Boston, MA – The possibility that vitamin D could help protect people from developing multiple sclerosis (MS) has been posited by researchers in recent decades, but evidence to support that link has been scant. In the first large-scale, prospective study to investigate the relationship between vitamin D levels and MS, researchers at the Harvard School of Public Health (HSPH) have found an association between higher levels of vitamin D in the body and a lower risk of MS. The study appears in the December 20, 2006, issue of the Journal of the American Medical Association.
What I wonder: Does Vitamin D reduce the risk by helping the immune system knock out pathogens at a very early stage before the can replicate enough to invoke a more specific immune response? MS might be caused by an immune reaction to a pathogen that has a protein on it that is similar to a surface protein on human nerves. If the immune system can knock out a pathogen at a very early stage (and vitamin D might help do this) then the larger immune response could be avoided and production of T cells carrying antibodies which have affinity for nerves could be avoided.
A big reduction in the incidence of MS could avoid hundreds of thousands of future cases.
MS is a chronic degenerative disease of the central nervous system. It affects some 350,000 people in the U.S. and 2 million worldwide, and occurs most commonly in young adults. Women, who are affected more than men, have a lifetime risk of about 1 in 200 in the U.S. Vitamin D is a hormone manufactured naturally in the body, and its levels can be increased with exposure to sunlight, consumption of foods rich in vitamin D, such as fatty fish, and by taking supplements.
The research was done on a population of 7 million military personnel and former personnel.
The researchers, led by Ascherio, worked in collaboration with colleagues in the U.S. Army and Navy to determine whether vitamin D levels measured in healthy young adults predict their future risk of developing MS. The investigation relied on a study population of more than 7 million individuals, whose serum samples are stored in the Department of Defense Serum Repository. Between 1992 and 2004, 257 U.S. Army and Navy personnel with at least two serum samples stored in the repository were diagnosed with MS. A control group, consisting of participants who did not develop MS, was randomly selected from the study population. Serum samples were analyzed for levels of 25-hydroxyvitamin D, a good indicator of vitamin D availability to tissues, and individuals were divided into five groups of equal size according to their average levels. Because vitamin D levels are strongly influenced by skin color, separate analyses were conducted among whites, blacks, and Hispanics.
The results showed that, among whites, MS risk declined with increasing vitamin D levels--the risk was 62% lower among individuals in the top fifth of vitamin D concentration (corresponding approximately to levels above 100 nmol/L or 40 ng/mL) than among those in the bottom fifth (approximately below 63 nmol/L or 25 ng/mL). The association was strongest among individuals who were younger than 20 when they first entered the study. No significant association was found among blacks and Hispanics, possibly because of a smaller sample size and the lower levels of vitamin D found in those groups. The average age of onset of MS cases was 28.5 years old; there was no significant difference in the results between men and women.
Doug of the Exoteric brought to my attention an abstract of a research paper which suggests influenza might be more common in the winter in part because of vitamin D deficiency. That abstract argues vitamin D prevents respiratory infections by strengthening the initial immune response to pathogens.
vitamin D deficiency is common in the winter, and activated vitamin D, 1,25(OH)2D, a steroid hormone, has profound effects on human immunity. 1,25(OH)2D acts as an immune system modulator, preventing excessive expression of inflammatory cytokines and increasing the ‘oxidative burst’ potential of macrophages. Perhaps most importantly, it dramatically stimulates the expression of potent anti-microbial peptides, which exist in neutrophils, monocytes, natural killer cells, and in epithelial cells lining the respiratory tract where they play a major role in protecting the lung from infection. Volunteers inoculated with live attenuated influenza virus are more likely to develop fever and serological evidence of an immune response in the winter.
Could avoidance of full blown infections reduce the risk of auto-immune disorder? Can we protect ourselves from infections, MS, and even cancer by taking vitamin D?
|Share |||Randall Parker, 2006 December 19 11:01 PM Aging Diet Studies|