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Inositol and PCOS

By Amber Charles-Alexis, MSPH, RDN

June 7, 2021

Inositol is a popular nutraceutical therapy for the management of PCOS. This article explains what inositol is, its function and potential role in mitigating negative symptoms of PCOS.

Picture: Wix, stock image

What is inositol?

Inositol is a family of 9 compounds found in the body and throughout nature (1, 2, 3).

In the body, inositol is made from glucose when phosphate sugar-containing compounds, such as phosphatidylinositol (PI) are broken down (2).

In women, some inositol is found in the ovaries and follicular fluid (3).

Inositol is also found in a variety of foods, including fresh fruits and vegetables, grains, meat, fish, eggs, milk, and their food products (2, 3).

On average, 500-700 mg of inositol is obtained from food per day, and up to 4g per day is made in the body (3).

However, the natural production of inositol is reduced in women with PCOS.

(Read the blog: Understanding PCOS and the role of nutrition if you're unfamiliar with PCOS).

What are the types of inositol?

Two of the nine inositol compounds are of prime interest for PCOS for their roles in insulin action (4, 5).

Myo-inositol (MI) is the most prevalent form of inositol in nature, while D-chiro-inositol (DCI) – which is made from myo-inositol – is found in lower quantities (2, 3, 6).

For instance, in the blood plasma, these two inositol compounds are found in a 40:1 MI to DCI ratio, and even up to 100:1 in the follicular fluid in the uterus (3, 6).

Despite their similar chemical structures, MI and DCI perform different metabolic functions.

What is the function of inositol?

Inositol is involved in many metabolic and biochemical pathways in the body, specifically female reproduction (3).

It stimulates the development and maturation of female eggs, fertilization, and implantation (3). It also plays a role in hormone production in the ovaries (3).

The inositol compounds are also involved in insulin production and the regulation of glucose (sugar) and fat/lipid in the body (2).

The role of inositol in PCOS management

Up to 95% of women with PCOS experience insulin resistance (7). (Learn more about PCOS and insulin resistance here).

Metformin is the main treatment for the management of high blood glucose (sugar) in women with PCOS, but it has negative side effects, including nausea, vomiting, diarrhea, abdominal pain and the reduced absorption of vitamin B12 (4, 8).

Given the “insulin sensitizing” functions of inositol, it continues to be explored as a safe replacement treatment for metformin (3, 4, 5, 8, 9). However, more research is needed.

Myo-inositol stimulates the uptake of glucose (sugar) from the blood into cells to produce energy or to be stored, and D-Chiro-inositol is involved in storing glucose as glycogen in the liver and muscles (3).

Combined, they both support improved blood sugar control in women with PCOS.

Therefore, many supplement companies have begun combining MI and DCI in a ratio that is found naturally in the body (40:1 MI to DCI) (2, 3, 6, 9).

Additional potential benefits of MI and DCI for PCOS include (1, 6, 8, 9):

  • Regular menstrual cycles

  • Matured oocytes (eggs) and restored ovulation

  • Reduced body mass

  • Reduced fatty liver (in mice studies)

Flaxseed and sweet potato have also been shown to have similar effects to inositol (4).

Risks of using inositol

Studies have shown that inositol has the benefit of improving the body’s response to insulin and that it does not have any side effects (8, 9).

The dosages used in the various studies were as much as 4 times greater than the amount of inositol consumed from foods and its long-term impact is yet to be determined.


Inositol is a family of compounds that is made in the body and that are naturally present in foods.

They are insulin sensitizers and are being explored as an alternative treatment for metformin for lowering blood glucose (sugar) levels without the negative side effects of metformin (nauseas, abdominal pain, diarrhea etc.).

Please consult with your healthcare provider/team to determine if inositol is right for you, the brand and the amount that will meet your individual needs.


The information provided in this blog is for general knowledge and is not intended to diagnose, cure or treat your medical condition. This information does not replace your need for personalized medical and nutritional expertise and intervention.


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