NAD in blood may be a cardiovascular signal, not an aging clock
Nicotinamide adenine dinucleotide, better known as NAD, has become a focal point in the market for longevity supplements. But a study of 1,068 adults from researchers at Vilnius University challenges a central assumption behind much of that interest: that NAD in human blood inevitably falls as people age.
The researchers found that whole-blood NAD levels stayed stable with age among healthy men and rose slightly among healthy women. Lower levels were instead most clearly associated with cardiovascular disease, particularly hypertension. The work, published in Nature Metabolism, suggests that blood NAD may reflect health status more closely than the passage of time alone.
Why the finding matters
NAD is involved in cellular metabolism and energy production. Animal research has reported age-related declines in NAD in tissues including muscle, brain and skin, helping drive interest in NAD-boosting products such as nicotinamide mononucleotide and nicotinamide riboside. Translating those findings to people, however, has been difficult. Previous human blood studies have produced inconsistent results.
The new analysis does not establish that low NAD causes cardiovascular disease, nor does it test whether supplements prevent disease or improve outcomes. It does, however, add an important caution to broad claims that a blood NAD measurement can serve as a universal marker of biological aging.
Healthy aging and chronic disease showed different patterns
In the healthy participants, whole-blood NAD did not show the expected downward trajectory with age. Men’s levels remained stable, while women’s levels increased slightly. Among people with chronic disease, the pattern changed: NAD was lower, levels declined with age in men, and the increase seen in healthy women was absent.
Cardiovascular disease showed the clearest association, with hypertension highlighted as a particularly strong link. That distinction matters because aging and chronic illness often occur together. A simple comparison of younger and older adults can mistakenly attribute a disease-related change to aging itself if underlying health conditions are not separated from age.
What the study does and does not say about supplements
The study addresses blood measurements, not the effects of taking NAD-related supplements. It therefore cannot determine whether raising NAD levels would improve cardiovascular health, slow aging or change disease risk. It also does not resolve how NAD levels in whole blood relate to NAD levels in specific organs and tissues.
Still, the findings sharpen the questions future research needs to answer. Studies of NAD interventions will need to distinguish between healthy participants and people with cardiovascular or other chronic diseases, consider sex-specific patterns, and measure clinical outcomes rather than relying solely on a blood biomarker.
- Whole-blood NAD was stable with age in healthy men.
- Healthy women showed a slight increase rather than a decline.
- Lower NAD was more clearly linked to cardiovascular disease, especially hypertension.
- The observational findings do not prove cause and effect or validate NAD supplements.
A more cautious framework for longevity claims
The appeal of a single molecule that could explain aging is understandable, but human biology rarely yields to a single readout. This study points toward a more nuanced interpretation: blood NAD may be influenced by sex, health and cardiovascular status, and chronological age alone may not explain its variation.
For consumers, the practical takeaway is restraint. Interest in NAD biology is scientifically legitimate, but a low or changing blood level should not be treated as proof of accelerated aging, and the research does not establish that commercially available NAD-boosting supplements provide a cardiovascular or longevity benefit. For researchers, the result offers a clearer direction: study NAD in the context of disease, rather than assuming it is simply a clock that runs down in every person.
This article is based on reporting by Medical Xpress. Read the original article.
Originally published on medicalxpress.com
