Inositol is found in all animal tissues, with the highest concentration found in the brain and heart. It is a component of the outer lining of all cells in the body, contributes to muscular and nerve function, and also plays a role in helping the processing of fats by the liver. Endogenous inositol is an essential component of cell membrane phospholipids. Inositol is a constituent of the intracellular phosphatidyl inositol second messenger system, which is linked to serotonin, norepinephrine, and cholinergic receptors. Inositol contains a variety of stereoisomers, including myo-inositol and D-chiro-inositol. Myo-inositol is the most abundant form in the central nervous system. Researchers think that D-chiro-inositol isomer induces may support insulin sensitivity and healthy testosterone levels in women with ovarian disorders.