- A nutrient in the vitamin B complex that the body needs in small amounts to function and stay healthy. Inositol helps cells make membranes and respond to messages from their environment. It has the same chemical formula as glucose (the chief source of energy for living organisms) but has a different arrangement of atoms. It is found in beans, peas, brown rice, wheat bran and nuts. It is water-soluble (can dissolve in water) and must be taken in every day. Inositol is being studied in the prevention of cancer. Also called myoinositol.