Those who lack this vitamin are 70 percent more likely to have muscle weakness and physical disability.
Vitamin D deficiency is a risk factor for muscle wasting (atrophy) and loss of muscle strength (dynapenia).
People with low vitamin D levels are more likely to see declines in muscle mass, strength, and function besides loss of bone density, a study reveals.
The research also shows that vitamin D supplementation could reduce the risk of dynapenia in seniors with low serum 25(OH)D levels by 78 percent.
Muscle atrophy and dynapenia can lead to physical disability in later life, indeed individuals with such conditions have a higher incidence of falling, hospitalisation, and premature death.
Professor Tiago da Silva Alexandre, the study’s co-author, said:
“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.”
Muscle tissue and bone are connected biochemically and physically so endocrine disorders such as low blood levels of 25-hydroxy vitamin D (25(OH)D) could result in bone loss and decreases in the size, strength and function of muscles.
Muscle weakness increased by 70 percent
In this study, more than 3000 adults with no history of dynapenia were followed over four years.
Serum 25(OH)D levels reflect the amount of vitamin D stored in the body, the concentration above 50 nmol/L is classified as sufficient, between 30 to 50 nmol/L as insufficient, and below 30 nmol/L as deficient.
The study found that participants with vitamin D deficiency were 70 percent more likely to dynapenia than those with sufficient levels.
Mr Maicon Luís Bicigo Delinocente, the study’s first author, said:
“This is itself an important finding as it shows that vitamin D deficiency heightens the risk of muscle weakness by 70%.
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.”
To obtain the correct data, those on vitamin D supplements and those with osteoporosis were excluded from the study.
Mr Delinocente added:
“we found that the risk of developing muscle weakness by the end of the four-year period was 78% higher for subjects with vitamin D deficiency at the start of the study than for subjects with normal vitamin D levels, and 77% higher for those with vitamin D insufficiency [30-50 nmol/L].”
Vitamin D is essential for the absorption of calcium and phosphorus, maintaining cognitive function, and supporting the immune system.
The main way of getting vitamin D is sunlight, but a large area of the skin requires exposure to the sun for at least 15 to 20 minutes.
Professor Alexandre said:
“The study analyzed data for people who live in the UK.
There are many more days of sunlight per year in Brazil, and yet we’re known to have a high incidence of vitamin D deficiency and insufficiency, especially among older people.
Indeed, this is the case worldwide.
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.”
The study was published in the journal Calcified Tissue International (Delinocente et al., 2022).
