What is inositol?

Inositol is a naturally occurring sugar found in many everyday foods.

Fruit
Beans
Grains
Nuts

What inositol does

Improves insulin sensitivity
Lowers androgen levels
Helps maintain osmotic balance
Regulates ion channels

Inositol exists as nine stereoisomers. Supplements use myo-inositol, usually combined with D-chiro-inositol, at a dose of 4 g per day.

What supplementing with inositol does

Androgen (male hormone) levels fall
Insulin sensitivity increases
The number of FSH and LH receptors on the follicles falls

In patients with PCOS

In patients with PCOS, inositol supplementation leads to:

More normal sex-hormone function
More regular ovulation
Better oocyte and embryo quality

In women who ovulate normally — and especially those with low ovarian reserve

In this group, inositol supplementation causes:

A fall in androgen — yet androgen is needed to increase the pool of early follicles and to prime them to grow once stimulation begins
Fewer FSH and LH receptors on the follicles, so follicles may not grow even when stimulated

In short

For women who ovulate normally, and especially those with low ovarian reserve, inositol offers no benefit — and it may leave even fewer eggs and a poorer response to stimulation.

References

Barad DH, Gleicher N. Optimal IVF Protocols for Women over 40 and Low Functional Ovarian Reserve. In: Nikolaou DS, Seifer DB, eds. Optimizing the Management of Fertility in Women over 40. Cambridge University Press; 2022:81-97.
Hart RJ. Nutritional supplements and IVF: an evidence-based approach. Reproductive BioMedicine Online. 2024;48(3). doi:10.1016/j.rbmo.2023.103770

If your ovarian reserve is low, do not take inositol