Myo-inositol is a compound that is a member of the vitamin B complex group. Myo-inositol is widely distributed in nature. It is found in a wide variety of foods including fresh fruits, beans, whole grains and seeds.
Myo-inositol has been used in the treatment of diabetic neuropathy, depression, Alzheimer’s disease, panic disorder and polycystic ovary syndrome. It has also been proposed as a preventing agent for folate resistant neural tube defects.
Myo-inositol is generally well tolerated and appears safe when used at doses up to 12 g per day. The longest reported utilization of myo-inositol for enhancing fertility is 12 months. Common side effects may include nausea fatigue, dizziness and insomnia.
Myo-inositol and PCOS
Many patients with PCOS are insulin resistant. Myo-inositol has been used as a supplement in patients with PCOS based on this observation. It is classified as an insulin-sensitizing agent acting to regulate a number of cellular functions including improved insulin utilization.
In several clinical studies, mainly from Europe, myo-inositol has been shown to improve menstrual regularity (80-85%) and improve ovulatory function (60-70%) in women with PCOS. It appears at least as effective as Metformin; another insulin-sensitizing drug.
Myo-inositol may help induce ovulation in women with PCOS by improving insulin sensitivity and utilization, therefore lowering serum insulin levels. Clinical studies have shown that both myo-inositol and D-chiro-inositol may:
- Decrease serum androgen
- Decrease triglycerides
- Increase HDL cholesterol
- Lower systolic and diastolic blood pressure
Myo-inositol and IVF
A positive correlation has been found between myo-inositol concentration in follicular fluid and oocyte maturity and quality.
Non-PCOS IVF Patients receiving 4 grams of myo-inositol with folic acid 800 mcg daily have demonstrated a reduction in the amount of FSH administered, a reduction in the total number of mature oocytes obtained with no resulting change in clinical pregnancy rates. In patients with a history of low oocyte quality, a recent study showed improved oocyte quality and pregnancy outcomes in patients who received myo-inositol, folic acid and Melatonin.
In studies of PCOS patients undergoing IVF, pretreatment with myo-inositol 4 grams with folic acid 800mcg daily resulted in less total FSH used for stimulation. The studies do differ in that both lower and higher numbers of mature oocytes were obtained in those taking myo-inositol. Pregnancy rates have been reported either similar or improved (trend, but not statistically significance) as compared to patient’s only taking folic acid.
Take home points
- Myo-inositol is a dietary supplement available without prescription.
- Myo-inositol appears safe and non-toxic at doses of up to 12 grams/day.
- The typical treatment dose is 2 grams with folic acid 400 mcg twice daily.
- In patient with PCOS, a high percentage of women will establish menstrual regularity and show evidence of ovulation. The average time to ovulation in 1 study was 25 days.
- For IVF, no standard time for pretreatment with myo-inositol has been established. The majority of studies start the myo-inositol 3 months before the actual IVF cycle.
- Emerging evidence shows promise for the use of myo-inositol in the reduction/prevention of gestational diabetes in patients with PCOS or at risk due to family history.