A Healthy Ingredient (No Matter What You've Heard)
by Michael Mooney, Updated March, 2013
Q. I've heard that magnesium stearate is unhealthy and that the stearic acid (as stearate) is a hydrogenated artificial fat that can harm the cardiovascular system. Dr. Mercola doesn't like magnesium stearate, however, I see that Dr. Ray Sahelian, who I regard as a good source of information, thinks it's ok. Who is right?
A. Magnesium stearate is magnesium bound to stearic acid, a natural fatty acid found in olive oil, cocoa (chocolate), beef, poultry, milk, cheese and many other vegetable and food sources. Stearic acid converts in the body about 99 percent into oleic acid, the primary heart-healthy fat in olive oil. (1) Oleic acid is a heart-healthy monounsaturated fat.
Magnesium stearate is an inert agent that is used as a lubricant to preventing ingredients from sticking to manufacturing equipment during the compression of vitamin and mineral powders into solid tablets; magnesium stearate is the most commonly used lubricant for tablets.
Any fear about it is completely misplaced.
In Dr. Mercola's case, he frequently says negative, fear-mongering things to get people to think they need to follow him. His primary modus is to create more viewers for his commercial web site so he can sell products. Ray Sahelian is right. Mercola is wrong. Note that Sahelian is not a salesman. He's primarily a researcher.
Stearic acid CAN be converted into hydrogenated fats and that's probably where it gets its unwarranted questionable reputation. But just because someone takes a healthy, natural saturated fat and does something artificial to it doesn't make it bad in its pure, natural form.
People take all kinds of healthy natural things and turn them into artificially modified things that aren't good for you.
No published studies on humans indicate that magnesium stearate does anything harmful to the body, especially at the low doses found in dietary supplements.
In fact, studies are clear that at greater amounts of stearic acid tends to lower cholesterol, which can improve artery health.
Additionally, dietary doses, much higher than the 20 or so milligrams in vitamin products have been shown in the study abstract from the New England Journal of Medicine that I reproduce below (2) to lower cholesterol and LDL cholesterol, while not affecting triglycerides or HDL cholesterol.
Stearic acid is good for our arteries in much higher quantities than the approximately 20 milligrams found in many multivitamin products.
USDA nutrition surveys tell us that the average American adult consumes between 5,900 to 8,800 milligrams of stearic acid every day, coming from food sources like beef, poultry, chocolate, milk and cheese.
If you eat an organic dark chocolate bar, you'll get several thousand milligrams of stearic acid and a taste of good health.
One so-called "expert" said that magnesium stearate can create a "biofilm" in the intestines, preventing the absorption of nutrients.
In fact, a laboratory study (Soni, J. Food Prot. 2008) found that stearic acid inhibited the formation of biofilms.
For another perspective, please take a look at the detailed scientific statement by Jarrow Formulas at: http://www.jarrow.com/eMarketing/magnesium-stearate-2010-02.html
Another good analysis is http://www.medicalinsider.com/files/stearate.pdf
And another: http://www.wellnessresources.com/health/articles/the_facts_on_magnesium_stearate/
And finally: http://www.nutricology.com/infocus/201304_mgstearatemyatt.htm
1. Schroepfer GJ, et al. The stereospecific conversion of stearic acid to oleic acid. J Biol Chem, 1965,240(1):54-68.
2. Bonanome A, Grundy SM. Effect of dietary stearic acid on plasma cholesterol and lipoprotein levels. NEJM May 12, 1988, 318(19):1244-1248
We studied the metabolic effects of stearic acid (18:0) on plasma lipoprotein levels in 11 subjects during three dietary periods of three weeks each. The three liquid-formula diets, which were used in random order, were high in palmitic acid (16:0), stearic acid, and oleic acid (18:1), respectively. Caloric intakes were the same during the three periods. As compared with the values observed when the subjects were on the high-palmitic-acid diet, plasma total cholesterol decreased by an average of 14 percent during consumption of the high-stearic-acid diet (P less than 0.005) and by 10 percent during consumption of the high-oleic-acid diet (P less than 0.02). Low-density lipoprotein (LDL) cholesterol levels fell by 21 percent in subjects on the high-stearic-acid diet (P less than 0.005) and by 15 percent in subjects on the high-oleic-acid diet (P less than 0.005). No significant differences were observed in the plasma levels of triglycerides or high-density lipoprotein (HDL) cholesterol among the three diets. Measurements of the intestinal absorption of palmitic, stearic, and oleic acids revealed essentially complete absorption of each during the three dietary periods. The oleic acid content of plasma triglycerides and cholesteryl esters increased significantly during the high-stearic-acid period, suggesting that stearic acid is rapidly converted to oleic acid. We conclude that stearic acid appears to be as effective as oleic acid in lowering plasma cholesterol levels when either replaces palmitic acid in the diet.