Clarifying the Effects of Magnesium Stearate

By AnnElise Hatjakes, M.A.

Is magnesium stearate dangerous?  In short, no.  The Food and Drug Administration (FDA) has approved hundreds of additives for medicine and dietary supplements, including magnesium stearate.   According to Stephen Ritter, Ph.D., senior correspondent for Chemical & Engineering News, many inactive ingredients including magnesium stearate help hold a dose of the active pharmaceutical ingredient together and keep it stable for a long shelf life.

Magnesium stearate is added to supplements because it creates an even distribution of active ingredients and prevents ingredients and tablets from sticking to encapsulation or tablet presses during production.  A very small amount of magnesium stearate is used in supplements; it typically comprises less than 1% of a total formulation.

If the FDA has stated magnesium stearate is safe, why has it been viewed as being potentially harmful?

Despite the fact that the FDA has approved these additives, some people are concerned that magnesium stearate may affect the gastrointestinal tract and the immune system.  This concern often stems from claims made by companies that produce magnesium stearate-free supplements.  According to ConsumerLab.com, an independent laboratory, one popular website claims that magnesium stearate can promote the growth of bacterial colonies in the gastrointestinal tract and create a biofilm, preventing the absorption of nutrients. The website states that there does not seem to be clinical evidence behind this.  In fact, a laboratory study performed at Texas A&M University found stearic acid to inhibit the formation of biofilms.  Several fatty acids (including magnesium stearate) in ground beef were tested.  The results of these tests indicated that both medium- and long-chain fatty acids inhibit the f ormation of biofilms.

Concern has also been voiced about the stearic acid in magnesium stearate raising cholesterol levels since it is a saturated fat.  A study regarding the relationship between cholesterol and magnesium revealed that this should not be a concern because normal dietary intake of stearic acid has been shown to have no significant effect on total cholesterol (Yu, Am. J. Clin. Nutr. 1995).  In addition, the amount of stearic acid from magnesium stearate in supplements is very small.  According to nutrition surveys from the United States Department of Agriculture (USDA), the average American adult consumes between 5,900 to 8,800 milligrams of stearic acid each day, typically from food sources like beef, poultry, cocoa butter, milk and cheese.  A single chocolate bar contains about 5,000 milligrams of stearic acid.  Meanwhile, the amount of stearic acid in the magnesium stearate in a dietary supplement is generally less than 20 milligrams.

What does this mean for you?

While there is no nutritional advantage to having magnesium stearate in your supplement, it does allow manufacturers to provide a more consistent and stable product. The clinical studies that have been conducted show that there are no identifiable adverse effects of taking supplements that contain magnesium stearate.  According to the investigation by ConsumerLab.com, it is highly unlikely the small amount of magnesium stearate in supplements causes immune suppression.  Such an effect has not been reported.  ConsumerLab.com is not the first entity to deem magnesium stearate safe.  According to the FDA’s Database of the Select Committee on GRAS (Generally Recognized as Safe) Substances, there is no current evidence that “suggests reasonable grounds to suspect, a hazard to the public when they are used at levels that are now current and in the manner now practiced, or which might reason ably be expected in the future.”