A new study has shown a significant link between a lack of vitamin D and Parkinson's disease.
Researchers at the Emory University School of Medicine in Atlanta, Georgia, US, found that lower blood levels of the vitamin were more common in people with Parkinson's than healthy individuals.
Whether vitamin D deficiency was a cause of Parkinson's or resulted from it still has to be determined, but scientists do know that the part of the brain most affected by the disease is highly sensitive to vitamin D, suggesting that the vitamin may be important to this region.
However, the link between Parkinson's and vitamin D could arise because of the poor mobility of elderly patients.
Most vitamin D is manufactured in the skin in response to sunlight. People with Parkinson's who do not get outside may suffer from under-exposure to the sun, and as a result have reduced vitamin D levels.
Lead researcher Dr Marian Evatt said: "We found that vitamin D insufficiency may have a unique association with Parkinson's, which is intriguing and warrants further investigation."
The findings are published in the journal Archives of Neurology.