This post was updated on April 3rd, 2023

By Kym Campbell, BSc. | Updated April 3rd, 2023

Medically Reviewed by Dr. Sarah Lee, M.D & Dr. Jessica A McCoy, Ph.D

There’s no such thing as a supplement for PCOS, but inositols may be the next best thing. This article tells you what you need to know about these medicines.

For inositol recommendations that are based on your specific health goals, take this PCOS inositol quiz.

What Is Inositol?

Inositols are a family of naturally occurring, vitamin-like compounds found in many foods. They play a vital role in cellular functioning and metabolism. This makes them important for fertility, mood regulation, and more.

The first controlled trial of inositols for PCOS was published in 1999 [1]. Since then, there’s been great interest in two particular forms of inositol, myo-inositol, and D-chiro-inositol. It’s understood that imbalances in these inositols can cause insulin resistance in PCOS women [2-4]. This is a problem because insulin resistance is one of the underlying causes of PCOS [5, 6].

Foods High in Inositols

Phytic acid is the main source of dietary inositol. Some of the best high-inositol foods for women with PCOS include [7]:

• Grains: Amaranth, buckwheat, wild rice, and popcorn.
• Legumes: Beans, chickpeas, and lentils.
• Nuts: Almonds, cashews, macadamia, walnuts, and pecans.
• Seeds: Flaxseeds, sunflower seeds, and sesame seeds.

I use these ingredients in a lot of my PCOS recipes. Many also feature in my free 30-Day PCOS Diet Challenge and free 3-Day Meal Plan.

Studies show that it’s possible to get enough inositol from diet alone [7, 8]. But these diets are too high in carbohydrates, especially for women with PCOS. Getting the right macros for PCOS is a fundamental aspect of managing PCOS symptoms. That’s why supplementing with inositol makes a lot of sense for women with PCOS.

Benefits of Inositol for PCOS

Insulin Sensitivity

In women with PCOS, both myo-inositol and D-chiro-inositol have positive effects on insulin sensitivity [9]. This can improve hormone balance for all types of PCOS [10-12]. Multiple meta-analyses show that inositol supplements are as good as metformin for a range of biomarkers. These include insulin sensitization, testosterone levels, body mass index, and menstrual frequency [13, 14].

Fertility

Large reviews of the scientific literature show uncertainty that inositol improves fertility [15, 16]. But smaller studies done on PCOS women show promising results. Myo-inositol has been shown to:

• Improve ovarian function [17].
• Increase egg quality [18, 19].
• Increase the yield of mature eggs during IVF [20].
• Increase pregnancy rates during IVF [21, 22].
• Reduce the risk of ovarian hyperstimulation syndrome [19].
• Be more effective than birth control at regulating ovarian function [23].
• Be better than metformin for boosting pregnancy rates [24].

In one study, overweight women with PCOS were given myo-inositol and folic acid during IVF. Pregnancy rates were nearly three times higher compared to women who only received folic acid. [22].

Researchers looking at women undergoing intrauterine insemination (IUI) had similar results. Pregnancy rates were roughly doubled after taking myo-inositol for 3 months [25].

Gestational Diabetes

Gestational diabetes is a common problem within the PCOS community. Studies show that inositol supplements can reduce these risks [26, 27].

Acne and Hirsutism

Unwanted hair and skin issues cause a lot of distress for women with PCOS [28]. But inositol can sometimes help. This is because inositol lowers androgen levels [4, 9].

Myo-inositol has shown statistically significant (but small) improvements in unwanted hair [29]. One study found that it helped about a third of women with hirsutism. More than half of the women studied also saw significant improvements in PCOS acne [30].

Weight Loss (But Not Much)

Despite its impact on insulin, inositol is not a good weight loss supplement. Nordio and Proietti 2012 conducted a famous trial giving women with PCOS inositol supplements. This helped with fertility but made no difference to hip-to-waist ratio or BMI [31]. Other trials have found the weight loss benefits to be small at best [17, 32]. We’re talking about only 1-2 pounds on average over 6 months of supplementation.

That’s a statistically significant amount, but it’s below most people’s expectations.

PCOS weight loss is best achieved using these 15 steps.

Which Type of Inositol Is Best

When selecting products, the first decision is what type of inositol you want to take. You have three choices:

1. Taking D-chiro-inositol alone.
2. Taking Myo-inositol alone.
3. Take a combination of myo-inositol and D-chiro-inositol.

Taking D-chiro-inositol alone is best left to women that have a BMI > 30, and who also have close relatives that are diabetic [33]. In most other cases, you’re better off taking myo-inositol.

Taking myo-inositol alone is the cheapest way to supplement inositol intake. The benefits of myo-inositol alone are well-proven, especially for fertility.

The best inositol supplements though contain a combination of both myo-inositol and D-chiro-inositol. Studies show that a mixture of 40 parts myo-inositol to 1-part D-chiro-inositol is more effective than other formulations [34].

During the 2010s the exact ideal ratio was the subject of debate [35]. But this question now seems to be settled.

The superiority of a 40:1 inositol combined supplement has been demonstrated in mouse models of PCOS [36]. It’s also been proven in PCOS patients seeking to restore ovulation [37]. Increasing the relative amounts of D-chiro inositol above 40:1 appears to reduce effectiveness and may have a negative effect.

Click here to take my PCOS inositol quiz.

Brands & Dosage Recommendations

Best Inositol Brand for PCOS

Ovasitol by Theralogix is the market-leading inositol supplement for women with PCOS. And for good reason. Ovasitol contains myo-inositol and D-chiro-inositol in a 40:1 ratio. As described above, this is the most effective formulation for the treatment of PCOS.

Ovasitol is made to the highest nutraceutical standards and is free from unnecessary ingredients. It’s recommended that you take one individual packet or a scoop of Ovasitol powder twice a day. Each of these doses contains 2000 mg of myo-inositol and 50 mg D-chiro inositol.

Myo-Inositol Only Products

It’s best to buy pure myo-inositol. Jarrow Formulas is a well-priced and reliable brand. Pure Encapsulations also make a top-quality myo-inositol product.

The recommended dosage of myo-inositol is 4000 mg/day taken in two doses. That’s equal to about 1 tsp twice a day.

It’s important to be wary of products that include sweeteners, vitamins, and other ingredients. The addition of these other ingredients amounts to a “marketing maneuver” and may inhibit gut absorption [38].

The addition of folic acid to inositol supplements should be viewed with particular caution. Several recent studies have associated PCOS with MTHFR gene mutations [39, 40]. For these women, taking folic acid during pregnancy can affect childhood lung function [41]. Supplementing with methyl folate, the active form of folate is generally advised for women with PCOS instead of folic acid [42].

This is one of the reasons I prefer Theralogix preconception vitamins.

Warnings

Myo-inositol is a safe supplement. High doses have been used in trials exploring the potential for inositol supplements to treat panic disorders [43]. Inositol supplements are safe to take during your period and throughout pregnancy. No adverse effects were found in many studies that looked at normal doses taken during pregnancy [44, 45].

D-chiro-inositol alone should be approached more cautiously. High dosages may adversely affect egg quality [46].

Combination products like Ovasitol are safe to take during pregnancy and breastfeeding. There are no expected side effects.

The biggest thing to be aware of when taking inositol supplements is their impact on blood glucose levels. Because they have a similar effect as metformin, PCOS women that are taking this drug may need to reduce their dose.

How to Get the Most Out of Inositol

The benefits of inositol supplements derive from their ability to improve insulin regulation. To get the most out of this intervention though, it makes sense to also change how you eat.

In my experience, both personally and as a health coach, no supplement can compete with a PCOS diet for efficacy.

A PCOS diet improves insulin regulation by reducing inflammation. You can achieve this by excluding these seven foods to avoid with PCOS. A PCOS diet also takes a direct approach to insulin regulation. This is best achieved by consuming the right macros for PCOS.

To see what this looks like in real life, join my free 30-Day PCOS Diet Challenge or download this free 3-Day Meal Plan.

The Bottom Line

Both myo-inositol and D-chiro-inositol can be good for women with PCOS. Especially when combined in a 40:1 ratio. These compounds can correct the hormone imbalances that characterize this syndrome.

Inositol supplements are safe when used as directed. They can improve metabolic health, fertility, skin, and hair. Inositol supplements alter insulin sensitivity. Because of this, they’re most effective when also following a PCOS diet.

For personalized inositol recommendations, click here to take my PCOS inositol quiz.

FAQ

What’s the difference between Ovasitol and inositol? Inositol is a general name for a family of nutrients. But most people use this term to refer to myo-inositol. Ovasitol is a brand-name inositol supplement. It contains a specific formulation of 40 parts myo-inositol to 1 part D-chiro-inositol.

Ovasitol weight loss – does it really help? A competitor product that is like Ovasitol, has been used in several PCOS studies. This product achieved a statistically significant reduction in body weight. The size of the effect was small though, at only 2 pounds on average over 6 months [32]. Other comparable studies have observed no improvements in BMI or hip-to-waist ratio [31].

What about myo-inositol for PCOS weight loss? The weight-loss benefits of myo-inositol may be less than 40:1 myo- / D-chiro-inositol formulations [32]. The size of the difference is small though. Neither is likely to be of much clinical value, without dietary intervention.

What are your views on the inositol PCOS weight loss success stories out there? Any meaningful weight loss achieved after taking inositol supplements is likely to be the result of other factors. This is clear from the randomized controlled trials that have studied this question. Many women will undertake diet and lifestyle changes when supplementing with inositol. These interventions are more likely to drive weight loss than inositol alone.

What is the best inositol supplement for PCOS? 40:1 myo- / D-chiro-inositol formulations appear to be the best inositol supplement for PCOS.

What is the best myo-inositol supplement for fertility? Myo-inositol is a commodity supplement. Most brands should be capable of delivering similar clinical results. But independent studies have observed significant issues with product quality and labeling accuracy [47]. It’s advised to only use trusted suppliers like those mentioned above.

What’s the right inositol dosage for PCOS / how much inositol per day for PCOS? The recommended dosage of myo-inositol for most women with PCOS is 4000 mg/day taken in two doses. This is similar to many 40:1 myo- / D-chiro inositol products. They use 4000 mg/day of myo-inositol and add in a commensurate quantity of D-chiro inositol (100 mg/day).

What is the best time of day to take inositol? Inositol is best taken with food, in two doses, at least six hours apart. It’s advised to take inositol following the first and last meal of the day.

What is the best time to take inositol for PCOS? Inositol is best taken when making changes to your diet and lifestyle. This helps further improve insulin regulation and hormone balance.

How long does myo-inositol take to work? / How long does it take for myo-inositol to regulate your period? Studies show that the benefits of myo-inositol supplements can be seen within 3 months. 6 months of treatment is better though [31].

What about inositol causing diarrhea? A 2011 review investigated the safety and side effects of myo-inositol. Only the highest dose of myo-inositol (12 g/day) induced mild gastrointestinal side effects. This included things like nausea, flatus, and diarrhea. The severity of side effects did not increase with the dosage [48]. The rates used for the treatment of PCOS (4 g/day) do not typically cause issues with diarrhea.

Can I take myo-inositol during my period? Yes. Myo-inositol should be taken daily for the duration of treatment. It is suitable to use during your period.

What are some Ovasitol alternatives? Ovasitol by Theralogix is the market leader in PCOS inositol supplements. Inofolic Combi by LOLI Pharma is a suitable alternative. This product has been used in many inositol trials.

Ovasitol Europe. Where can I order it? European and other international customers can order Ovasitol from evitamins.com. E-vitamins are the global distributor for Theralogix.

Ovasitol USA. Where can I get the lowest price? US customers can buy Ovasitol directly from the manufacturer, Theralogix. Use the Provider Referral Code (PRC) A29927 at checkout, for $14 off the retail price.

Ovasitol Canada. Where can I get the lowest price? Canadian customers can buy Ovasitol directly from the manufacturer, Theralogix Canada. Use the discount code KYM at checkout, for $10 off the retail price.

Author

Kym Campbell

Combining rigorous science and clinical advice with a pragmatic approach to habit change, Kym is on a mission to show other women how to take back control of their health and fertility. Read more about Kym and her team here.

Co-Authors

Dr. Jessica A McCoy, Ph.D

This blog post has been critically reviewed to ensure accurate interpretation and presentation of the scientific literature by Dr. Jessica A McCoy, Ph.D. Dr McCoy has a master’s degree in cellular and molecular biology, and a doctorate in reproductive biology and environmental health. She currently serves as a University professor at the College of Charleston, South Carolina.

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Dr. Sarah Lee, M.D

This blog post has also been medically reviewed and approved by Dr. Sarah Lee, M.D. Dr. Lee is a board-certified Physician practicing with Intermountain Healthcare in Utah. She obtained a Bachelor of Science in Biology from the University of Texas at Austin before earning her Doctor of Medicine from UT Health San Antonio.

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