Monday October 13, 2008 (foodconsumer.org) -- Parkinson's disease may have a lot to do with vitamin D insufficiency, according to a new study by researchers from Emory University School of Medicine.

The study led by Marian Evatt, MD, assistant professor of neurology at Emory and colleagues found 55 percent of people with Parkinson's disease were vitamin D insufficient compared to 41 percent among those with Alzheimer's disease and 36 percent in healthy people.

But the study published in the October, 2008 issue of Archives of Neurology in no way suggests Parkinson’s disease leads to the insufficiency or vice versus.

The researchers initiated the study to evaluate the possibility that neurodegenerative diseases lead to vitamin D insufficiency.

Ultra-violet B ray in sunshine is the most common source for vitamin D.   Vitamin D is found in a limited number of foods such as oily fish like salmon, fortified foods such as juice and milk and some processed foods, and supplements.

"We found that vitamin D insufficiency may have a unique association with Parkinson's, which is intriguing and warrants further investigation," Evatt said.

The finding is understandable because people with Parkinson's disease often have mobility problem and are seldom exposed to the sun.  This means that it is likely that these people lack vitamin D because they are exposed to less sunshine.

But low vitamin D levels may also be possibility associated with some pathological process, condition, or disease.

Evatt said the observation is striking because study subjects came from the southeast where vitamin D insufficiency is not expected as common as in the north where exposure to sunlight is less common and insufficiency of the vitamin could be more of a problem.

The researchers also found that the rate of vitamin D deficiency among people with Parkinson's disease was also higher than that in the Alzheimer's group and the healthy group, 23 percent versus 16 and 10 percent respectively.

The study involved 100 people with Parkinson's disease, 100 people with Alzheimer's and 100 healthy people who were recruited between 1992 and 2007.

Vitamin D insufficiency means that a person has less than 30 nanograms per milliliter of blood of the 25-hydroxy form (the major storage form) of the vitamin while deficiency refers to a level of less than 20 nanograms per milliliter.

In addition to its role in maintaining bone health, vitamin D has also been found to play a number of other roles including producing antibacterial protein in the skin, regulating blood pressure, and insulin levels and maintaining the nervous system.

Low vitamin D levels have been associated with a whole range of chronic diseases including autoimmune disease, cancer and heart disease.

Parkinson's disease may have something to do with vitamin D insufficiency because early studies have found that in the part of the brain affected by Parkinson's - the substantia nigra - has high levels of the vitamin D receptor.

The study merely found that there was an association between low levels of vitamin D and Parkinson's disease. But further research is needed to determine if there is a causal relationship between the two.