Is Hypovitaminosis D one of the Environmental Risk Factors for Multiple Sclerosis?

Charles Pierrot-Deseilligny; Jean-Claude Souberbielle

Disclosures

Brain. 2010;133(7):1869-1888. 

In This Article

Abstract and Introduction

Abstract

The role of hypovitaminosis D as a possible risk factor for multiple sclerosis is reviewed. First, it is emphasized that hypovitaminosis D could be only one of the risk factors for multiple sclerosis and that numerous other environmental and genetic risk factors appear to interact and combine to trigger the disease. Secondly, the classical physiological notions about vitamin D have recently been challenged and the main new findings are summarized. This vitamin could have an important immunological role involving a number of organs and pathologies, including autoimmune diseases and multiple sclerosis. Furthermore, human requirements for this vitamin are much higher than previously thought, and in medium- or high-latitude countries, they might not be met in the majority of the general population due to a lack of sunshine and an increasingly urbanized lifestyle. Thereafter, the different types of studies that have helped to implicate hypovitaminosis D as a risk factor for multiple sclerosis are reviewed. In experimental autoimmune encephalomyelitis, vitamin D has been shown to play a significant immunological role. Diverse epidemiological studies suggest that a direct chain of causality exists in the general population between latitude, exposure to the sun, vitamin D status and the risk of multiple sclerosis. New epidemiological analyses from France support the existence of this chain of links. Recently reported immunological findings in patients with multiple sclerosis have consistently shown that vitamin D significantly influences regulatory T lymphocyte cells, whose role is well known in the pathogenesis of the disease. Lastly, in a number of studies on serum levels of vitamin D in multiple sclerosis, an insufficiency was observed in the great majority of patients, including at the earliest stages of the disease. The questionable specificity and significance of such results is detailed here. Based on a final global analysis of the cumulative significance of these different types of findings, it would appear likely that hypovitaminosis D is one of the risk factors for multiple sclerosis.

Introduction

Vitamin D and its effects on bone have been known for a long time. However, nowadays we are progressively discovering that major actions of this vitamin involve a number of other organs and pathologies, most likely including multiple sclerosis. The recent considerable increase in publications on vitamin D, involving almost all medical specialities, is without precedent in the history of vitamin research. New findings may even prompt changes in medical practice in the very near future, not only in the field of general medical primary prevention but perhaps also in the treatment of some specific pathologies. In multiple sclerosis, although reliable results on a curative effect of vitamin D are still lacking, the notion that hypovitaminosis D may be one of the risk factors has greatly progressed in the last few years (Hayes, 2000; van Amerongen et al., 2004; Ascherio and Munger, 2007b). After a brief review of the main currently suspected risk factors for multiple sclerosis, we will discuss the different physiological, experimental, epidemiological, immunological and biological arguments that suggest that hypovitaminosis D is one of the risk factors.

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