Harmful or Harmless: Magnesium Stearate | Chris Kresser
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Harmful or Harmless: Magnesium Stearate

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Is finding magnesium stearate on your food label a cause for concern? monkeybusinessimages/iStock/Thinkstock

One of the benefits of ancestral eating is that you avoid potentially harmful food additives like artificial colors, MSG, and artificial sweeteners. But even on a Paleo diet, it can be hard to avoid some fillers, thickeners, and additives. In fact, many common Paleo foods contain more additives than their Neolithic counterparts! For instance, commercial nut milks and coconut milk often contain thickeners like gums or carrageenan, while your run-of-the-mill grocery store whole cow’s milk is additive-free.

Over the next few weeks, I’ll review the science on some of the most common additives, and let you know whether you should be concerned about consuming them. First up – magnesium stearate!

Is magnesium stearate a harmless additive or dangerous chemical? Tweet This

What Is Magnesium Stearate?

Magnesium stearate is a salt that is produced when a magnesium ion bonds with two stearate molecules. Stearate is just the anion form of stearic acid, which you’ve most likely heard of before. Stearic acid is a long-chain saturated fat that is abundant in beef, cocoa butter, coconut oil, and other natural foods. As I mentioned in my red meat article, it’s also the only long-chain saturated fat that scientists and medical practitioners agree doesn’t raise cholesterol levels, and doesn’t increase risk of heart disease.

Magnesium stearate is most commonly used in supplement manufacturing as a ‘flow agent,’ which helps ensure that the equipment runs smoothly and the ingredients stay blended together in the correct proportions.

Given the seemingly benign components of this additive, it’s a little surprising how controversial it is. There are a lot of misconceptions and inaccurate statements about it floating around the internet, and while I wouldn’t recommend consuming vats of the stuff (not that you’d want to), I think the concern over magnesium stearate is largely overblown.

Effect on Immune Cells

One study that many people have used as evidence against magnesium stearate is a 1990 experiment entitled “Molecular basis for the immunosuppressive action of stearic acid on T cells.” This baffles me, and I suspect that anyone using this study to indict magnesium stearate hasn’t actually read it.

In the experiment, scientists isolated T-cells and B-cells from mice, put them in a Petri dish, and bathed them in a solution containing stearic acid (along with some other components). They observed that the T-cells incorporated the stearic acid into their cell membrane, eventually de-stabilizing the membrane enough that the cell died.

First of all, this study has nothing to do with magnesium stearate. They just used the plain old stearic acid that you’d find in your beef, chocolate, or coconut oil, so this study could just as easily be used against those foods. If you’re going to be concerned about this study (which you shouldn’t be), you’d have much bigger sources of stearic acid to worry about than the magnesium stearate in your supplements.

Second, the study has nothing to do with stearic acid consumed in the diet. Under normal conditions, your T-cells are not bathed in stearic acid, even if you consume superhuman amounts of coconut oil, tallow, and cocoa butter.

Finally, the researchers used T-cells from mice, and in this case, the results cannot be applied to humans. The mouse cells incorporated stearic acid into their membranes because they lacked the ability to de-saturate fatty acids. However, human T-cells do have the ability to de-saturate fatty acids, so even if you did bathe your T-cells in stearic acid, they would be able to maintain their membrane function. (1)

In case you got lost, here’s a summary: this study has no relevance whatsoever to human consumption of magnesium stearate, I have no idea why the study is being referenced in this manner, and you shouldn’t be concerned about it.

Concerns about Pesticides and GMOs

Another criticism is that because stearate is often derived from cottonseed oil, it can be contaminated with pesticides. Keep in mind that magnesium stearate is a highly purified substance, and goes through an intensive refining process before appearing in your supplements. So far, I haven’t come across any reports indicating that magnesium stearate retains substantial amounts of pesticide residue.

As for the concern that cottonseed oil is often genetically modified, the source of crude fat shouldn’t make a difference in the final form of the stearate. Stearic acid is an 18-carbon molecule with a specific chemical structure that will be the same whether the stearic acid is from a genetically modified cotton plant, a bar of Hershey’s chocolate, or a grass-fed ribeye steak.

Effect on Nutrient and Drug Absorption

Another criticism is that magnesium stearate might inhibit nutrient absorption. One in vitro study conducted in 2007 found that tablets containing magnesium stearate dissolved more slowly than tablets without magnesium stearate when placed in artificial gastric juice. (2) The study authors concluded that in vivo studies are needed to determine whether this finding has any practical significance. However, an earlier study found that although magnesium stearate increased the time it took for a drug to dissolve, it had no effect on overall bioavailability, as evidenced by blood levels of the drug in test subjects. (3) Further, another study found that levels of magnesium stearate didn’t affect tablet dissolution at all. (4)

All of this indicates that although magnesium stearate might affect the rate of tablet dissolution in some circumstances, it doesn’t affect the overall bioavailability of the drug or supplement.

Biofilms

I’ve seen this claim pop up in a few places around the internet, so I’ll address it briefly. Some critics of magnesium stearate claim that it can induce formation of harmful biofilms in the intestine. This assertion appears to be based on the fact that soap scum contains magnesium and calcium stearate, so they insist that just as soap scum creates films on your sink or shower, magnesium stearate creates films on your intestines.

It should be pretty obvious that the intestinal lumen is a vastly different environment from a shower door, but some people still seem to be concerned. Rest assured, there is no conceivable reason why this would take place, and I haven’t seen a single scientific article that even hints at this possibility.

Allergies

A 2012 study entitled “Magnesium stearate: an underestimated allergen” reported on a 28-year-old woman who had an allergic reaction to magnesium stearate, resulting in hives. I’m very curious about this, because an allergy to either magnesium or stearate seems highly unlikely, but unfortunately I don’t have full-text access to that study. But needless to say, if you develop hives (or another allergic response) after consuming magnesium stearate, you should probably avoid it in the future.

As a final note, a rat study determined that you’d have to take 2500mg of magnesium stearate per kilogram of bodyweight per day to start seeing toxic effects. (5) That means a 150lb person would have to consume 170,000 mg per day, which is so far beyond any amount you would encounter in supplements that it’s a non-issue.

Overall, I haven’t found scientific evidence to substantiate the claims against magnesium stearate, and the small amounts found in supplements shouldn’t be a problem for the majority of the population.

Now I want to hear from you. Were you concerned about magnesium stearate? Are you still concerned? Did I miss anything? Let me know in the comments!

768 Comments

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  1. I just want you to know that magnesium stearate is my bete noir. After two years being plagued by upset stomach and the mother of all headaches (lasts 5 days) each time I consumed it, I finally worked out what it was that I was intolerant to. Since it is in virtually all drugs and supplements, as well as processed foods its very hard to eliminate. I have arthritis and need to take anti inflamatories but they all contain MS. I dont think its harmless, but why it affects me so much I dont know. It just does

  2. I came across this post when i discovered that magnesium stearate was responsible for the pain i was experiencing. For one month i had been taking marine collagen capsules as a supplement. For one month i had also begun experiencing pain in my pancreas which also led to drop in energy (i didn’t make any connection though it seems obvious now.) However, as luck would have it I forgot to take my marine collagen capsules for a week. In that week the pain had subsided though i still did not make the connection until i took the marine collagen again that morning. By mid afternoon, i felt whacked. And the annoying pain in my pancreas returned. Then i clicked. However, I couldn’t believe that marine collagen would cause this – seems healthy/harmless enough? UNTIL i read the fine print at the bottom of the container ‘also contains MAGNESIUM STEARATE’. I was absolutely horrified. I think it is helpful having peoples experiences on this post. I can understand the experiences other people have posted. Thank goodness for me I found out after a month and it didn’t progress to my joints etc (where the body often stores ‘stuff’ it cannot deal with). AVOID.

  3. PLEASE AVOID MAGNESIUM STEARATE! Because of joint pain, bone pain, and arthritic symptoms 20 years ago, I did my own study to find the cause (at times I could barely move.) For 1 year, I listed every supplement, medications, etc. that I took and the list of ingredients contained in them. I found that the common ingredient was Magnesium Stearate. After eliminating anything with magnesium stearate, my condition improved greatly. No more feelings of the “tin man” when I moved my joints, no pain on the top and bottom of feet when walking, no more pain in any of my bones–knuckles, wrists, neck, etc. Sometimes it was necessary to take a medication which contained mag. stearate, and within 1 or 2 days, the same symptoms started and got worse the longer I took that med. All my doctors are aware of this, and have found this reaction in other patients. You have to be very vigilant and read every ingredient to avoid mag. stearate–even tylenol, aspirin, ibuprofen, vitamins ,etc. Thus far, I have found Andrew Lessman products (ProCaps Laboratories of HSN–no inactive ingredients of any kind) and Thorne Labs to be free of Mag. Stearate. If a med contains this, I take the oral liquid equivalent if available.

    • Sigh, while it’s good and helpful when folks share their experiences in these situations, it’s absolutely wrong to label something as harmful and to be avoided based on your personal data. Simply provide your experience, then others may judge for themselves. No substance known to man is without reaction to some people, just because you and some others have a reaction does not mean anything to the general public except that they can look to your example if they have a similar experience.

    • every time I take something with magnesium stearate, I have a panic attack and shortness of breath, haven’t had any attacks since I have stayed away from that poison… What I can’t understand is why is this not reported to the medical establishment and it should be taken out of prescribed drugs and even in candies, vitamins, anything that carry this, pretty sure that there are safer ingredients out there…are we actually being made sick on purpose so that we need to take more drugs because of the symptoms it created, this is so corrupted. Who can we trust to protect our health?

    • Dr. Joseph Mercola warns about the sinister side effects of magnesium stearate, and refuses to use it in any of his supplements. You might want to check out some Mercola supplements.

    • I totally have the same reaction when taking Tablets that contain MS but also get very bad diarrhoea. Thanks Sue for your post.

    • Hey, sounds exactly like happened to me! How you talked about the pain in your feet and the Tin Man feeling.

  4. I have been taking various supplements more than a few years. Put in many years of study and do my own trials for myself. Eliminated my fibro pain, chronic pain, chronic fatigue, diabetes, high blood pressure, hair loss, sleep issues, arthritis pain, the list goes on and on.

    Prior to trying anything, I research it to the extreme. So everything I take has worked miracles for me. I am at a hundred percent better in every aspect. Magnesium stearate, I learned some time back it is a filler of sorts. Okay no harm no foul. KEEP IN MIND, I completely change my life in all aspects, foods everything. Nothing toxic, even stopped smoking cigarettes after over 30 yrs of smoking.

    My a.n.a has tested positive for lupus since 2012. Number started low, gray area. My focus was on me getting better riding all the other issues beside the lupus possibility or at best being able to get out of bed C.F.S. had me sleeping 20 hrs daily.

    every 6 months blood work gets done, as of may 2016 the number went up a little bit. So I decided to focus on getting rid of it completely. I went hard on vitamin D, Selenium, probiotics, vitamin C, all the ones needed to make my immune system healthy again. Everything I took has magnesium stearate in it. Saturday November 12, 2016 watched a video by Dr. Johnson, stating stop taking anything with this. If you have an immune issue magnesium stearate will make you worse. I swear every time I watch this video I learn some thing else.

    I thought this addictive was not harmful but the reason for my interest in researching magnesium stearate once again. It is the common factor in everything I take. In October 2016, I had blood work again, my results for A.N.A. positive again but this time the numbers sky rocketed. I feel great, I look healthy. Recently lost 2 pants sizes in inflammation alone.

  5. I have seen magnesium sterate on avoid lists for those with sensitivity to nightshades. I have no idea why that is but for many years any supplements I have taken with magnesium sterate have caused me joint pain. I’ve tried a lot of them. Did not realize the connection, the common factor was they all had magnesium sterate. I have some rather strange supplement reactions– After 20+ years of taking cal/mag formulas they began causing me foot and leg cramps. Especially from Calcium and the only Magnesium I can take now is a L-threonate (with only Glycerin, vegetable cellulose, purified water as ‘other ingredients’ ). Vitamin C supplements in many forms, buffered, food sourced etc. cause me slight bowel bleeding and after taking mcg to 3 mg doses of Melatonin for 20+ years it began causing me eye pain within 15 min of taking. I have trouble sleeping and miss being able to take Melatonin. No doctors, MD’s ND’s DO’s, nutritionists, genetic metabolic counselors or homeopathic docs have been able to answer these strange reactions. I have Non-celiac gluten sensitivity (causes mild digestive symptoms) and nightshade and caffeine sensitive (joint pain).

  6. YES,, You did not point out WHAT & HOW magnesium stearate effects the digestive track. I learned years ago as a kid later in my life I knew WHAT was making my digestive track work in a 1st gear stage or NUTERAL when it did not work. MAG Stearate cause it to work like it did for 27 years from being on DILANTIN, as many to all AED’s & other drugs has it in them, and we wonder why people are FAT ? Also. MAG Stearate causes more of the MSG’s & other gluatmic acids that causes seizures to stay in the body longer that the effects to the brain is not good. That explained WHY I had the seizures as I did in the 1960’s 70’s & early 80’s to when my brain was still developing, as today all these things can and DOES cause GRAND MAL SEIZURES to happen to me, and I will never take generic or any drugs with MAG Stearate or Aspartame in them aka DEXTROSE or any OSE drug with those 3 last letters in that name which can be forms of ASPARTAME. All gums & some other sources of fillers are pure MSG’s or some will say & call them ”agents in the drug” to activate MSG which again makes that drug unsafe to take, or foods & supplements to eat or drink. By eliminating all toxic forms of stearates, MSG’s & Aspartames, most seizures will stop on their own & the brain will prove it & work like it should. You then start thinking & believing,,there is a God & the people of the drugs, supplement, food & medical world are NOT wanting anyone to live a healthy life or a life in general.

  7. You are a L.Ac, what would you know, my mom’s best friend is mycrobiologist, she also has other credentials and she says the same thing dr. mercola says. Your opinion is invalid, quite honestly. And by the way i buy the highest quality supplements and none of them (NONE) have magnesium stearate included, i wonder why… LOL.

  8. I was looking at the possibility of a magnesium additive to my diet (because of a problem I am having). You blog is really interesting and also very informative. My reaction is very positive.

    Thank you.

    • i also add to my diet but to help my body absorb the ibuprofen. i had only barely noticed the effect myself and i looked online but good info is hard to find. it turns out magnesium stearate can affect absorbtion of certain medications, usually helping the medication become more water soluble. if you take ibuprofen, magnesium stearate will make the ibuprofen more water soluble and can be absorbed more easily but they also will not protect your stomach lining from the negative side effects. some few other medications also have this effect, sorry i don’t have a list, but i do take a half an antacid with my ibuprofen and it does wonders..

  9. hi, chris—i just read you article regarding the safety of magnesium stearate—it did set my mind at ease since it confirmed other research i have read—so thanks for that—the material was presented well—now, off that subject, but a concern for which no one seems to have the answer—zeolite—i was using it to detox heavy metals as instructed by D.O.and recently heard that it works to detox, but it lays down aluminum—irony—as one of the metals i am in need of detoxing is aluminum—do you have any concrete study or other evidence to confirm/deny this?

    • Hi Cath, we have been testing people on the Oligoscan(Spectrophotometer) that take zeolite and found that they usually test for excess aluminum. many of the Zeolite products contain aluminum. If you find a practitioner around that has a Oligoscan they can test instantly for 14 heavy metals, this device test the non-dominate palm with a light. hair testing can be compromised. As far as purging aluminum, the skin is the first approach as the aluminum salt ions are absorbed in the sodium/Potassium channels of the skin. If you have excess aluminum your probably low in potassium, losing calcium from aluminum binding to the calcium(remember how the dye(alum) in easter eggs are trapped) and low in magnesium.
      You can only understand this from interpreting a Oligoscan test. Mike from Herbalix Restoratives

  10. That last paragraph about how much magnesium sterate you would have to consume to be toxix sounds earily similar to that of Splenda and that you would have to drink 10 +/- cans of soda per day containing Spenda to feel negative effects ,well guess what? Everyones body is different in processing toxins, and some just more sluggish as they age. The effects that you will have compounded with the many various other toxins that we inhale, ingest, and live in and near also add to the increased negative effects of toxins like magnesium sterate and the many other additives that are added to our food and drink that we consume all throughout the day, everyday. I try not to consume any of these harmful additives that merely raise the bottom line for the manufacturer. Eat Whole Foods, and supplements with little to no additives.

  11. notice chris never responds to things that get a rise out of the readers. disturbing that he wrote this, makes me readdress my following of him

  12. I’ve just found about about the Mag stearate controversy and stopped a whole bunch of supplements as they all had it in. After a couple of weeks without them I am feeling generally better and people are telling me I’m looking more healthy. This additive in my book is something to avoid. I was fully prepared to start taking them again if I noticed no change but I’m afraid I have to consign a whole heap of expensive supplements to the bin.

    • there is no price for your health… I cannot take anything with magnesium stearate as it makes me feel so sick, lightheaded, nauseated, shortness of breath, and could be the cause of some panic attacks as well… since I don’t take anything with this, I also, feel so much better, no more symptoms….I think that the big cooperations are making the people sick so they can sell more pills and make more money… how can you put your trust in mankind anymore.. it is all about greed…Also stay away from gmo products and buy organic because anything sprayed with round up or any product that has glysophate causes cancer, panic attacks, alziemer and other diseases. I now take one a day gummies as it has no magnesium stearate and my energy seems to have come back with the sun vitamin and the nice fresh air from the beach….

  13. I too have contracted alpha gal mamallian meat allergy and am not able to tolerate food or supplements/medications containing meat sourced magnesium stearate. This is a very difficult issue as so many prescription meds and other medical products contain it. I can cook all my food and even make my own almond milk to avoid these meat byproducts but meds and supplements are another story. Even an ingredient list is insufficient many times and manufacturers have to be called to verify contents. This tick bourne allergy is on the rise and more and more people are having to deal with these byproducts in everything.

  14. Hello Chris. i have a question for you.: Supplements containing magnesium stearate are included if you have no stomacch acid? As a result of esophageal cancer i swallow antacids. Greetings Ed.

  15. My gf can’t use Magnesium citrate or stearate. Both causes somekind of eczema reaction. Magnesium chelate is ok.

  16. You stated you were curious about this so thought I’d comment. I’m allergic to magnesium, not sure specifically which types but if I recall correctly I’ve had reactions to magnesium stearate included. I’ve been allergic to it I think 4 years now, and I’ve had a range of mild to severe reactions with it, dependant on the type and amount consumed. I used to get headaches just from drinking bottled water, but that’s not too bad now as it’s something I have regularly. I’m prone to getting ill easily and I can’t remember the last time I had a full night’s sleep without waking up at least once because of my magnesium deficiency, which unfortunately I can’t do much to help because of the horrible reactions I get that interfere with how I function day to day. When my allergy first came to be, the main reactions I got included a very red, leathery, rashy face from using a face wash, and the second time my face quite literally tripled in size and was swollen. It was horrible. I’m currently taking tablets at the moment for another problem, and they contain magnesium (stearate, I’m fairly sure) and the past few days have been hell. I’ve been feeling nauseous, had horrible stomach pains, and my body aches so much. I sometimes have a bit of difficulty breathing as it feels like I’ve been punched in the chest and I’m winded, and I can’t get comfortable because when I put pressure on my bones (particularly my back and ribcage) from being in a certain position, they feel covered in bruises and ache so much I’ve already been woken up several times in the night with the discomfort and nausea. It’s horrible, but I have the choice between this temporary hell or to suffer with the other problem that will prevent me from doing things and will only get worse in time, so it’s really the lesser of two evils. A while back, I wanted to test my allergy (stupid I know, but I hadn’t had a reaction in a while so wanted to see how it went ) and ate some Parma violets, which I used to love. I barely ate 5 before I felt sick and couldn’t stand to have anymore, they tasted horrible to me and that’s probably because I know I shouldn’t be having them. Anyway, after having just a few of them I ended up with horrific stabbing pains in my stomach that lasted about a week. They may have been the worst pains I’ve ever experienced, honestly thought I could’ve died, felt like my stomach was being ripped up from the inside. Another time I took a (prescribed) pill to help with menstrual pain (again, magnesium deficiency makes them sometimes unbearable) and vomited shortly after because of the magnesium content. I’ve wondered before whether what I have is just a magnesium deficiency rather than allergy (tried to get a blood test done after the first reaction but local doctors said they only do that if the throat is completely swollen up and since I was still managing to breathe they refused me, so we found out by noticing the common factors in things), but even in small doses (e.g. magnesium oxide in the air after a science experiment) I have reactions to it like in that example, a pounding headache that interrupted my concentration and lasted literally all day, so at this point I’m fairly sure it is indeed an allergy otherwise I don’t understand why my body would react in such a way. Sorry for such a long post, just trying to include any notable experiences you may be interested in knowing. If you have any questions I’d be happy to answer to the best of my ability but I don’t really know much of the scientific/medical aspects of this as, like I said, doctors turned me down for testing. Thanks for reading

    • Mag stearate is not a magnesium source. It is a flow agent used in supplements to keep from clumping. Red Blood Cell Magnesium is a common blood test at most labs. RBC Magesium. Find a doctor who knows about and will order this for you. I suspect it is the excipients in the source of magnesium that you have reactions to. Magnesium is a very highly needed mineral and we cannot do without it. Good supplements are not a problem for most. Fibromyalgia is helped with magnesium malate. Magnesium Threonate helps with sleep, etc. Seekinghealth.com is a good source. An on line source is ReMag™ The Magnesium Miracle™ $29.99 and for minerals ReMyte™ Mineral Solution $39.99 visit Carolyn Dean MD ND and sign up for the newsletter. I have used these for years, I get no financial benefit from this recommendation to you.
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    • It sounds to me that your immune system is in need of some serious repair and restoration by YOU TAKING ACTION. If you are truly serious about getting yourself healthy and whole and are willing to do what it takes, I suggest you buy the book “The Wahls Protocol” by Terry Wahls MD. Also look in to “EDTA Chelation Therajpy.” Research Dr Garry Gordon who is considered one of the World Authorities in Toxicology and a big proponent of EDTA Chelation Therapy. gordonresearch.com

  17. Magnesium Srearate Is generally considered safe for human consumption at levels below 2500 mg/kg per day.
    In 1979, the FDA’s Subcommittee on GRAS (generally recognized as safe) Substances (SCOGS) reported, “There is no evidence in the available information on … magnesium stearate … that demonstrates, or suggests reasonable grounds to suspect, a hazard to the public when they are used at levels that are now current and in the manner now practiced, or which might reasonably be expected in the future.”

  18. Chris, I have Alpha Gal Allergy, and my allergy numbers are so high that any form of animal derived magnesium stearate can, and did nearly kill me (Heart attack at age 48, January 8 of this year culprit: Alpha Gal and ALLERGY tablets containing lactose and magnesium stearate), thank you very much. So I guess in certain circumstances say…..deadly allergies to meat, yes, it’s a pretty big deal. This “new” illness is not playing around, and it is spreading at an alarming rate. One bite of a tick, and I’m forced to be a pesco pollo vegetarian, can’t eat anything derived thereof, either, including any milk products, overnight, likely for the rest of my life, no treatment, no cure, with few if any, over-the counter medications I can now take to help me at all. I hope I never become diabetic, need stitches, or have surgery requiring blood thinners, or I can kiss my happy butt goodbye, too. Take care on your next nature walk, folks. 🙂

  19. Mag Steaeate caused me to have HPB, nausia and a feeling of anziety that was not based on a response to stress but an internal feeling that I suspected was a chemical reaction. Once I got rid of any supplements that contained mag stearate…guess what…yes…my symptoms magically disappeared…so I don’t care what your “facts” are…that’s what my experience is.

  20. Milk: one should examine the XO factor in homogenized milk not to mention all the other complications with mainstream “MILK’
    seeing your publication tells me that you are either on their side (those who are trying to get people to harm their body) or you are just uneducated or both.
    anyway your article is pathetic.

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