Vitamin D deficiency ‘may impair muscle function’

Lack of hormone also linked to greater risk of Covid-19

Vitamin D deficiency may impair muscle function due to a reduction in energy production in the muscles, according to new research.

Vitamin D deficient mice were found to have impaired muscle mitochondrial function, which may have implications for muscle function, performance and recovery.

The results, researchers said, suggested that preventing vitamin D deficiency in older adults could help maintain better muscle strength and function and reduce age related muscle deterioration.

The important role vitamin D plays in maintaining bone health and preventing rickets and osteoporosis is widely known.

But more recently, vitamin D deficiency has been linked to increased risk for several conditions, including Covid-19, cancer and diabetes.

Dr Andrew Philp and his team at the Garvan Institute of Medical Research in Sydney, Australia, and collaborating universities, used a mouse model to determine the effects of diet-induced vitamin D deficiency on skeletal muscle mitochondrial function in young, male mice.

Mice were either fed a diet with normal quantities of vitamin D, or with no vitamin D to induce deficiency, for a period of three months.

A typical vitamin D level for humans is 40-50 nmol/L, and acute vitamin D deficiency is diagnosed when levels drop below 12 nmol/L.

On average, the mice in this study had vitamin D levels of 30 nmol/L, with diet-induced vitamin D deficiency leading to levels of just 3 nmol/L.

Although this level was more extreme than typically observed in people, it is still within the clinically recognised range.

Tissue and blood samples were collected monthly to quantify vitamin D and calcium concentrations and to assess markers of muscle mitochondrial function and number.

After three months of diet-induced vitamin D deficiency skeletal muscle mitochondrial function was found to be impaired by up to 37 per cent, which was not as a result of reduced number of mitochondria or a reduction in muscle mass.

Commenting on the findings, Dr Philp said the researched showed a clear link between vitamin D deficiency and oxidative capacity in skeletal muscle.

“They suggest that vitamin D deficiency decreases mitochondrial function, as opposed to reducing the number of mitochondria in skeletal muscle,” he added.

Whilst this study indicated that vitamin D deficiency could alter mitochondrial function in skeletal muscle, Dr Philp and his team were unable to determine precisely how this process occurred.

Their future work, he said, would aim to establish how vitamin D deficiency alters mitochondrial control and function in skeletal muscle.

The study, ‘Diet-Induced Vitamin D Deficiency Reduces Skeletal Muscle Mitochondrial Respiration’ is published today (April 16) in the Journal of Endocrinology.

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