The Cocktail Report (sounds really smart around your friends):
Researchers at the Cardiopulmonary Institute in Germany published a study in Communications Biology (a Nature journal) showing that NAD+ (nicotinamide adenine dinucleotide, a molecule essential for cellular energy and repair) controls the heart's internal daily rhythm, and that this rhythm breaks down with age as NAD+ levels fall.
In aged female mice, the number of genes in the heart that follow a daily rhythmic pattern dropped from 1,231 in young mice to just 302, and the pattern itself was rewired toward pathways associated with cancer and insulin resistance rather than healthy metabolism.
Long-term supplementation with NR (nicotinamide riboside, a form of vitamin B3 that raises NAD+ levels) reversed this disruption and, strikingly, completely abolished the naturally occurring cardiac enlargement (pathological growth of the heart muscle, a leading risk factor for heart failure) seen in aged mice.
NR also reprogrammed the cardiac circadian transcriptome, restoring rhythmic expression of genes involved in FoxO signaling and AMPK pathways, both central to healthy aging.
The effect appears to work through SIRT1, a longevity protein that requires NAD+ to function and helps regulate the core clock factor PER2, linking NAD+, the circadian clock, and cardiac aging into one connected mechanism.
Here is a finding that connects three things scientists already knew were important in aging, but had not previously linked in the heart: NAD+ levels, circadian rhythms, and cardiac enlargement. The new study shows they are not independent problems but part of the same biological chain, and that breaking into that chain with a supplement may interrupt the whole process.
Your heart has its own internal clock, a set of genes that switch on and off in a daily rhythm to coordinate energy use, ion signaling, and heart rate around your sleep-wake cycle. As you age, NAD+ (nicotinamide adenine dinucleotide, the molecule that powers cellular energy production and activates key longevity proteins) falls steadily in heart tissue, and the researchers show this decline is what causes the clock to break down.
The consequences are more than theoretical. Mice with disrupted cardiac rhythms developed cardiac hypertrophy (abnormal thickening or enlargement of the heart muscle that reduces pumping efficiency and raises heart failure risk), one of the most common age-related cardiac changes in humans and a major predictor of adverse outcomes.
When aged mice were supplemented with NR (nicotinamide riboside, a commercially available precursor that the body converts into NAD+) for ten months, their hearts did not enlarge. The cardiac stress marker ANP dropped significantly, rhythmic gene expression partially returned to a younger pattern, and genes involved in longevity pathways like FoxO and AMPK regained normal daily oscillations.
The mechanism runs through SIRT1, a NAD+-dependent deacetylase (an enzyme that requires NAD+ as fuel to regulate proteins) that controls the stability of PER2, a core clock protein. When NAD+ falls, SIRT1 loses activity, PER2 accumulates, the clock slows, and NR restores enough NAD+ to restart that cycle.
This matters personally because enlarged hearts develop silently over decades of aging, often without symptoms until function is already compromised. A supplement already widely available and studied in humans now has a specific, mechanistically explained cardiac target.
Why Should You Care?
Heart disease remains the leading cause of death in older adults, and cardiac enlargement is a key step on that path. This study identifies NAD+ decline as a driver of that process through the heart's own clock, and points to NR supplementation as a strategy worth watching as human trials develop.
1. Carpenter BJ. et al. "NAD+ controls circadian rhythmicity during cardiac aging." Communications Biology, Mar 11, 2026. https://www.nature.com/articles/s42003-026-09818-1
2. PubMed abstract — https://pubmed.ncbi.nlm.nih.gov/41813966/
3. Max Planck Society press release, April 17, 2026 — https://www.mpg.de/26389653/low-nad-levels-disrupt-the-body-s-internal-clock-during-cellular-aging
