NAD+ and muscle
3 papers in the library, strongest Preliminary.
Graded Preliminary · Three small studies with 30 to 39 people per group, measured before and after NR or training, with no comparison group on a dummy pill.
Papers 3
- Muscle Age Clocks: Younger After NR, Partly Older After HIITPreliminaryn = 1062026Aging cellNicotinamide riboside, or NR, is a building block of vitamin B3. Like hard interval training, it has been proposed as a way to support aging muscles. In muscle, though, the two pointed in opposite directions. After five months of NR, several epigenetic clocks read younger. After four to six weeks of interval training, some clocks ran faster. Epigenetic clocks estimate biological age from chemical tags on our DNA. The researchers looked at muscle samples from three studies. In one, 30 adult twins aged 30 to 65 took NR, ending at 1,000 milligrams a day. In two others, 39 and 37 people did short, hard intervals three times a week. After NR, three of seven clocks went down, while one went up. After training, the clock that estimates the pace of aging rose in both studies. Another clock fell in the six-week study. None of the studies compared people with a group on a dummy pill, and the groups were small. The researchers measured clocks, not muscle strength or health. Whether NR actually keeps muscles young cannot be read from this. In muscle cells grown in the lab, NR made no clear difference to the clocks.
- NR Kept Muscle Power Plants Working in Mice With Rare MyopathyPreliminaryn = 62026Human molecular geneticsIn mice with a rare inherited muscle disease, the power plants of the muscle cells kept working normally when the animals got nicotinamide riboside early in life. The compound, known as NR, is a building block for NAD+. Cells need this molecule to make energy. The disease is called nemaline myopathy type 6 and causes muscle weakness from birth. The mice carry the same gene change found in most patients. Without treatment, their calf muscles used less oxygen for energy from three months of age, but not at one month. Their NAD+ levels also fell as the disease progressed. So the researchers added NR to the drinking water for eight weeks, starting at four weeks of age. At three months, the treated mice's cell power plants worked about as well as those of healthy mice. Typical tissue changes in the muscle still appeared, though. There was no dummy treatment group, which the authors name as a weakness. Only a few animals were treated, and how NR works here stayed unclear. Whether it helps people with this disease has not been shown.
- NMN Plus Apigenin Slows Bone and Muscle Loss in Old MicePreliminary2026Aging cellAs the body ages, levels of NAD+ fall, a molecule that plays a key role in how cells age. Researchers in China tried to raise it from two sides at once. Old mice received NMN, a building block the body turns into NAD+. They also got apigenin, a compound that blocks an enzyme that uses up NAD+. The combination eased the breakdown of joint cartilage, bone and muscle in the animals. The mice could also exercise better. The mice had aged naturally and were mostly 20 months old. They took the mix by mouth, while control mice got salt water. In cell experiments, NAD+ levels rose and signs of cell aging declined. In mice lacking SIRT3, an enzyme in the cell's power plants that uses NAD+, the benefits were partly smaller. Gut bacteria mattered too: microbes from treated mice reversed signs of aging in the cartilage, bone and muscle of old mice. All results come from mice and cell cultures. Whether the combination protects human bones and muscles was not tested. The paper gives no dose or duration in its text and reports no safety data.
How this map is computed
A mark's size is the number of papers we hold on that pairing. It is a count, not a weighting by study design or sample size.
The fill shows the strongest grade in the cell. One Strong paper among four Preliminary ones still fills it dark, so open the cell to see the rest.
Grades and verdicts are assigned by a named person, never by counting.
An empty cell means our library holds no paper on that pairing yet. It is a gap in our library, not proof that nobody has studied it.