the ingredient and the blood test separate.
Higher readings in those people weren't proof of extra years of life.
Nicotinamide mononucleotide (NMN) raised NAD+, while its selling rules remain disputed
Short human studies have tested NMN, a substance cells use to make NAD+. Taking 250 milligrams a day helped muscles respond to insulin over 10 weeks [1]. At 300-900 milligrams a day for 60 days, higher amounts brought larger rises in blood NAD+ [3]. Those results don't settle the separate dispute over NMN's place among supplements. The FDA's position was that permission for drug testing came first. Under the rule the FDA cited, that earlier drug-testing permission kept NMN outside the supplement category. The dispute affects the rules for NMN sales, rather than proving NMN unsafe or banned [15].
A pill being offered for sale doesn't establish approval or a health benefit.
Mouse muscle released less energy when NAD+ replacement was weakened
Researchers studied mouse muscle cells in a dish and whole muscle. Those tests can't establish treatment for your muscles. Weakening a protein needed to reuse spent NAD+ left less NAD+ in the muscle. The muscle could then release less energy at its greatest effort. Giving NR restored NAD+ and increased that measured energy output [11]. Aging mice bred without a protein that consumes NAD+ also kept more NAD+ and better energy release [2]. Researchers think poor replacement helps explain energy loss in older tissue [5][12].
These tests measured muscle cell work, without proving a pill strengthens people.
NR improved memory tests in mice with brain changes resembling Alzheimer's
Researchers bred these mice to develop brain changes resembling Alzheimer's disease, so the experiment examined those animals and didn't test a treatment in people living with Alzheimer's or establish help for you. After five months of NR, the mice had more NAD+ in their brains. Their brains also had fewer substances driving inflammation, the immune response that can damage tissue when too active. Brain cells involved in that response were less active. Part of the immune system's alarm response also calmed down. The mice did better in memory tests, and tests showed better communication between brain cells [8]. The findings concern memory and brain inflammation in those mice, not proof of preventing, treating, or reversing Alzheimer's in people.
Your care can't be settled by an experiment in mice.
Short pill studies and specially mixed shots have different safety concerns
Short pill studies can't settle years of safety for you. NR at 100-1000 milligrams a day over eight weeks caused no reported flushing, meaning red, hot skin. Side effects didn't differ clearly from placebo, the similar-looking pill containing no NR [4]. A separate Parkinson's safety test reached 3000 milligrams a day, without moderate or severe side effects. NMN studies at 250-900 milligrams a day reported no safety concerns [1][3].
Shots carry separate risks from pills.
Fast NAD+ drips can cause chest pressure, belly discomfort, nausea, and red, hot skin. One specially mixed shot product contained too much harmful material from bacteria. The FDA recalled that product under Class I, the most serious kind. Healthy cells use NAD+ for repairs; cancer cells can use the supply to grow. Extra NAD+ might support growth of an existing cancer, but that concern remains uncertain. Researchers haven't established that extra NAD+ causes cancer or helps people fight cancer.
Your health matters alongside the treatment's risks.