This post was updated on May 9th, 2022
By Kym Campbell, BSc. | Updated May 9th, 2022
There’s no such thing as a supplement for PCOS, but inositol may be the next best thing.
Inositols are a family of naturally occurring, vitamin-like compounds found in many foods. They play a vital role in cellular functioning and metabolism. Inositols are also important for fertility, mood regulation, and more.
The Inositol – PCOS Connection
The first controlled trial of inositols for PCOS was published in 1999 . 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 may 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]. Over the past two-plus decades, scientists have been studying the use of inositol supplements for PCOS. The hope is that fixing inositol imbalances will improve health and fertility.
So far, this seems to be the case.
If you’re curious about using inositol for PCOS, this article will tell you what you need to know.
1. Inositol Improves Insulin Sensitivity
For women with PCOS, improving insulin sensitivity is everything.
Poor insulin sensitivity (a.k.a. insulin resistance), causes androgenic hormones like testosterone to become elevated. Elevated insulin and androgenic hormones then cause the range of symptoms seen in PCOS . This includes weight gain, infertility, hirsutism, and acne. Insomnia, mood swings, anxiety, and depression are also common PCOS symptoms. By improving insulin sensitivity, women with PCOS can reduce or even eliminate these symptoms. This has been proven by many women that have completed my free 30-Day PCOS Diet Challenge.
Both myo-inositol and D-chiro-inositol have positive effects on insulin sensitivity . As a result, studies of these nutrients show improvements in several hormone-related biomarkers.
In a systematic review of 21 studies, researchers found that myo-inositol improved the hormone parameters of PCOS. Cholesterol levels and glucose/insulin ratios were also improved .
Doses of 600 mg per day of D-chiro-inositol have improved insulin and androgen levels in lean women with PCOS . Doses of 1000 mg per day have improved metabolic health in a more representative PCOS population .
2. Inositol May Be Better Than Metformin
Myo-inositol is an effective insulin-sensitizing agent. So much so that it is now used as an alternative to metformin.
A 2019 meta-analysis of randomized clinical trials compared these two treatments. The research showed that myo-inositol was just as good as metformin at improving insulin sensitivity. It also performed just as well for improving testosterone levels, body mass index, and more . Some randomized controlled trials have even found myo-inositol to be more effective than metformin .
Metformin has well-documented side effects . Myo-inositol by comparison is well-tolerated making it a preferred option for many women with PCOS.
3. Skip D-Chiro-Inositol When TTC
There’s evidence showing that D-chiro-inositol is effective at improving ovarian function in women with PCOS [10, 14]. But when taken alone, this supplement is not recommended for women that are trying to conceive. While small amounts may be helpful, these benefits are lost at higher dosages and can reduce embryo quality .
Studies on IVF patients with PCOS have compared myo- and D-chiro-inositol. This research showed that, when it comes to fertility, myo-inositol is the better choice .
4. A 40:1 Ratio Is The Best Inositol Formulation
Both myo-inositol and D-chiro-inositol are effective treatments for PCOS. But clinical studies have shown that a combination supplement that contains both inositols is best. A ratio of 40 parts myo-inositol to 1 part D-chiro-inositol is optimal .
During the 2010s the exact ideal ratio was the subject of debate , 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 . It’s also been proven in PCOS patients seeking to restore ovulation . Increasing the relative amounts of D-chiro inositol above 40:1 appears to reduce effectiveness and may have a negative effect.
For inositol product recommendations and discount codes take my PCOS Inositol Quiz.
5. Myo-Inositol Improves Fertility
The limited data collected to date means there’s still scientific uncertainty about inositol’s impact on fertility [20, 21]. But there’s growing evidence supporting its use in PCOS fertility treatments.
Myo-inositol has been shown to:
- Improve ovarian function .
- Increase egg quality [23, 24].
- Increase the yield of mature eggs during IVF .
- Increase pregnancy rates during IVF [26, 27].
- Reduce the risk of ovarian hyperstimulation syndrome .
- Be more effective than birth control at regulating ovarian function .
- Be better than metformin for boosting pregnancy rates .
One study looked at overweight women with PCOS that were given myo-inositol + folic acid during IVF. 32% of these women had a successful pregnancy within the 12-month study period. This was nearly three times the rate of the women who only took a straight folic acid supplement without the inositol .
Researchers looking at women undergoing intrauterine insemination (IUI) had similar results. Pregnancy rates were roughly doubled after taking myo-inositol for 3 months .
6. Inositol Isn’t Great For Weight Loss
It’s well understood that inositol improves insulin sensitivity. But many trials have shown only a very modest improvement in body composition.
For example, Nordio and Proietti 2012 showed positive fertility outcomes from 40:1 myo- / D-chiro-inositol. But when it came to weight loss, they found no change in hip-to-waist ratio or BMI .
In a 3-month trial of myo-inositol, women who were moderately overweight lost approximately two pounds on average. The women in this trial that were severely obese didn’t lose any weight at all .
A more recent study found similar results. One trial compared diet only to diet + myo-inositol supplements. They also looked at diet + both myo- and D-chiro-inositol. Over 6 months, patients who took the myo-inositol lost only 1 pound more than those that dieted without supplementation. The women who took the combined supplements fared a little better. They lost an extra 2 pounds .
Two pounds is a statistically significant amount, but it’s well below most people’s expectations. Many women erroneously anticipate meaningful weight loss results after starting inositol supplements.
7. Inositol May Help With Hirsutism And Acne
Unwanted hair and skin issues like acne are common in PCOS. Unfortunately, these symptoms cause significant psychological distress , but inositol can help. Because inositol improves insulin sensitivity, it can help lower androgen levels [4, 7].
One study looked at women taking 4000 mg per day of myo-inositol. They saw a statistically significant (but small) improvement in unwanted hair . It’s worth noting that these women were not taking birth control at the time. Similar benefits may not be seen in women on hormonal birth control.
Another similar trial had better results. About a third of the women were able to eliminate their hirsutism after 6 months. More than half of the women studied also saw significant improvements in acne .
There is a lack of comprehensive trials looking at hirsutism and acne in women with PCOS. But from what we do have, it seems that myo-inositol can help with these symptoms. The thing to keep in mind here is that it doesn’t work for everyone.
8. Inositol Dosage Recommendations
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).
In the less-common circumstances where D-chiro-inositol is used on its own, typical dosages start at 500 mg per day.
For inositol recommendations that are more tailored to your personal circumstances, click here to take my PCOS inositol quiz.
9. Inositol Safety And Side Effects
When it comes to side effects and safety, myo-inositol is considered a safe supplement. Doses of 18,000 mg/day have been used in trials exploring the potential for inositol supplements to treat panic disorders . No relevant adverse effects were found in several human studies that looked at doses of 4000 mg per day throughout pregnancy [37, 38].
To further illustrate the safety profile, women take myo-inositol during pregnancy. For PCOS women with insulin resistance, this nutritional supplement can reduce the risk of gestational diabetes [39, 40].
D-chiro-inositol, above the levels found in a 40:1 formulation, should be approached more cautiously. Taking D-chiro-inositol alone, at high dosages can adversely affect egg quality. Experts warn against its use in certain circumstances .
10. Be Wary Of Other Ingredients
Clinical evidence has demonstrated the effectiveness of inositol supplementation for women with PCOS. But, many commercially available products include other ingredients that can be counterproductive. For example, sweeteners, such as sorbitol, maltodextrin, and sucralose may inhibit the absorption of myo-inositol in the gut .
According to Dr. Scott Roseff, board-certified OBGYN and RE at South Florida Institute for Reproductive Medicine, “…the addition of macro-and microelements, several vitamins, and other molecules [to inositol products], despite being possibly useful in some cases, basically appears to be a pure marketing maneuver and could even impair inositol absorption.”
The addition of folic acid to inositol supplements should also be viewed with particular caution. Several recent studies have associated PCOS with MTHFR gene mutations [43, 44]. This is a small genetic variation that impacts how folate is processed to make DNA and protein within cells. Folic acid, a synthetic form of folate, is not suitable for women with an MTHFR gene mutation. For these women, taking folic acid during pregnancy can affect childhood lung function .
Supplementing with methyl folate, the active form of folate is generally advised for women with PCOS instead of folic acid .
11. Maximize Inositol Benefits With Diet & Lifestyle Changes
Inositol has positive effects on metabolic health, fertility, hirsutism, and acne. These outcomes reflect the predictable benefits of improved insulin sensitivity.
Diet and lifestyle changes can further enhance these benefits.
An unhealthy diet is considered by many experts to be a key risk factor for PCOS pathology. Dr. Barrea and colleagues describe a “deadly quartet” of factors that includes insulin resistance, elevated androgen levels, low-grade inflammation, and high carbohydrate consumption .
The right diet can treat PCOS by adjusting macronutrient ratios and switching to whole food sources of carbs that have a low glycemic index. These changes, along with reduced sugar consumption, can reverse insulin resistance. This pulls the rug out from beneath the biggest driver of most PCOS-related health issues.
A PCOS diet can also reduce inflammation, another underlying cause of this syndrome. This is because a PCOS diet eliminates pro-inflammatory ingredients and other foods that impact gut health. Over time, this helps to minimize many PCOS symptoms.
Ready To Take Action?
The Bottom Line
Both myo-inositol and D-chiro-inositol can be beneficial for women with PCOS. Especially when combined in a 40:1 ratio, these naturally occurring vitamin-like compounds can correct the hormone imbalances that characterize this syndrome.
Inositol supplements are safe and they can improve metabolic health, fertility, skin, and hair. Because they address insulin resistance, inositol supplements are most effective when also following a PCOS diet.
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 similar to 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 . Other comparable studies have observed no improvements in BMI or hip-to-waist ratio .
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 . The size of the difference is small though. Neither are 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 . It’s advised to only use trusted suppliers like those linked to in my PCOS inositol quiz.
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 .
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 . 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 $10 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.
Since 2010, Kym Campbell has used evidence-based diet and lifestyle interventions to manage her PCOS. After getting her symptoms under control and falling pregnant naturally, Kym now advocates for dietary change as part of any PCOS treatment plan. 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.
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.
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.
1Nestler, J.E., et al., Ovulatory and metabolic effects of D-chiro-inositol in the polycystic ovary syndrome. N Engl J Med, 1999. 340(17): p. 1314-20.
2Baillargeon, J.P., et al., Altered D-chiro-inositol urinary clearance in women with polycystic ovary syndrome. Diabetes Care, 2006. 29(2): p. 300-5.
3Unfer, V., et al., Altered Ovarian Inositol Ratios May Account for Pathological Steroidogenesis in PCOS. Int J Mol Sci, 2020. 21(19).
4Dinicola, S., et al., Inositols: From Established Knowledge to Novel Approaches. Int J Mol Sci, 2021. 22(19).
5Marshall, J.C. and A. Dunaif, Should all women with PCOS be treated for insulin resistance? Fertil Steril, 2012. 97(1): p. 18-22.
6Wang, J., et al., Hyperandrogenemia and insulin resistance: The chief culprit of polycystic ovary syndrome. Life Sciences, 2019. 236.
7Kamenov, Z. and A. Gateva, Inositols in PCOS. Molecules, 2020. 25(23).
8Unfer, V., et al., Effects of myo-inositol in women with PCOS: a systematic review of randomized controlled trials. Gynecol Endocrinol, 2012. 28(7): p. 509-15.
9Iuorno, M.J., et al., Effects of d-chiro-inositol in lean women with the polycystic ovary syndrome. Endocr Pract, 2002. 8(6): p. 417-23.
10Laganà, A.S., L. Barbaro, and A. Pizzo, Evaluation of ovarian function and metabolic factors in women affected by polycystic ovary syndrome after treatment with D-Chiro-Inositol. Arch Gynecol Obstet, 2015. 291(5): p. 1181-6.
11Facchinetti, F., et al., Short-term effects of metformin and myo-inositol in women with polycystic ovarian syndrome (PCOS): a meta-analysis of randomized clinical trials. Gynecol Endocrinol, 2019. 35(3): p. 198-206.
12Jamilian, M., et al., Comparison of myo-inositol and metformin on clinical, metabolic and genetic parameters in polycystic ovary syndrome: A randomized controlled clinical trial. Clin Endocrinol (Oxf), 2017. 87(2): p. 194-200.
13Aiken, C., et al., An Update to the Article “Efficacy and Side Effect Profile of Different Formulations of Metformin: A Systematic Review and Meta-Analysis”. Diabetes Ther, 2021. 12(11): p. 2813-2816.
14Pizzo, A., A.S. Laganà, and L. Barbaro, Comparison between effects of myo-inositol and D-chiro-inositol on ovarian function and metabolic factors in women with PCOS. Gynecol Endocrinol, 2014. 30(3): p. 205-8.
15Roseff, S. and M. Montenegro, Inositol Treatment for PCOS Should Be Science-Based and Not Arbitrary. Int J Endocrinol, 2020. 2020: p. 6461254.
16Unfer, V., et al., Myo-inositol rather than D-chiro-inositol is able to improve oocyte quality in intracytoplasmic sperm injection cycles. A prospective, controlled, randomized trial. Eur Rev Med Pharmacol Sci, 2011. 15(4): p. 452-7.
17Sortino, M.A., et al., Polycystic Ovary Syndrome: Insights into the Therapeutic Approach with Inositols. Front Pharmacol, 2017. 8: p. 341.
18Bevilacqua, A., et al., Myo-inositol and D-chiro-inositol (40:1) reverse histological and functional features of polycystic ovary syndrome in a mouse model. J Cell Physiol, 2019. 234(6): p. 9387-9398.
19Nordio, M., S. Basciani, and E. Camajani, The 40:1 myo-inositol/D-chiro-inositol plasma ratio is able to restore ovulation in PCOS patients: comparison with other ratios. Eur Rev Med Pharmacol Sci, 2019. 23(12): p. 5512-5521.
20Laganà, A.S., et al., Inositol in Polycystic Ovary Syndrome: Restoring Fertility through a Pathophysiology-Based Approach. Trends Endocrinol Metab, 2018. 29(11): p. 768-780.
21Showell, M.G., et al., Inositol for subfertile women with polycystic ovary syndrome. Cochrane Database Syst Rev, 2018. 12(12): p. Cd012378.
22Gerli, S., et al., Randomized, double blind placebo-controlled trial: effects of myo-inositol on ovarian function and metabolic factors in women with PCOS. Eur Rev Med Pharmacol Sci, 2007. 11(5): p. 347-54.
23Ciotta, L., et al., Effects of myo-inositol supplementation on oocyte’s quality in PCOS patients: a double blind trial. Eur Rev Med Pharmacol Sci, 2011. 15(5): p. 509-14.
24Papaleo, E., et al., Myo-inositol may improve oocyte quality in intracytoplasmic sperm injection cycles. A prospective, controlled, randomized trial. Fertil Steril, 2009. 91(5): p. 1750-4.
25Garg, D. and R. Tal, Inositol Treatment and ART Outcomes in Women with PCOS. Int J Endocrinol, 2016. 2016: p. 1979654.
26Zheng, X., et al., Inositol supplement improves clinical pregnancy rate in infertile women undergoing ovulation induction for ICSI or IVF-ET. Medicine (Baltimore), 2017. 96(49): p. e8842.
27Artini, P.G., et al., Endocrine and clinical effects of myo-inositol administration in polycystic ovary syndrome. A randomized study. Gynecol Endocrinol, 2013. 29(4): p. 375-9.
28Ozay, A.C., et al., Different Effects of Myoinositol plus Folic Acid versus Combined Oral Treatment on Androgen Levels in PCOS Women. Int J Endocrinol, 2016. 2016: p. 3206872.
29Raffone, E., P. Rizzo, and V. Benedetto, Insulin sensitiser agents alone and in co-treatment with r-FSH for ovulation induction in PCOS women. Gynecol Endocrinol, 2010. 26(4): p. 275-80.
30Emekçi Özay, Ö., et al., Myo-inositol administration positively effects ovulation induction and intrauterine insemination in patients with polycystic ovary syndrome: a prospective, controlled, randomized trial. Gynecol Endocrinol, 2017. 33(7): p. 524-528.
31Nordio, M. and E. Proietti, The combined therapy with myo-inositol and D-chiro-inositol reduces the risk of metabolic disease in PCOS overweight patients compared to myo-inositol supplementation alone. Eur Rev Med Pharmacol Sci, 2012. 16(5): p. 575-81.
32Le Donne, M., et al., Effects of three treatment modalities (diet, myoinositol or myoinositol associated with D-chiro-inositol) on clinical and body composition outcomes in women with polycystic ovary syndrome. Eur Rev Med Pharmacol Sci, 2019. 23(5): p. 2293-2301.
33Pasch, L., et al., Clinician vs Self-ratings of Hirsutism in Patients With Polycystic Ovarian Syndrome: Associations With Quality of Life and Depression. JAMA Dermatol, 2016. 152(7): p. 783-8.
34Minozzi, M., G. D’Andrea, and V. Unfer, Treatment of hirsutism with myo-inositol: a prospective clinical study. Reprod Biomed Online, 2008. 17(4): p. 579-82.
35Zacchè, M.M., et al., Efficacy of myo-inositol in the treatment of cutaneous disorders in young women with polycystic ovary syndrome. Gynecol Endocrinol, 2009. 25(8): p. 508-13.
36Palatnik, A., et al., Double-blind, controlled, crossover trial of inositol versus fluvoxamine for the treatment of panic disorder. J Clin Psychopharmacol, 2001. 21(3): p. 335-9.
37Regidor, P.A. and A.E. Schindler, Myoinositol as a Safe and Alternative Approach in the Treatment of Infertile PCOS Women: A German Observational Study. Int J Endocrinol, 2016. 2016: p. 9537632.
38D’Anna, R., et al., Myo-inositol may prevent gestational diabetes in PCOS women. Gynecol Endocrinol, 2012. 28(6): p. 440-2.
39Sobota-Grzeszyk, A., M. Kuźmicki, and J. Szamatowicz, Myoinositol in the Prevention of Gestational Diabetes Mellitus: Is It Sensible? J Diabetes Res, 2019. 2019: p. 3915253.
40D’Anna, R., et al., Myo-Inositol for the Prevention of Gestational Diabetes Mellitus. A Brief Review. J Nutr Sci Vitaminol (Tokyo), 2019. 65(Supplement): p. S59-s61.
41Vitagliano, A., et al., “Empiric” inositol supplementation in normal-weight non insulin resistant women with polycystic ovarian disease: from the absence of benefit to the potential adverse effects. Arch Gynecol Obstet, 2015. 291(5): p. 955-7.
42Garzon, S., A.S. Laganà, and G. Monastra, Risk of reduced intestinal absorption of myo-inositol caused by D-chiro-inositol or by glucose transporter inhibitors. Expert Opin Drug Metab Toxicol, 2019. 15(9): p. 697-703.
43Li, Y., et al., Significant association between methylenetetrahydrofolate reductase gene C677T polymorphism with polycystic ovary syndrome risk: A meta-analysis update. Medicine (Baltimore), 2020. 99(4): p. e18720.
44Zhu, X.Y., et al., Association of methylenetetrahydrofolate reductase C677T and A1298C polymorphisms with genetic susceptibility to polycystic ovary syndrome: A PRISMA-compliant meta-analysis. Gene, 2019. 719.
45den Dekker, H.T., et al., Maternal folic acid use during pregnancy, methylenetetrahydrofolate reductase gene polymorphism, andchild’s lung function and asthma. Clinical and Experimental Allergy, 2018. 48(2): p. 175-185.
46Serapinas, D., et al., The importance of folate, vitamins B6 and B12 for the lowering of homocysteine concentrations for patients with recurrent pregnancy loss and MTHFR mutations. Reprod Toxicol, 2017. 72: p. 159-163.
47Barrea, L., et al., Source and amount of carbohydrate in the diet and inflammation in women with polycystic ovary syndrome. Nutr Res Rev, 2018. 31(2): p. 291-301.
48Papaleo, E., et al., Myo-inositol products in polycystic ovary syndrome (PCOS) treatment: quality, labeling accuracy, and cost comparison. Eur Rev Med Pharmacol Sci, 2011. 15(2): p. 165-74.
49Carlomagno, G. and V. Unfer, Inositol safety: clinical evidences. Eur Rev Med Pharmacol Sci, 2011. 15(8): p. 931-6.