What is myo-inositol?
Myo-inositolused to be considered a vitamin within the vitamin B family but no longer has this designation. It is increasingly prescribed within the fertility field under the claim that it improves egg and embryo quality and, therefore, pregnancy rates in IVF. It is a so-called second messenger in signal transduction pathways and has been reported to be involved in the secretion of hormones by ovaries and some other endocrine glands. Its alleged effects have been especially highlighted in women with polycystic ovary syndrome (PCOS), where it is considered an insulin sensitizer, like metformin. Some studies have suggested that it reestablishes ovulation in a high percentage of anovulatory PCOS patients. At least one report in the literature suggests that supplementation with myo-inositol reduces the risk of gestational diabetes in pregnancy.
How is myo-inositol used in IVF cycles?
In female infertility, it has been suggested to reduce the amount of gonadotropin required for ovarian stimulation, improves egg numbers and quality and that high levels in amniotic fluid are associated with improved follicle stimulating hormone (FSH) signaling, oocyte maturation and embryo development.
Up to a dosage of 12 grams daily, myo-inositol appears to be well tolerated without significant side-effects, though nausea, fatigue, dizziness and insomnia have been reported. The most widely used dosage is 2 grams of myo-inositol in a 40:1 mixture with D-chiro-inositol in combination with 400 micrograms of folic acid twice a day. When supplementation should be initiated in association with IVF is unclear; but most reported studies initiated treatment 1-3 months before cycle start.
How does myo-inositol work?
Myo-inositol reduces androgen (male hormone levels). In hyper-androgenic PCOS patients, that may represent a significant benefit. In many other women with infertility, such as women with premature ovarian aging (POA, also called occult primary ovarian insufficiencyor oPOI) or in women with hypo-androgenic PCOS (H-PCOS), both conditions where women actually have abnormally low androgen levels, this hypo-androgenism may be exacerbated by myo-inositol supplementation.
CHR, therefore, does not recommend automatic myo-inositol supplementation since it may counteract androgen supplementation in women with POA/oPOI and H-PCOS, which at CHR is routine since ovaries must have normal testosterone levels within the ovarian micro-environment in order to produce good quality eggs at maximum numbers.
Who reaps myo-inositol fertility benefits?
In selected infertile women, especially in women with so-called classical PCOS phenotype, who demonstrate abnormally high testosterone levels in their blood, using myo-inositol supplements for fertility and pregnancy, therefore, appears indicated. CHR advises against routine supplementation in all infertile women, as the nutritional supplement industry, unfortunately, recommends without basis.