Inositol For PCOS: What It Is And How It Works

If you have polycystic ovarian syndrome (PCOS), chances are you've heard of inositol supplements. Some people who take this supplement highlight its benefits, such as menstrual cycle regulation. Research also shows that it can improve insulin resistance and ovulatory frequency, among other PCOS symptoms.

This article explores how this supplement works and presents a balanced argument about its efficacy. This will help you make an informed decision about using inositol.

Have you considered clinical trials for Polycystic ovarian syndrome (PCOS)?

We make it easy for you to participate in a clinical trial for Polycystic ovarian syndrome (PCOS), and get access to the latest treatments not yet widely available - and be a part of finding a cure.

What is PCOS?

PCOS is a complex hormonal condition affecting women of reproductive age. The exact cause of this condition is unknown, but symptoms include the following:

  • Elevated male sex hormones

  • Enlarged ovaries

  • Fluid-filled sacs (polycystic ovaries)

  • Absent or irregular ovulation

  • Irregular periods

Other signs and symptoms can include acne, facial hair, infertility, male pattern baldness, and weight gain. Many women with PCOS also experience insulin resistance, increasing their risk of diabetes and other metabolic conditions.

With no definitive cure, health experts currently focus on providing symptomatic relief for PCOS. Of the options available, inositol is one of science’s most-researched supplements.

What is inositol?

Inositol is a type of sugar molecule with many biological functions. It's found in tissues throughout your body, mainly in the brain and heart. It plays a vital role in cell signaling, regulating multiple pathways like:

  • Egg maturation

  • Insulin sensitivity

  • Cell growth and differentiation

  • Chemical messengers in the brain

  • Glucose metabolism

People often call inositol vitamin B8, although it's not an actual vitamin because it can be synthesized from glucose. There are nine forms of inositol, and two of these play important roles: Myo-inositol (MI) and D-chiro-inositol (DCI). It also occurs naturally in fruits, grains, nuts, beans, and organ meats.

How does inositol work for PCOS?

At the basic level, PCOS is all about insulin resistance. This is where inositol supplements can come in to improve insulin sensitivity.

Insulin regulates sugar (glucose) availability and use in your blood. This hormone moves sugar out of the bloodstream into your cells for energy. For this to happen, the hormone has to bind to a receptor on the cell's surface. Once insulin binds to its receptors, “second messengers” unlock and release, telling the cell it's time to take in the glucose from the blood.

In short, a second messenger is a go-between from hormone receptors outside your cells to the inside. Inositols are naturally present molecules in the body, acting as second messengers in various cellular processes.

Women with PCOS may have lower amounts of inositol in their tissue, so being unable to properly metabolize inositol may contribute to further insulin resistance. This is where supplements can come in. Given that inositol works as an insulin-signaling messenger, it can help combat PCOS symptoms.

Other benefits of using inositol for PCOS

Clinical studies have shown that inositol can relieve PCOS symptoms and effects, including:

Reducing androgen levels (including testosterone)

Women with PCOS have higher than usual androgens, including testosterone and dihydrotestosterone (DHT). This triggers unwanted symptoms like male pattern baldness, facial hair, and acne. In one study on women with PCOS, myo-inositol supplementation reduced androgen levels. The women also noticed an improvement in PCOS symptoms.

Regulating menstrual cycles

Women with PCOS experience irregular or no periods at all. This may be in part due to the impact of insulin on the menstrual cycle and the impact of abnormal gonadotropin (reproductive hormone, such as FSH) release. However, there is also evidence of intrinsic issues of the ovaries with egg production.¹

As we've seen above, treatment with inositol improves insulin sensitivity. It can also improve periods as myo-inositol impacts FSH signaling, including at the ovarian level.

Inositol supports fertility

70-80% of women with PCOS experience infertility caused by the ovaries not releasing eggs.² Secondly, people with PCOS may not ovulate regularly, reducing pregnancy rates. Research also suggests that PCOS alters the physiological MI: DCI ratio in the ovaries, affecting ovulation and egg quality.³

Although inositol is not a cure for infertility, it may manage PCOS in many ways, increasing your chances of getting pregnant.

Inositol may normalize FSH signaling, enhance oocyte (immature egg) quality, and reestablish proper ovarian functioning. Combining myo-inositol with folic acid supports ovulation and egg quality.

While myo-inositol can help with fertility, higher D-chiro-inositol may have the opposite effect. One study noted that more D-chiro-inositol could worsen oocyte quality and ovarian response.⁴ You need the right inositol balance: A lack of MI and too much DCI may be a factor in PCOS development.

Preventing gestational diabetes

Research shows that women with PCOS have an increased risk of gestational diabetes.⁵ This diabetes occurs during pregnancy, complicating 2-10% of pregnancies in the US every year.⁶

Research has linked inositol supplements to improved insulin sensitivity and glucose tolerance. These are the key risk factors for gestational diabetes. Studies show that a combination of 4g of myo-inositol and 400mcg of folic acid may prevent gestational diabetes.⁷

Mental health and inositol

You may find PCOS symptoms difficult to deal with, resulting in mental health problems. The condition is associated with symptoms of depression, anxiety, bipolar disorder, and obsessive-compulsive disorder (OCD).

The use of inositol for mental health in people with PCOS is less extensive than for the other benefits, but there's promising research. One study concluded that inositol might be beneficial for depression.⁸ Additionally, inositol can support neurotransmitter signaling. Neurotransmitters are your brain's chemical messengers, playing a role in everything from your mood to your sleep. 

Metabolic health and inositol

People with PCOS have features of metabolic syndrome, including visceral obesity and insulin resistance. This increases the risk of developing cardiovascular disease, diabetes, stroke, and certain cancers. Inositol can improve insulin sensitivity and reduce cholesterol.

Potential side effects

Inositol is well-tolerated and is classified as generally recognized as safe (GRAS) by the FDA.⁹ There haven't been any documented cases of drug interactions with other FDA-approved drugs. Women have taken myo-inositol during pregnancy, further illustrating the inositol safety profile.

Plus, it reduces the risk of gestational diabetes. However, we need further studies to establish safety in different ethnicities and ensure neonatal safety.

It’s best to speak to your doctor to determine if it’s right for you and the right dosage. High doses above 12g daily can cause hypoglycemia and mild gastrointestinal effects, such as nausea, flatulence, and diarrhea.

How much inositol should I take for PCOS?

We've talked about two types of inositols: Myo-inositol and d-chiro-inositol. Both are effective treatments for PCOS, but research suggests that a combination of both is best, specifically a ratio of 40:1 MI: DCI.¹⁰

The most common dosages in inositol studies range from 2000–4000 mg of myo-inositol and 50–100 mg of D-chiro-inositol a day.

However, research does not provide a clear picture of the appropriate therapeutic dose or adverse effects. Speak to your doctor to determine the best dosage for your needs.

The lowdown

Your body makes inositol, and you can also get it from certain foods. But supplementing can have many health benefits if you have PCOS. These supplements can improve insulin resistance and fertility when taken in the right ratio and dosage.

As with all supplements, talk to your doctor before starting with inositol. Your doctor will answer other questions about inositol and ensure you get the right dosage.

Frequently asked questions

Inositol vs metformin for PCOS

Metformin is one of the most utilized treatment options for type 2 diabetes and PCOS. But it has side effects like gastrointestinal distress, and it can lead to vitamin B12 deficiency.

This doesn't mean you should stop taking metformin if you have PCOS. Be sure to speak with your doctor before swapping any supplements or medications. Data is uncertain whether MI improves ovulation or pregnancy rates compared with metformin.

  1. Follicle dynamics and anovulation in polycystic ovary syndrome (2008)

  2. Fertility treatment options for women with polycystic ovary syndrome (2019)

  3. Altered ovarian inositol ratios may account for pathological steroidogenesis in PCOS (2020)

  4. Concern: Does ovary need D-chiro-inositol? (2012)

  5. Increased prevalence of gestational diabetes mellitus among women with diagnosed polycystic ovary syndrome : A population-based study (2006)

  6. Gestational diabetes | Centers for Disease Control and Prevention (CDC)

  7. Antenatal dietary supplementation with myo‐inositol in women during pregnancy for preventing gestational diabetes (2015)

  8. A meta-analysis of inositol for depression and anxiety disorders (2014)

  9. CFR - Code of federal regulations title 21 | U.S. Food & Drug Administration

  10. The 40:1 myo-inositol/D-chiro-inositol plasma ratio is able to restore ovulation in PCOS patients: comparison with other ratios (2019)

Other sources:

Have you considered clinical trials for Polycystic ovarian syndrome (PCOS)?

We make it easy for you to participate in a clinical trial for Polycystic ovarian syndrome (PCOS), and get access to the latest treatments not yet widely available - and be a part of finding a cure.

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