Please let Dr. Gardner know that I had been very happy with the vitamins. Today; however, during my research, I came across some information on magnesium stearate. As I read about it and its potential damage to the digestive system, I was feeling grateful that I was taking high quality vitamins. However, after I finished on the computer, I went to look at my bottle of vitamins and found that (yikes!) there IS magnesium stearate in my vitamins.
For that reason, I’ve decided to discontinue my vitamin subscription. Thank-you for your services and please let me know if any vitamins are produced without magnesium stearate.
Your confusion and concern about magnesium stearate is easy to understand, especially given the “controversy” that abounds on the internet. First, let me set your mind at ease, and then I’ll explain the truth about magnesium stearate.
There is no research in humans that shows any negative effect of magnesium stearate in the human population. It is unclear if the companies marketing “magnesium stearate-free” nutritional supplements are based on misunderstanding or willful misinterpretation of data, but they clearly are trying to gain a marketing advantage and not trying to disseminate the truth. Anyone who has had any anxiety about the use of magnesium stearate in my Primivia supplement line can relax and be confident of its high quality.
Magnesium stearate is used in the production of foods, cosmetics, medications and nutriceuticals. Stearic acid is an 18-carbon chain saturated fatty acid, and the stearate form is a safe isomer of the fatty acid. Although not mentioned, magnesium palmitate is also used for the same purpose, and is a higher concentration than stearate. Palmitate is a 16-carbon chain saturated fatty acid. Both the stearic and palmitic acids in magnesium stearate are derived from natural, edible sources. The normal ingestion of stearic acid in food on a daily basis is about 7,000 mg. If you were to take 20 tablets of nutritional supplements that weighed about 1,000 mg each, you would ingest 300 mg of stearic acid, less than 5% of a normal daily intake.
There have been some rat studies and in-vitro studies (in test tubes) with magnesium stearate that showed two potential problems. One is that it affected the immune system. However–and this is a big however– although rats are usually tested before humans because so much of their physiology is like humans, this is not so with the stearic acid. Rats do not have the enzyme to break down stearic acid into the 18-carbon oleic acid with one double bond. This means the stearic acid builds up to toxic levels in rats in these studies.
The other potential problem with intake of fat is that it could slow down the breakdown and absorption of nutrients, including supplements. Two randomized studies done on the medications propranolol and metoprolol with three levels of magnesium stearate levels in the product showed no difference in bioavailability.