Magnesium stearate is a salt of magnesium and stearic acid, a saturated fatty acid naturally present in many oils and animal products. It is used as an anti-caking agent and lubricant in food and drug processing. The U.S. Food and Drug Administration generally regards magnesium stearate as safe, and no credible evidence exists to suggest that the amount present in foods presents a health hazard.
Magnesium Safety
Magnesium is a natural mineral essential for health. Magnesium is involved in learning and memory in the brain and bone structure, and it is critical for many enzymes to function throughout the body. The Office of Dietary Supplements cites the tolerable upper limit of elemental magnesium at 300 mg per day for adults. This is the mass of only the magnesium, not the total weight of any salts containing magnesium, such as magnesium stearate. Magnesium overdose has only been known to occur from large acute doses from pharmaceutical sources; Excess dietary magnesium is easily removed via the kidneys.
Stearic Acid Safety
Stearic acid is an 18-carbon saturated fatty acid that is commonly found in many foods and oils. Stearic acid is present in high amounts in margarine, shortening, butter spreads and animal fat. Stearic acid is present in much higher amounts in these foods than any that use magnesium stearate. The American Heart Association reports that stearic acid has little effect on cholesterol levels in the blood.
Health Concerns
Many alarmist articles portraying magnesium stearate as a toxin are also promoting the sale of their own magnesium stearate-free supplements. Cited research studies are taken wildly out of context, as no well-controlled research study exists that demonstrates a health risk of magnesium stearate, according to the FDA. Some studies suggest that oils used to make magnesium stearate may be contaminated with pesticides or other contaminants, though they do not present reliable evidence.
Recommendations
The FDA considers consumption of up to 2,500 mg per day of magnesium stearate to be safe. It is estimated that 300 mg or less is found in the average daily diet. Reducing your daily consumption of processed foods can be a part of a healthy diet. Excess calories and poor nutrition is a much greater concern than any adverse health effects of magnesium stearate.
References
- FDA.gov: Database of Select Committee on GRAS Substances (SCOGS) Reviews: Magnesium Stearate; Oct. 31, 2006
- University of Maryland Medical Center: Medical Reference: Complementary Medicine: Magnesium; S.D. Ehrlich, NMD; June 25, 2009
- Office of Dietary Supplements: Magnesium Fact Sheet
- American Heart Association: Stearic Acid
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