In a study of 1,068 adults, healthy people’s blood did not show the age-related NAD drop often linked to the search for longer life. Instead, the clearest difference appeared among people with cardiovascular disease, especially those with high blood pressure.
NAD, short for nicotinamide adenine dinucleotide, is a molecule that helps cells use energy. It has drawn growing interest because animal studies have found age-related declines in NAD in tissues such as muscle, brain and skin. That research has helped drive the sale of supplements intended to raise NAD. But whether blood NAD falls as people age has remained uncertain, with earlier studies reaching different conclusions.
To examine the question, a team at Vilnius University in Lithuania measured whole-blood NAD in 1,068 adults, including healthy participants and people with chronic illnesses. They made 1,340 measurements using dried blood spot samples collected under standardized conditions. The study was published in Nature Metabolism.
Among healthy men, blood NAD stayed stable with age. Among healthy women, it rose slightly, and the increase was statistically significant. The pattern differed in people with chronic disease: their NAD levels were lower, and in men with chronic disease levels declined with age. The rise seen in healthy women was not present. The strongest association with low NAD was among participants with cardiovascular disease, particularly hypertension.
The findings challenge the idea that a fall in blood NAD is a normal, universal part of getting older. They suggest that a person’s health, especially heart and blood-vessel health, may matter more than age when interpreting a blood NAD result. That distinction is useful as consumers weigh claims that supplements can reverse an age-related decline in NAD. In this study, researchers found no evidence of such a decline in the blood of healthy adults.
The results do not show that low NAD causes heart disease, or that raising NAD would prevent or treat it. The study found an association, and the direction of any link remains unclear: lower NAD could be related to cardiovascular disease, or other factors could help explain both. More research will be needed to answer those questions and to establish what blood NAD measurements can tell doctors about heart health.
For now, the Vilnius team’s findings offer a more specific way to think about NAD: in blood, it may be less a simple marker of age than a clue tied to health. Future studies can test whether that clue has a practical role in understanding cardiovascular disease, while keeping supplement claims in line with what the evidence actually shows.