PLEASE check out the link that Dubious posted re the Marshall Protocol, which includes the following:

Dr. Trevor Marshall has two degrees, both in electrical engineering. Before I begin, I want to again remind you that I am a psychiatrist who works at a state mental hospital. In my duty to full disclosure, I must say that I have known a lot of psychiatrists in my life and a few electrical engineers. If I knew nothing else of a disagreement between two people but their professions, I would believe the electrical engineer, not the psychiatrist.

In reading his two articles, Dr. Marshall's main hypotheses are simple. (1) Vitamin D from sunlight is different than vitamin D from supplements. (2) Vitamin D is immunosuppressive and the low blood levels of vitamin D found in many chronic diseases are the result of the disease and not the cause. (3) Taking vitamin D will harm you, that is, vitamin D will make many diseases worse, not better. If you read his blog, you discover that the essence of the Marshall protocol is: "An angiotensin II receptor blocker medication, Benicar, is taken, and sunlight, bright lights and foods and supplements with vitamin D are diligently avoided. This enables the body's immune system, with the help of small doses of antibiotics, to destroy the intracellular bacteria. It can take approximately one to three years to destroy all the bacteria." That is, Dr. Marshall has his "patients" become very vitamin D deficient.

Again, Dr. Marshall conducted no experiment and published no study. He wrote an essay. He presented no evidence for his first hypothesis (sunlight's vitamin D is different than supplements). From all that we know, cholecalciferol is cholecalciferol, regardless if it is made in the skin or put in the mouth. His second hypothesis is certainly possible and that is why all scientists who do association studies warn readers that they don't know what is causing what. Certainly, when low levels of vitamin D are found in certain disease states, it is possible that the low levels are the result, and not the cause, of the disease. Take patients with severe dementia bedridden in a nursing home. At least some of their low 25(OH)D levels are likely the result of confinement and lack of outdoor activity. However, did dementia cause the low vitamin D levels or did low 25 (OH)D contribute to the dementia? One way to look at that question is to look at early dementia, before the patient is placed in a nursing home. On the first day an older patient walks into a neurology clinic, before being confined to a nursing home, what is the relationship between vitamin D levels and dementia? The answer is clear, the lower your 25(OH)D levels the worse your cognition.

Wilkins CH, Sheline YI, Roe CM, Birge SJ, Morris JC. Vitamin D deficiency is associated with low mood and worse cognitive performance in older adults. Am J Geriatr Psychiatry. 2006 Dec;14(12):1032-40.

Przybelski RJ, Binkley NC. Is vitamin D important for preserving cognition? A positive correlation of serum 25-hydroxyvitamin D concentration with cognitive function. Arch Biochem Biophys. 2007 Apr 15;460(2):202-5. Epub 2007 Jan 8.

These studies suggest that the low 25(OH)D levels are contributing to the dementia but do not prove it. Only a randomized controlled trial will definitively answer the question, a trial that has not been done. So you will have to decide if vitamin D is good for your brain or not. Dr. Marshall seems to be saying demented patients should lower their 25(OH)D levels. Keep in mind, an entire chapter in Feldman's textbook is devoted to the ill effects low vitamin D levels have on brain function.

Brachet P, et al. Vitamin D, a neuroactive hormone: from brain development to pathological disorders. In Feldman D., Pike JW, Glorieux FH, eds. Vitamin D. San Diego : Elsevier, 2005.

[Emphasis added.]

The point being, who needs evidence when you've got a compelling theory? Oh yeah, that and there's lots of evidence that Vit. D. deficiencies can be really bad for you.

Once more, the link is http://209.85.173.132/search?q=cache...lnk&cd=8&gl=us

Mike