Description: Phosphatidylserine capsules provided by Douglas Laboratories contain 500 mg of plant-derived (soybean) phospholipids supplying 100 mg of phosphatidylserine (PS). Until recently, PS was only available as a very expensive product derived from bovine sources, with microbiological safety problems. New technology has made it possible to concentrate this important brain nutrient from soybean lecithin, a safe and well-recognized source of phosphatidylserine.