Vitamin D deficiency heightens the risk of muscle weakness

Vitamin D is known to play a major role in the regulation of calcium and phosphorous absorption, while also keeping the brain and immune system working properly. Now, according to a recent study led by the Federal University of São Carlos (UFSCar) in Brazil and University College London (UCL) in England, vitamin D supplementation reduces the risk of dynapenia – an age-associated loss of muscle strength – in older people by 78 percent.

Dynapenia is partly explained by muscle atrophy and is a major risk factor for physical incapacity in the elderly. People with this condition are more likely to fall, need to be hospitalized or prematurely institutionalized, and die.

“Vitamin D is known to participate in various functions of the organism. Actually, it’s a hormone and its many roles include helping to repair muscles and releasing calcium for muscle contraction kinetics. It was therefore expected to cause muscle alterations of some kind. That’s exactly what our study proved,” reported study senior author Tiago da Silva Alexandre, a professor of Gerontology at UFSCar. “Endocrine disorders such as vitamin D deficiency or insufficiency can lead to loss of bone mineral density as well as a reduction in muscle mass, strength and function.”

The scientists analyzed data for 3,205 non-dynapenic participants aged 50 or older who were followed for four years by the English Longitudinal Study of Ageing (ELSA), a long-term multi-cohort study that began in 2002. The analysis revealed that individuals with vitamin D deficiency (defined as less than 30 nanomoles per liter of blood) had a 70 percent higher risk of developing dynapenia by the end of the four-year study than those with normal vitamin D levels (above 50 nmol/L).

“This is itself an important finding as it shows that vitamin D deficiency heightens the risk of muscle weakness by 70 percent. However, because we knew there are many worldwide cases of people with osteoporosis who take vitamin supplements, we needed to try to measure the effectiveness of vitamin D supplementation,” said study lead author Maicon Luís Bicigo Delinocente, an expert in Collective Health and Gerontology at UFSCar.

When participants with osteoporosis and those taking vitamin D were excluded from the analysis, the researchers found that the risk of developing muscle weakness after four years was 78 percent higher for individuals with vitamin D deficiency at the beginning of the study, and 77 percent higher for those with vitamin D insufficiency (30-50 nmol/L).

These findings offer evidence that the risk of muscle weakness is heightened by both vitamin D deficiency and insufficiency. “It’s necessary to explain to people that they risk losing muscle strength if they don’t get enough vitamin D. They need to expose themselves to the sun, eat food rich in vitamin D or take a supplement, and do resistance training exercises to maintain muscle strength,” Alexandre concluded.

The study is published in the journal Calcified Tissue International and Musculoskeletal Research.

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By Andrei Ionescu, Earth.com Staff Writer

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