NAD+ Supplements After 45: Higher Blood Levels, Uncertain Benefits

October 16, 2026

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Healthy Aging

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On October 13, 2026, The Conversation published Justin Roberts's assessment of NAD-related supplements and healthy aging. It reported that a systematic review of 33 human studies found inconsistent effects on physical function, metabolism and other healthy-aging measures.

How studies differed

The news concerns a review of existing research rather than a new supplement trial. Roberts is a professor of nutritional physiology at Anglia Ruskin University. His article covers NAD+ and its precursors nicotinamide riboside, known as NR, and nicotinamide mononucleotide, known as NMN.

According to NutraIngredients, the broader review covered 113 intervention studies: 33 in humans and 80 in rodents. It considered research published between January 2010 and October 2025.

For men interested in strength and mobility after midlife, the human studies are the most directly relevant part of that evidence. Understanding them starts with who participated and how long researchers followed them.

The human examples described by Roberts included these groups:

Middle-aged adults taking NR: A randomized, placebo-controlled study followed 140 overweight but otherwise healthy adults aged 40 to 60 for eight weeks.
Healthy adults taking NMN: A study involving 30 healthy adults lasted 12 weeks.
Older men taking NMN: A study enrolled 42 men over 65 and assessed outcomes over 12 weeks.
Older men with diabetes: A separate NMN study followed 14 older men with diabetes and reduced physical function for 24 weeks.
Recreational runners: An exercise study assessed NMN alongside six weeks of training.
People taking liposomal NAD+: A 2026 study involved 14 people and lasted two weeks.

Across these examples, researchers measured different things. Some tracked blood NAD+ or NAD+ inside cells. Others assessed walking speed and grip strength. The runners' study examined oxygen use during exercise.

That distinction shapes how the findings should be read. A laboratory measurement answers a different question from a test of physical performance. Both belong in the account of what happened, but they should remain clearly identified.

What actually changed

Roberts's account reports the following outcomes from the individual studies. NutraIngredients adds context from the broader review.

NR raised blood NAD+. In the trial of 140 middle-aged adults, the NR group had a 142% rise in blood NAD+ after two weeks. Levels remained raised during the eight-week study. This was a measured change in a blood marker.
NMN also raised blood NAD+. In the study of 30 healthy adults, blood NAD+ rose by around 50% after four weeks. Levels remained raised during the 12-week trial.
One older-men study found functional gains. After 12 weeks of NMN, the study in men over 65 reported approximately 7% faster walking speed and 4% greater left-hand grip strength. These were specific performance findings rather than blood measurements.
Another older-men study found no significant functional improvement. The 24-week study involving 14 older men with diabetes and reduced physical function found no significant improvement in walking speed or grip strength.
The runners' study found an exercise signal. Some measures of oxygen use improved after six weeks of training alongside NMN. The reported finding concerned oxygen use during exercise rather than a direct measure of lifespan or independence.
Liposomal NAD+ changed an intracellular marker. The 2026 study involving 14 people reported an increase of more than 64% in NAD+ inside cells after two weeks. This measured a cellular marker rather than walking speed or strength.
The broader human results were mixed. NutraIngredients reports that metabolic, vascular and physical-performance outcomes varied across the review. Findings often showed no effect or were limited to particular measures or participant groups.

For a man concerned about staying capable, these outcomes belong in different categories. Walking speed and grip strength describe tested physical performance. Blood and cellular NAD+ describe biological measurements. Oxygen-use measures describe one aspect of the response to exercise.

The useful reading is therefore more precise than asking whether a supplement “worked.” It asks what changed in the study and whether that change matches the benefit being discussed. A blood-marker result and a walking-speed result should not become interchangeable claims.

Where evidence stops

The positive older-men study has a major completion problem: only 20 of 42 participants completed it as planned. The contrasting study in older men with diabetes involved only 14 participants. Both studies used the same NMN dose but involved different health profiles. Their small samples make broad conclusions about older men difficult.

Roberts also notes a gap between blood and tissue measurements. Whether higher blood NAD+ translates into higher levels in muscle and organs remains unclear. A blood increase therefore cannot stand in for a demonstrated benefit in those tissues.

The reported studies do not establish that these supplements prevent disease, preserve independence, sustain long-term strength and mobility, or extend human life. That gap includes whether the runners' oxygen-use findings lead to lasting fitness benefits. The two-week liposomal NAD+ result also needs confirmation in larger, carefully controlled studies.

Animal findings require a separate boundary. Roberts describes animal research reporting improvements in physical performance, insulin sensitivity and cellular energy production. Those findings are not evidence that the same benefits occur in people. The review's animal studies should not be counted as additional human trials.

The proposed next step is clearer research rather than broader claims. NutraIngredients reports that the researchers called for larger and longer randomized trials using consistent measures of meaningful health outcomes. Roberts reaches the same conclusion about the need for stronger clinical evidence.

This is also the distinction behind assessing biological age scores against real health outcomes. A measurement can be scientifically interesting without answering the practical question that matters to the person reading it.

The practical verdict

For men after 45, this review is best read as an evidence check rather than a supplement plan. The practical task is to match a claim to the outcome actually studied, not to the broader promise attached to the product.

When assessing a claim, the useful questions are concrete: Was walking speed measured? Was strength tested? Did the study assess a metabolic outcome or only NAD+? The answer should determine how the finding is described.

It also helps to identify which compound was tested. A result involving NR should not be casually presented as a finding for NMN or liposomal NAD+. The review covers related interventions, but that does not make every finding a shared property of the whole category.

Roberts points instead to a varied and nourishing diet, stress management and regular physical activity that supports strength and fitness. His article identifies these as the measures with the strongest evidence for healthy aging. Mobility remains part of that practical focus.

For readers thinking about muscle and metabolic changes through midlife, keeping the desired outcome in view helps organize the evidence. Better physical capability is the goal under discussion. A laboratory number is one possible research measurement along the way.

Personal questions about supplement use belong with a qualified health professional rather than a percentage taken from a study summary.

What this changes: this research confirms the existing focus on regular activity, a nourishing diet and stress management rather than establishing NAD-related supplements as a new best practice.

How Everfitguys helps

Treating a higher NAD+ reading as proof of lasting strength confuses a laboratory change with a physical outcome, a gap Everfitguys addresses through evidence-led reporting. For men concerned about losing muscle and physical capability with age, the publication explains healthy-aging research in plain English to help separate measured results from claims about staying capable.

Read the research