Magnesium Stearate: What It Is, Its Uses, and More
Magnesium stearate is a salt comprised of the mineral magnesium and the saturated fat stearic acid. Stearic acid is a long-chain saturated fat that can be found in a wide range of foods such as beef, cocoa butter, coconut oil, palm oil, safflower oil, eggs, and dairy products.
Magnesium stearate is a fine, white, and insoluble powder and inactive ingredient used in many health and food products.
What Is the Purpose of Magnesium Stearate?
Magnesium stearate has been widely used in the food industry but also in cosmetics, medications, and supplements primarily as a bulking and anti-caking agent.
It is used as a diluent and filler in pharmaceutical tablets and dietary supplements, including tablets, capsules, and powders. Its main purpose is to maintain quality and consistency of products on the market.
Magnesium stearate is used in supplement manufacturing in order to ensure that the ingredients in the product stay blended together in the right proportions to prevent the powders from clumping. This allows companies to be coherent with their formulas and provide the same quality to consumers with guaranteed consistency.
In addition, magnesium stearate is an additive that is used as a lubricant to improve flowability of formulations and prevent the ingredients from sticking to the surfaces of processing equipment.
The Health Effects of Magnesium Stearate
There is quite a bit of controversy and confusion around the safety of magnesium stearate. Concerns have been raised around the fact that magnesium stearate might cause negative effects such as inhibiting nutrient absorption, raising cholesterol levels, causing allergic reactions, and suppressing immune function.
So what's the verdict?
Claims around immunosuppression have been based on the consumption of large amounts of stearic acid in mice (1).
The laboratory conditions included in the study do not accurately represent what happens when humans consume normal amounts of magnesium stearate from their diet or even smaller amounts from their supplements.
In addition, the concerns around cholesterol levels are mainly associated with the notion that stearic acid in magnesium stearate is a saturated fat. However, studies revealed that even larger amounts of stearic acid consumed from the diet had no significant effects on cholesterol levels (2)(3). In fact, they have been found to lower cholesterol levels and even benefit heart health (4)(5).
The average American adult is said to consume 5,900 to 8,800 milligrams of stearic acid every day from their diet while the amount of stearic acid found in supplements is much lower averaging around 20 milligrams per dose. The magnesium stearate found in supplements at the dose that is recommended remains quite minimal and with low risks of side effects.
Though rare, a case of an allergic reaction in the form of skin hives has been reported in a 28 year old woman from consumption of magnesium stearate (6). If you do find yourself reacting to supplements, it is always recommended to stop consuming right away.
There is also talk about magnesium stearate inhibiting the absorption of nutrients. Studies have found that supplements containing magnesium stearate took longer to dissolve than those without (7). However, other studies showed that magnesium stearate had no overall effect on the bioavailability or blood levels of the consumers and did not have any effect on absorption.
The bottom line is that magnesium stearate lacks scientific evidence proving that it is not safe for consumption. The small amounts that are found in supplements should not pose a problem for most consumers though you should always pay attention to any side effects that may occur from consuming any products.
How Much Magnesium Stearate Is Safe to Consume?
Overall, the scientific evidence against magnesium stearate is lacking as the small amounts that are found in supplement products are too small to cause a problem for the majority of the population (8). Reaching toxicity levels is quite rare and hard to do.
An animal study determined that it would take 2,500 mg of magnesium stearate per kg of body weight per day in order to reach toxic effects (9). This represents a far greater dose than you would encounter in supplement products.
Of course it goes without saying that if you do suspect that you might be reacting to magnesium stearate then discontinue use and consult with your doctor.
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