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The PCOS Newsletter is a weekly publication answering one PCOS question at the time so we can be empowered by knowledge.

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PCOS and Inositol

Hi there,

How was your week? This is Francesca from The PCOS Newsletter. Today we are discussing Inositol 🤗.

This week’s question

Should I take Inositol for my PCOS?

The answer

Inositol has some very good evidence behind it to suggest its effective use in regulating hormonal cycles and improving all PCOS symptoms. In the style of this newsletter, let’s break down what it is and how it works.

What is Inositol?

Inositol is a family of 9 molecules. The ones that have been studied and are the most relevant for us are Myo-inositol (MI) and D-chiro Inositol (DCI). They are naturally occurring in our body and can be found in food 🌽.

They act as messengers and regulate several hormones such as thyroid-stimulating hormone, FSH (follicle-stimulating hormones) and insulin. I have never heard of them outside of the PCOS context but it turns out they are quite hard-working molecules 💪🏼. Inositol is considered a pseudovitamin. This means it doesn’t quite qualify to be an essential vitamin as a deficiency in this molecule does not translate into severe consequences (even though it kind of does ⏬).

What does inositol do in the body?

Inositol's main role in the body is glucose metabolism. Insulin helps transport glucose into the cells. Inositol can mimic the action of insulin and encourage the cells to take in glucose to be used for energy production. Our ovaries use MI to mature the egg and prepare it for ovulation. Naturally, our body takes Myo-inositol and converts it to D-chiro Inositol. They act differently but are both involved in insulin signaling and glucose metabolism. Myo-inositol is involved in the transportation and use of glucose, while D-Chiro is mainly involved in synthesis and storage.

How does inositol link to PCOS?

Interestingly, each organ has a specific MI/DCI ratio related to its function. Usually, in the ovaries, the MI/DCI ratio is 100:1 but when analysed in women with PCOS it was 0.2:1 (reduced by 500 times 🙀). The impairment of ovarian function in PCOS patients has been specifically associated with this imbalance.

There seems to be an issue with the availability of Inositol as an increased urinary loss of Myo-inositol has been noticed in those that are insulin resistant. It is thought that this loss is due to the poor conversion of Myo-inositol into D-chiro inositol. Imbalances in the MI:DCI ratios are so tightly linked to insulin abnormalities to be considered an early marker of insulin resistance.

When supplementing with Inositol, it leads to:

  • An increase in the ovaries’ sensitivity to FSH. As we reviewed in the Irregular period article, an imbalance between LH and FSH (the hormones that tell your ovaries to mature the egg) causes your ovaries to overproduce androgens. An enhanced action of FSH means that LH and FSH are more in balance, reducing the number of androgens produced.

  • A decrease in insulin resistance Less insulin in the body means less overproduction of androgens. We know that excess insulin stimulates excess production of testosterone (if you want to revise how insulin resistance impacts PCOS please head over here)

  • An increase in SGHB This is the testosterone transporter we really need. Its levels are often reduced in women with PCOS leaving testosterone running free.

As a result of the above, it can restore normal menstrual cycles and induce ovulation 🎉.

A recent 2023 meta-analysis of 26 randomised control trials (the gold standard for studies) evaluating data of 1691 patients who were treated mainly with MI showed:

  • improved cycle regulation at an efficiency similar to Metformin

  • decrease levels of free testosterone

  • increased SHBG

  • reduced fasting glucose

Which foods are high in Inositol?

The food categories that contain the highest concentration of inositols are fruits, beans, corn and nuts:

  • Grains: Buckwheat, wild rice, and popcorn.

  • Legumes: Beans, chickpeas, and lentils.

  • Nuts: Almonds, cashews, macadamia, walnuts, and pecans.

  • Seeds: Flaxseeds, sunflower seeds, and sesame seeds.

You will notice that these foods are very high in fibre. Several investigations have shown that the effect fibre has on the decrease of colon cancer incidence and diabetes is due to the high inositol content of these foods. Fibre is not only important for 💩.

What supplement formulation should I chose?

There are multiple supplement formulations out there. There seems to be good evidence to suggest that MI alone (2000mg taken twice a day) or MI:DCI (40:1) ratio can lead to an improvement in symptoms.

There are a few studies that show that supplementing with higher doses of DCI (compared with MI) can negatively impact PCOS through an increase in testosterone. Some experts have shown concern over the different formulations available in the market so I would proceed with caution for any supplements with higher dosages of DCI.

It is advisable to keep taking Inositol for at least 24 weeks to see improvements. A study showed that a significant increase in serum SHBG was observed only in those studies where MI was administered for at least 24 weeks but none for 16 weeks. This is an important point for all PCOS changes you make. The follicles that will develop the egg are dormant and it takes them over a year to develop from their state and 190 days to get a blood supply. It is often the case that when you make changes to your lifestyle or supplement regime it can take between 6 months and 1 year to show results. Unfortunately, most of us give up by then.

For some women supplementing with Inositol seems to not work. There are reports of ‘inositol resistance’ which is linked to poor absorption of inositol. Innovative approaches combining alpha-lactalbumin with Myo-inositol seem to increase the absorption of inositol and overcome this resistance.

Inositol can also come with side effects. These tend to be mild and may include nausea, stomach pain, tiredness, headaches, and dizziness.

Back to the original question, should I take inostiol?

Inositol supplementation seems to be safe and effective.I would recommend speaking to a healthcare provider before taking it, especially if you are on other medication. Healthcare providers have tools to check for potential interactions.

In my personal experience, I have been taking Myo-Inositol for 1 year. It has restored my periods and decreased my PCOS symptoms. This is in combination with a good diet and exercise, which play a massive role in the management of PCOS.

I hope you enjoyed this week’s post. If you’d like me to cover any other topic please don’t hesitate to submit it here.

See you next Sunday,



Bevilacqua, A., & Bizzarri, M. (2018). Inositols in insulin signaling and glucose metabolism. International Journal of Endocrinology, 2018, 1968450.

Greff, D., Juhász, A. E., Váncsa, S., Váradi, A., Sipos, Z., Szinte, J., Park, S., Hegyi, P., Nyirády, P., Ács, N., Várbíró, S., & Horváth, E. M. (2023). Inositol is an effective and safe treatment in polycystic ovary syndrome: a systematic review and meta-analysis of randomized controlled trials. Reproductive Biology and Endocrinology: RB&E, 21(1), 10.

Kalra, B., Kalra, S., & Sharma, J. B. (2016). The inositols and polycystic ovary syndrome. Indian Journal of Endocrinology and Metabolism, 20(5), 720–724.

Merviel, P., James, P., Bouée, S., Le Guillou, M., Rince, C., Nachtergaele, C., & Kerlan, V. (2021). Impact of myo-inositol treatment in women with polycystic ovary syndrome in assisted reproductive technologies. Reproductive Health, 18(1), 13.

Monastra, G., Vucenik, I., Harrath, A. H., Alwasel, S. H., Kamenov, Z. A., Laganà, A. S., Monti, N., Fedeli, V., & Bizzarri, M. (2021). PCOS and inositols: Controversial results and necessary clarifications. Basic differences between D-chiro and myo-inositol. Frontiers in Endocrinology, 12, 660381.

Nordio, M., Basciani, S., & Camajani, E. (2019). The 40:1 myo-inositol/D-chiro-inositol plasma ratio is able to restore ovulation in PCOS patients: comparison with other ratios. European Review for Medical and Pharmacological Sciences, 23(12), 5512–5521.

PubChem. (n.d.). Inositol. Retrieved March 13, 2023, from

Unfer, V., Facchinetti, F., Orrù, B., Giordani, B., & Nestler, J. (2017). Myo-inositol effects in women with PCOS: a meta-analysis of randomized controlled trials. Endocrine Connections, 6(8), 647–658.

Disclaimer: We are all so unique in our own ways so this information is for education purposes only. Please further consult your healthcare provider about your health needs.

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