Stearic acid (magnesium stearate, mag stearate) is an essential saturated fatty acid that is found in all vegetable, seed, nut, and animal oils. Although stearic acid can be from several sources, the most common source in better quality nutritional supplements is vegetable stearic acid. Tablet manufacturing requires certain substances like stearic acid to help powders flow smoothly through the tableting machines and help the tablets hold their shape. Stearic acid is ideal because of its natural source and inactive state, so it doesn't interfere with the proper utilization or absorption of active ingredients in the tablet.