New research presented at a London endocrinology conference this week reveals a link between vitamin D levels and muscle efficiency, which may explain why patients with a deficiency of the vitamin commonly experience physical fatigue.

The research, out of Newcastle University, measured the response to exercise in the calf muscles of 12 patients with severe vitamin D deficiency.

The results revealed recovery significantly improved in patients who took a fixed dose of oral vitamin D for 10-12 weeks.

Vitamin D is a hormone produced in the skin through exposure to sunlight, and to a lesser extent can be derived from dietary sources.

Study leader Dr Akash Sinha said: “This is the first time a link has been shown between vitamin D status and muscle aerobic function.

“To do so we used a non-invasive scan to get a unique biochemical perspective on muscle mitochondrial metabolism during exercise: a window into what is really going on in the muscle as it works.”

The researchers hope further study will reveal the mechanisms underpinning this effect, and establish whether vitamin D supplements could alleviate frailty in the elderly or improve the exercise capacity of athletes.