Diet and multiple sclerosis

Multiple sclerosis (MS) is believed to be an inflammatory disease with autoimmune mechanisms, and much of the epidemiologic data point to an important, possibly predominant, role of environmental factors in its etiology.^1,2 In this regard, diet is an important subject of etiologic research. Frequent contact with numerous microbial, and potentially toxic, agents and their presentation to the gut-associated lymphoid tissue,³ provide an important biological rationale. Similar to MS incidence, diet shows striking geographic and ethnic variability, and may be preserved or changed after migration to another sociocultural environment. This is in accord with the divergent results of recent migrant studies in MS.^4,5 Furthermore, the fact that the risk of MS is correlated in both ecologic^6-8 and individual^9-11 terms with some gastrointestinal disorders argues in favor of a role for nutrition in the etiology of MS.

Considering the likely high frequency of subclinical disease in MS,¹² epidemiologic research is unable to clearly differentiate between "risk factors" and "triggers"; the latter lead, by definition, to a transitory accentuation of the inflammatory process. Since triggers can act to increase the incidence of the disease, they may also be classified as risk factors in epidemiologic terms. Furthermore, variables that affect prognosis may also provide clues to causal factors that act before clinical manifestations, and for this reason it may also be useful to take into account the result of trials on lifestyle variables such as diet when studying the etiology of MS.

This is a review of available epidemiologic data on the possible role of diet in the etiology of MS, with particular emphasis on methodologic issues.

Ecologic studies. In light of a comparatively low intra-population variability¹³ in diet, ecologic investigations are particularly valuable in the study of nutritional factors and MS. This is in contrast to …