Researchers in Sydney measured NAD+ directly in human skin samples donated by people across a wide range of ages, rather than relying on blood levels or animal tissue, to see how the molecule's own concentration actually changes as a person gets older.
In the peer-reviewed study of 49 skin samples, donors over 71 averaged well under half the NAD+ of donors aged 30 to 50, and newborns carried the most of all. DNA damage rose with age at the same time, the kind of cellular wear and tear NAD+ normally helps the cell manage and repair.
The decline was measured directly in donated human tissue, not estimated from blood or animal studies, which gave the finding more direct relevance to human aging than earlier NAD+ research. The study compared different people of different ages rather than following the same people over time, so it shows a strong association between age and falling NAD+, not proof of what restoring it would do.
Read the original study
Massudi et al., PLoS ONE, 2012 · doi.org/10.1371/journal.pone.0042357
A molecule every cell needs, fading with age.
Source
- Massudi, H., Grant, R., Braidy, N., Guest, J., Farnsworth, B., & Guillemin, G. J. (2012). Age-associated changes in oxidative stress and NAD+ metabolism in human tissue. PLOS ONE, 7(7), e42357. https://doi.org/10.1371/journal.pone.0042357