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Safety and Efficacy of Magnesium Stearate

Safety and Efficacy of Magnesium Stearate

By Cyrus Kuhzarani, R.Phm.
Owner, Pure Lab Vitamins

08 Feb 2019

Safety and Efficacy of Magnesium Stearate

What is magnesium stearate?
Magnesium stearate is a simple salt made of two common nutritional substances, the mineral magnesium and the saturated fat stearic acid. It is used as a flow agent, lubricant, binder or anti-caking agent in the production of many nutritional supplements and pharmaceuticals.

Magnesium and stearic acid are bound together to create magnesium stearate. We all know what magnesium is… it’s an essential mineral abundant in dark green leafy vegetables. (1) Stearic acid is a saturated fatty acid found in many foods including eggs, chicken, grass-fed beef, coconut oil, walnuts, cheese, chocolate, salmon and human breast milk, to name just a few. (2)

Why is it necessary for production?
The use of magnesium stearate in the manufacturing process helps ensure consistency and quality control. In it’s absence, the machinery that creates the capsules can ‘jam’ up. This would cause potential variances in the amount of active ingredients between capsules.

What are sources of magnesium stearate?
Stearic acid is derived from animal sources or plant-based sources.
Vegetarian sources of magnesium stearate include palm oil, coconut oil and vegetable oil.
PURE LAB VITAMINS uses “plant based” as their source of magnesium stearate.

Safety of Magnesium Stearate
There are claims being made in the media and on the internet that magnesium stearate suppresses immune T-cell function and causes the collapse of cell membrane integrity in helper T-cells. Is there any scientific proof to support this?

There is no human data to support this hypothesis. There is one study from 1990 that examined T-cells of mice. The T-cells were immersed in stearic acid (not magnesium stearate) in a Petri dish. The result was that the mouse T-cell activity was compromised. (3)

Humans are not mice. In the case of the 1990 study, it was noted that mice lack the enzyme (delta-9 desaturase) that allows stearic acid (again not magnesium stearate) to convert to oleic acid (healthy monounsaturated omega-9 fatty acid). (4)

Human T-cells do contain the delta-9 desaturase enzyme that converts stearic acid to oleic acid. Human T-cells will not develop toxic build-up when exposed to stearic acid.
What is a safe level of consumption of magnesium stearate?

The scientific community considers a safe amount of magnesium stearate for human consumption to be below 2,500 mg/kg per day. For a 150-pound adult this is equivalent to 170,000 mg per day. (5)

Adults in North America typically consume 7,000mg of stearic acid per day from all food sources. (6)

120ml of human breast milk contains more than 5,000 mg of stearic acid.

A small chocolate bar will also provide well over 5,000 mg of stearic acid.

How much stearic acid is generally contained in supplements?
Supplement manufacturers use between 0.25% and 5% of magnesium stearate in their production process.
To put this into perspective, an individual taking 20 vitamin capsules daily, each weighing 500 mg and containing 1% magnesium stearate would consume less than 96 mg of stearic acid per day (or less than 1.3% of the total daily adult intake).

Magnesium stearate is currently approved by the FDA for use in food and supplements (7) and also by Health Canada. (8)


1. National Institutes of Health, Office of Dietary Supplements: Magnesium.
2. 2. USDA National Nutrient Database for Standard Reference, Release 24.
3. Tebbey PW, Buttke TM. Molecular basis for the immunosuppressive action of stearic acid on T cells. Immunology. 1990 Jul;70(3):379-84. PMID: 2379942
4. Anel A, Naval J, González B, Uriel J, Piñeiro A. Fatty acid metabolism in human lymphocytes. II. Activation of fatty acid desaturase-elongase systems during blastic transformation. Biochim Biophys Acta. 1990 Jun 14;1044(3):332-9. PMID: 2114179
5. Søndergaard D, Meyer O, Würtzen G. Magnesium stearate given perorally to rats. A short term study.Toxicology. 1980;17(1):51-5. PMID: 7434368
6. Alija Uzunović, Edina Vranić. Effect Of Magnesium Stearate Concentration On Dissolution Properties Of Ranitidine Hydrochloride Coated Tablets. Bosn J Basic Med Sci. 2007 Aug;7(3):279-83. PMID: 17848158
7. Food and Drug Administration, Select Committee on GRAS Substances (SCOGS) Opinion: Magnesium stearate, accessed Sept. 10, 2012. GenerallyRecognizedasSafeGRAS/ GRASSubstancesSCOGSDatabase/ucm260466.htm

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