Vitamin D levels associated with Parkinson's disease risk

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Public release date: 12-Jul-2010

http://www.eurekalert.org/pub_releases/2010-07/jaaj-vdl070810.php

Contact: Knekt, D.P.H.

paul.knekt@...

JAMA and Archives Journals

Vitamin D levels associated with Parkinson's disease risk

Individuals with higher levels of vitamin D appear to have a reduced

risk of developing Parkinson's disease, according to a report in the

July issue of Archives of Neurology, one of the JAMA/Archives journals.

Vitamin D is known to play a role in bone health and may also be linked

to cancer, heart disease and type 2 diabetes, according to background

information in the article. " Recently, chronically inadequate vitamin D

intake was proposed to play a significant role in the pathogenesis of

Parkinson's disease, " the authors write. " According to the suggested

biological mechanism, Parkinson's disease may be caused by a

continuously inadequate vitamin D status leading to a chronic loss of

dopaminergic neurons in the brain. "

Knekt, D.P.H., and colleagues at the National Institute for Health

and Welfare, Helsinki, Finland, studied 3,173 Finnish men and women age

50 to 79 who did not have Parkinson's disease at the beginning of the

study, in 1978 to 1980. Participants completed questionnaires and

interviews about socioeconomic and health background, underwent baseline

examinations and provided blood samples for vitamin D analysis.

Over a 29-year follow-up, through 2007, 50 of the participants developed

Parkinson's disease. After adjusting for potentially related factors,

including physical activity and body mass index, individuals in the

highest quartile (one-fourth of the study population) of serum vitamin D

levels had a 67 percent lower risk of developing Parkinson's disease

than those in the lowest quartile of vitamin D levels.

" Despite the overall low vitamin D levels in the study population, a

dose-response relationship was found, " the authors write. " This study

was carried out in Finland, an area with restricted sunlight exposure,

and is thus based on a population with a continuously low vitamin D

status. Accordingly, the mean [average] serum vitamin D level in the

present population was about 50 percent of the suggested optimal level

(75 to 80 nanomoles per liter). Our findings are thus consistent with

the hypothesis that chronic inadequacy of vitamin D is a risk factor for

Parkinson's disease. "

The exact mechanisms by which vitamin D levels may affect Parkinson's

disease risk are unknown, but the nutrient has been shown to exert a

protective effect on the brain through antioxidant activities,

regulation of calcium levels, detoxification, modulation of the immune

system and enhanced conduction of electricity through neurons, the

authors note.

" In intervention trials focusing on effects of vitamin D supplements,

the incidence of Parkinson disease merits follow up, " they conclude.

(Arch Neurol. 2010;67[7]:808-811. Available pre-embargo to the media at

www.jamamedia.org.)

Editor's Note: This work was supported by a National Institutes of

Health grant. Please see the article for additional information,

including other authors, author contributions and affiliations,

financial disclosures, funding and support, etc.

Editorial: Findings Add to Research on Neurological Effects of Vitamin D

" The study by Knekt et al in this issue of the Archives is the first

longitudinal analysis of vitamin D status as a risk of incident

Parkinson's disease and examines a cohort of more than 3,000

participants from the Mini-Finland Health Survey, " writes n

Evatt, M.D., M.S., of Emory University, Atlanta, in an accompanying

editorial.

" A growing body of basic research lends plausibility to a role for

adequate vitamin D status protecting against development of Parkinson's

disease, " Dr. Evatt writes. " Knekt and colleagues' study provides the

first promising human data to suggest that inadequate vitamin D status

is associated with the risk of developing Parkinson's disease, but

further work is needed in both basic and clinical arenas to elucidate

the exact role, mechanisms and optimum concentration of vitamin D in

Parkinson's disease. "

" With the animal data showing a U-shaped curve for neuroprotective

effects of vitamin D, it seems prudent to confirm the findings presented

in this issue and investigate whether the apparent dose-response

relationship observed in the current study maintains its slope, levels

off or becomes negative with higher 25-hydroxyvitamin D concentrations.

In the interim, data from interventional studies of fractures and falls

appear to justify optimizing vitamin D levels to greater than 30 to 40

nanograms per milliliter. "

(Arch Neurol. 2010;67[7]:795-797. Available pre-embargo to the media at

www.jamamedia.org.)

Editor's Note: Please see the article for additional information,

including author contributions and affiliations, financial disclosures,

funding and support, etc.

==================

Public release date: 12-Jul-2010

http://www.eurekalert.org/pub_releases/2010-07/eu-nes070910.php

Contact: Kathi Baker

Emory University

New evidence shows low vitamin D levels lead to Parkinson's disease

A new study on vitamin D levels and Parkinson's disease risk points to

the need for further research on whether vitamin D supplements can

protect against the movement disorder, according to an editorial in the

July 2010 issue of Archives of Neurology.

The author of the editorial is n Evatt, MD, assistant professor of

neurology at Emory University School of Medicine and director of the

Atlanta Veterans Affairs Medical Center's Movement Disorders Clinic.

The study, also reported in Archives of Neurology, is the first to show

that low vitamin D levels can help predict whether someone will later

develop Parkinson's disease. Researchers at Finland's National Institute

for Health and Welfare measured vitamin D levels from more than 3000

people, using blood samples taken between 1978 and 1980, and then

followed those people to see whether they developed Parkinson's. People

with the lowest levels of vitamin D were three times more likely to

develop Parkinson's, compared to the group with the highest levels.

Previous research had suggested a link between low vitamin D and

Parkinson's, but whether this is a cause-and-effect relationship is

unknown. Vitamin D may help protect the population of neurons gradually

lost by people with Parkinson's disease, Evatt writes in her editorial.

Parkinson's disease affects nerve cells in several parts of the brain,

particularly those that use the chemical messenger dopamine to control

movement. The most common symptoms are tremor, stiffness and slowness of

movement. These can be treated with oral replacement of dopamine.

Research on animals suggests that vitamin D may protect neurons that

produce dopamine from toxins. Besides vitamin D levels, factors such as

genetics and exposure to pesticides also are associated with the risk

for developing Parkinson's disease.

Doctors have known for decades that vitamin D promotes calcium uptake

and bone formation, but evidence is accumulating for additional roles

regulating the immune system and the development of the nervous system.

Humans can get vitamin D from exposure to sunlight or eating foods such

as fatty fish or fortified foods such as milk and packaged cereals.

People living at high latitudes tend to have less exposure to the sun;

in the Finnish study, the average vitamin D level was about half of the

currently recommended level.

Vitamin D levels are usually measured by looking at the stable,

25-hydroxy form; the current recommended level is 30-40 nanograms per

milliliter of blood.

Evatt writes that public health authorities should consider raising the

target vitamin D level above the current recommended target because of

known benefits for bone health as well as potential benefits for the

nervous system. Still, animal data suggests that too much vitamin D can

also be harmful for the nervous system, and megadoses of vitamin D can

induce hypercalcemia, or an excess of calcium in the blood.

" At this point, 30 ng/ml or more appears optimal for bone health in

humans. However, researchers don't yet know what level is optimal for

brain health or at what point vitamin D becomes toxic for humans, and

this is a topic that deserves close examination, " she says.

###

At Emory, Evatt and colleagues are conducting a pilot clinical trial,

which examines the effects of vitamin D supplementation on patients with

Parkinson's disease who have low vitamin D levels as well as conducting

further epidemiological studies of vitamin D in Parkinson's disease.

http://www.clinicaltrials.gov/ct2/show/NCT00571285

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http://www.eurekalert.org/pub_releases/2010-07/eu-nes070910.php