Both myo-inositol and D-chiro-inositol have been shown to effect ovarian function and metabolic factors in women with polycystic ovarian syndrome (PCOS). They have been shown to improve androgen levels, increase the action of insulin, reduce systolic blood pressure and more.
The purpose of the current study was to compare the effects of myo-inositol and D-chiro-inositol in women with PCOS. Fifty women were enrolled, with a diagnosis of PCOS, according to the Rotterdam criteria. They were randomized into two groups, and 25 were treated with 4 gm of myo-inositol plus 400 mcg of folic acid daily for 6 months and the other 25 were treated with 1 gm of D-chiro-inositol plus 400 mcg/folic acid per day.
In the myo-inositol group, there were statistically significant reductions of diastolic and systolic blood pressure, lowering of luteinizing hormone (LH), lowering of the LH/FSH (follicle stimulating hormone) ratio lowering of total testosterone and free testosterone and androstenedione and prolactin and the HOMA Index (homeostasis model assessment)- to check for insulin resistance. These same patients also had a statistically significant increase of SHBG (sex hormone binding globulin) and of the glycemia/immunoreactive insulin ratio.
In the D-chiro-inositol group, there was a statistically significant reduction of systolic but not diastolic blood pressure, a statistically significant reduction of the Gallwey-Ferriman Score (a measure of hirsutism), of LH, LH/FSH ratio, total testosterone, free testosterone , androstenedione, prolactin and the HOMA Index.
Both inositols reduced systolic blood pressure, LH, LH/FSH ratio, circulating androgens, prolactin and increased insulin sensitivity and SHBG. Myo-inositol may decrease in a more statistically significant way, the LH/FSH ratio, total testosterone, and the HOMA index. D-chiro-inositol is likely to reduce mostly, but not statistically significant, the LH and free testosterone levels and may increase, but not in a significant way, the glycemia/IRI ratio.
It could be concluded from this comparison that both the inositol isoforms are effective in improving the ovarian function and metabolism of women with PCOS, although myo-inositol showed the greater impact on the metabolic profile and D-chiro-inositol affected more positively the hyperandrogenism measurements. In comparing the two products pre and post treatment, there was a higher regularization of menstrual cycles in those treated with D-chiro-inositol compared to those with myo-inositol, although this was not statistically significant.
Commentary: Polycystic ovarian syndrome (PCOS) is one of the most common endocrine disorders in reproductive aged women. The majority of women with PCOS (about 74%) do not ovulate, almost half (about 42%) have insulin-resistance, and almost half (48%) have hyperandrogenism. It’s important to remember that PCOS is a syndrome… and not all women with PCOS have any one sign or symptom. Not all actually have multiple cysts on the ovaries, not all have excess body hair and not all have abnormal menstrual cycles. In women with PCOS though, the insulin-resistance is commonly associated with hyperinsulinemia which then enhances the production of androgens by the ovarian theca cells, leading to a reduction in circulating levels of sex hormone binding globulin (SHBG), which then leads to increased levels of free testosterone. Nutritional, lifestyle, nutritional supplements and pharmaceutical strategies try to address the syndrome by targeting this core issue of improving insulin sensitivity which thereby addresses the signs and symptoms of PCOS. Both myo-inositol and D-chiro-inositol in the doses used in this study, have benefit in improving ovarian function and metabolism in PCOS, but myo-inositol showed the most effect on the metabolic profile and D-chiro-inositol reduced the hyperandrogenism better.
Pizzo A, Lagana A, Barbara O. Comparison between effects of myo-inositol and D-chiro-inositol on ovarian function and metabolic factors in women with PCOS. Gynecological Endrocrinology 2014; 30(3): 205-208