Inositol

Inositol is the trivial name for a naturally occurring (in animals and plants), hexavalent cyclic alcohol with the molecular formula C6H12O6 (same molecular formula as glucose and fructose - but inositol is not a carbohydrate), which occurs in 9 different stereo-isomers, of which only myo-inositol is biologically active.

Inositol is a white, crystalline, odourless solid with a sweetish taste. Inositol is not a vitamin (the substance was formerly classified as a B vitamin). The substance can be produced by the body itself from glucose and is therefore not essential. Myo-inositol is released in the muscle, in different types of muscle. In various organs, especially in the brain and liver, myo-inositol is present as 1-phophatidylinositol. Inositol occurs in almost all higher plants as a component of sphingolipids, an important building block of cell membranes. In fungi, bacteria and some higher plants the alcohol is mainly found as phytic acid (inositol hexaphosphoric acid).

Physiology: The 1D-myo-inositol-1,4,5-trisphosphate (simplified inositoltrisphosphate, IP3) and other phosphoinositols play an important role as secondary messengers for signal transduction in cells.

Nutrition: Inositol is mainly found in nuts, beans, wheat, wheat germ and oranges. It is mainly found in the form of phytates (salts/esters of phytic acid). Inositol is commercially available as a food supplement for humans.

Medical indications: The substance shows positive effects in diabetic metabolic disorders (Croze ML et al. (2013). The inositolisomers, myo-inositol and D-chiro-inositol have been successfully used in polycystic ovarian syndrome (Dinicola S et al. 2014). The substance is suitable to enhance the effect of the phytoestrogen resveratrol (Parazzini F 2014).

In 7 RCTs concerning depressive disorders (bipolar disorders and premenstrual dysphoric disorders - PMDD) positive effects of inositol could be demonstrated (Mukai T et al. 2014).

Cosmetics: Inositol and 2 other inositol derivatives are used in cosmetic formulations:

• Inositol hexa-PCA - preserves the moisture of the skin; nourishes the skin
• Inositol hexanicotinate - preserves the moisture of the skin

1. Bevilacqua A et al (205) Results from the International Consensus Conference on myo-inositol and D-chiro-inositol in Obstetrics and Gynecology--assisted reproduction technology. Gynecol Endocrinol 31:441-446.
2. Croze ML et al (2013) Potential role and therapeutic interests of myo-inositolin metabolic diseases. Biochemistry 95:1811-1827.
3. Dinicola S et al. (2014) The rationale of the myo-inositol and D-chiro-inositol combined treatment for polycystic ovary syndrome. J Clin Pharmacol 54:1079-1092.
4. Mukai T et al.(2014) A meta-analysis of inositol for depression and anxiety disorders Hum Psychopharmacol 29:55-63.
5. Parazzini F (2014) Resveratrol, inositol, vitamin D and K in the prevention of cardiovascular and osteoporotic risk: a novel approach in peri- and postmenopause. Minerva Ginecol 66:513-518.
6. Schneider S (2015) Inositol transport proteins. FEBS Lett 589:1049-1058.
7. Unfer V et al (2014) Updates on the myo-inositol plus D-chiro-inositol combined therapy in polycystic ovary syndrome. Expert Rev Clin Pharmacol 7:623-631.