Expert advice | Magnesium Stearate – what’s it doing in your supplements?

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Magnesium Stearate: harmful or harmless?

Q. Why do you use magnesium stearate in your capsules? I’ve heard it negatively affects the immune system and could inhibit the absorption of supplements.

A. This is a question we receive a lot. Generally speaking, we try our best to avoid the use of unnecessary excipients in our products.

Our production team batters down the amounts of non-medicinal ingredients used in the products to the point where it is just the bare minimum required to manufacture.

We use a miniscule amount of magnesium stearate as an inert flow agent in order to blend our ingredients. It is essential for making sure doses are consistent from capsule to capsule.

So, what is magnesium stearate, anyway? It’s a magnesium salt created by joining magnesium to two stearic acid molecules. Stearic acid is a very common fatty acid found in foods like coconut oil. Recently, there have been some concerns as to whether magnesium stearate suppresses the immune system and inhibits nutrient absorption. We’ll go over each point.

The centrepiece to the first argument involves a 1990 study in the journal Immunology entitled “Molecular basis for the immunosuppressive action of stearic acid on T cells.”

A little context is needed: The purpose of this study was to find an immunosuppressive drug for people with organ transplants or who suffer from autoimmune diseases. Researchers exposed cultured T and B cells to a concoction of stearic acid mixed with diatomaceous earth and bovine albumin hoping that it would damage these cells.

First of all, this study is using regular stearic acids (like those found in foods) rather than magnesium stearate.

Secondly, while the study implicated stearic acid, this is really a case of  “the dose makes the poison.”

The study is not relevant to orally consumed stearic acid, because those immune cells were bathed in a clinically and physiologically impossible amount of stearic acid.

Magnesium is generally recognized as safe for ingestion up to 2500mg per kg of body weight daily. That means A 70kg man would have to ingest 175,000mg of magnesium stearate per day!

The other common criticism is that magnesium stearate may inhibit nutrient absorption. A few studies suggest that tablets or capsules containing magnesium stearate dissolve more slowly than those without. While this may be so, bioavailability studies show that magnesium stearate had no impact on the actual overall bioavailability of the supplement in blood serum.

If you are still concerned about magnesium stearate as a non-medicinal ingredient, it might be helpful to consider this. Stearic acid (the one talked about in the study) is a very common saturated fatty acid. An average person can ingest far more actual stearic acid from food than he or she would magnesium stearate in a dietary supplement.

A bar of chocolate can easily contain over 5,000 milligrams of stearic acid versus 10mg in a capsule. Furthermore, the liver converts stearates and stearic acid into oleic acid, a common monounsaturated fat, on a regular basis.

Hope this helps!


Disclaimer: The experts’ responses are for general information purposes only and is not intended to be medical advice. If you have any specific questions about any medical matter, you should always consult your naturopathic doctor or other health care practitioner. Don’t delay seeking medical advice, disregard medical advice or discontinue medical treatment because of the information presented here.

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