Inositol Supplements for PCOS

Why Inositol Should be Part of Your Plan for PCOS

Dr. Jolene BrightenPublished: Last Reviewed: PCOS, Preconception & Fertility, Thyroid & Hormone Balance Leave a Comment

Millions of women are affected by polycystic ovary syndrome (PCOS)—up to 20 percent worldwide. And often I hear from patients and readers looking for options in managing their PCOS. This is one reason why supplements like inositol are growing in popularity.

Inositol, often called vitamin B8 (although it's actually not a vitamin because the body can make it), is found in tissues throughout your body and plays an essential role in cell signaling. It's involved in various cellular and reproductive processes, including glucose metabolism, insulin sensitivity, and egg maturation.

I'm very careful to only use evidence-based supplements in practice, and inositol is one of those that has a significant amount of research behind its use, especially for PCOS. In this article, I'll explain what inositol does in the body and why you may want to consider adding it to support the symptoms and root causes of PCOS.

How Does Inositol Work?

Inositol works to help regulate cell signaling pathways for hormones and neurotransmitters, so it's especially beneficial for insulin regulation. There are nine different types of inositol, but d-chiro-inositol (DCI) and myo-inositol (MI) are especially important for PCOS, according to the research (and what I see in practice).

PCOS is often characterized by elevated androgens, like high testosterone. In PCOS, insulin stimulates the ovaries to produce testosterone. In some people with PCOS, insulin resistance is present, which means your cells aren't responding correctly to insulin. Insulin is a hormone secreted by your pancreas that helps shuttle glucose from your bloodstream into your cells for energy. 

When you have insulin resistance, your pancreas has to secrete more and more insulin to get the same effect, leading to higher than normal insulin levels in your bloodstream (hyperinsulinemia).

Inositol is made from glucose (the sugar found in carbohydrates) and incorporated into your cell membranes. It acts as a second messenger for hormones like insulin and follicle-stimulating hormone (FSH). 

A second messenger acts like a go-between from hormone receptors outside your cells to the inside. When hormones like insulin bind to their receptors outside of your cells, inositol helps relay the message inside.

Inositol can help the cells become better at responding to insulin, which means the body secretes less and blood sugar balance is improved.

Interestingly, there's a link between low levels of DCI and an increased risk of insulin resistance. Most body tissue has an myo-inositol to d-chiro-inositol ratio close to 40 to 1, but it is often much higher for people with PCOS because they have lower DCI. People with PCOS may also be less efficient at converting myo-inositol to d-chiro-inositol, so supplementation with MI and DCI could help restore levels.

We formulated Myoinositol Plus to have a 40:1 ratio of myo-inositol to d-chiro-inositol with this understanding in mind.

What Does Inositol Do for PCOS? 

Studies suggest that inositol not only supports blood sugar and insulin levels for people with PCOS but also can help with cycle regulation, fertility, androgen (testosterone) levels, and more.

Inositol Helps with Insulin and Blood Sugar Regulation

As mentioned earlier, the primary reason inositol is so helpful for PCOS is the impact on blood sugar because it aids the cellular response to signals from insulin. In fact, multiple studies have concluded that inositol supplementation is as effective as Metformin (if not more) for enhancing insulin sensitivity.

Metformin is a medication used to treat type two diabetes and PCOS, and it's the most common medication prescribed to women with PCOS. But here's the thing: Metformin has side effects like gastrointestinal distress and can even lead to vitamin B12 deficiency. If you have PCOS and take Metformin, please don't stop without speaking with your healthcare provider, but it may be worth a conversation about inositol. Keep in mind that supplements are made to support the body and not provide treatment like a medication.

DCI is especially important for insulin regulation, and research suggests that people with blood sugar dysregulation (as with PCOS) often have low levels of DCI. A study on women with PCOS found that supplementation with DCI helped with insulin and androgen levels.

But research also shows that both myo-inositol and d-chiro-inositol support insulin sensitivity, especially when supplemented in a ratio matching the 40 to 1 ratio found in the body.

Inositol Could Help Lower Androgens

Lower insulin levels may also help reduce androgens. With PCOS, androgens, like testosterone and dihydrotestosterone (DHT), are much higher than usual, triggering cycle irregularities and unwanted symptoms like unwanted hair growth (hirsutism) and acne. Inositol also appears to help with reductions in androgens, likely because of the positive effect on insulin.

As mentioned in the previous section a study on women with PCOS found that taking inositol lowered androgens, which improved ovulation frequency. Another study showed similar findings, with androgen levels significantly dropping after six months of supplementing with inositol. 

As androgens drop, women may notice a reduction in excess hair growth and acne. One study found that taking inositol improved acne and hirsutism after six months, and more than half of the participants no longer had acne.

Inositol May Improve Ovulation and Menstrual Cycles

Many people with PCOS also experience irregular menstrual cycles and anovulation (a cycle without ovulation), but inositol may help. Aside from the adverse impact of insulin and androgens on the menstrual cycle, research suggests people with PCOS may have altered amounts of myo-inositol or d-chiro-inositol in the ovaries. 

After just 6 to 8 weeks of supplementing with d-chiro-inositol daily, a study on women with PCOS saw reduced androgens and increased frequency of ovulation. Multiple studies suggest that inositol can help with ovulation, and it also helps improve the regularity of menstruation.

Combining myo-inositol with folate could further support ovulation, which is why many practitioners will recommend myo-inositol with a quality prenatal. A study comparing MI and folic acid with Metformin found that the supplements improved ovulation and pregnancy rates more than Metformin.

Mental Health and Inositol

Depression and anxiety often show up with PCOS, and as many as 40% of women with PCOS meet the criteria for depression, especially younger girls. The inositol and mental health data isn't as robust as for some of the other benefits, but there is some promising research.

As mentioned earlier, inositol could also support neurotransmitter signaling. Neurotransmitters are the brain's chemical messengers, and they play a role in everything from our mood to our sleep. 

In one study, inositol supported feelings of anxiety and depression after 12 weeks for women with PCOS compared to Metformin. A review also concluded that inositol was beneficial for depression. But much more research is needed. 

If you’re on medication for anxiety or depression, talk to your practitioner before making any changes or adding a supplement.

Inositol Significantly Supports Fertility

Infertility is a big concern I hear about from people with PCOS. And while inositol is not a “cure,” it may help support fertility (and it's absolutely possible to get pregnant if you live with PCOS). 

Since inositol can improve the frequency of ovulation, it's linked to increased fertility and may even improve eggs' maturation and quality. It also appears helpful for people going through fertility treatment for egg retrieval during IVF and may improve pregnancy rates.  

While myo-inositol is likely beneficial for fertility, higher d-chiro-inositol may adversely impact egg quality and ovarian response, so more is not better. Ovarian response refers to the number of eggs retrieved during fertility treatments. 

One study also noted that more d-chiro-inositol progressively worsened egg quality—a case of more does not always equal better. These findings point to why it's essential to have the right balance of the two inositols. The ratio of MI to DCI is much higher in the ovaries (meaning they contain much higher levels of myo-inositol), so too much d-chiro-inositol could throw the natural ratios off balance and negatively impact fertility.

Metabolic Health and Inositol

Insulin resistance is tied to metabolic factors like heart health and weight control. Women with PCOS are at an increased risk of metabolic syndrome, a cluster of conditions including high blood pressure, high insulin levels, and abnormal cholesterol or triglyceride levels. Metabolic syndrome raises your risk of heart disease, stroke, and type II diabetes.

Inositol studies show it could help by improving insulin sensitivity and reducing blood pressure and cholesterol levels. 

A 12-week study on women with PCOS found that inositol supported many metabolic health changes, including positive changes in weight loss and HDL (good) cholesterol and reduced LDL (bad cholesterol) and triglycerides. 

How Much Inositol Should I Take a Day for PCOS?

The most common dosages used in studies range from 2000-4000 mg of myo-inositol and 50-100 mg of d-chiro-inositol a day to match the physiological ratio that exists in the body (40 to 1 of MI to DCI).

The general dose that has benefited and is well tolerated appears to be 2,000 mg of myo-inositol to 50 mg d-chiro-inositol. This is the amount of each inositol you’ll find in our Myoinositol Plus, with additional nutrient and herb support with PCOS in mind.

Discussing inositol supplementation with your doctor, especially if you have any other medical conditions or are taking medication, is the best way to determine the right dose for you.

Foods High in Inositol

You can get some inositol from food (although supplements are usually needed to reach therapeutic levels for PCOS). Foods high in inositol include:

  • Grapefruits
  • Orange
  • Cantaloupe
  • Beans 
  • Brown rice
  • Peanut butter
  • Whole wheat
  • Almonds
  • Walnuts
  • Organ meat

Does Inositol Cure PCOS? 

Inositol won't cure PCOS, but it can help manage symptoms. In fact, at this time, there is no known cure for PCOS. 

PCOS is a complex condition with many possible underlying causes. In my experience, PCOS is a completely manageable condition, but it usually requires a multifaceted approach that includes diet and lifestyle changes in addition to any supplements you might be taking. And yes, medications do help in the management of some cases of PCOS. It’s all about choosing what’s the best strategy for you.

Can Inositol Make PCOS Worse? 

As mentioned in the fertility section, d-chiro-inositol in high amounts without the right balance of myo-inositol could negatively impact fertility. That's why it's important to use a supplement with the correct ratio of myo-inositol and d-chiro-inositol separately.

Does Inositol Have Side effects?

Myo-inositol and d-chiro-inositol are well tolerated by most people with little to no side effects. Since they are so effective in blood sugar regulation, inositol could potentially lead to low blood sugar if you have a propensity towards that, so it's extra important to check with your health care provider if you take blood sugar lowering medication.

There have been reports of mild gastrointestinal side effects in one study, but only when an exceptionally high dosage was taken (12 g/d). Otherwise, inositols are considered very safe. 

Key Takeaways

  • Inositol is made by the body and used by your cells to help with hormone signaling.
  • Studies show that supplemental inositol effectively supports insulin resistance, fertility, acne, hair growth, cycle regulation, and metabolic health.
  • Make sure you take inositol in a ratio that matches the 40 to 1 MI to DCI found in the body (and discuss with your healthcare provider).

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About The Author

Dr. Jolene Brighten

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Dr. Jolene Brighten, NMD, is a women’s hormone expert and prominent leader in women’s medicine. As a licensed naturopathic physician who is board certified in naturopathic endocrinology, she takes an integrative approach in her clinical practice. A fierce patient advocate and completely dedicated to uncovering the root cause of hormonal imbalances, Dr. Brighten empowers women worldwide to take control of their health and their hormones. She is the best selling author of Beyond the Pill and Healing Your Body Naturally After Childbirth. Dr. Brighten is an international speaker, clinical educator, medical advisor within the tech community, and considered a leading authority on women’s health. She is a member of the MindBodyGreen Collective and a faculty member for the American Academy of Anti Aging Medicine. Her work has been featured in the New York Post, Forbes, Cosmopolitan, Huffington Post, Bustle, The Guardian, Sports Illustrated, Elle, and ABC News. Read more about me here.