Recently, there has been a lot of interest in the role of inositol in the treatment of polycystic ovarian syndrome (PCOS). A recent systematic review has weighed up the evidence behind the claims (1).
The systematic review looked at the clinical outcomes of myo-inositol supplementation as a treatment for PCOS. Specifically, it examined the effects of myo-inositol on ovarian function and metabolic and hormonal parameters in PCOS sufferers.
What is inositol?
Inositol is a substance that occurs naturally in the human body, and is also present in foods such as fruits, seeds, grains and nuts. It was once thought to be a member of the B Vitamin group, but this is not strictly true – vitamins are essential nutrients that the body cannot make on its own, whereas our body can actually synthesise inositol from glucose.
Inositol is used by the body to form signalling molecules, and so it is crucial for a whole range of processes, from nerve signals to the breakdown of fats. There are several different forms of inositol, and the two forms that are considered helpful in PCOS are myo-inositol and d-chiro-insolitol.
How is inositol helpful in PCOS?
The researchers found evidence that suggests myo-inositol is helpful in PCOS because it decreases levels of excessive androgens. The study also found evidence that the nutrient improves the ovarian response to hormones called gonadotropins, helping to achieve regular menstrual cycles and successful ovulation.
Women with PCOS often have a defect in the way that their body processes insulin. This has a knock-on effect on other hormones and proteins. Sex hormone binding globulin (SHBG) is decreased, testosterone levels are raised, and the results are problems with acne, hirsutism (excessive hair growth) and fertility.
The insulin-signalling pathway is heavily dependent on myo-inositol. Supplementing extra myo-inositol therefore appears to correct the mal-functioning insulin pathways, reducing the signs and symptoms of PCOS.
The blights of PCOS: ovulation problems, acne and hirsuitism
Other studies echo these findings. A previous randomised controlled trial investigated the effects of myo-insolitol supplements versus placebo on ovarian function (2). Ninety-two women with PCOS were given either 2g myo-inositol twice daily, or a placebo pill for 16 weeks. At the end of the study, significantly more women in the inositol group were found to have normal levels estrogen and progesterone, and experienced normal ovulation. The women in the myo-inositol also showed a significant amount of weight loss over the study period. The researchers concluded that the results indicate “a beneficial effect of myo-inositol in women with oligomenorrhea and polycystic ovaries in improving ovarian function.”
A further study investigated the benefits of myo-inositol on symptoms such as acne and excessive hair growth in women with PCOS (3). After three months of supplementation, levels of insulin, testosterone and luteinizing hormone were significantly reduced. At the six-month mark, both hirsutism and acne had also decreased. The researchers concluded that myo-inositol is a “simple and safe treatment that ameliorates the metabolic profile of patients with PCOS, reducing hirsutism and acne.”
Myo-inositol is not considered toxic even at high doses. It has been supplemented in doses up to 18g daily without significant side-effects, though digestive symptoms may be experienced at this level (4). Of course, it is not at all necessary to supplement at such as high dose for PCOS where results are seen at levels of around 2-4g daily.
I always consider the two most important questions to ask when considering supplementation to be ‘is it safe?’ and ‘is it effective?’ In light of the supporting evidence for the safety and effectiveness of this particular nutrient, I would not hesitate to use myo-inositol alongside a low G.I diet as an initial therapeutic approach to address PCOS.
- Unfer V, Carlmango G, Dante G, Facchinetti F (2012) Effects of myo-inositol in women with PCOS: a systematic review of randomized controlled trials. Gynecol Endocrinol 28(7):509-15.
- Gerli S, Papleo E, Ferrari A, Renzo GC (2007) Randomized, double blind placebo-controlled trial: effects of Myo-inositol on ovarian function and metabolic factors in women with PCOS. European Review for Medical and Pharmacological Sciences 11: 347-354.
- Zacchè MM, Caputo L, Filippis S, Zacchè G, Dindelli M, Ferrari A (2009) Efficacy of myo-inositol in the treatment of cutaneous disorders in young women with polycystic ovary syndrome. Gynecol Endocrinol 25(8):508-13.
- Lam S, McWilliams A, leRiche J, MacAulay C, Wattenberg L, Szabo E (2006) A Phase I Study of myo-Inositol for Lung Cancer Chemoprevention. Cancer Epidemiol Biomarkers Prev 15: 1526.