Vitamin D and Parkinson's

Looking at the health sector of BBC news I found recent information on Parkinsons: http://www.bbc.co.uk/search/news/?q=Parkinsons


For example I found out that there is shown to be a link between vitamin D and Parkinson's disease.


Previous studies have shown that the substantia nigra, part of the brain that's most affected in Parkinson's, has high levels of vitamin D receptor, suggesting vitamin D may be important for normal functions of dopamine producing cells

One theory is that people with Parkinson's may be particularly vulnerable because their condition limits the amount of time they spend out of doors. However, scientists say it may also be possible that low vitamin D levels are in some way related to the genesis and origin of the disease.

The researchers examined vitamin D levels in 100 people with Parkinson's, 100 with Alzheimer's disease and 100 who were healthy. The groups were matched for age, and economic circumstance. Among the Parkinson's group 23% of patients had vitamin D levels so low that they could be described as deficient. In the Alzheimer's group the figure was 16%, and in the healthy group 10%.

researchers do not yet know if the vitamin deficiency is a cause or the result of having Parkinson's. Therefore Further research is required to determine at what stage the deficiency in vitamin levels occur in the brains of people with Parkinson's and whether the provision of a dietary supplement, or increased exposure to sunlight may help alleviate symptoms or have an effect on the rate of the condition's progression.
(http://news.bbc.co.uk/1/hi/health/7666749.stm)

I'm wondering now if further research has already been done and whether findings show that its a cause or result of having Parkinson's