Is Magnesium Stearate in Supplements Dangerous?

Magnesium stearate is present in up to 95% of the supplements produced by the pharmaceutical industry. However, its effect on health is not really known.
Is Magnesium Stearate in Supplements Dangerous?
Mariel Mendoza

Written and verified by the doctor Mariel Mendoza.

Last update: 19 October, 2022

Magnesium stearate is a chalk-like excipient used in vitamin supplements and foods to prevent ingredients from clumping together. This improves manufacturing processes and transit through the gastrointestinal tract.

It is used as an anti-caking agent, emulsifier, release agent, thickener and lubricant.

Although magnesium stearate has magnesium in its name, it isn’t a source of this nutrient. But is it harmful to health?

What is magnesium stearate?

Magnesium stearate is a salt formed by the union of a magnesium ion with 2 stearate molecules. Stearate is the anionic form of stearic acid. It is odorless and insoluble in water, with wide use in the pharmaceutical, food and cosmetic industries.

Stearic acid is a saturated fatty acid found in vegetable and animal oils, such as cocoa, coconut oil, red meat and flaxseed. Although it contains magnesium, its content is very low and it doesn’t really provide this mineral.

Currently, magnesium stearate is the most commonly used ingredient as an anti-caking agent and lubricant for capsules and tablets. Its function streamlines the production process in the industry, thus reducing costs and production times.

Magnesium stearate.
The pharmaceutical industry uses this compound to streamline its production processes.

Its importance in the pharmaceutical industry

Magnesium stearate is needed only in very small quantities. In addition, it facilitates production, because it prevents drugs from sticking to the machinery. It is, therefore, an economical and efficient way to produce medicines and supplements.

In addition, it speeds up the transit of capsules and tablets in the gastrointestinal tract. As an excipient, it can enhance the therapeutic effects. In this way, absorption, solubility, and consistency are improved.

In addition to its traditional name, it can be found on labels under the following designations:

  • Magnesium salts
  • Magnesium salts of fatty acids
  • Octadecanoic acid
  • E-572

Health effects of magnesium stearate

According to the U.S. Food and Drug Administration (FDA), magnesium stearate is classified as a safe substance. Therefore, its use as an additive in supplements and foods doesn’t pose any risk, as long as it’s added in low amounts.

Furthermore, according to the National Center for Biotechnology Information, it’s considered safe if consumed in amounts less than 2.5 grams per kilogram per day. Therefore, it’s assumed that the small amounts present in the pharmaceutical industry have no harmful effects.

However, there’s much controversy. There are no scientific studies that clearly and convincingly demonstrate its effects.

Effects of magnesium stearate on the immune system

For years it has been believed that magnesium stearate affects the function of T lymphocytes. The most widely reported scientific evidence is a 1990 study on a single mouse.

In this case, T lymphocytes were incubated with stearic acid (not magnesium stearate). Over time, the cell membranes collapsed.

However, the results can’t be replicated in humans. Mouse T lymphocytes don’t contain an enzyme capable of converting stearic acid to oleic acid.

It may be contaminated with pesticides

Magnesium stearate is obtained from cottonseed oil, so it’s believed that it may contain pesticides or come from genetically modified organisms. However, the raw material is purified before being incorporated as an ingredient.

Cottonseed oil.
Cottonseed oil is the raw material to obtain magnesium stearate.

Magnesium stearate may be laxative

It may have a laxative effect if ingested in excess, because it irritates the mucosal lining of the intestine, causing spasms and increased gastrointestinal transit. In very high doses it can damage the skin and be toxic to the liver.

So, is magnesium stearate harmful to health?

There’s no definitive consensus showing any harmful effects on health because there doesn’t seem to be enough scientific evidence.

According to the FDA, its use as an additive in supplements and foods isn’t considered to pose any risk, provided it’s used in low amounts. So, there are no harmful effects in the doses provided by pharmaceutical industries.

Of course, for the pharmaceutical industry it’s key in manufacturing, because it lowers their costs. It also improves the digestion and mobilization of the tablets through the gastrointestinal tract.

That’s why, from an economic point of view, industries don’t invest in exhaustive studies on the subject. Eliminating the substance from their ingredients would imply higher manufacturing costs.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.