Inositol is a naturally occurring isomer of glucose. It is classified as a member of the vitamin B complex. Sometimes people refer to it as B8, but it is not really a vitamin itself. Inositol is a natural chemical compound present in the human body and in certain ordinary foods. It is direct precursor of phospholipids which are a major component of cellular membranes. Phospholipids are fat-soluble, naturally-occurring molecules that help make up our cellular structure. Both inositol and the phospholipids play a major role in signal transmission for many neurotransmitters and hormones. Inositol is important for regulating serotonin and insulin, and breaking down fats and reducing blood cholesterol.