Vitamin D has been found to reduce the severity of multiple sclerosis (MS) - a disease affecting nerves in the brain and spinal cord, causing problems with muscle movement, balance and vision - if patients take it in early stages.
Low levels of vitamin D were found to strongly predict disease severity and hasten its progression, according to a new study led by Harvard School of Public Health (HSPH) investigators in collaboration with Bayer HealthCare.
"Because low vitamin D levels are common and can be easily and safely increased by oral supplementation, these findings may contribute to better outcomes for many MS patients," said lead author Alberto Ascherio, professor of epidemiology and nutrition at HSPH.
According to the World Health Organisation's (WHO) estimates, nearly 2.5 million people in the world suffer from MS.
Previous research indicated a connection between low levels of vitamin D and risk of developing MS or having MS symptoms worsen.
But those studies included patients with long-standing MS whose vitamin D levels could partly be a consequence, not a predictor, of disease severity, said the study that appeared in the journal JAMA Neurology.
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The new study looked at vitamin D levels among patients at the time of their first symptoms of the disease.
Researchers analysed data from 465 MS patients from 18 European countries, Israel and Canada.
The scientists looked at how the patients' vitamin D levels - which were measured at the onset of their symptoms and at regular intervals over a 24-month period - correlated with their disease symptoms and progression over a period of five years.
They found that early-stage MS patients who had adequate levels of vitamin D had a 57 percent lower rate of new brain lesions, a 57 percent lower relapse rate, and a 25 percent lower yearly increase in lesion volume than those with lower levels of vitamin D.
Loss in brain volume, which is an important predictor of disability, was also lower among patients with adequate vitamin D levels.
The results suggest that vitamin D has a strong protective effect on the disease process underlying MS, and underscore the importance of correcting vitamin D insufficiency, which is widespread in Europe and the US, the researchers said.
"The benefits of vitamin D appeared to be additive to those of interferon beta-1b, a drug that is very effective in reducing MS activity," said Ascherio.