Sunday Sep 13, 2014 (foodconsumer.org) -- A report published Jan 28, 2014 in Front Pharmacology suggests vitamin D may be a preventative or therapeutical that can be used to fight Alzheimer's disease or reduce the risk of developing the disorder that affects an estimated five million American people.

It has been observed that 70 to 90 percent of Alzheimer’s disease patients suffer vitamin D deficiency.   Epidemiological studies consistently show low serum concentrations of vitamin D are associated with global cognitive impairment and people with hypovitaminosis D are more likely to be diagnosed with more cognitive disorders, particularly executive dysfunctions.

People with Alzheimer's disease are found to have lower vitamin D status than controls and reduced levels of 25-hydroxyvitamin D in the cerebrospinal fluid, compared to controls.  Studies have also found that hypovitaminosis D is often found before the onset of cognitive decline.

People with Alzheimer's disease or with cognitive decline are also likely to have increased levels of vitamin D-binding protein and reduced  levels of vitamin D receptor (VDR) mRNA.  In contrast, the over-expression of VDR may suppress amyloid precursor protein transcription and the VDR gene APA1 polymorphism is linked to the onset of Alzheimer's disease.

On the other hand, high intake of vitamin D (from food, supplements or sun exposure) has been associated with better cognitive function in older people.  

Taking more than 8000 IU of vitamin D per day makes a difference in the risk Alzheimer's disease during a  seven-year follow-up.  The neuroprotective effect has been confirmed by clinical trials of general aged populations and people with Alzheimer's disease.  The vitamin D supplementation improves cognitive function at four weeks, particularly executive functions and processing speed.

Not all people with hypovitaminosis D suffer Alzheimer's disease indicating that other risk factors are also involved in the pathology of the disease while vitamin D supplementation may help some Alzheimer's patients.

Vitamin D deficiency has been associated with more than 100 health conditions or diseases.  A high dose of vitamin D should be taken in order to have a preventative effect against the diseases like cancer, diabetes mellitus and Alzheimer's disease. Even if the vitamin does not help Alzheimer's disease, everyone should make sure they have sufficient daily intake for other benefits.  (david Liu, PHD)

Cedric Annweiler, Spyridon N. Karras, Panagiotis Anagnostis, and Olivier Beauchet, Vitamin D supplements: a novel therapeutic approach for Alzheimer patients, Front Pharmacol. 2014; 5: 6. Published online Jan 28, 2014. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3904112/