What is magnesium stearate and where can we find it?
Magnesium stearate is a magnesium salt of stearic acid. More specifically, it is a compound made of two particles of stearic acid and magnesium. Stearic acid is a saturated fatty acid and it can be found in many food products, mainly in animal and plant fats. The examples of such are: cacao, flaxseed, eggs, cheese, nuts, salmon, which consist of huge amounts of stearic acid (1,2). When magnesium stearate is digested in our digestive system, it breaks into its components, the stearic acid, which is digested as a fat, as well as, some sources inform that, the magnesium present in these compounds can also be used in many cellular processes by our body (3). Knowing how often we hear about magnesium deficiency, we can state, that magnesium stearate can be a valuable source of this element for our body.
Studies confirm the harmlessness of magnesium stearate
Magnesium stearate is one of the most frequently used additions in drugs and supplements. It is hard to find any dietary supplement, which wouldn’t have it in its composition. It also occurs under different names – “plant stearate” or stearic acid. Many people give this compound bad fame, but also they don’t support their words with any scientific publications. Same as many additives, magnesium stearate is not entirely healthy in high doses, although it occurs in milligram quantities in dietary supplements and this amount of this compound won’t do us any harm. Magnesium stearate makes the tablets easier to swallow and their transport through digestive system is enhanced. Magnesium stearate is also and excipient, which means that it, augments the therapeutic effect of the active compounds of the drug or dietary supplement composition – it increases absorption and solubility. There is a possibility of using alternative excipients such as ascorbyl palmitate, but such compounds exhibit different physical properties and do not always fulfil their role in drugs or dietary supplements. Magnesium stearate, as well as other chelated minerals (magnesium ascorbate, magnesium citrate etc.) does not exhibit any negative effects, because it is a regular compound built of mineral and fatty acid (plant fatty acid neutralised by magnesium salts). To exhibit any side effects one should ingest this compound intravenously on the course of several hours (National Institute of Health data), the amount present in the capsules is entirely save and harmless for us.
Common sense is the key
Before we start to boycott all supplements and healthy food having magnesium stearate present in their composition, we should remember the famous sentence said by Paracelsus: “All things are poisons, for there is nothing without poisonous qualities. It is only the dose which makes a thing poison.” In other words, if we do not ingest an enormous dose of magnesium stearate intravenously and we wouldn’t care for laboratory research on rats, which were fed with doses not possible for us to ingest, we can surely state that magnesium stearate is a safe dietary supplement additive. Example of study would be the one published in 1980 in Journal of Toxicology, in which 40 rats were fed a diet consisting of 0, 5, 10 and 20% of magnesium stearate over 3 months. Here is, what was discovered (4):
- 20% Group – reduced body mass, reduced liver mass, reduced iron level, kidney stones, nephrocalcinosis (too high level of calcium resulting in kidney calcinosis)
- 10% Group – reduced liver mass
- 0-5% Group – no side effects (this dose resembles the quantity of lower than 2500mg for kg of human body mass daily, so in case of a person weighing around 70kg, the safe amount is 170000mg per day).
It should be again highlighted that, the amounts of this compound used during the production of dietary supplements are only trace. Normally, magnesium stearate is of 0.25 to 1.25% tablet mass, so in case of 500mg tablet, the amount of magnesium stearate is roughly 5mg.
Vital is the fact that, if the magnesium stearate present in the capsule was to make harm to anybody, the person ought to swallow thousands of them daily.
Rumors and research on magnesium stearate
In the internet, there are rumours that, magnesium stearate debilitated the functioning of T and B lymphocytes, which are an important part of our immune system. I advise to read the publication, which elevates in this subject (5). In this study, experiment was performed in which lymphocytes T and B were isolated from mice, immobilised on the Petri dish and rinsed with buffer containing stearic acid. They observed that, T lymphocytes incorporated the stearic acid into their membranes, which destabilized their structure and caused cell death. Firstly, one should highlight that; stearic acid was used in the study, not the magnesium stearate. The same stearic acid, which is present in chocolate, eggs, cheese etc., so we can easily assume that ingesting any of these products will have a negative impact on the immune system, but we should remember that they have much more of this compound in their composition, than the capsule of dietary supplement. Secondly, this study had nothing to do with ingesting this compound in everyday diet. In our everyday life, T lymphocytes are not bathed in stearic acid, even though we ingest it every day, for example, in a piece of chocolate. Thirdly, mouse T lymphocytes were used in the study, so this study cannot refer to human cells. Mice cells incorporated the stearic acid in their membranes, because they are not able to desaturate the fatty acids. It is directly connected with the lack of the certain enzyme responsible for desaturation of fatty acids, which is present in human lymphocytes. So we can assume that, even if we would rinse human T lymphocytes with stearic acid, the presence of that enzyme would allow to maintaining the integrity and functionality of the membranes. If during this read, you were kind of lost, here you can find the final conclusion: that study had no connection to consumption of magnesium stearate by humans and should not be reviewed in case of its toxicity.
- Steinberg FM, Bearden MM, Keen CL. Cocoa and chocolate flavonoids: implications for cardiovascular health. J Am Diet Assoc. 2003 Feb; 103(2):215-23.
- Babu US, Bunning VK, Wiesenfeld P, Raybourne RB, O’Donnell M. Effect of dietary flaxseed on fatty acid composition, superoxide, nitric oxide generation and antilisterial activity of peritoneal macrophages from female Sprague-Dawley rats. Life Sci. 1997; 60(8):545-54.
- Bruno G. Examining the stearic acid and magnesium stearate. Vit Retailer. 2013; 35: 52-56.
- Søndergaard D, Meyer O, Würtzen G. Magnesium stearate given perorally to rats. A short term study. Toxicology. 1980; 17(1):51-5.
- Tebbey PW, Buttke TM. Molecular basis for the immunosuppressive action of stearic acid on T cells. Immunology. 1990; 70: 379-384.