Friday, November 21, 2008
Vitamin D Insufficiency Linked to Parkinson’s Disease
Vitamin D, also called the sunshine vitamin, has already been shown in studies to be important for a healthy immune system, preventing and even reversing cancer, as well as strong bones; it has also been linked to lower incidences of depression as well as diseases such as diabetes, heart disease and multiple sclerosis. Now, a recent study published in the Archives of Neurology has found that low levels of vitamin D could also have a part to play in the development of Parkinson's Disease (PD).
The potential link between lack of vitamin D and PD may, it seems, go beyond just being a case of being caused by general ill health and weak immunity. There could be another chemical link, or at least that is the hypothesized theory.
The chemical dopamine in the brain helps one to control one's physical movements. In PD, one's levels of dopamine are lowered because the nerve cells which make the chemical have either died or lost their usual functioning. With less dopamine, control of physical movements becomes affected, and one begins to move slowly, have stiff muscles, shake or lose balance.
Now, previous research has shown that the part of the human brain which is the most affected by PD has high levels of vitamin D receptors. It thus follows, theoretically, that vitamin D deficiency would have a negative impact on the functioning of that part of the brain, thereby translating to higher chances of getting PD.
Details of Study
For this study, the research team examined the levels of plasma 25-hydroxyvitamin D (25[OH]D) in a clinical research database at Emory University School of Medicine. The participants had been recruited into the study from May 1992 to March 2007. In all, three groups of people were compared – 99 healthy adults to act as the control group, 97 Alzheimer's Disease (AD) patients, and 100 PD patients. The study subjects were matched for age, gender, race and geographic location.
You may be wondering why the group of AD patients was included. That was because the study team wanted to find out if there was a link between vitamin D insufficiency and other diseases which also cause a loss of nerve cells.
Findings of Study
The findings of the study revealed that 55% of the PD patients had insufficient levels of vitamin D. The corresponding figures for AD and healthy people were 41% and 36% respectively. When it came to severe vitamin D insufficiency, or vitamin D deficiency, the correlations were similar – 23% of PD patients were deficient in the vitamin, compared with 16% of AD patients and 10% of healthy people.
One interesting finding was that PD patients had less vitamin D than AD patients. According to the study team, this suggests that lack of vitamin D may be linked specifically to Parkinson's, rather than to neurodegenerative diseases in general.
It is premature to conclude that lack of vitamin D is a precursor to the development of Parkinson's Disease. In fact, between the two factors, we cannot even be clear about which is the cause and which is the consequence. For example, people with restricted movements would largely be confined to indoor areas, and the subsequent lack of sun exposure could then have caused their vitamin D insufficiency. In fact, the connection could even work both ways.
In any case, there is already a long list of reasons for us to ensure that our bodies have sufficient amounts of vitamin D. And, as many experts agree, an adequate and commonsensical amount of time spent in open sunshine (without any sunscreen, of course) is the best way to get our fix of vitamin D. When we do that, we will enjoy better health all round.
As for Parkinson's and even Alzheimer's patients, this study also reminds them of the need to boost their levels of vitamin D. Otherwise, other health complications may result.