New reports suggest that a compound called myo-inositol may have beneficial effects on Polycystic Ovary Syndrome (PCOS), and improve symptoms of insulin resistance and metabolic syndrome. DietDoc takes a closer look.
Like the many desperate members of the public who ask for advice on how to treat Polycystic Ovary Syndrome (PCOS) and to conceive, or to combat metabolic syndrome and lose weight, I also sometimes get despondent that researchers have as yet not come up with simple solutions to counteract these modern-day scourges and produce effective weight loss. After all, finding a solution to insulin resistance and permanent weight loss is one of the top research priorities if we want to stem the inexorable tides of metabolic derangements and obesity that are engulfing the world.
New research findings
As mentioned last week, researchers have recently been busy publishing the results of a variety of studies that have bearing on obesity. Some of these relate to the finding that myo-inositol with, or without folic acid and melatonin, seems to help in PCOS, metabolic syndrome and weight loss (Unfer et al, 2011; Giordano et al, 2011).
Potential benefits of myo-inositol
A number of reports have been published in the scientific press suggesting that a compound called myo-inositol may have beneficial effects on Polycystic Ovary Syndrome (PCOS), and improve the symptoms of insulin resistance and the metabolic syndrome.
A range of studies, mainly conducted in Italy, have shown that myo-inositol with/without folic acid and/or melatonin increases fertility in women with PCOS, which affects approximately 7.5% of the female population (Bloomgarden et al, 2001). PCOS is characterised by an inability to conceive due to high testosterone levels and anovulation, as well as impaired glucose tolerance and insulin resistance with weight gain and problems with losing weight in up to 40% of these patients (Papaleo et al, 2007).
Myo-inositol & PCOS
The following results have been obtained with myo-inositol/folic acid/melatonin treatments in PCOS:
D-chiro-inositol (one form of inositol) has been used successfully as a so-called ‘insulin-sensitizing agent’ in PCOS patients to improve insulin sensitivity, promote weight loss, reduce raised testosterone levels and increase ovulation rates and thus fertility (Bloomgarden et al, 2001).
Another form of inositol, known as myo-inositol, and sold commercially with folic acid as a product called “Inofolic” produced spontaneous menstrual cycles in up to 88% of anovulatory patients and maintained normal ovulation in 72% of patients for up to 6 months (Papaleo et al, 2007)
A double-blind trial using myo-inositol plus folic acid treatment compared to folic acid alone, significantly reduced testosterone levels, blood triglyceride levels (high triglyceride levels are associated with PCOS and metabolic syndrome), blood pressure and blood glucose tolerance curve values (indicating improved insulin sensitivity). In addition ovulation was restored in nearly 70% of the women receiving the myo-inositol plus folic acid treatment (Costantino et al, 2009)
Addition of melatonin (a hormone that regulates sleep) to myo-inositol treatment improved ovarian function and fertility in infertile women (Unfer et al, 2011).
Myo-inositol & the metabolic syndrome
The following studies also produced positive results with the use of myo-inositol to improve the symptoms of metabolic syndrome in PCOS patients and overweight post-menopausal women:
Overweight PCOS patients had improved insulin levels, glucose tolerance curves and increased insulin sensitivity after 12 weeks of treatment with myo-inositol and/or folic acid (Genazzani et al, 2008).
Another study in 80 overweight postmenopausal women suffering from the metabolic syndrome (characterised by increased BMI, high blood pressure, raised blood fat levels including LDL-cholesterol, and low HDL-levels, high glucose and insulin levels indicating insulin resistance), were treated with low-energy diets and then randomly assigned to receive either 2 g of myo-inositol or placebo twice a day for a period of 6 months. In comparison to placebo (low-energy diet only), positive results were obtained with the myo–inositol treatment for the following parameters:
Systolic and diastolic (-11%) blood pressure decreased
The decreases in ‘bad’ LDL-cholesterol and triglyceride (-20%) levels were highly significant
‘Good’ HDL-cholesterol levels increased by 22% (a positive finding)
A significant decrease in waist circumference was found
A decrease of -70% in hyperinsulinaemia was obtained
(Giordano et al, 2011)
Because both the treatment and the placebo groups in the study conducted by Giordano and his coworkers (2011), used a low-energy diet, the difference in weight loss between the treatment and the control groups was not significant. However, if the pronounced improvement in hyperinsulinaemia is taken into account and the reduction in waist circumference (indicating loss of abdominal fat), then it is possible that the use of myo-inositol will also aid weight loss in postmenopausal women as was demonstrated in the PCOS study in younger women conducted by Bloomgarden and coworkers (2001) mentioned above.
What is myo-inositol?
Inositol is a carbohydrate that was originally classified as one of the B vitamins, namely vitamin B8. But, because humans are able to synthesise inositol from glucose, it is currently not regarded as an essential nutrient like the other members of the B complex. Inositol is found in certain fruits such as cantaloupe (spanspek) and oranges. Phytate, the indigestible hexaphosphate form of inositol, is relatively common in many plant foods, including high-bran cereals, legumes and nuts. Mother’s milk contains inositol and it has been found that the inositol content of baby formulas used for premature infants needs to be increased to promote optimum growth.
Up to nine different so-called stereo-isomers of inositol have been identified, which is why some of the studies have used D-chiro-inositol (Bloomgarden et al, 2001), while others have used myo-inositol (Unfer et al, 2011).
Inositol appears to play a role in a process called ‘insulin signal transduction’ (i.e. facilitating insulin signalling to body cells, thus reducing insulin resistance), improving fertility and lowering ‘bad’ LDL-cholesterol and triglyceride levels in the blood, while increasing ‘good’ HDL-cholesterol concentrations.
At this stage, it is important to emphasise that research into the role of myo-inositol in infertility, metabolic syndrome, insulin resistance and weight loss, is in the early stages and that there are still many questions that need to be answered before myo-inositol can be freely prescribed for all these conditions. For example, we don’t know if high doses of myo-inositol can cause negative side-effects and how effective the treatment will be in patients who are overweight without suffering from insulin resistance or PCOS. Giordano and his coworkers (2011), have also mentioned that some populations have been found to react favourably to myo-inositol (i.e. Italian and Venezuelan subjects), whereas other have not (American subjects). This could indicate that the effect of myo-inositol may be linked to a genetic predisposition.
Although Inofolic (a combination of myo-inositol and folic acid) as used by Papaleo and his team (2007), is available in South Africa, patients suffering from infertility, metabolic syndrome, insulin resistance, and obesity associated with metabolic syndrome and PCOS, should discuss the use of Inofolic with their medical doctors before using this supplement.
As more research results become available, we will hopefully obtain answers to the questions listed above and if myo-inositol with/without folic acid proves safe and effective, then there may at last be a glimmer of light at the end of the obesity and associated diseases tunnel.
- (Dr IV van Heerden, DietDoc, November 2011)
(Bloomgarden ZT et al, 2001. Use of insulin-sensitizing agents in patients with polycystic ovary syndrome. Endocr Pract, Vol 7(4):279-86; Costantino D et al, 2009. Metabolic and hormonal effects of myo-inositol in women with polycystic ovary syndrome. Eu Rev Med Pharmacol Sci, Vol 13(2):105-10; Genazzani AD et al, 2008. Myo-inositol administration positively affects hyperinsulinemia and hormonal parameters in overweight patients with polycystic ovary syndrome. Gynecol Endocrinol, Vol 24(3):139-44; Giordano D et al, 2011. Effects of myo-inositol supplementation in postmenopausal women with metabolic syndrome: A prospective, randomized, placebo-controlled study. Menopause, Vol18(1):102-104; Papaleo E et al, 2007. Myo-inositol in patients with polycystic ovary syndrome: a novel method of ovulation induction. Gynecol Endocrinol, Vol 23(12):700-3; Unfer V et al, 2011. Effect of a supplementation with myo-inositol plus melatonin on oocyte quality in women who failed to conceive in previous in vitro fertilization cycles for poor oocyte quality: a prospective, longitudinal, cohort study. Gynecol Endocrinol, Vol 27(11):857-61)
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