ON THE CAUSES OF MULTIPLE-SCLEROSIS

Evidence on aetiology in multiple sclerosis suggests that the prevalen ce depends on the interaction of two factors, diet and exposure to vis ible sunlight. The dietary features which may be beneficial include su pplementation with fish oils, avoidance of saturated fats, and the ass ociated intake of antioxidants with unsaturated fatty acids. Inhibitio n, by antioxidants, of the enzyme lipoxygenase inhibits leukotriene sy nthesis, and the presence of fish oils leads to the production of leuk otrienes with less inflammatory properties. This is of particular impo rtance in the retina where leukotrienes might be the underlying cause of retrobulbar neuritis. The antioxidant properties of vitamin A may a lso lead to inhibition of leukotriene synthesis. Visible solar radiati on could be of benefit therefore by releasing vitamin A from visual pi gment rhodopsin. The interaction of these two factors may explain the epidemiological observations on the prevalence of multiple sclerosis.