MOTS-c Bone Health and Density Impact: What the Evidence Shows

What MOTS-c is

MOTS-c is a 16-amino-acid peptide encoded in mitochondrial DNA, first reported in 2015 by Lee and colleagues in Cell Metabolism [2]. In mouse work its main target organ is skeletal muscle. Its cellular action is to inhibit the folate cycle and the de novo purine synthesis attached to it, which activates AMPK [2]. It is not an FDA-approved drug and is not a component of one [1].

Does any study show an effect on bone?

The key MOTS-c studies were done in mice and measured other outcomes.

Lee et al. reported that MOTS-c treatment prevented age-dependent and high-fat-diet-induced insulin resistance, and diet-induced obesity, in mice [2]. Reynolds et al. found that MOTS-c injection improved physical performance in young, middle-aged and old mice. Intermittent treatment begun at 23.5 months of age increased physical capacity and healthspan, with median lifespan of 912 days in controls versus 970 days in treated animals [1][3]. Neither paper's summary reports bone density, bone turnover or fracture outcomes. Effects in mice cannot be taken as evidence of an effect on bone in people.

Where osteoporosis appears in the MOTS-c paperwork

Osteoporosis was one of six uses nominated when MOTS-c was proposed for compounding, alongside insulin resistance, obesity, vascular calcification, muscle and fat metabolism, and longevity, at 5 mg and 10 mg subcutaneous injections [1].

FDA staff recommended in July 2026 against adding the free base or the acetate to the pharmacy bulk substances list. They cited no human safety or effectiveness data, no animal toxicity studies, and the existence of FDA-approved treatments for obesity and osteoporosis, two of the nominated uses [1]. The Pharmacy Compounding Advisory Committee took MOTS-c up on July 23, 2026 and voted in favor of adding it, against the staff recommendation. The vote is advice only and did not add MOTS-c to the FDA list; adding it takes formal rulemaking [5][6]. A separate HHS draft policy filed in October 2026 states that HHS does not intend to take enforcement action against certain licensed pharmacies and physicians who compound MOTS-c acetate for injection under stated conditions. It is non-binding, and it does not approve MOTS-c or add it to any FDA list [6][7].

Human studies measured the body's own MOTS-c

The human research so far has looked at naturally circulating peptide, not injected peptide. Reynolds et al. reported that exercise raises the body's own MOTS-c expression in skeletal muscle and in the circulation [3]. In a randomized trial of 30 healthy adults, von Walden et al. assigned 10 people to endurance exercise, 10 to resistance exercise and 10 to no exercise. Circulating humanin rose after endurance exercise, MOTS-c showed only a trend to increase, and plasma MOTS-c was not related to fitness [8]. Nobody in these studies received MOTS-c.

Safety and status

There is no approved dose and no human dosing study of administered MOTS-c [1]. FDA's adverse-event database searches through March 9, 2025 returned no MOTS-c reports, which does not establish safety. FDA found no human exposure data by any route and no animal toxicity studies, and for injections it cited immunogenicity risk from peptide aggregation and impurities [1]. One in-vitro observation, that MOTS-c is broken down quickly in human blood, raises the question of whether an injection can produce active levels at all [1]. WADA names MOTS-c in section S4.4.1 of its Prohibited List, so it is banned in and out of competition, and it stays on the 2027 List [4][9].