Myo-inositol and PCOS: a natural ally validated by science

For several years now, one active ingredient has been attracting particular attention from researchers: myo-inositol. Increasingly studied, it is emerging as a promising natural approach to support women with PCOS. But what exactly is myo-inositol, and what do studies actually say about it?

1. Understanding PCOS (Polycystic Ovary Syndrome)

a. Definition and key symptoms

Polycystic ovary syndrome (PCOS) is an endocrine disorder affecting nearly 10% of women of reproductive age. It is characterized by:

• Menstrual cycle disorders: irregular cycles, anovulation, infrequent or absent periods.
• Excess androgens: hormonal acne, hirsutism, hair loss.
• Metabolic effects: insulin resistance, abdominal weight gain, increased risk of type 2 diabetes.

Beyond the visible symptoms, PCOS is a multifactorial disease that affects metabolic, hormonal, and reproductive health.

b. PCOS and insulin resistance: a vicious cycle

Nearly 70% of women with PCOS have insulin resistance (Diamanti-Kandarakis et al., 2006). This means their bodies respond less effectively to this hormone, leading to:

• an increase in insulin production,
• excessive stimulation of the ovaries, which produce more androgens (male hormones),
• symptoms such as acne, excessive hair growth, or anovulatory cycles,
• and often weight gain or metabolic disorders.

This imbalance explains why many women with PCOS struggle to naturally regulate their cycle and fertility.

2. Myo-inositol, a molecule at the heart of hormonal balance

a. A key isomer of inositol

Inositol is a molecule belonging to the polyol family, often associated with B vitamins. Of its nine isomers, myo-inositol is the most abundant in the body. It acts as an intracellular second messenger, playing a role in the regulation of insulin, sex hormones, and neurotransmitters.

b. Origins and physiological roles of myo-inositol

Myo-inositol is a substance naturally present in food (fruits, legumes, whole grains) and synthesized in our bodies. Sometimes (incorrectly) referred to as "vitamin B8," it actually acts as a cellular messenger. It plays a crucial role in the transmission of signals from insulin (the hormone that regulates blood sugar) and sex hormones involved in ovulation.

In other words, it intervenes at the crossroads of the two major axes disrupted in PCOS: hormonal balance and metabolism.

In women with PCOS, a functional deficiency in myo-inositol may be observed, justifying the interest in supplementation.

3. Myo-inositol and PCOS: proven benefits

a. Improvement in insulin resistance and metabolic profile

Numerous clinical studies show that myo-inositol improves insulin sensitivity and contributes to better blood glucose regulation. This helps reduce hyperinsulinemia, limit weight gain, and improve lipid profile.

According to Costantino et al. (2009), taking 4 g/day of myo-inositol reduces insulinemia and improves insulin sensitivity, with benefits on weight management and lipid profile.

b. Restoration of ovulation and regulation of cycles

By acting on insulin signaling and hormonal regulation, myo-inositol promotes the return of more regular menstrual cycles and the restoration of ovulation. It is therefore a valuable tool among dietary supplements for regulating menstrual cycles .

A study conducted by Gerli et al. (2007) showed that after 3 months of supplementation, 65% of women regained spontaneous ovulation (compared to only 21% in the placebo group).

c. Oocyte quality and success in ART/IVF

Myo-inositol plays a major role in oocyte maturation. Studies have shown that supplementation improves oocyte quality and increases success rates in assisted reproductive technology (ART), particularly in vitro fertilization (IVF).

Papaleo et al. (2009) observed that myo-inositol improved oocyte quality and increased the chances of pregnancy in women with PCOS undergoing fertility treatment.

It is thus used in some fertility supplements based on myo-inositol .

d. Other related benefits

In addition to its impact on metabolism and reproduction, myo-inositol is being studied for its potential in various fields:

• Reducing anxiety and improving mood through its role in neurotransmission.
• Thyroid balance.
• Energy metabolism.

4. Optimal dosage and practical recommendations

a. Usual dosage

The majority of studies converge on a dosage of 4 g of myo-inositol per day.

This assay is now recognized as the clinical reference by several learned societies, including the ESHRE (European Society of Human Reproduction and Embryology).

🔎 These dosages are found in several myo-inositol-based food supplements .

b. Ratio with D-chiro-inositol

Recent studies ( Frontiers in Endocrinology , 2021; MDPI , 2023) show that an excess of D-chiro-inositol (DCI) can reduce oocyte quality and promote hyperandrogenism. Conversely, myo-inositol alone remains the safest and most effective form for supporting ovulation, regulating cycles, and improving hormonal balance in PCOS.

c. Relevant associations

Myo-inositol is even more effective when combined with other micronutrients:

• Folic acid (vitamin B9) : to support fertility and cell division.
• Vitamin D and chromium : to enhance insulin sensitivity.
• Omega-3 : to reduce inflammation and improve metabolic profile ( learn more about the role of omega-3 in managing PCOS ).

d. A reassuring security profile

Myo-inositol is generally very well tolerated. However:

• It should be used under medical supervision, particularly in women undergoing hypoglycemic treatment.
• Supplementation should be adjusted in case of pregnancy and breastfeeding.
• It is not a substitute for a balanced diet or a healthy lifestyle.

5. Myo-inositol: a natural ally in the management of PCOS

Myo-inositol is currently one of the most studied and recommended supplements for the natural management of PCOS. By improving insulin sensitivity, promoting ovulation, and optimizing fertility, it offers a valuable alternative or complement to conventional drug treatments.

Its safety profile, natural origin and proven effectiveness make it a valuable ally for women with PCOS who wish to better manage their symptoms and preserve their reproductive and metabolic health.

FAQ: Myo-inositol and PCOS

✔️ Is myo-inositol effective in PCOS?

Yes. Numerous clinical studies show that myo-inositol improves insulin sensitivity , promotes regularity of menstrual cycles and restores ovulation in women with PCOS (Unfer V. et al., Gynecol Endocrinol , 2017, PubMed ID: 28322154).

✔️ What is the difference between myo-inositol and D-chiro-inositol?

Myo-inositol and D-chiro-inositol are two isomers of inositol. Myo-inositol primarily affects fertility and hormonal signaling , while D-chiro-inositol acts more on glucose metabolism . Studies ( Frontiers in Endocrinology , 2021; MDPI , 2023) warn against excessive intake of D-chiro-inositol, which could impair oocyte quality and promote hyperandrogenism.

✔️ Why favor myo-inositol alone in PCOS?

Myo-inositol alone is better documented for improving oocyte quality, regulating ovulation, and supporting fertility. At high doses, D-chiro-inositol can reduce the bioavailability of myo-inositol, which is essential for FSH signaling (Frontiers, 2021), and interfere with aromatase (MDPI, 2023), potentially exacerbating certain PCOS symptoms.

✔️ What is the recommended dosage in the case of PCOS?

The usual dosage is 4 g of myo-inositol per day , often combined with 400 µg of folic acid, taken in two doses. This dosage has shown the greatest efficacy in clinical trials. It is found in several myo-inositol-based dietary supplements such as GYN OPK®.

✔️ Can myo-inositol improve outcomes in ART/IVF?

Yes. Myo-inositol helps improve egg quality and success rates in assisted reproductive technology (ART/IVF). It is notably included in certain fertility supplements based on myo-inositol, such as those in the GAMETIX® range.

✔️ Is myo-inositol well tolerated?

Myo-inositol is generally well tolerated, with very few reported side effects. It can be used long-term, under appropriate medical supervision and in conjunction with a healthy lifestyle.