Inositol is a sugar alcohol that is ubiquitous in the human body. It has two forms, myo-inositol and D-chiro-inositol, the former being most bioactive in humans. Inositol is very important because it is a structure of the phospholipid bilayer in cell membranes, and it is used in countless inter-cellular signalling pathways. Supplementation research shows efficacy in insulin resistance, type 2 diabetes, gestational diabetes, PCOS, infertility, and some mental health disorders.
Myo-Inositol is found to concentrate in the human brain, and in rat models supplementation found increased levels in the hippocampus and frontal cortex. (1) Supplementation has produced clinical improvements in depression (while medicated), panic disorder, and obsessive compulsive disorder. With panic disorder, 18 g/day of myo-inositol showed as effective as 150 mg of fluvoxamine; and 18 g/day in OCD had a 50% reduction in Yale Brown Obsessive Compulsive Scales. (2-4) Autism studies need to be conducted to prove efficacy as there is very little research in this area.
Inositol is inserted into the phospholipid bilayer (cell membrane) as PIP2, which turns into DAG upon external stimulatory signaling. Various phosphorylation responses cascade within the cell from this. It is an integral part of cellular and metabolic communication, including those related to insulin response. It is also hugely responsible for activating calcium response downstream, which is of particular interest in neurotransmission, and may explain some of the mental health results listed above. (5, 6) Clinically it has yielded results in those with COMT SNPs, therefore regulating their dopamine and epinephrine excesses, along with blood sugar control.
1). Kofman O, et al. Chronic dietary inositol enhances locomotor activity and brain inositol levels in rats. Psychopharmacology (Berl). 1998 Oct;139(3):239-42.
2). Levine J, et al. Follow-up and relapse analysis of an inositol study of depression. Isr J Psychiatry Relat Sci. 1995;32(1):14-21.
3). Palatnik A, et al. Double-blind, controlled, crossover trial of inositol versus fluvoxamine for the treatment of panic disorder. J Clin Psychopharmacol. 2001, Jun;21(3):335-9.
4). Fux M, et al. Inositol treatment of obsessive-compulsive disorder. Am J Psychiatry. 1996 Sep;153(9):1219-21.
5). Irvine RF. Inositol lipids in cell signalling. Curr Opin Cell Biol. 1992 Apr;4(2):212-9.
6). Berridge MJ, Irvine RF. Inositol phosphates and cell signalling. Nature. 1989 Sep 21;341(6239):197-205.