Confusion About Magnesium Stearate

Please let Dr. Gardner know that I had been very happy with the vitamins.  Today; however, during my research, I came across some information on magnesium stearate. As I read about it and its potential damage to the digestive system, I was feeling grateful that I was taking high quality vitamins. However, after I finished on the computer, I went to look at my bottle of vitamins and found that (yikes!) there IS magnesium stearate in my vitamins.

For that reason, I’ve decided to discontinue my vitamin subscription.  Thank-you for your services and please let me know if any vitamins are produced without magnesium stearate.

Your confusion and concern about magnesium stearate is easy to understand, especially given the “controversy” that abounds on the internet.  First, let me set your mind at ease, and then I’ll explain the truth about magnesium stearate.

There is no research in humans that shows any negative effect of magnesium stearate in the human population.  It is unclear if the companies marketing “magnesium stearate-free” nutritional supplements are based on misunderstanding or willful misinterpretation of data, but they clearly are trying to gain a marketing advantage and not trying to disseminate the truth.  Anyone who has had any anxiety about the use of magnesium stearate in my Primivia supplement line can relax and be confident of its high quality.

Magnesium stearate is used in the production of foods, cosmetics, medications and nutriceuticals. Stearic acid is an 18-carbon chain saturated fatty acid, and the stearate form is a safe isomer of the fatty acid.  Although not mentioned, magnesium palmitate is also used for the same purpose, and is a higher concentration than stearate.  Palmitate is a 16-carbon chain saturated fatty acid.  Both the stearic and palmitic acids in magnesium stearate are derived from natural, edible sources.  The normal ingestion of stearic acid in food on a daily basis is about 7,000 mg.  If you were to take 20 tablets of nutritional supplements that weighed about 1,000 mg each, you would ingest 300 mg of stearic acid, less than 5% of a normal daily intake.

There have been some rat studies and in-vitro studies (in test tubes) with magnesium stearate that showed two potential problems.  One is that it affected the immune system.  However–and this is a big however– although rats are usually tested before humans because so much of their physiology is like humans, this is not so with the stearic acid.  Rats do not have the enzyme to break down stearic acid into the 18-carbon oleic acid with one double bond.  This means the stearic acid builds up to toxic levels in rats in these studies.

The other potential problem with intake of fat is that it could slow down the breakdown and absorption of nutrients, including supplements.  Two randomized studies done on the medications propranolol and metoprolol with three levels of magnesium stearate levels in the product showed no difference in bioavailability.


  • Suz
    May 19, 2010 - 10:40 am | Permalink

    Dr. Gardner is saying what any mainstream doc would say. As a nutritionist, I try to buy all (or at least most) of my vitamins without magnesium stearate. There are several brands that don’t have this in them:
    Garden of Life’s raw vitamins which you can get for a very reasonable price at

    You can also order from: (and recommended by Dr. Carolyn Dean — MD and ND) (also has a superior green powder)

    Hope these help.

    • Glad
      July 27, 2013 - 4:46 am | Permalink

      Suz, I don’t know why you would recommend I just went there and the very first vitamin I looked at had the following:

      Other Ingredients: Gelatin (capsule), rice flour, stearic acid, magnesium stearate and silicon dioxide.


      I went no further.

  • Cathy D.
    May 19, 2010 - 11:40 am | Permalink

    It is important to note that Dr. Gardner is Not a “mainstream” doc, having achieved the Certified Nutrition Specialist designation, which is the highest achievement in the scientific field of Nutrition. Further, the generic term “nutritionist” has no value in the field of Nutrition & Food Science, and according to the American College of Nutrition anything less than a Registered Dietitian is merely a Salesperson. I will continue to take Dr. Gardner’s supplements because having done thorough research & personal testing, I have found them to be both high quality and moderately priced, but most of all, I Feel Better.

  • May 24, 2010 - 6:17 am | Permalink

    Ouch! Calling me a mainstream doc hurts. I am always open to dialogue–show me the research that shows any harmful effects of magnesium stearate in humans so I can review it.

  • Susan Burt
    May 30, 2010 - 1:14 pm | Permalink

    I want to come to the seminar on June 25, Please give me more info and when and who do I pay

  • Phillip VB
    February 16, 2011 - 11:12 am | Permalink

    Perhaps you could direct me to a study showing magnesium stearate as harmful. I’m not looking for opinions. I want “facts” or at least studies. I’ve been looking off and on for weeks and have found nothing legitimate and not self serving.

  • Ron Johnson
    March 9, 2011 - 3:59 pm | Permalink

    Hey Doc, there may well be no scientific research on magnesium Stearate, but that doesn’t mean people aren’t having allergic reaction to it.
    First of all, it’s the stearate part that is the problem. So, whether its magnesium, calcium or zinc Stearate makes little to no difference to anyone who is allergic to it and what exactly we are allergic to is the cotton oil used to make the Stearate. Why? Because cotton has been genetically altered to accept chemical pesticides and herbicides, which then become a physical part of the plant. When the oil is extracted from it, it contains the residue of these chemicals. In small amounts to be sure, but, obviously, enough so that some of us react to it.
    Personally, I’m so sensitive to Stearates that just one pill will cause blisters to appear on my hands and feet within just a few hours. Yet it will take a few weeks to get over it.
    So you’re right, the medical researchers have not found the link, but the rest of us have. My doctor (allergist) and I have proven time and again, that I am allergic to Stearate. Period.
    So now what???

  • Fan B
    July 8, 2011 - 10:14 am | Permalink


    I was told that Magnesium sterate is or has hydrogenated plant material. I don’t want to consume anything that is hydrogenated, as it is well documented that hydrogenated oils and fats are extremely bad for humans. Can you clarify? Thanks!

  • Ron J
    January 11, 2014 - 3:42 pm | Permalink

    Dr. Stan Gardner I understand you not endorsing the claims made concerning magnesium stearate without medical research data supporting it, but I do not understand you summarily dismissing peoples claims either. Just because there is no scientific data to support these claims does not, in any way, mean they’re not true. It only means you are being unscientific in your refusal to acknowledge the possibility, has if you can be so certain of your claim that a negative, a la, a lack of data, is somehow evidence to the contrary.

    Let’s take me for example. I’m 66 years old, never had an allergic reaction to anything my entire life. Then one day I noticed a couple of blisters on the palm of my hands. Soon after I noticed the same kind of blisters on the soles of my feet. After a few days of them both getting worse by the day I made an appointment to see my primary physician, who, in turn, referred me a dermatologist. Upon seeing them and experiencing the indignity of them barely acknowledging my presents let alone any information I had to offer concerning my condition they merely looked at me and decided to give me a bunch of stuff to cover it telling to try thins and see how that works and get back to us if it doesn’t. Well it didn’t and I continued to get worsen on a daily basis. This went on for two more sessions before I realized they had no clue what it was, let alone the cause or how to stop it. Now what? Is what I was thinking.

    So, I returned to my doctor and asked if I could see an allergist, which he agreed to and made the appointment for me then and there and I met with an alergist that very day. Of course the first thing he wanted was a complete history, both long term family stuff and too, what had I been doing recently. Well the only thing I had been doing differently recently was taking a couple medications, one for pain, I have a nerve damage from a broken back that happened years ago but was getting worse after 40 some years and my blood pressure was on high side of normal and I was having some acid indigestion problems once in awhile too.

    With that we did two things. First he suggested I start testing for common allergens and second to make a list of all the meds and to obtain the medical data sheets for them.

    Over the course of the next two visits it was becoming clear I was not allergic to any of the common things people are usually allergic to. That then led us to investigating the meds of which I had gathered all the data about. A quick look at the data sheets showed that all three of them had one thing in common and that was, you guessed it, magnesium stearate. With that it was easy to decide to eliminate them by replacing them with meds that did not have magnesium stearate in them and, well, son-of-a- gun, you’ll never guess what happened next. Literally, the next day, I stopped producing any new blisters, which by then I looked like the worst leper case you’ve ever seen. The good news was it cleared up almost completely within just 4 or 5 days.

    At that point we just stopped and life was good again. That is until, Halloween came around and I eat a couple of the candy bars my wife got for the kids. The next day my hands broke out again. Suspecting I had come in contact with magnesium stearate again I immediately looked back at anything new or different I might have done and sure enough it was eating that candy, which I rarely eat, and guess what, yep, it had magnesium stearate in it too. hmmm…

    Since then about five years have passed and on four more occasions I have experienced the same kind of thing as I did with the candy bar. Only one time was a new vitamin I had switched to and sure enough it had it too and as soon as I stopped taking I immediately cleared up. Go figure.

    All the while, mind you, both my primary doctor and the allergist were aware of each episode, although nothing was done medically, other than a kindly reminder not to do that again. heehee… gee aren’t they brilliant.

    At this point I decided to look into it further so, on the do the internet I went and after about a week of reading everything I could find, which include the process by which it is made, what ingredients they can use, etc. I really didn’t find anything that made sense, at least to me that would explain why I was experiencing this problem with the magnesium stearate. That is until one day I was explain all of this to my daughter, who just so happens to have a master’s degree in microbiology and it’s in agriculture, specifically dealing in food production. Well at least that was her thesis for graduation purposes, but, as it turned out it has also been her career ever since. Anyway, in my explanation to her I had mentioned that one of the ingredients normally used in foods, pharmaceuticals and nutriceuticals to make the stearate process is “cotton seed oil.” To which she nearly exploded saying, OMG Dad!, that’s the most genetically alerted product in farming. It, in fact, has been altered to absorb both herbicides and pesticides in a way that they become a part of the plant, not just something that is lying on top of it as most of us would assume. Right?

    In short then, what I’m suggesting is and with her blessing, as far as that goes with you, that it is the minute amounts of these chemicals that is ever present within the oils derived from the cotton that is the underlying cause of so many of the claims that we’re hearing coming from every corner of the country with such a variety of alignments that no one can seem to tie it all together. So, you all think it’s just a bunch of BS.

    Well, the next logical step, it seemed to me, was to try and find products that while they had magnesium stearates in them they were produced using something other than cotton seed oil and guess what doc, yeo, I had no allergic reaction.

    Now, I hope that 1) you’ll at least give this issue some kind of due concern by admitting there is at least some possibility that all of these people are right about magnesium stearate even if you don’t know why, but surely, something is causing these people whatever their problems are, and 2) that you will do some of your own research given the information I’ve shared with you’re here and by your actions, being the concerned physician your surely are, as an advocate for those who suffer from whatever ailment, and suggest to those within the medical industry a good place to start doing some real research.

    Actually, the antidotal evidence is so overwhelming I’m perplexed to understand why it hasn’t already been done. Except, it does occur to me that it would not be cost effective for the industry to do so. For you see, the ONLY reason they use it is because it allows them to run their pill making machines about ten times faster than they’ll run without it. Oh, and the cost is pretty cheap too. DUH!

    Or, are you a part of the agenda to protect the cotton industry and those who use their products???

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