Here’s an all to common example of a selenium pill with magnesium stearate (undesirable):

Selenium (as L-selenomethionine) 200 mcg 286%

Other Ingredients

Microcrystalline cellulose, dicalcium phosphate, silicon dioxide, magnesium stearate, gelatin capsule.

“… magnesium stearate can cause a biofilm to be created in your intestine, which will prevent the absorption of nutrients.“

http://articles.mercola.com/sites/articles/archive/2011/08/22/is-your-multivi...

How Some Supplements Can do More Harm Than Good

There are a few ways that nutritional supplements may do you more harm than good.

Concentrated formulas make you absorb less -- It’s important to understand that when you take vitamins or antibiotics that are concentrated above what is found naturally, in nature, your small intestine actually forms defenses against the absorption of these excessively concentrated ingredients.

It does this by creating a biofilm – a barrier that effectively blocks the absorption of nutrients – as a form of self defense, if you will.

According to Dr. Klinghardt, who frequently monitors his patients’ nutrient levels, oftentimes the more supplements you take the less your body actually absorbs.

Additives make your body develop protective mechanisms – In the U.S. many supplement makers are adding flowing agents into their capsules. Two common, and potentially toxic, additives are:

·         Magnesium stearate

·         Titanium dioxide

... more