Sphingomyelins (SMs) are bioactive sphingolipids found in mammalian cell membranes. SMs make up 2-15% of the total organ phospholipid population but are found at higher concentrations in the brain and myelin sheaths surrounding peripheral nerves. They interact with cholesterol to control its distribution within cellular membranes and maintain cholesterol homeostasis in cells. SMs undergo hydrolysis by sphingomyelinase to form ceramides, which are sphingolipid mediators of intracellular signaling. This product is a mixture of SMs, with variable fatty acid chain lengths, extracted from bovine spinal cord.