NAD+ combination treatment restores muscle and bone in old mice
Topping up one supplement helps a little. But what if you also plug the leak at the same time? Researchers put that combination strategy to the test for NAD+, and the results in old mice are striking.
NAD+ (nicotinamide adenine dinucleotide) is a molecule found in every cell of the body, where it plays a central role in energy metabolism, DNA repair, and the regulation of proteins that slow aging, known as sirtuins. The trouble is that as you age, NAD+ concentrations drop sharply in most tissues, and that decline has been linked to muscle weakness, bone loss, and impaired metabolic function.
Researchers gave old mice a simultaneous combination of NMN (nicotinamide mononucleotide), a precursor compound the body converts into NAD+, and apigenin, a plant-derived substance that inhibits the enzyme CD38. CD38 is one of the body's main NAD+ consumers, and it becomes increasingly active with age. By boosting supply while cutting consumption at the same time, NAD+ levels rose substantially more than with either agent alone, reports Lifespan.io.
Measurable gains in muscle function and bone structure
The effects showed up in two systems that typically deteriorate sharply with aging: muscle and bone. Mice that received the combination treatment showed improved muscle function, measured by grip strength and treadmill performance, along with better bone density and structure. Both improvements were greater than in the groups that received only NMN or only apigenin.
That sounds promising, but a word of caution is in order: mouse studies do not reliably translate to humans. NAD+ supplementation through precursors such as NMN or NR (nicotinamide riboside) has already been studied extensively in people, and the results so far have been modest, with measurable rises in NAD+ levels but more limited clinical effects than those seen in mice. Whether the combination strategy tested here would deliver the same results in humans remains an open question.
Why the combination strategy makes sense
What makes this research compelling is the logic behind it. Most supplement strategies focus on one side of the problem: putting more in. But if the "leak" in the system, in this case CD38, stays open, the effect is limited. By tackling both sides at once, essentially catching NAD+ metabolism in a pincer movement, the net increase is larger. That principle has broad applications and could point the way toward future combination therapies for age-related conditions.