How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
Myo-inositol
A molecule similar to sugars, found in food. Almost all research into it focuses on women’s health: gestational diabetes, polycystic ovary syndrome and IVF.
Benefits
- Reduces the incidence of gestational diabetes: 14.0 per cent compared with 33.6 per cent in the placebo group amongst obese pregnant women, and 6 per cent compared with 15.3 per cent amongst those with a family history of type 2 diabetes
- Confirmed by a meta-analysis: across five randomised trials, the risk of gestational diabetes is reduced by more than half (relative risk 0.43), with fewer preterm births
- In women with polycystic ovaries undergoing ovulation induction, more mature follicles and oocytes are retrieved, embryo quality is better, and fewer immature oocytes are retrieved
- In in vitro fertilisation, it reduces the amount of gonadotropins required for ovarian stimulation (8 studies, 812 participants)
- In postmenopausal women with metabolic syndrome, it improves blood glucose levels, insulin levels, HOMA-IR, triglycerides, cholesterol and blood pressure over the course of a year
Precautions
The studies focus on medical conditions — pregnancy, polycystic ovary syndrome, IVF treatment, the menopause — and are carried out under medical supervision. Medical advice is therefore essential before taking it, particularly during pregnancy. Almost all of these trials combine myo-inositol with folic acid, making it difficult to isolate the effect of myo-inositol alone. It is also worth noting that the most favourable meta-analysis found no effect on blood glucose levels two hours after a glucose load, nor on gestational age, birth weight or macrosomia. In IVF, the duration of stimulation is shortened only in women with polycystic ovary syndrome. And in overweight women with this syndrome, the combination of myo-inositol and D-chiro-inositol performs better than myo-inositol alone.
Recommended dosage
2 g twice daily, almost always combined with folic acid: this is the dosage regimen used in virtually all trials, both in pregnant women and in cases of polycystic ovary syndrome. The study on the thyroid uses 600 mg per day, combined with selenium.
How to take it
- Dose: 2 g twice a day, almost always with folic acid. This is the protocol used in almost all trials.
- During pregnancy: trials on gestational diabetes involve women at risk (overweight, obesity, family history of diabetes). In one of them, 14% developed gestational diabetes versus 33.6% in the placebo group.
- How long: 3 to 6 months for polycystic ovary syndrome; 6 to 12 months in trials on metabolic syndrome after menopause.
- With D-chiro-inositol: in polycystic ovary syndrome, the combination outperformed myo-inositol alone at 3 months; at 6 months, both were equivalent.
- For the thyroid: 600 mg per day with selenium, in an observational study only.
Did you know?
During in vitro fertilisation (IVF), myo-inositol may reduce the amount of hormones required for ovarian stimulation, in both women with and without polycystic ovary syndrome.
What the studies say
This systematic review and meta-analysis examined the effect of myo-inositol supplementation on the prevention of gestational diabetes mellitus (GDM) in overweight and obese pregnant women. The results, based on four randomized trials, show that myo-inositol significantly reduces the incidence of GDM, as well as fasting blood glucose levels and those after the glucose tolerance test. It also reduces the incidence of GDM complications such as gestational hypertension and preterm delivery.
Mashayekh-Amiri S, Mohammad-Alizadeh-Charandabi S, Abdolalipour S, Mirghafourvand M. — Diabetology & metabolic syndrome (2022) — View the source study
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more