Magnesium stearate is a magnesium salt containing stearic acid that is commonly found in much of our food supply.4 It is derived from vegetable oil. Stearic acid is unique among saturated fatty acids because it does not raise LDL cholesterol Low-density lipoprotein (the bad cholesterol).1,3
Stearic acid is naturally present in many common foods in far greater quantities than in supplements. Stearic acid is naturally found in vegetable oils, meats, and even in large quantities in chocolate. Stearic acid is the immediate precursor of oleic acid, an important fatty acid found in healthy olive oil.2,5
Magnesium stearate is used for its natural lubricant properties in the manufacturing process. Without lubrication, supplements would stick to the machines and be virtually impossible to produce. Magnesium stearate keeps them from sticking together.
Magnesium stearate also allows supplements to form a smooth consistency to ensure uniformity.
In the body, stearic acid is primarily converted into oleic acid (a monounsaturated fatty acid). Oleic acid is a healthy monounsaturated fatty acid commonly found in olive oil. Oleic acid may also be involved in the blood pressure regulating effects of olive oil.3
In 2009, an osteopathic physician based in Illinois first published an article claiming that stearic acid is dangerous to one's immune system, and was the equivalent of consuming chalk over long periods of exposure.2 However, Byron J. Richards, a holistic physician and supplement maker based in Minneapolis, refuted the claim: "[T]he amount of stearic acid ingested in a vitamin product is a small percent of a fatty acid that you consume every day as part of your diet, a type of fatty acid that is not problematic in the first place."2
According to Richards, stearate is already found in dozens of organic food products people consume every day. It's part of a natural, healthy diet!
The alleged danger of Magnesium stearate is a contrived "non-issue" according to Stephen Cherniske, M.S. of UniveraScience:
“...This magnesium stearate controversy falls into the category of 'unproven and exaggerated,' and the sheer durability of this non-issue is what is so surprising. I do not know a single organic chemist who feels that magnesium stearate is dangerous, let alone toxic. Nor do I know a manufacturer (other than a few whose marketing strategy is to demonize this common ingredient) who believes it poses a problem with the production of tablets or capsules.”1