from wikipedia:
Inositol (of which the most prominent naturally occurring form is myo-inositol, cis-1,2,3,5-trans-4,6-cyclohexanehexol) is a carbocyclic polyol that plays an important role as the structural basis for a number of secondary messengers in eukaryotic cells, including inositol phosphates, phosphatidylinositol (PI) and phosphatidylinositol phosphate (PIP) lipids. It is found in many foods, in particular, in cereals with high bran content, nuts, beans, and fruit, especially cantaloupe melons and oranges. Inositol is not considered a vitamin itself because it can be synthesised by the body.
Other naturally occurring isomers (though in minimal quantities) are scyllo-, chiro-, muco-, and neo-inositol. Other possible isomers are allo-, epi-, and cis-inositol.
Myo-Inositol was classified as a member of the vitamin B complex (often referred to as vitamin B8), but was found to be synthesized by the human body (thus, declassifying it as a vitamin).
Patients suffering from clinical depression generally have decreased levels of inositol in their cerebrospinal fluid.[6]
Some preliminary results of studies on inositol supplements show promising results for people suffering from problems such as bulimia, panic disorder, obsessive-compulsive disorder, and unipolar and bipolar depression.[6]
Myo-inositol has been found in a single double-blind study to significantly reduce the symptoms of obsessive-compulsive disorder (OCD) with effectiveness equal to SSRIs and virtually without side-effects.[7] In a double-blind, controlled trial, myo-inositol was superior to fluvoxamine for decreasing the number of panic attacks and had fewer side effects.[8] A double-blind, placebo-controlled study of depressed patients showed that a high dose of inositol (12 grams daily) resulted in significant improvement of symptoms, with no changes noted in liver, kidney, or hematological function.
6 ) Nick, Gina L. (2004). "Inositol as a treatment for psychiatric disorders: a scientific evaluation of its clinical effectiveness". Townsend Letter for Doctors and Patients (October). Retrieved on 2008-05-24.
7 ) Fux M, Levine J, Aviv A, Belmaker RH (1996). "Inositol treatment of obsessive-compulsive disorder". American Journal of Psychiatry 153 (9): 1219–21. PMID 8780431.
8 ) Palatnik A, Frolov K, Fux M, Benjamin J (2001). "Double-blind, controlled, crossover trial of inositol versus fluvoxamine for the treatment of panic disorder". Journal of Clinical Psychopharmacology 21 (3): 335–339. doi:10.1097/00004714-200106000-00014. PMID 11386498.
