Magnesium stearate is a white substance, solid at room temperature, used in the manufacture of pharmaceutical and supplement tablets and capsules. It is composed of magnesium and stearic acid, and oftentimes, palmitic acid as well.
The role of magnesium stearate in supplements (and in pharmaceutical capsules and tablets as well) is to act as a lubricant to prevent tablet and capsule contents from sticking to the machinery that processes them. This ensures that production machinery can operate at maximum speeds, because the materials flow much better and clean-up is much easier. Encapsulated supplements can be produced without the use of stearates (as is done here at Barlowe's Herbal Elixirs), but it is a much more time consuming and demanding process.
Hydrogenated oils are a common source for the magnesium stearate used in pharmaceuticals and supplements. The stearates are made by hydrogenating cottonseed or palm oil. Cottonseed oil has the highest content of pesticide residues of all commercial oils; cotton crops are heavily sprayed. Cotton crops are oftentimes genetically modified. In the hydrogenation process, the cottonseed or palm oil is subjected to high heat and pressure in the presence of a metal catalyst for several hours, creating a hydrogenated saturated fat. Hydrogenated vegetable fats contain altered molecules derived from fatty acids.
The main problem with stearates (primarily magnesium stearate and stearic acid) which is found in almost all pharmaceutical and herbal capsules and tablets is not necessarily toxicity, but is the fact that stearates greatly inhibit the absorption of substances into your body. Here is a short youtube video which clearly demonstrates how stearates inhibit absorption into the body. Thanks to Dr. Randy Johns with Elevation Health for such an informative video. http://www.youtube.com/watch?v=qP8i3_EfP7M
It is commonly noted in medical literature that magnesium stearate increases the time it takes for tablets and capsules to dissolve due to the film it forms on capsule or tablet ingredients. Magnesium stearate coats most of the molecules in a tablet or capsule, requiring digestive enzymes to break down the magnesium stearate coating before being able to access the nutrients or medicine it envelops. In a study published in the journal Pharmaceutical Technology in April of 1985, the percent dissolution for capsules after 20 minutes in solution went from 90% without stearates to 25% with stearates. Thus, stearates reduced the rate the capsule dissolved by 65%! This may result in the nutrients not dissolving in the appropriate section of the intestines as intended. This is particularly worrisome in individuals with impaired digestion who may have more difficulty absorbing nutrients or medicines coated with magnesium stearate.
Thus, when all the above is considered, why would anyone take a product containing magnesium stearate or other types of stearates when stearate free alternatives at a reasonable cost are available?