NAD⁺ is sold on four promises: more energy, sharper thinking, better sleep, and slower aging. This page is about which of those has actually been measured in a human trial, and what the trials found — including the ones that found nothing, because those are the results the rest of the category tends not to mention.
The benefit that is well established
Oral precursors raise NAD⁺. That is not in dispute, and it is worth separating from everything else on this page because it is the one claim the evidence fully supports. In a randomized, double-blind, placebo-controlled trial of 80 healthy middle-aged adults (n = 80), blood NAD rose significantly in every NMN dose group at day 30 and day 60 against both placebo and baseline (all p ≤ 0.001) [1]. NR raised the NAD⁺ metabolome in aged human skeletal muscle [2].
But “raises a blood marker” is a mechanism, not a benefit. The question that matters is what follows from it.
Benefits with real, narrow trial support
Metabolic markers. In a study of overweight or obese middle-aged and older adults, an NMN formulation safely increased circulating NAD and significantly reduced body weight (P = .008), diastolic blood pressure (P = .034), total cholesterol (P = .004) and LDL cholesterol (P = .007) [3]. Those are genuine, measurable findings. Note what they are not: they are not energy, focus, or aging.
Insulin sensitivity. In postmenopausal women with prediabetes who were overweight or obese, NMN increased insulin-stimulated glucose disposal measured by hyperinsulinemic-euglycemic clamp — the reference method — with no change on placebo [4]. A real result in a specific population with a specific problem.
The benefit that was tested and did not appear
This is the part worth reading twice. In a placebo-controlled randomized trial in older adults with mild cognitive impairment, whose primary objective was safety, NR did not alter cognition[5]. The placebo group’s scores improved across the study — consistent with a practice effect from repeated testing — while the NR group’s did not change.
Think about what that means for the “sharper focus” claim. When somebody actually measured cognition in a population you would expect to have the most room to improve, the supplement did not beat placebo. That is one pilot study and not the last word, but it is a great deal more than the marketing has on its side.
Energy, sleep and aging
These are the claims that sell the category and the ones with the least behind them. There is no controlled human outcome trial establishing that NAD⁺ supplementation makes a healthy person more energetic or slows their aging. Some trials have measured adjacent things — one NMN study tracked walking distance and sleep quality alongside blood NAD[6] — but a measured six-minute walk is not the same as the promise on the label.
And all of the above concerns oral precursors. The injections, drips and nasal sprays sold as NAD⁺ therapy have no controlled outcome trials at all for these benefits, while costing several times more. If you want the version of this comparison with prices attached, we keep one on the cost page.
How to read any NAD⁺ benefit claim
Three questions handle almost all of them. Was it measured in humans, or in mice and cells? Was the outcome something a person would notice, or a blood marker? And was it the format being sold to you, or an oral precursor standing in for one?
Most claims in this category fail at least one. The ones on this page that survive all three are narrow, specific, and mostly about metabolic markers in people who already had something wrong — which is a real finding, and a long way from reversing aging.
If you want the fuller picture of what NAD⁺ is and why any of this is plausible in the first place, start with our explainer, and see the safety evidence before you start anything.