Researchers at Johns Hopkins suggest that low levels of vitamin D could double the risk of stroke in white people, but not black people.

Erin Michos, assistant professor at the Johns Hopkins University School of Medicine and its Heart and Vascular Institute, theorised that black people may have adapted to this deficiency over generations.

“Higher numbers for hypertension and diabetes definitely explain some of the excess risks for stroke in black compared to white but not this much risk.

Separate studies have also noted that the strong association between vitamin D levels and stroke in white people is limited to individuals who are severely deficient.

Other studies have contended that the view that vitamin D deficiency is a risk factor for stroke is wrong, suggesting that low vitamin D levels are a consequence of a stroke incident instead.

There is other evidence that vitamin D supplements could lower stroke risk and improve recovery.