Is magnesium stearate safe?
Magnesium stearate is a compound comprised of stearic acid (a naturally-occurring fatty acid) bound to the element magnesium. It is used only when necessary, in very small quantities as a lubricating agent in the manufacture of supplements. Without such lubrication many ingredients would “stick” to the processing equipment, building up and interfering with the filling process. The first thing to realize is that stearic acid is very common in the human diet, comprising as much as 25 percent of total fatty acid intake and is considered a neutral fatty acid (i.e., does not increase LDL or decrease HDL cholesterol levels). Stearic acid occurs naturally in some of our most prized foods, including chocolate, Brazil nuts, coconut, dairy products, Macadamia nuts, and a variety of meats such as beef, lamb and pork. Second, because stearic acid is very digestible, it lacks the ability to interfere with nutrient absorption in any significant way. After absorption stearic acid is taken up into the liver, where it is rapidly converted to oleic acid, the highly desirable mono-unsaturated fatty acid found abundantly in olive oil. This is most likely why studies have repeatedly shown that stearic acid does not elevate LDL, total cholesterol or triglycerides. The issue of magnesium stearate’s impact on immune function has also been raised. Studies have been cited that purport to show adverse effects on mouse B and T-lymphocytes. These in vitro studies are completely irrelevant for two reasons. First, extraordinarily large concentrations of stearic acid were used. Second, a crucial enzyme needed for stearic acid metabolism is present in human immune cells that mice do not have. No adverse impact on human health has ever been demonstrated for stearic acid at any reasonable intake. Finally, we use only USP (pharmaceutical grade) magnesium stearate, derived solely from non-hydrogenated palm oil and is often less than 1 mg per capsule, when needed as a flow agent.
Should I be concerned about the use of stearic acid?
Stearic acid functions as a flow agent in the manufacture of quality products, and stearic acid also occurs naturally in the foods you eat. For example, four ounces of dark chocolate contain 3,625 mg of stearic acid; a cup of kidney beans contains 1,655 mg of stearic acid; an ounce of raw ground beef (grass-fed) contains 2,063 mg of stearic acid; and a half pound of lean raw turkey contains 1,642 mg of stearic acid. Even a tablespoon of allspice contains 1,513 mg of stearic acid! Our supplements, on the other hand, typically contain no more than 10 mg per capsule. We always use the lowest level of magnesium stearate possible.
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