Magnesium stearate safety, side effects, toxicity, problems and review of studies by Ray Sahelian, M.D.
Is magnesium stearate present in supplement capsules safe?
Are people overly concerned about this ingredient?

Some websites have misleading information regarding the safety of magnesium stearate. Some of these sites claim magnesium stearate, even in amounts a fraction of a gram as found in dietary supplement capsules, is dangerous. There is no evidence this is true, particularly the tiny amounts found in supplements. I am not aware of any studies that show magnesium stearate, in the small amounts found in capsules, has any side effects or causes any harm. There is no evidence that small amounts of stearic acid are harmful. If anyone knows of a study that indicates magnesium stearate, in the small amounts found in capsules, has shown to have harmful effects, email me. I have searched extensively and not seen any such clinical trials. I believe there is misinformation on web sites that claim this substance is harmful even in less than 1 gram amounts. Much of this mis-information is posted by companies who are trying to differentiate themselves from other vitamin companies by providing products that are free of mag stearate. If anyone tells you magnesium stearate in the small amounts found in capsules is harmful, challenge them to provide you with a human study that proves their point. For some people this whole issue has become almost a psychological obsession going way beyond any logical reasoning. Read below my answers to some concerned emailed that explains why I feel this way.
   Most dietary supplement capsules have about 500 mg of herbs or nutrients and perhaps 20 mg or less of magnesium stearate. Since magnesium mineral is part of the overall weight of the magnesium stearate, the amount of stearate alone would is even less. One gram equals 1000 mg.
   I have been taking dietary supplements for more than thirty years and I know older people who have been taking a handful of vitamin capsules with magnesium stearate for more than 40 years and they are in their 70s and 80s and in full health. If MS was so toxic, how come none of these vitamin users have become ill?

Subscribe to a FREE Supplement Research Update newsletter. Twice a month you will receive an email with a review of several new studies on various supplements and natural medicine topics and their practical interpretation by Ray-Sahelian, M.D. We will mention research updates on magnesium stearate safety when published.

What is it?
Magnesium stearate is a white substance that has two equivalents of stearate and one magnesium cation. It is safe for human consumption. Magnesium stearate is often used as a filling agent in the manufacture of supplement capsules. This substance has lubricating properties and prevents ingredients from sticking to manufacturing equipment during the compression of chemical powders into capsules or tablets.
   Chocolate contains cocoa butter, which is high in saturated fat. About a third of the fat in chocolate is in the form of stearic acid.

Stearic acid in food
Stearic acid is the most common of the long-chained fatty acids. Stearic acid is found in many foods including vegetable and animal oils, beef fat, and cocoa butter. A person who eats a chocolate bar will ingest hundreds of times more stearic acid than someone taking a dietary supplement with magensium stearate. Yet, some people are unnecessarily concerned about the minute amounts of magnesium stearate found in capsules yet have little concern eating cocoa products.

Safety of magnesium stearate and stearic acid
There is misleading information on some websites that claim magnesium stearate is dangerous. There is no evidence this is true, particularly in the less than tiny amounts found in supplements. I am not aware of any studies that show magnesium stearate, in the small amounts found in capsules, has any side effects or causes any harm. There is no evidence that small amounts of stearic acid are harmful. The studies below prove that stearic acid, even in moderate amounts, has not been shown to be harmful. If that is the case, then the tiny amounts of magnesium stearate cannot possibly be harmful.

A stearic acid-rich diet improves thrombogenic and atherogenic risk factor profiles in healthy males.
Eur J Clin Nutr. 2001 February. Department of Food Science, RMIT University, Victoria, Melbourne, Australia.
To determine whether healthy males who consumed increased amounts of dietary stearic acid compared with increased dietary palmitic acid exhibited any changes in their platelet aggregability, platelet fatty acid profiles, platelet morphology, or haemostatic factors. Results from this study indicate that stearic acid (19g/day) in the diet has beneficial effects on thrombogenic and atherogenic risk factors in males. The food industry might wish to consider the enrichment of foods with stearic acid in place of palmitic acid and trans fatty acids.

Influence of stearic acid on hemostatic risk factors in humans.
Lipids. 2005 December. Tholstrup T. The Research Department of Human Nutrition, Centre of Advanced Food Research, The Royal Veterinary and Agricultural University, Frederiksberg, Denmark.
Stearic acid has been claimed to be prothrombotic. Elevated plasma factor VII coagulant activity (FVIIc) may raise the risk of coronary thrombosis in the event of plaque rupture. Fibrinogen, an acute-phase protein, is necessary for normal blood clotting; however, elevated levels of fibrinogen increase the risk of coronary heart disease (CHD). Here I report the results of three controlled, human dietary intervention studies, which used a randomized crossover design to investigate the hemostatic effects of stearic acid-rich test diets in healthy young men. A diet high in stearic acid (shea butter) resulted in a 13% lower fasting plasma FVIIc than a high palmitic acid diet, and was 18% lower than a diet high in myristic and lauric acids after 3 wk of intervention. The present investigations did not find dietary stearic acid to be more thrombogenic, in either fasting effects compared with other long-chain fatty acids, or in acute effects compared with dietary unsaturated FA, including trans monounsaturated FA.

Magnesium stearate danger, or lack thereof
I am not aware of any documented cases of magnesium stearate danger caused by consuming magnesium stearate in the small amounts found in capsules and tablets.

Q. Thank you for your Passion Rx. It actually works!!! The report below on magnesium stearate concerns me and conflicts with your own experience. Here is a quote from a website, "The Truth About Vitamin Supplements: Check your vitamin labels. Do they contain Magnesium Stearate or Stearic Acid? Studies by the University of Texas Health Science Center and the East Carolina University School of Medicine reveal that these toxic excipients cause a rapid collapse of T-cell membrane function and cell death; therefore suppressing the immune system. (Immunology, 1990, July). It is estimated that 90% of the vitamin and mineral products consumed today contain stearates. Stearates are used as binders in tablets and in the processing of gelatin capsules. Consumers often take handfuls of capsules and tablets to get vitamins, minerals and other key nutrients from supplements that contain stearates, and instead, in reality, get a powerful immune suppressive treatment. For more information on this topic and copies of the above-quoted studies as well as other studies and warnings concerning stearates, send an email to Quantum Nutrition Labs' nutritional supplements. Our products are 100% free of toxic excipients, including magnesium stearate or stearic acid.
   A. Much of the misinformation about the safety or toxicity is posted by companies who are trying to differentiate themselves from other vitamin companies by providing products that are free of this ingredient. If anyone tells you magnesium stearate in the small amounts found in capsules is harmful, challenge them to provide you with a human study that proves their point. The study referred to by this company was actually done in a cell culture.
   Below is the study that is referred to and my comments.

Molecular basis for the immunosuppressive action of stearic acid on T cells.
Immunology. 1990 Jul; Tebbey PW, Buttke TM. Department of Microbiology and Immunology, East Carolina University School of Medicine, Greenville 27858-4354.
Studies were performed to determine the mechanism by which stearic acid (18:0) selectively inhibits T-dependent immune responses in vitro. Incubation of mitogen-activated B and T cells with stearic acid resulted in dissimilar patterns of incorporation of the saturated fatty acid into their membranes. High-performance liquid chromatography (HPLC) analyses of T cells showed an accumulation of disaturated 18:0-containing phosphatidylcholine (PC) that replaced normal cellular PC. Less significant quantities of the same PC species were seen to accumulate in B-cell membranes; rather, they increased their proportion of oleic acid (18:1)-containing PC. The different lipid compositions of the lymphocyte cell membranes after exposure to 18:0 were correlated with their plasma membrane potentials. In T cells, the accumulation of disaturated, 18:0-containing PC coincided with a rapid (within 8 hr) collapse of membrane integrity, as determined by flow cytometry. The collapse of membrane integrity was found to be time and dose dependent. No such depolarization was observed in B cells which, by virtue of their desaturating ability, were able to avoid incorporating large amounts of disaturated 18:0-containing phospholipids into their membranes. It is proposed that a lack of stearoyl-CoA desaturase in T cells precludes them from desaturating exogenously derived 18:0, thus leading to increased proportions of 18:0-containing disaturated PC in their cell membranes. The increased abundance of this PC species may enhance membrane rigidity to an extent that plasma membrane integrity is significantly impaired, leading to a loss of membrane potential and ultimately cell function and viability.

Comments: This study is totally irrelevant to what would occur in the human body due to the tiny amounts of stearic acid ingested in capsules. If you directly put a particular nutrient, vitamin, fatty acid, amino acid, medications, herb or any substance in a high enough dosage directly in a cell culture you will get results that have nothing to do with what happens when a tiny amount is ingested as part of a medicine, supplement, or through diet. For instance, you can kill a cell if you put too high an amount of fish oil fatty acids near it in a cell culture, but that does not mean fish oil fatty acids are harmful to you when ingested in reasonable amounts. People or companies who use this type of in vitro study to make such a leap either do not understand medicine or science, or are purposely doing it for marketing reasons.

Q. Are these studies not valid? Please advise.
“Stearic Acid inhibits T-cell dependent immune responses. Plasma membrane integrity is significantly impaired, leading to a loss of membrane potential and ultimately cell function and viability.”
Tebbey PW, Buttke TM, “Molecular Basis For The Immunosuppressive Action of Stearic Acid on T cells” (Immunology, 1990 Jul; 379-86)
“When cells were exposed to stearic acids and palmitic acids, there was a dramatic loss of cell viability after 24 hours. Cell death was induced by stearic and palmitic acid.”
PMID: 12562519 (PubMed) Ulloth, JE, Casiano CA, De Leon M. Department of Microbiology and Immunology, East Carolina University School of Medicine.
“T-helper cells become the target of stearic acid.”
PMID: 6333387 (PubMed)
“The addition of palmitate or stearate to cultured cells led to activation of a death program with a morphology resembling that of apoptosis. Palmitates and stearates caused cardiac and other types of cells to undergo programmed cell death.”
Sparagna, GC, Hickson-Bick, DL, Department of Pathology and Medicine, University of Texas Health Science Center, Houston. American Journal of Medical Science, Jul 1999; pg. 15-21.
    A. See my explanation written above. You can put an excess of any healthy substance, including fish oils, around cells in a petri dish and the cells can die. This does not mean that fish oils are harmful when ingested in reasonable amounts. What happens in an isolated cell in a Petri dish has no practically no relevance to the actual ingestion of that substance since the dilution of that substance that ends up in trillions of cells in the body makes it insignificant.

Q. Can you comment on these I found on some website?
“Stearic Acid, Magnesium Stearate, Calcium Stearate, Palmitate, and Hydrogenated Vegetable Oils are lubricants which enable manufacturing equipment to run more efficiently but inhibit eventual dissolution of the nutrient. Stearic acid may prevent absorption by individuals with compromised digestive systems. Magnesium stearate and stearic acid also present the problem that delivery of the active ingredient may be considerably further down the intestinal tract than the site originally intended. This may result in the nutrient being delivered away from its optimal absorption site. Not only can this impede absorption, in some cases it might be harmful to the liver.”
Czap, AL. Townsend Letter For Doctors and Patients, July 1999, Vol.192; Pg. 117-119.

Consumers often take handfuls of capsules to get nutrients from supplements containing magnesium stearate or stearic acid and instead, get a powerful immuno suppressive treatment! Most retailers are not aware of this threat and mistakenly claim 100% purity for their products. Ask suppliers to provide a written statement that guarantees their supplements are free of stearates. In fact, ask for full label disclosure listing every compound used to produce each product, and eliminate those supplements that have potentially harmful additives.
    A. The statements above are probably written by someone who does not have a good understanding of the human body, physiology, metabolism and digestion.

Magnesium stearate side effects
I am not aware of any documented cases of magnesium stearate side effects caused by consuming magnesium stearate in the small amounts found in capsules and tablets.

Magnesium stearate toxicity
I am not aware of any documented cases of magnesium stearate toxicity caused by consuming magnesium stearate in the small amounts found in capsules and tablets..

Magnesium stearate questions
Q. I would like to purchase Passion Rx but I can't take magnesium stearate due to a scaly lip condition. Salts of vitamins and minerals make the condition worse. But I need help in the sexual area. Does Passion Rx product contain this? What are the inactive ingredients?
   A. Passion Rx has miniscule amounts of magnesium stearate. There is no evidence that these tiny amounts of magnesium stearate have untoward health effects.

Q. Does the tongkat ali supplement contain magnesium stearate?
   A. Yes, the tongkat ali supplement does have a tiny amount of magnesium stearate.

Q. Is magnesium stearate bad for you? Does it cause problems?
   A. Some websites claim magnesium stearate is bad for you even in the tiny amounts found in capsules but there is no evidence for this claim. I am not aware of any health problems with magnesium stearate ingestion from capsules and tablets.

Q. Thorne Research references in their catalog magnesium stearate affecting the solubility and bioavailability of nutrients and therefore does not use it in their product line. The study mentioned was in Pharmaceutical Technology. That's the only info I have. I would love to know differently as I am concerned about all the magnesium stearate in all the supplements I take and would like to get the full availability of a nutrient/supplement intended. I do enjoy your website and information and use it often in my research since I am an herbalist.
   A. I have a different opinion. In my experience, the use of magnesium stearate does not have any noticeable influence on nutrient or herbal absorption. I have taken countless products that have magnesium stearate and felt the potency of such products. For instance, I take Passion Rx which contains magnesium stearate and I notice the powerful effects of the herbs. There is quite a lot of misleading information and unnecessary concern about the tiny amounts of magnesium stearate found in supplements.

Q. Thank you doctor . I recently bought a hoodia product. When I got it I was disappointed to see magnesium stearate (from vegetable products ) on the label ! Rival hoodia products regards hoodia containing magnesium stearate as POISON ! I subsequently did some research on various sites ...including yours ...and was relieved to find out it was harmless in the manufacture of supplement tablets ! THANK YOU again ! Now I don't have to switch my hoodia for another brand !

Q.  In your email newsletter in November 2008 there was a question about magnesium stearate. Recently, by chance, I have been trying to gather information about this additive since it seems to be in almost all tablet or capsule form supplements. This is what I have gleaned. Most of the time magnesium stearate is made by subjecting cottonseed or palm oil to high heat and pressure in the presence of a metal (in this case magnesium) catalyst for several hours. This creates a hydrogenated saturated fat. I did the math and it follows that if each 1000mg capsule has approximately 2% magnesium stearate in it ( this seems to be about average) that means 20 mg of the capsule is hydrogenated fat. If I take ten capsules a day I would be ingesting about 73,000mg of hydrogenated fat per year or about 2.5oz. Like most people who pay attention to their health and do take supplements, I take a lot more than ten capsules a day. As a person who reads labels at the grocery store and promptly rejects any foodstuff with hydrogenated oil in it, why would I take a supplement with hydrogenated oil in it? I believe you when you say that you haven't seen any studies that indicate that magnesium stearate has any negative side effects. Maybe there aren't any, but the tobacco industry used to say that there were no studies that showed a conclusive link between cigarettes and cancer and we all know how that shook out. Common sense seems to suggest that if hydrogenated oil is no good for you when it’s in the food you eat, then its probably not good for you when its in your supplements. I have read, in my limited research, it is not necessary to use magnesium stearate to make supplement tablets and capsules; it’s just easier and cheaper. Its only purpose is to keep the production machinery running smoothly. To me, the choice between smooth running machinery and my health is really a no brainer. Also, I've read that the presence of magnesium stearate significantly impedes absorption of the nutrient. I really don't know if this information is accurate its just what I've read as I surfed many sites on the internet. I think its worth considering. What do you think?
   A. The amount of stearate consumption is even less since the magnesium part of magnesium stearate is part of the weight. Therefore, even if there is 20 mg or so of magnesium stearate in a 1,000 mg supplement capsule, some of that weight is magnesium, a healthy mineral. Some people can get quite obsessed about minutia that, practically speaking, have little or no influence on their health. One could get worried about these tiny amounts of magnesium stearate that is not likely to have any health effects yet have no concerns about getting in the car to drive to the local movie theatre. The risk of a car accident with bodily harm or inhaling pollutants while on the road are much more likely to occur than the minute amounts of magnesium stearate causing harm to health. If a person is that worried about every possible harm that could occur to them, then they would stay home and not even go out of the house. Then again that has its own risks since once could become vitamin D deficient due to lack of sunlight and possibly get depressed due to lack of human interaction. I have not seen any evidence that magnesium stearate impedes absorption of vitamins and herbs.
   The amount of hydrogenated oils you mention as a result of ingesting 10 capsules a day about the same or less than eating half a donut over a period of one year. (See an email below that questions the presence of hydrogenated oils in mag stearate.) If your diet is so perfect (with absolutely no sugar, bad fats, cookies, cakes, ice cream, etc) that eating the equivalent of half a donut over a period of year would concern you, then you may look to find supplements that do not contain magnesium stearate. How many people can truly claim that throughout the whole year they do not ingest any ice cream, regular soda, cookies, pastries, a piece or birthday cake, white bread, more than 2 cups of coffee a day, cream added to the coffee, artificial sweeteners, margarine, or any type of unhealthy food? I think drinking several ounces of fruit juice at one time is a much more significant health issue since it raises blood sugar levels and promotes an excess insulin response. I am certain there are many people who are concerned about mag stearate in their capsules yet consume unhealthy foods on a regular basis without worrying about that. For some people this whole issue has become almost a psychological obsession going way beyond any logical reasoning. I think there are more important health issues to worry about than the insignificant amounts of magnesium stearate in capsules. One other point to keep in mind is that some websites or nutrition writers who make a big deal about magnesium stearate may be doing so as a marketing tool in order to differentiate their products from others and to use this as a selling point.
   If a person is taking more than 10 capsules of supplements a day, there is a significantly higher risk of side effects from the active ingredients in all of these pills rather than the insignificant amount of magnesium stearate. One should reevaluate why they are taking so many pills in the first place.
   It often surprises me on how some people go to great lengths in trying to avoid ingesting something that has practically no harm to them yet do not realize there is a higher risk of harm from so many other activities they do routinely, for instance driving for leisure.

Q. Thank you for the clear responses about mag stearate and stearic acid. I work for a vitamin company and have been doing a little reading up on these substances, and have read your responses. There is one response you might want to redo. My concern is that you did not address the fact that stearic acid / mag stearate, does not have any trans fatty acids in it. The person asking the question is making it sound as if there is a concern about this, and your response implies that there is so little, that it should not be a concern. It’s my understanding, that there is 0 trans fatty acids. The trans fatty acids are formed when the oil is only partially hydrogenated. This Statement by Now Foods talks about it a little and says there are 0 trans fats. http://www.nowfoods.com/Quality/QualityNotes/M093528.htm
   Perhaps you could change that response? This seems to be coming more of an issue.
   A. Yes, you are right, I am assuming that there are are some hydrogenated oils in the magnesium stearate since high temperatures may be used in the preparation. I would still like to see an independent analysis to determine whether any of the stearic acid is hydrogenated,. Not that it matters much since the amounts that are consumed are so tiny to be practically irrelevant.

Q. January 2009 - Dr. Mercola just sent out an email warning against using supplements that use magnesium stearate or stearic acid as filler. I have researched and there are other sources that also warn of toxicity. What is your stance on this? I appreciate your efforts, your newsletter and products.
   A. I have a different viewpoint. I have personally taken supplements with magnesium stearate for 20 years without any ill effects. The amount of magnesium stearate in these pills is so infinitessimally low that it is not worth worrying about it. Some people worry about magnesium stearate but do not seem to be concerned about eating chocolate which has a high sugar and fat content along with a high stearic acid content, but, for some reason, the tiniest amount of magnesium stearate in capsules raises concern for them. Makes no sense.

I really do appreciate all the hard work you have put in on your site. It is so nice to have factual information instead of unsubstantiated hype and fluff. My question is this: is there any truth to the assertion that magnesium stearate and stearic acid, substances which most supplement manufacturers add to their pills and capsules, appear to have some negative side effects in humans? One website maintains that magnesium stearate and stearic acid cause allergic reactions, impede absorption, and do bad things to one's immune system (T-cells). In short, it claims that these excipients cause most supplements to not live up to their potential, since the supplement is harassing the body as well as helping the body. Is this true? If true, is there any substance I might take with a pill containing magnesium stearate and/or stearic acid that might nullify their bad effects? By the way, I do not sell supplements and have no connection whatsoever to any supplement company. I merely want to know for personal reasons. I have food allergies and food sensitivities and have to watch what I eat. I don't do well with red wine vinegar, some fermented beverages, malted barley, caffeine, and some cheeses. I'm wondering if these vitamin excipients could be harming my absorption and perhaps somehow indirectly, gradually making my allergies worse.
    See my explanations above.

I have been reading through the information about magnesium stearate. It also concerns me greatly. Even the small amounts of hydranated oils it may contain still concerns me. I know you said it is like eating half a doughnut a year. That would be ok but taking these pills are a little bit everyday and everyday your body has to detox it out; at least once a year the body has a whole year break. My question is, if this is a major concern for some people and it will prevent some people from taking advantage of your otherwise excellent products. My question is why not just take the magnesium serrate and steric acid out your pills?
    This is not a concern for me, only for some people who seem to be unreasonable obsessed about this issue and are being misled by some websites. If I were concerned about it, I would advise manufacturers to not use. I am not concerned and I take supplements with this substance in it. I have been taking supplements with this substance now for more than 30 years without any problems.