Question

I have been supplementing my horse with MSM for many years. Recently, I have been advised that feeding MSM causes magnesium deficiency. Is this true?

Answer

There has been no published research that I can find that suggests that MSM (methylsulfonylmethane) causes a magnesium deficiency. It has been established to be a very safe supplement for horses and humans alike. However, no safety testing has been conducted in pregnant or lactating animals and therefore MSM should probably not be used in them.

MSM is a common addition to joint supplements that are used with no side effects in horses. The major concern with MSM is the purity of the product. Inexpensive forms of the supplement can be contaminated with heavy metals, lead, and chlorinated hydrocarbons if impure solvents are used in crystallization processes.

Look for MSM that is made in the USA by a reputable manufacturer that adheres to FDA standards of manufacturing practices, and that is made by the distillation process that produces MSM of the highest purity.