Magnesium Stearate: Is It a Safe Ingredient in Supplements?

Autoimmunity & Healing Diets

Apr 23

Magnesium stearate is a common flow agent used in supplements. Some people criticize its use in supplements for a variety of reasons that are mostly unsubstantiated. While it is always better to take supplements that are as pure as possible, is magnesium stearate as bad as some would have you think? I’ll tell you what I found out.

What is Magnesium Stearate?

Magnesium stearate is a salt that combines the mineral magnesium and the saturated fat stearic acid. Magnesium, as you probably know, is an extremely important mineral that many people are actually deficient in. Stearic acid is a saturated fat that is found in many foods, such as eggs, chicken, grassfed meat, coconut oil, walmuts, cheese, chocolate, salmon and human breast milk to name a few.

Put together, it is a salt that breaks apart easily in the presence of acid — the environment of the stomach. Both magnesium and stearic acid (stearate) are clearly safe for human consumption, and beneficial to human health.

What is a Flow Agent?

Supplement companies have used magnesium stearate for 40 years in encapsulated and tablet products. The flow agent helps to keep individual ingredients from sticking together or sticking to the machinery.

The nay sayers state that the flow agent is used for economic gain — that it saves money because the machinery can run faster if the product is not sticking, resulting in more product in less time.

Consistency is Key to Quality

There is another reason to use the flow agent, and that is to ensure a consistent dose of the product in the capsule or tablet. If the individual ingredients stick together, the mixture may not be homogenous and the active ingredients may not be consistent in each capsule.

Magnesium stearate ensures consistency and this ensures a quality product.

Most Companies Use Inactive Ingredients

It is almost impossible to find a company that does not use some kind of inactive ingredient, such as a flow agent or a filler. When the dose is a tiny amount, as it would be in any product dosed in micrograms, there has to be some kind of filler in the capsule. This is part of manufacturing a good quality, consistent product.

While I am all for the purest possible products, I do recognize the need for a flow agent or filler in capsules and tablets as a quality control matter for consistency in dosage.

Study Showing Immune Suppression from Mag Stearate

There was a study published in the journal, Immunology in 1990 that showed immune (T-cell) suppression in mice in vitro. This study seems to be the only study on this topic and it has been used again and again to illustrate the toxicity of mag stearate.

However, the study used stearic acid (not magnesium stearate) and was never repeated. So much for proof of toxicity. Additionally, mouse cells are known to lack the enzyme delta-9 desaturase which is necessary to convert stearic acid into oleic acid. Therefore, huge amounts of stearic acid would be toxic to mice.

Humans have the enzyme delta-9 desaturase and stearic acid is converted to oleic acid in the human liver so that there is no buildup of stearci acid and no toxicity.

Claims of Supporting Biofilms

There have been claims that mag stearate supports the formation of biofilms. However, this study published in the journal, Infection and Immunology in 2004 concluded that stearic acid was one of the fatty acids that inhibited biofilm formation.

Safety Studies

This study, published in Toxicology in 1980 evaluated the effects of magnesium stearate on rats and concluded that the no-effect-level is estimated to be 5% magnesium stearate in the diet — equivalent to an intake of 2.5 grams per kg bodyweight per day. This would be the equivalent of a daily intake of approximately 170 grams per day for a 150-pound individual. This would be about 6 ounces of  pure magnesium stearate — quite a bit more than a typical average daily intake.

In fact, a person taking 20 vitamins a day, consisting of 500 mg, and 1% mag stearate, would be consuming less than 96 mg of stearic acid per day. Supplements usually contain between .25% and 5% of mag stearate in each capsule.

To put that into perspective, four ounces of human breast milk has more than 5 gms of stearic acid and a two ounce bar of chocolate provides over 5 gms of stearic acid. There’s nothing toxic about chocolate — or breast milk, right?

The Caveat

Another claim against use of mag stearate is that it is derived from genetically modified crops and contaminated with pesticides. It is, in fact, sourced from either cottonseed or palm oil. The cottonseed oil is most likely genetically modified. I’m more concerned with the fact that it is from genetically modified crops than the pesticide residues.

The stearic acid from the oil is highly processed and purified so that pesticide residue is hardly an issue. However, the fact that it is from a genetically modified source is worrisome. I would want the mag stearate to be from organic sources if possible. If it is derived from palm oil, that would also be best.

I asked one of my supplement suppliers (that I use in my office) for the source of their mag stearate. They told me it was from palm oil which made me feel a whole lot better. You could call the supplement company and ask them what the source of mag stearate is, if you are very concerned about it being from cottonseed oil.

The Codex Committee on Food Additives

There has been some reporting of the Codex Committee removing mag stearate from the acceptable food list. In fact, they did remove it because it had no place as a food additive — but they reinstated it after manufacturers pointed out the use in supplements.

Magnesium stearate is primarily for use in supplements and is currently approved by the FDA for use in food and supplements. (Not that that makes it safe).

Nocebo Effect

There have been anecdotal reports of negative effects from magnesium stearate. Those in support of mag stearate call this the nocebo effect. This is essentially the opposite of the placebo effect whereby someone experiences a negative effect and attributes it to the ingredient in question.

We know that the placebo effect is real and certainly the nocebo effect is real as well. Both phenomena can be produced and exaggerated by factors such as, written opinion, verbal suggestion and past experience. These are a direct result of the psychosocial context or therapeutic environment on a person’s mind-body connection. There have been discussions on how to use these effects in therapeutic ways.

Dietrich Klinghardt MD PhD Supports the Use of Magnesium Stearate

In the latest newsletter from Allergy Research Group, Dr. Klinghardt retracts his previous statements against magnesium stearate (interview with Mercola in 2009).

Now that he practices in the USA and has access to high quality supplements he realized that the one study he based his opinion on (the one with mice and T-cells as explained above) does not apply to humans because we have the enzyme needed to convert stearic acid to oleic acid. Additionally, he realized that magnesium and stearic acid are both abundant in many foods that we eat.

Dr. Klinghardt treats really sick people who are sensitive to many things. If he finds that magnesium stearate is acceptable, then I think it is fine for most people and should not be a concern, especially if the supplement’s active ingredients are such that will help a person’s condition.

When taking supplements, as with anything one has to weigh the risk versus the potential benefits.

What do you think about this? Leave a comment and let me know!

Where to find supplements that have no flow agents.

This post is shared at: Party Wave Wednesday, Real Food Wednesday, Seasonal Celebration, Thank Your Body Thursday, Simple Lives Thursday

Photo Credit

Eat to nourish your mind, body, and spirit.

Inspire Your Real Food Healing Journey with my FREE Grain-Free Meals e-Cookbook and Getting Started email series!