D-Glucosamine is an amino sugar synthesized from glucose and glutamine. It is found in cartilage, tendons and ligaments in our body. It is a component of glycoproteins, proteoglycans and glycosaminoglycans, which are the building blocks of cartilage. In human beings, glucosamine is synthesized endogenously from glucose but also may be obtained from exogenous dietary supplements. Glucosamine or its precursors, like collagen-containing food supplements, are commonly recommended to promote osteoarticular health. A typical use is to attenuate osteoarthritis in humans because of glucosamine’s high concentration in joint tissue. After oral administration, 87% of glucosamine is absorbed, and it is mainly incorporated into skeletal muscle and articular cartilage. Different studies have shown that oral glucosamine supplementation stimulates the synthesis of synovial fluid, inhibits degradation and improves healing of articular cartilage. However, despite extensive research, the data related to glucosamine’s effect on pain relief in patients with osteoarthritis have been inconsistent.
In the last few years, elite athletes have been taking glucosamine supplements because of their potential chondro-protective effects. But recently, some studies have shown that glucosamine has a favorable effect on cellular energy metabolism. The VITAL study evaluated the associations between a 10-year average intake of 20 dietary supplements (including 13 vitamins and minerals, fish oil, Gingko biloba, glucosamine, fiber and garlic) and mortality in a cohort of 77,719 subjects. For most of the supplements examined, there was no association with mortality. However, the strongest association with decreased risk of total mortality was that observed for glucosamine and chondroitin supplementation.
In our manuscript, published in the March 2022 issue of Medicine & Science in Sports & Exercise®, we aimed to study the potential beneficial effects of glucosamine on mitochondrial content, physical performance and oxidative stress in mice that were aerobically trained and supplemented with three different doses of glucosamine for a period of six weeks. We measured exercise performance (grip strength, motor coordination and running capacity) before and after the training period. Proteins involved in mitochondrial biogenesis or content, like PGC-1, NRF-1 and cytochrome c, were increased by glucosamine supplementation in skeletal muscle. We did not observe changes in markers of oxidative stress (GSSG/GSH) or a damage like increase in lipid peroxidation (MDA) or protein carbonylation.
Our findings showed that glucosamine increases the protein levels of mitochondrial biogenesis markers and content. This resulted in an increase in motor coordination and also endurance capacity (i.e., the capacity to run long distances). This suggests that glucosamine could improve exercise performance, and it might be considered as an ergogenic aid — especially for cardio-respiratory training. Because glucosamine has an excellent safety profile and its adverse effects are uncommon and mild, it could be considered for use as a supplement for endurance athletes.
Jose Viña is a full professor of physiology at the University of Valencia in Valencia, Spain, where he combines his teaching duties with research work, the latter in two main lines: ageing and exercise. Viña leads a successful research group (FreshAge) working on different aspects of oxidative stress, with whom he has won numerous prizes for research work. He has published more than 300 papers on glutathione, mitochondria, exercise, ageing and nutrition.
Mari Carmen Gomez-Cabrera is also a full professor of physiology at the University of Valencia. She is the author of more than 120 peer-reviewed international publications, which have collectively accumulated over 8,500 citations in the broad area of exercise redox biology and more recently in healthy aging, frailty and sarcopenia.
Disclosure: Jose Viña is a member of the Scientific Advisory Board of NuSkin Pharmanex Research.
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