What Is Magnesium Stearate?

FDA regulations at 21 CFR 184.1440 describe magnesium stearate as the magnesium salt of stearic acid, made from a stearate derived from stearic acid obtained from edible sources, and list its food uses as a lubricant and release agent, a nutrient supplement and a processing aid. They affirm it as generally recognized as safe as a direct human food ingredient, used with no limitation other than current good manufacturing practice. A 2017 study in Toxicology Reports says magnesium stearate is widely used in producing dietary supplement and pharmaceutical tablets, capsules and powders, as well as many foods, including confectionery, spices and baking ingredients.

The 2017 study reported that its data indicate a lack of genotoxic risk from magnesium stearate consumed at current estimated dietary exposures, but said the health effects of cumulative exposure to magnesium from multiple food additives may be of concern and warrant further evaluation. In a 2018 opinion, the European Food Safety Authority panel concluded there was no need for a numerical acceptable daily intake and that sodium, potassium, calcium and magnesium salts of fatty acids (E 470a and E 470b) were of no safety concern at the reported uses and use levels.