Low levels of the 'sunshine vitamin' may increase the risk of developing multiple sclerosis in women, a study has found.
Multiple sclerosis (MS) disrupts the ability of parts of the nervous system to communicate, resulting in a range of signs and symptoms, including physical, mental, and sometimes psychiatric problems.
"There have only been a few small studies suggesting that levels of vitamin D in the blood can predict risk," said Kassandra Munger, from the Harvard TH Chan School of Public Health in the US.
"Our study, involving a large number of women, suggests that correcting vitamin D deficiency in young and middle-age women may reduce their future risk of MS," said Munger.
Researchers used a repository of blood samples from more than 800,000 women in Finland, taken as part of prenatal testing.
They identified 1,092 women who were diagnosed with MS an average of nine years after giving the blood samples. They were compared to 2,123 women who did not develop the disease.
Deficient levels of vitamin D were defined as fewer than 30 nanomoles per litre (nmol/L).
Insufficient levels were 30 to 49 nmol/L and adequate levels were 50 nmol/L or higher.
Of the women who developed MS, 58 per cent had deficient levels of vitamin D, compared to 52 per cent of the women who did not develop the disease.
Researchers found that with each 50 nmol/L increase in vitamin D levels in the blood, the risk of developing MS later in life decreased by 39 per cent.
In addition, women who had deficient levels of vitamin D had a 43 per cent higher risk of developing MS than women who had adequate levels as well as a 27 per cent higher risk than women with insufficient levels.
"More research is needed on the optimal dose of vitamin D for reducing risk of MS. But striving to achieve vitamin D sufficiency over the course of a person's life will likely have multiple health benefits," said Munger, lead author of the study published in the journal Neurology.