Magnesium Stearate – Is It Really That Bad?

We commonly get questions about magnesium stearate, which is considered an inert (non-active) ingredient found in many supplements. In this post I wanted to set the record straight regarding magnesium stearate found in many supplements…

Turning a powder into a capsule or tablet is far more complicated than people think. In fact, there’s an entire science to the manufacture of capsules and tablets. The magnesium stearate is added to the nutritional ingredients to allow the powder to flow through the encapsulating machine more efficiently, this allows for a product with good consistency, which means that each capsule or tablet will have a consistent amount of active ingredient. This also allows the capsules and tablets to be produced faster, resulting in lower cost to the manufacturer and end user.

If It’s Inert, Why Is It There And What’s The Big Deal

The problem is that magnesium stearate is a magnesium salt that is bound to a saturated fat called stearic acid. Some supplement companies are throwing a fit about products that contain magnesium stearate, claiming that the stearic acid is doing the body harm. This allows them to sell “Stearate-free” products which gives them, what is called in marketing, a Unique Selling Proposition (USP). In a nutshell, it makes their products stand out from the rest. But let’s explore some of the facts:

  1. Stearic acid is found in the diet in much higher quantities than are found in supplements
  2. The average capsule contains 10-20 mg of stearic acid compared to 5,000 mg in a bar of chocolate
  3. Stearic acid is easily converted by the body into oleic acid which is the monounsaturated fatty acid found in extra virgin olive oil.
  4. Encapsulating supplements uses far less magnesium stearate than tablets. Poor quality companies use excess amounts of magnesium stearate in order to increase the speed at which they can manufacture capsules and tablets.
  5. Good quality companies (such as professional companies like Pure Encapsulations, Metagenics, Thorne Research, Carlson Labs, Life Extension, etc.) follow strict pharmaceutical standards to assure that they use only the necessary amounts of inert ingredients.
  6. The magnesium stearate found in supplements is negligible compared to the amounts found in the diet. If you were to swallow an entire bottle of a  supplement containing magnesium stearate you would likely get just 1,000-2,000 mg of stearic acid (less than half the amount found in a chocolate bar).


One thought on “Magnesium Stearate – Is It Really That Bad?

  1. Kelly Czap says:

    Ah, but you miss the point about magnesium stearate in supplements vs chocolate bars or other foods. Thorne Research has never said that magnesium stearate is bad or harmful just that it has no business being in a dietary supplement.

    The idea is to have supplements absorb correct? So by mixing vitamin C for instance with stearic acids you are coating the vitamin C crystals with thin layers of fat. The more you mix the more layers wrap around and all of a sudden you have vitamin C that is more or less time release. Pharmaceutical Technology did an article showing the dissolution of products mixed with magnesium stearate – the more you mix the less it dissolves. Period.

    Magnesium stearate is used in the dietary supplement and pharmaceutical industries because it makes the products run better in the machines. It acts as a lubricant. Like any fat does. It is not used because it is better for the patient rather it is better for the company’s bottom line – aka profit margin.

    If you don’t care what you put in your body then fine. But if you want to get the best from your dietary supplement no matter what it is find a product that does not use magnesium stearate or vegetable stearate. Thorne Research started in 1984 and has never used stearates.

    I know, I started Thorne Research.

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