Vitamin D is perhaps best known for its role in bone formation, and vitamin D deficiency is an established cause of rickets (soft, deformed bones in children), as well as a potential underlying factor in osteoporosis. In recent years, the role of vitamin D in muscle function has come to the fore. Two potential features of vitamin D deficiency are muscle pain and fatigue. Not so long ago, I wrote here about how my vitamin D-deficient mother seemed to be profoundly helped through supplementation with vitamin D.
I noticed this report today of a study concerning the potential role of vitamin D in muscle function. In this study, muscle function was assessed in a group of 12 individuals with known vitamin D deficiency. The assessment centred around timing the replenishment in the muscle of a substance known as phosphocreatine. Phosphocreatine is a key molecule in the production of energy (in the form of what is known as ATP) by tiny ‘powerhouses’ in the cells of our body known as mitochondria (pronounced my-toe-con-dree-ah). Shorter phosphocreatine replenishment times after activity are a sign of better mitochondrial function.
Vitamin D supplementation was found to lead to a significant reduction in phosphocreatine replenishment times, signalling an improvement in mitochondrial functioning. Fatigue ratings improved in all the study participants too.
This study is the first to show direct link between vitamin D status and this measure of muscle functioning, as well as an improvement in this functioning through supplementation with vitamin D.
The benefits of optimising vitamin D levels likely go way beyond the impact of this nutrient on muscles and bones. Research links higher levels of vitamin D with protection from a wide range of health issues including depression, cancer, heart disease and ‘auto-immune’ conditions including multiple sclerosis and rheumatoid arthritis. See here for a guide to vitamin D dosing.