Evaluating NAD+ Data: Clinical Evidence vs. Blood Biomarkers
As a dietitian, I spend a large part of my day helping people separate scientific evidence from internet hype. Recently, NAD+ has dominated conversations about healthy aging. A new study by Tretowicz and colleagues, covered widely in the press, has sparked intense debate about how we measure NAD+ and what those measurements truly mean. We need to look closely at this data to understand the real story.
What NAD+ Does in the Body
Before we dive into the new research, we should quickly review what NAD+ actually does. Nicotinamide adenine dinucleotide is a vital molecule found in every cell of your body. It helps convert the food you eat into cellular energy and plays a major role in repairing damaged DNA. For years, we have known that NAD+ levels drop as animals and humans get older. This decline links directly to several signs of aging.
What the Tretowicz Study Found
The Tretowicz study set out to see if whole-blood NAD+ could serve as a simple, reliable marker for biological aging. The research team examined over 300 individuals across various groups, including young adults, elite athletes, and frail older adults. The results surprised many people. The researchers discovered that whole-blood NAD+ levels remain remarkably stable as we get older. Furthermore, lifestyle interventions like exercise programs and protein-rich diets did not significantly alter these blood levels.
While blood NAD+ might not track the aging process, the study confirmed a crucial detail about supplementation. When participants took a specific NAD+ precursor called nicotinamide riboside (NR), their blood NAD+ levels increased significantly. This finding is essential because it proves that NR works exactly as intended to deliver NAD+ to the body.
Blood NAD+ vs. Tissue NAD+
You might wonder why blood levels stay stable if NAD+ is famous for declining with age. The answer lies in where we look. Blood NAD+ acts primarily as a marker of exposure. It simply tells us that a supplement entered the system. The real, biologically meaningful work of NAD+ happens inside solid tissues, such as your muscles, brain, skin, liver, and immune cells.
Multiple human studies show that NAD+ levels do indeed drop in these specific tissues as we age. Tissue NAD+ gives us a much more accurate picture of biological aging and cellular function than a basic blood draw ever could.
Why Clinical Outcomes Matter More Than a Single Biomarker
We must look beyond a single blood test to understand true health benefits. The clinical research on NR, extends far past simply changing a number on a lab report, and evidence shows that NR supplementation leads to real-world outcomes, like consistent anti-inflammatory effects across multiple populations. These are measures of actual effect, whereas blood NAD+ is just a measure of exposure.
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Practical Takeaways for Dietitians
Contextualize the blood tests: Explain clearly that blood NAD+ does not tell the whole story. Tissue levels matter far more for cellular energy and healthy aging. We should not use blood tests as the ultimate judge of a longevity protocol.
Focus on proven clinical outcomes: Shift the focus from raising a single biomarker to actual health benefits. Remind clients that studies link NR to better physical function and lower inflammation.
Distinguish between ingredients: Help clients understand that not all NAD+ supplements are the same. NR has a distinct, robust base of clinical evidence showing how it acts in the body. We cannot lump all precursors into one generic category.
Ground the conversation in reality: The longevity space suffers from intense hype. Remind clients that no supplement replaces a solid foundation of good nutrition, regular physical activity, and adequate sleep. Supplements work to support these foundational habits, not replace them.
The Bottom Line
Science moves quickly, and rigorous studies like this one help us refine our understanding of human health. The Tretowicz study brings valuable clarity to the conversation by showing the limits of whole-blood tests. It also reassures us that NR supplements effectively raise NAD+ levels. By focusing on tissue biology and proven clinical outcomes, we can continue to have honest, evidence-based conversations about aging well.
This blog post was created in partnership with Niagen Biosciences