The data is the first time such a link has been found, and could help to explain the physical fatigue that is commonly experienced in people with low vitamin D levels, say the British researchers behind the study.
The team, led by Dr Akash Sinha from Newcastle University, UK, report that supplementation with vitamin D for between 10 and 12 weeks significantly improved muscle phosphocreatine recovery in people with vitamin D deficiency.
Sinha and his colleagues said the findings from the study have broad implications for a large section of society:
“Patients with vitamin D deficiency often experience symptoms of muscle fatigue," explained Sinha, who presented the findings from the study at the Society for Endocrinology annual conference in the UK.
Previous research has suggested that vitamin D could help to reduce muscle and joint pain in cancer patients and could help to improve muscle power in obese people, however these are the first findings to reveal a functional benefit to skeletal muscle from supplementation with the sunshine vitamin.
"Our findings in a small group of patients with very low vitamin D levels show that muscle efficiency significantly improves when vitamin D status is improved.’’
“We'll need further research in more patients to work out how this is happening and whether non-deficient patients can benefit from this too,” he said.
Sinha and his team investigated phosphocreatine recovery times in patients with vitamin D deficiency using magnetic resonance scans to measure phosphocreatine dynamics in response to exercise in the calf muscles of 12 patients with severe vitamin D deficiency - before and after supplementation with vitamin D.
The team found that phosphocreatine recovery significantly improved after the patients took a fixed dose of oral vitamin D for 10-12 weeks (average phosphocreatine recovery half time decreased from 34.4sec to 27.8sec, p<0.001).
All participants also reported an improvement in symptoms of fatigue following supplementation.
“This is the first time a link has been shown between vitamin D status and muscle aerobic function," said Sinha, who added that a parallel study performed by the group demonstrated that low vitamin D levels are associated with reduced mitochondrial function.
The group added that while their studies were small, they establish a 'clear proof of principle' and for the first time confirm a link between vitamin D and mitochondria in humans.
Sinha and his colleagues will now explore the mechanisms underpinning this effect, and also aim to establish whether vitamin D supplementation could alleviate frailty in the elderly or improve the exercise capacity of athletes.
Source: Endocrine Abstracts
Abstract published online, doi: 10.1530/endoabs.31.OC1.6
"Improving the vitamin D status of vitamin D deficient adults is associated with improved mitochondrial oxidative function in skeletal muscle"
Authors: Akash Sinha, Kieren Hollingsworth, Steve Ball & Tim Cheetha