Zinc supplementation is sometimes recommended for MS. In fact, zinc phosphate was one of the earliest recommended therapies for MS. Zinc phosphate was used in the 1880s as a treatment by colleagues of Charcot, a French neurologist who played a major role in defining MS as a disease. At this time, there are no clear reasons for people with MS to take zinc supplements.
Some recent studies suggest that zinc lozenges may prevent or shorten the duration of the common cold. Other studies have not shown beneficial effects. With these mixed results, the effects of zinc on the common cold are not known. This possible effect of zinc is of potential importance to people with MS because the common cold and other viral infections may trigger MS attacks.
Zinc supplements are also sometimes recommended in MS because zinc is involved in the chemical pathway of polyunsaturated fatty acids, as discussed in the section on diet. This chemical pathway has been implicated in MS. However, it is not known if the pathway is indeed involved in MS, and it is not known whether zinc supplements are necessary for this pathway to function normally.
It is important to recognize that zinc may actually stimulate the immune system. This may be the mechanism by which zinc exerts its presumed effects on the common cold. Zinc activates several different immune cells, including macrophages and T cells. In fact, zinc supplements appear to increase the amount of brain inflammation in EAE, an animal model of MS. This suggests that supplements in humans may worsen MS.
A possible toxic role for zinc was suggested by a report of a relatively high occurrence of MS in a zinc-related industry in New York. Blood levels of zinc were increased in people in this facility. Studies of zinc levels in other MS populations have produced inconsistent results: Some studies show high levels, but other studies indicate low levels. A deficiency of zinc produced benefits in a mouse model of lupus, an autoimmune disorder like MS. This finding is consistent with immune stimulation by zinc.
Immune system activation by zinc could worsen MS. Given the fact that zinc has unclear benefits and that it may potentially stimulate the immune system, it is reasonable for people with MS to avoid zinc supplements or to use low doses of supplements—such as 10 to 15 milligrams or less daily.