Inositol, also called “Inosit”, is a sugar alcohol with the chemical formula C6H12O6. Nine possible forms (stereoisomers) of inositol exist. The most commonly known is myo-inositol (cis-1,2,3,5-trans-4,6-cyclohexanehexol).

Myo-inositol is widely common in the human metabolism. It was once categorized as Vitamin B8, but since our body is able to produce a certain amount of inositol by itself, it is no longer classified as vitamin.

Other stereoisomers of inositol occurring in naturally in the body are scyllio-inositol, muco-inositol, neo-inositol and d-chiro-inositol. The most important of these and most interesting one in health science and i.e. in the field of PCOS and fertility is d-chiro-inositol.

Inositol is found in fruits, i.e. in cantaloupes and oranges.

Functions of Inositol

Quick facts

  • Naturally occurring substance

    Inositol is a substance that is part of natural metabolic processes. It´s mother nature´s invention, not created by man.

  • Myo-Inositol vs Chiro-Inositol

    Myo-Inositol is NOT a brand, but the commonly used scientific name. Both forms of inositol, myo and chiro, are natural and have different, but equally favourable effects in women with PCOS.

  • Scienctific Background

    Inositol has created increasing attention in science, i.e. in the area of female fertility. It is well documented and considered very safe.

Inositol has several functions as secondary messenger and and signaling molecule in a wide variety of biological processes, such as:

  • insulin signalling,
  • nerve guidance,
  • breakdown of fats,
  • gene expression,
  • maintenance of cell membranes,
  • calcium control inside of cells.

Studies of myo-inositol and PCOS

The effects of myo-inositol on women with PCOS have been subject in a number of published clinical studies.

  • A study published 2014 from Italian researchers concludes “MYO administration positively modulates insulin sensitivity in non-obese PCOS patients without compensatory hyperinsulinemia, improving hormonal parameters. The presence of bromelin in the formulation modulated the pro-inflammatory state that characterizes PCOS, independently of BMI.1)Genazzani AD1, Santagni S, Ricchieri F, Campedelli A, Rattighieri E, Chierchia E, Marini G, Despini G, Prati A, Simoncini T.; “Myo-inositol modulates insulin and luteinizing hormone secretion in normal weight patients with polycystic ovary syndrome”; J Obstet Gynaecol Res. 2014 May;40(5):1353-60. doi: 10.1111/jog.12319. Epub 2014 Mar 9
  • In another study from 2015, myo-inositol combined with alpha-lipoic acid was tested on women with PCOS undergoing an IVF treatment. The author´s conclusion: “Our preliminary data suggest that the supplementation of myo-inositol and α-lipoic acid in PCOS patients undergoing an IVF cycle can help to improve their reproductive outcome and also their metabolic profiles, opening potential for their use in long-term prevention of PCOS.“.2)Rago R1, Marcucci I, Leto G, Caponecchia L, Salacone P, Bonanni P, Fiori C, Sorrenti G, Sebastianelli A.; “Effect of myo-inositol and alpha-lipoic acid on oocyte quality in polycystic ovary syndrome non-obese women undergoing in vitro fertilization: a pilot study.”; J Biol Regul Homeost Agents. 2015 Oct-Dec;29(4):913-23
  • The number of ocytes was increased following the intake of myo-inositol and folic acid. The authors write “These data show that in patients with PCOS, treatment with myo-inositol and folic acid, but not folic acid alone, reduces germinal vesicles and degenerated oocytes at ovum pick-up without compromising total number of retrieved oocytes. This approach, reducing E(2) levels at hGC administration, could be adopted to decrease the risk of hyperstimulation in such patients.3)Papaleo E1, Unfer V, Baillargeon JP, Fusi F, Occhi F, De Santis L.; “Myo-inositol may improve oocyte quality in intracytoplasmic sperm injection cycles. A prospective, controlled, randomized trial”; Fertil Steril. 2009 May;91(5):1750-4. doi: 10.1016/j.fertnstert.2008.01.088. Epub 2008 May 7.
  • A meta-study is a study that analyses a larger number of similar studies, in order to find out how robust results are. The researchers from a 2012 meta-study confirm “Among the insulin-sensitizing compounds, there is myo-inosiol (MYO). Previous studies have demonstrated that MYO is capable of restoring spontaneous ovarian activity, and consequently fertility, in most patients with PCOS.”4)Unfer V1, Carlomagno G, Dante G, Facchinetti F.;”Effects of myo-inositol in women with PCOS: a systematic review of randomized controlled trials.”;Gynecol Endocrinol. 2012 Jul;28(7):509-15. doi: 10.3109/09513590.2011.650660. Epub 2012 Feb 1..

Studies of chiro-inositol and PCOS

d-chiro-inositol was also the subject of a number of clinical studies, and the effect on ovulation of women with PCOS was confirmed:

  • A study from 2015 confirms the effect of chiro-inositol “D-Chiro-Inositol is effective in improving ovarian function and metabolism of patients affected by PCOS.”5)Laganà AS1, Barbaro L, Pizzo A.; “Evaluation of ovarian function and metabolic factors in women affected by polycystic ovary syndrome after treatment with D-Chiro-Inositol”;Arch Gynecol Obstet. 2015 May;291(5):1181-6. doi: 10.1007/s00404-014-3552-6. Epub 2014 Nov 22.

Myo-inositol or chiro-inositol for PCOS, what is better?

Since both forms of inositol have been reviewed quite intensively for the same application, some researchers went one step beyond this and asked the question: what is better, my-inotol or chiro-inositol for women with PCOS?

The main finding seems to be: both forms are effective and have different effects. This is what researchers write:

  • A study from 2014 Pizzo A., et al. “Comparison between effects of myo-inositol and D-chiro-inositol on ovarian function and metabolic factors in women with PCOS” 6)Pizzo A1, Laganà AS, Barbaro L. “Comparison between effects of myo-inositol and D-chiro-inositol on ovarian function and metabolic factors in women with PCOS”; Gynecol Endocrinol. 2014 Mar;30(3):205-8. doi: 10.3109/09513590.2013.860120. Epub 2013 Dec 19.; http://www.ncbi.nlm.nih.gov/pubmed/24351072 concluded: “Both the isoforms of inositol were effective in improving ovarian function and metabolism in patients with PCOS, although myo-inositol showed the most marked effect on the metabolic profile, whereas D-chiro-inositol reduced hyperandrogenism better.
  • In a study from 2015, the authors conclude similarily “Definitely, we assumed that both treatments with myo-inositol and with D-chiro inositol could be proposed as a potential valid therapeutic approach for the treatment of patients with PCOS7)Formuso C1, Stracquadanio M, Ciotta L.;”Myo-inositol vs. D-chiro inositol in PCOS treatment”; Minerva Ginecol. 2015 Aug;67(4):321-5. Epub 2015 Feb 11.
  • Another study from 2012 analysed the combined application of myo-inositol and chiro-inositol and recommends “The combined administration of MI and DCI in physiological plasma ratio (40:1) should be considered as the first line approach in PCOS overweight patients, being able to reduce the metabolic and clinical alteration of PCOS and, therefore, reduce the risk of metabolic syndrome.8)Nordio M1, Proietti E.; “The combined therapy with myo-inositol and D-chiro-inositol reduces the risk of metabolic disease in PCOS overweight patients compared to myo-inositol supplementation alone.”; Eur Rev Med Pharmacol Sci. 2012 May;16(5):575-81.

References   [ + ]

1. Genazzani AD1, Santagni S, Ricchieri F, Campedelli A, Rattighieri E, Chierchia E, Marini G, Despini G, Prati A, Simoncini T.; “Myo-inositol modulates insulin and luteinizing hormone secretion in normal weight patients with polycystic ovary syndrome”; J Obstet Gynaecol Res. 2014 May;40(5):1353-60. doi: 10.1111/jog.12319. Epub 2014 Mar 9
2. Rago R1, Marcucci I, Leto G, Caponecchia L, Salacone P, Bonanni P, Fiori C, Sorrenti G, Sebastianelli A.; “Effect of myo-inositol and alpha-lipoic acid on oocyte quality in polycystic ovary syndrome non-obese women undergoing in vitro fertilization: a pilot study.”; J Biol Regul Homeost Agents. 2015 Oct-Dec;29(4):913-23
3. Papaleo E1, Unfer V, Baillargeon JP, Fusi F, Occhi F, De Santis L.; “Myo-inositol may improve oocyte quality in intracytoplasmic sperm injection cycles. A prospective, controlled, randomized trial”; Fertil Steril. 2009 May;91(5):1750-4. doi: 10.1016/j.fertnstert.2008.01.088. Epub 2008 May 7.
4. Unfer V1, Carlomagno G, Dante G, Facchinetti F.;”Effects of myo-inositol in women with PCOS: a systematic review of randomized controlled trials.”;Gynecol Endocrinol. 2012 Jul;28(7):509-15. doi: 10.3109/09513590.2011.650660. Epub 2012 Feb 1.
5. Laganà AS1, Barbaro L, Pizzo A.; “Evaluation of ovarian function and metabolic factors in women affected by polycystic ovary syndrome after treatment with D-Chiro-Inositol”;Arch Gynecol Obstet. 2015 May;291(5):1181-6. doi: 10.1007/s00404-014-3552-6. Epub 2014 Nov 22.
6. Pizzo A1, Laganà AS, Barbaro L. “Comparison between effects of myo-inositol and D-chiro-inositol on ovarian function and metabolic factors in women with PCOS”; Gynecol Endocrinol. 2014 Mar;30(3):205-8. doi: 10.3109/09513590.2013.860120. Epub 2013 Dec 19.; http://www.ncbi.nlm.nih.gov/pubmed/24351072
7. Formuso C1, Stracquadanio M, Ciotta L.;”Myo-inositol vs. D-chiro inositol in PCOS treatment”; Minerva Ginecol. 2015 Aug;67(4):321-5. Epub 2015 Feb 11.
8. Nordio M1, Proietti E.; “The combined therapy with myo-inositol and D-chiro-inositol reduces the risk of metabolic disease in PCOS overweight patients compared to myo-inositol supplementation alone.”; Eur Rev Med Pharmacol Sci. 2012 May;16(5):575-81.