This post was updated on January 17th, 2021
What No One Else Is Telling You
You wouldn’t trust a fox to take care of your hen house, but it’s easy to make this mistake when it comes to supplements.
Reliable information on any PCOS supplement is a hard thing to find given the number of websites that write about the virtues of a product but then also sell it on their website. Inositol supplements are no exception to this common conflict of interest.
Having met literally tens of thousands of women with PCOS through my free 30-Day PCOS Diet Challenge, I completely understand why supplements in general, and inositol more specifically, are so popular amongst women who appreciate natural remedies for PCOS.
But if you’re going to consider taking supplements as part of your PCOS treatment regime then let me help you do so with the most accurate and reliable information possible.
After first busting two of the most common myths deceptively touted by the supplements industry, I’m then going to share with you a comprehensive critical review of inositol supplements for various different PCOS symptoms.
This article also considers safety and side effects and includes some helpful tips on how much inositol to take for PCOS.
If after reading this information you’d like more personalized guidance on how best to include an inositol supplement within your PCOS treatment plan, take 30 seconds to complete my PCOS Inositol Quiz. I’ll then send you a customized report that includes independent product recommendations and dosages based on your particular symptoms and health goals.
Inositol And PCOS: The Basics
Inositol is a term used to describe a family of nine naturally occurring, vitamin-like compounds that play a vital role in how all our cells function. While our bodies can synthesize inositol naturally, most of what we need comes from the foods we eat.
In women with PCOS, the cellular processes that produce and use inositol fail to function correctly. This upsets our insulin regulation which then leads to the widespread hormone imbalances that eventually present themselves as all of the typical PCOS symptoms we hate.
Researchers have shown that taking inositol supplements can have a positive effect on this faulty cell functioning. Improvements have been observed in both insulin sensitivity and free testosterone levels providing a clear mechanism to the health and fertility benefits that many people have experienced.
In this article when I refer to “inositol supplements” I’m generally talking about products that contain either myo-inositol, D-chiro-inositol, or a combination of the two. These are the two types of inositol compounds most commonly used as nutritional supplements.
While myo-inositol on its own is the most widely studied form of this supplement for women with PCOS, new products that combine both myo and D-chiro forms of inositol have been promoted heavily since about 2013 as I discuss more below.
I have no affiliation or relationship with any supplement-related business, so what you’ll read here is strictly an independent perspective. Unlike just about every other online resource that talks about inositol supplements, this gives me the freedom to tell you the honest truth about both the benefits and the limitations of these products.
As you’ll see below, there are many reasons to consider supplementing with inositol and I’ve made this thought-process easy for you by also creating a PCOS Inositol Quiz. After completing this short questionnaire, I’ll send you a customized report that includes product recommendations and dosages based on your particular symptoms and goals.
1. Myth 1 Busted: Taking Myo-Inositol For Weight Loss
The first thing I want to point out is that if you suffer from PCOS, then inositol supplements are unlikely to help you much with weight loss. If this contradicts what you may have read elsewhere then this is because when I looked at all the studies on myo-inositol for PCOS, and the combination inositol supplements that contain both myo-inositol and D-chiro-inositol, I considered not just whether these products lead to weight loss or not, but also how much women lose depending on their diagnosis. This was the approach I used when reviewing all the different compounds included in my PCOS Supplements Guide.
Ovasitol, and its competitor product Inofolic Combi are marketed as the best PCOS inositol supplements because they contain both myo-inositol and D-chiro-inositol in a ratio of 40:1. But here’s a key fact that I’ve taken straight out of the SAME blockbuster study that almost all experts and marketing machines quote when talking about the virtues of these products:
No change in hip to waist ratio or BMI was detected in the patients that were assigned either myo-inositol on its own, or the combined 40:1 inositol supplement during this highly cited trial (Nordio and Proietti 20121).
These women were all overweight to start with too meaning it should have been fairly easy for the inositol supplements to help them lose weight if it was actually going to work.
These women took the supplements for a 6-month period which for you or I would cost around $180.
This finding is consistent with many other studies that have shown very modest weight loss at best when giving women with PCOS inositol supplements.
For example, during a 3-month trial of myo-inositol, women who were moderately overweight lost approximately two pounds on average, while women that were severely obese didn’t lose any weight at all (Gerli et al. 20072).
Two pounds is a statistically significant amount, but it’s not exactly a life changing result is it?
If you compare this to the women that take part in my free 30-Day PCOS Diet Challenge, two pounds of weight loss is hardly anything. During this free live event it’s not uncommon for participants to lose 5-15 pounds during the 30 days, with some stand out women like April and Ashley losing more than 20 pounds without going near a nutritional supplement!
There are also other studies showing body weight is unaffected by inositol supplements if you’re a normal weight to start with (Genazzani et al. 20143) or you’ve been through menopause already (Santamaria et al. 20124).
If you ask me simply putting the words myo inositol and weight loss together to grab a headline is a bit misleading.
None of this is to say that there aren’t some great health benefits from taking inositol supplements (see below), it’s just that they’re probably not going to help with weight loss if this is one of the main reasons you’re considering them.
2. Myth 2 Busted: You Don’t Necessarily Need Ovasitol If You Have PCOS
If there was a prize for the PCOS supplement that generated the most conversation during my free live 30-Day PCOS Diet Challenge hands-down it would go to Ovasitol. But just because it’s popular, it doesn’t necessarily mean that everyone with PCOS needs it.
I’ve already mentioned the magic 40:1 ratio of myo-inositol and D-chiro-inositol used by some of the market leading inositol supplement providers, but how rigorous are their claims to having the most effective blend of ingredients?
When doing some in depth research for my PCOS Supplements Guide I saw that there are a lot of expert reviews that support the 40:1 ratio claims (Dinicola et al. 20145; Genazzani 20166; Monastra et al. 20177).
But then I realized that all of these experts rely on just two randomized controlled trials for evidence (Nordio and Proietti 20121; Colazingari et al. 20138) and it turns out that the sample sizes of women that received the 40:1 combination was fairly small in both trials (26 and 47, respectively). Clearly, further research is needed before anyone can have much confidence in the results.
While it seems highly likely that a combination of both myo-inositol and D-chiro-inositol is the best way to take these supplements for PCOS, the jury is definitely still out when it comes to the 40:1 ratio claims.
According to a team of independent experts, “The ratio chosen [40:1] seems arbitrary” (Sortino et al. 20179). They explain that while the ratio may be 40:1 in the ovaries, the combination of the two forms of inositol is very different in our blood and that any supplement taken needs to go into our blood before it gets to our ovaries.
Researchers also point out that based on the results of lab studies looking at how myo-inositol and D-chiro inositol ratios are balanced in the ovary tissue of women with PCOS (Heimark et al. 201410), it’s possible that using an overwhelming amount of myo-inositol over D-chiro-inositol in a 40:1 ratio could “exert paradoxical effects”.
They conclude that “without further scientific evidence, the 40:1 ratio has no reason to be considered preferable to other available formulations” (Sortino et al. 20179).
The take home message from all of these details is that it’s still very early days in the research into using inositol supplements for the treatment of PCOS. If you’re buying Ovasitol or its competitor product Inofolic Combi (which is only available in Europe, I believe) then you’re really ahead of what the science can be sure of.
To me it seems pretty clear that while things may change with further research, at this point in time, the truth claims made by people promoting these products are more of a marketing artifact than a scientific conclusion.
With this in mind, the recommendations I provide to women who complete my PCOS Inositol Quiz, includes another product you won’t read about elsewhere online. The supplier is a highly regarded supplement manufacturer that has developed a combined myo/D-chiro inositol product that has a 15:1 ratio.
3. Inositol For Women With PCOS Who Are Trying To Get Pregnant
As someone who struggled for years with PCOS related infertility, I can completely relate to the burning desire to do everything in your power to maximize your chances of success. And inositol supplements may be a helpful step along the way.
According to the experts, approximately 75% of women with PCOS have clinically evident menstrual problems and a further 20% of women have ovulatory problems that are harder to detect unless your doctor really knows what they’re doing (Azziz et al. 200611).
Put mildly, if you have PCOS and you didn’t have trouble falling pregnant, then you’re darn lucky…
Combating the ovulatory disorders that lead to infertility is one of the areas where inositol supplements show the most promise for women with PCOS.
When it comes to using inositol supplements to enhance your fertility you essentially have three options:
- Take myo-inositol on its own
- Take D-chiro-inositol in its own
- Take a combination of myo-inositol and D-chiro-inositol.
Here’s what the science says about each of these options:
4. Myo-Inositol, PCOS & Fertility Treatments
When it comes to fertility, a supplement that consists of 2000 mg of myo-inositol plus 200 μg of folic acid taken twice daily for at least 3 months has shown some pretty impressive results. This supplement has been shown to:
- Reduce AMH levels and the size of polycystic ovaries better than birth control (Ozay et al. 201612).
- Increase egg quality and reduce the risk of ovarian hyperstimulation syndrome in women undergoing ovulation induction (Papaleo et al. 200913; Ciotta et al. 201114).
These benefits can correlate to real results for women trying to conceive.
In a study of overweight women with PCOS that were given myo-inositol + folic acid during IVF, 32% of women had a successful pregnancy within the 12-month study period, compared to just 12% of women who only took a straight folic acid supplement without the inositol (Artini et al. 201315).
These really positive results have been repeated by other researchers that used a similar supplement regime to treat women undergoing intrauterine insemination (IUI) rather than IVF. In a recent study of IUI patients with PCOS, pregnancy rates were improved by approximately 50% (regardless of whether or not they had insulin resistance) after taking myo-inositol for just 3 months beforehand (Ozay et al. 201716).
The take home from this is that if you’re being prescribed recombinant follicle stimulating hormone (r-FSH) as part of an ovulation induction cycle (either with IVF or IUI), then make sure your fertility doctor also puts you on myo-inositol.
This one’s a no-brainer as far as I can see.
5. Beware Of Myo-Inositol Products That Contain Folic Acid
It’s worth paying attention here to the fact that one of the most widely used myo-inositol products also includes folic acid.
Inofolic by LOLI Pharma (not to be confused with their other product Inofolic Combi) is often the product of choice for researchers studying the effects of myo-inositol on women trying to conceive. If you’re ever in the market for this supplement keep in mind that that this product goes by the name Pregnitude in the US and Canada (it’s the exact same drug, just a different brand name).
Inofolic (Pregnitude) is certainly a good quality product as independent analysis has shown this brand actually contains the dose rates of active ingredients stated on the label. The same cannot be said for some of their competitors where myo-inositol concentrations were found to be 25% less than the labelling amount (Papaelo et al. 201117).
While folic acid is generally considered essential for anyone that’s trying to conceive or already pregnant, a common genetic disorder known as the MTHFR gene mutation can mean that folic acid can potentially be harmful to both you and your baby.
Rather than taking folic acid supplements, women with this gene mutation instead need to take the active form of folate, known as methyl folate or 5-MTHF.
If you are going to take folic acid it’s important that you get tested for this gene mutation. And if you have it make sure to find a competent doctor that can supervise your 5-MTHF dosage rates as these need to be monitored to avoid adverse side effects.
I don’t want to get too far off topic here, but if you’re interested in learning more, I discuss this further in my PCOS Supplements Guide.
The key thing to take note of here is that if you’re considering myo-inositol to assist with your fertility, it’s also worth taking the time to figure out the source of supplementary folate that is most appropriate for you personally.
For many people folic acid will be fine, in which case products like Inofolic (Pregnitude) are going to be a good option. But for women that test positive for the MTHFR gene mutation, you’ll want to avoid this product brand and stick with a pure myo-inositol supplement and take 5-MTHF as well.
For my personal preferences of specific myo-inositol products, you can complete this short PCOS Inositol Quiz by clicking here and I’ll send you a report with my recommended brands and dosages based on your particular symptoms and health goals.
6. If You Have PCOS Myo-Inositol Is Better Than Metformin For Fertility
The same combined myo-inositol / folic acid supplements were also found to be better than metformin at restoring ovulation and achieving a natural pregnancy in women with PCOS. In a study that put these two treatments in a head to head battle, metformin achieved an 18% pregnancy rate over a 6-month period compared to 30% of women who managed to fall pregnant naturally just by taking the myo-inositol / folic acid supplements (Raffone et al. 201018).
This isn’t the only time myo-inositol has proven to be better than metformin in certain circumstances.
For example, inositol’s potential was demonstrated during a recent randomized controlled trial where researchers pitted 1500 mg per day of metformin up against 4000 mg per day of myo-inositol. In this direct comparison that included patients both with and without insulin resistance, myo-inositol outperformed metformin when it came to improving insulin sensitivity and reducing testosterone levels, hirsutism, and markers of inflammation (Jamilian et al. 201719).
With results like these continuing to come out, I don’t think it’ll be long before metformin finally gets a long overdue retirement pension.
In my view, if you’re trying to conceive, then it’s well worth giving myo-inositol a try before messing with metformin. You’ll get better results and with less side effects too!
And since we’re talking about one of the most commonly prescribed PCOS drugs, it’s also worth mentioning that researchers are now investigating using myo-inositol to improve the efficacy of clomid for ovulation induction. While it’s too soon to say for sure, early results look very promising (Rolland et al. 201720).
Again, the key message here seems to be that myo-inositol is well worth considering when trying to conceive given its low cost and low risks (see the Side Effects and Safety section below).
Click here to take my PCOS Inositol Quiz and receive my independent brand and dosage recommendations based on the answers you provide.
7. Taking Straight D-Chiro-Inositol Is A Bad Idea When Trying To Conceive With PCOS
There is some evidence showing D-chiro-inositol is effective in improving ovarian function in women with PCOS that are a normal weight (Pizzo et al. 201421; Lagana et al. 201522), as well as in those that are overweight (Nestler et al. 199923).
However, recent studies on IVF patients with PCOS suggest that in a straight comparison between these two forms of inositol supplements, myo-inositol seems to be better at improving fertility than D-chiro-inositol (Unfer et al. 201124).
This is likely due to the fact that D-chiro-inositol improves the insulin sensitivity of non-ovarian tissues, while myo-inositol specifically targets the ovaries (Monastra et al. 20177).
It’s also worth noting that taking high doses of D-chiro-inositol negatively affect egg quality during IVF cycles when administered to women that have PCOS without insulin resistance and/or hyperglycemia (Isabella et al. 201225).
Given these findings and associated ethical concerns, researchers now hesitate to investigate straight D-chiro-inositol as a supplement to improve fertility (Colazingari et al. 20138). However, as I discuss below, this supplement does show promise for improving other metabolic parameters that are often out of whack in women with PCOS.
My take on this is that straight D-chiro-inositol supplements are not worth messing with when trying to conceive.
8. Inositol Helps With PCOS Hirsutism… A Little
Unwanted hair growth often feels like one of the most upsetting aspects of a PCOS diagnosis. Not that this will be news to anyone who has experienced it of course, but there are a lot of studies showing that hirsutism is a major source of distress for many of us (Pasch et al. 201626), and it’s something I see discussed a lot in my Facebook community for women with PCOS.
So can myo-inositol really help with this symptom? It seems that it can, but the magnitude of the effect is possibly a little less than what many people would hope for.
Here’s how it works: Hirsutism occurs as a consequence of the high androgen (testosterone) levels caused by PCOS. Taking myo-inositol can help with this problem because this supplement is known to lower our insulin levels, and lower insulin levels means lower androgens.
This is the same mechanism by which the low carbohydrate meals I prescribe in my free 30-Day PCOS Diet Challenge and free 3-Day PCOS Diet Meal Plan achieve such great results too. Lowering your intake of carbohydrates, and switching to the low GI whole food sources I recommend results in steadier blood glucose levels throughout the day so your body doesn’t need to produce as much insulin.
Speaking from experience here, when you eat this way for long enough, your body can repair itself and you can actually decrease your insulin resistance.
At the time of writing, there were two randomized controlled trials that experts use to demonstrate the efficacy of myo-inositol supplements for reducing unwanted hair growth in women with PCOS.
In one study, 4000 mg per day of myo-inositol resulted in a statistically significant improvement in unwanted hair when taken for a 6-month period. These women were not taking birth control or any other hormone regulating medications at the time, meaning the positive effects of the inositol was free to do its thing as well as it could have.
This last point is an important nuance that most other people will fail to tell you. What it means is that if you’re already taking a hormone regulating medication, then you’re unlikely to see the same results. In any case, the change was quite small and it’s worth pointing out that this was another trial where myo inositol weight loss did not occur (Minozzi et al. 200827).
Another team of researchers conducted a very similar trial and had slightly better results. About a third of the women were able to eliminate their hirsutism after 6 months although these were likely the same women who started the trial with a “mild” diagnosis.
And of the women that started the treatment with “severe” hirsutism, about half of them still had this diagnosis after the 6-month study period (Zacche et al. 200928). While this was good news for the half that managed to see a reduction in unwanted hair growth, this goes to show that myo-inositol is not a cure for hirsutism.
When writing my Beat PCOS Supplements Guide, I spent a lot of time searching the scientific literature for other supplements that can help with hirsutism. While there are a few herbs with testosterone lowering compounds in them which might do something to help in theory, as far as high quality scientific trials go, the only other potential candidate appears to be chromium picolinate.
The problem with chromium though is that the size of the benefit appears to be modest at best and there is insufficient evidence for me to recommend this supplement in good conscience – especially given the potential for this compound to be carcinogenic (Wu et al. 201629).
With this finding in mind, I keep coming back to the conclusion that switching to a PCOS diet is the best way to combat unwanted hair.
9. Myo-Inositol Can Help With PCOS Acne
When it comes to acne, only the study by Zacche and colleagues provides an indication of how effective myo-inositol can be in treating this symptom. The results look fairly good, with more than half of the women who had moderate or severe acne at the start of the treatment clearing up after 6 months. A few women still had pretty bad acne at the end of this trial but my guess is that these treatment resistant women were likely to be the same ones that also still had the worst hirsutism.
What this tells us is that myo-inositol is fairly effective at reducing acne, but it still doesn’t work for everyone with PCOS.
My personal view is that just like hirsutism, the best treatment for PCOS acne, whether you’re taking inositol supplements or not, is to also switch to a PCOS friendly diet. Doing both is clearly the best way to maximize your results.
After my own experience of winning a 15-year battle with acne, as well as overcoming many of the other common PCOS symptoms I’m 100% conscious of my natural bias here – even though I’ve seen countless others do the same.
But the hard truth is that if you really want to clear your skin of acne, nothing is more effective than quitting sugar and refined carbohydrates. This is one of the key strategies we implement during my free live 30-Day PCOS Diet Challenge.
10. Inositol And General Metabolic Health In Women With PCOS
So far, I’ve talked about how inositol supplements can help us with the things that bug us the most when it comes to PCOS: weight loss, infertility, unwanted hair, and acne. But we all know that the effects of PCOS run much deeper than this in terms of our overall health.
After reviewing the latest scientific literature at length, it seems fairly certain that both myo-inositol and D-chiro-inositol supplements can have a positive effect on our cardiovascular and metabolic health to some extent or other. This seems to be equally true for women with lean type PCOS that don’t have insulin resistance as it is for overweight women that do (Genazzanni 20166).
Here’s a quick summary of the evidence supporting the use of inositol supplements for metabolic health.
In a systematic review of 21 studies researchers found that myo-inositol (Unfer et al. 201230):
- Had a significant impact on the hormonal parameters of PCOS patients.
- Improved glucose/insulin ratios.
- Sent cholesterol levels in all the right directions – HDL increased, while LDL decreased.
It’s been noticed though that although myo-inositol is effective in improving insulin sensitivity and most hormonal parameters in overweight or obese PCOS patients, not all obese women see an improvement in metabolic health with this supplement – even when they lose weight. Experts suggest that this is because obesity is not the only element triggering insulin resistance and that most, but not all women with PCOS have some other built-in abnormal mechanism that causes this problem (Genazzani et al. 20166).
To anyone that’s been told by their doctor that they need to “just lose some weight” to fix their insulin resistance, this news should come as some relief. You don’t have insulin resistance just because you’re overweight… it’s the PCOS itself!
Now I know that earlier I said taking straight D-chiro-inositol is probably not a good idea if you’re trying to conceive, but if this isn’t an issue for you, then there’s something to be said for this less common inositol supplement.
When it comes to metabolic health, D-chiro-inositol shows plenty of promise for women with PCOS that suffer from insulin resistance regardless of their bodyweight. Doses of 600 mg per day of D-chiro-inositol have been shown to improve insulin and androgen levels in lean women with PCOS (Luorno et al. 200231), while doses of 1000 mg per day have been effective at improving a range of metabolic and cardiovascular health indicators on a more representative PCOS population (Lagana et al. 201522).
The group of women that are most likely to benefit from D-chiro-inositol supplements however are those that are significantly overweight (BMI > 30), especially if they have close relatives that are diabetic (type II diabetes). Having diabetes in the family makes you more likely to naturally be low in D-chiro-inositol as a result of a genetic abnormality (Genazzani et al. 2014b32), which means you have more to gain from taking this supplement.
My thoughts are that if you’re at a high risk of diabetes and not trying to conceive than D-chiro-inositol could be a sensible way to go, while for everyone else I think that taking a combination of both myo-inositol and D-chiro-inositol is probably going to give you the best results.
As I mentioned at the top of this article, that while researchers are yet to satisfactorily determine the optimum blend of myo-inositol and D-chiro-inositol, most experts agree that taking a combination of these supplements appears to be best for overall health in the general PCOS population.
After writing this article, I soon realized that with all this conflicting information, it can be really confusing for people to figure out what’s the best course of action to take. With this in mind, I created my quick, PCOS Inositol Quiz. If you can afford 30 seconds to answer 3 simple questions, I’ll send you a report with product and dosage recommendations based on your particular symptoms and health goals. I have zero affiliation with any supplement company, so these recommendations are strictly independent and are based on what I genuinely think is best.
11. Inositol For Anxiety And Depression In Women With PCOS
One of the things many people don’t realize about PCOS is just how much their diagnosis makes them more sensitive to stress, anxiety, and depression. This is such a pervasive issue amongst the women I have met through my free live 30-Day PCOS Diet Challenge, and my heart goes out to anyone who has to fight these powerful emotions on a regular basis. I’ve had more than my fair share of mental health challenges over the years too.
Women with PCOS are reported to experience depressive episodes approximately three times more frequently than healthy control groups (Setji et al. 201433) with some estimates putting the ratio closer to an eight-fold increase (Cinar et al. 201134). And despite controlling for age and body weight, researchers have found that women with PCOS have higher scores for anxiety, worry, phobias, and pain (Jedel and Waern 201035).
So we’re a group of worriers alright… and this is where inositol supplements might provide some of their greatest benefit to us.
There are several studies that show high doses of inositol can reduce panic attacks in people susceptible to them with one trial showing 18000 mg per day of inositol to be more effective than the SSRI drug fluvoxamine (Palatnik et al. 200136).
When it comes to depression, inositol supplements have been shown to have a small but significant impact also (Levine et al. 199539) with the people most likely to see a benefit being those that experience premenstrual dysphoric disorder (Mukai et al. 201440). PMDD is a lot like PMS, but with emotional symptoms that have a debilitating effect on your daily life.
12. Inositol Dosage PCOS Pro Tip 1: Take Myo-Inositol On Its Own For Fertility.
If after reading all of this you’re wondering what type of inositol is right for you, or how much inositol should I be taking for PCOS, then here are a few pro-tips that can save you money while also getting you the best results.
Alternatively, you can just take my PCOS Inositol Quiz and I’ll send you my personal recommendations based on the answers you give to three key questions.
The first thing worth keeping in mind is that if you’re only (or mostly) interested in taking inositol supplements to help with fertility, you may be just as well off taking a straight myo-inositol supplement on its own, rather than buying the more expensive 40:1 combination products.
In the blockbuster study I mentioned earlier, 4000 mg per day of myo-inositol on its own was just as effective at restoring ovulation over a 6-month period as taking 1100 mg per day of the combined myo-inositol/ D-chiro-inositol supplement (Nordio and Proietti 20121).
To be fair, this study did show that the combined product outperformed the straight myo-inositol at the 3-month mark. This suggests a short-term advantage in using the combined product especially if you’re in a rush and the cost difference doesn’t phase you, but over the longer term this advantage was not significant.
As I have explained above, there is a high degree of confidence that myo-inositol significantly improves your chances of falling pregnant whether you’re trying naturally, or you’re getting a little help.
By my estimates, taking the combined myo-inositol/ D-chiro-inositol supplements will cost you around $180 for 6 months’ supply, while you’ll spend less than $60 for the required amount of straight myo-inositol powder taken for the same period.
Take my PCOS Inositol Quiz to learn my preferred myo-inositol product brands and dosage based on your particular circumstances.
13. Inositol Dosage PCOS Pro Tip 2: Taking D-Chiro-Inositol
If after reading the section above on metabolic health you’re considering taking D-chiro-inositol and you’re wondering how much inositol for PCOS to take, then 500 mg per day taken once in the morning seems to be a good dose to start with.
This is how much they used in the study on overweight women with PCOS I mentioned earlier, where they found that those who benefit the most are those at high risk of developing type II diabetes (see above).
Take my PCOS Inositol Quiz to learn my preferred D-chiro-inositol product brands and dosage based on your particular circumstances.
14. Inositol Dosage PCOS Pro Tip 3: Taking Myo & D-Chiro Inositol Together
As I’ve already explained above, the latest thinking on inositol supplements for PCOS is that taking a combined supplement that includes both myo-inositol and D-chiro-inositol is the best for metabolic health and works just as well as myo-inositol for improving fertility (Unfer et al. 201641).
While more competitors are starting to pop up, there are still only two big brands that dominate the combined inositol supplement market for women with PCOS, Ovasitol by Theralogix, and Inofolic Combi by LOLI Pharma. My understanding is that Inofolic Combi is pretty hard to find in the US but can be found readily across Europe, while Ovasitol is more widely distributed.
As far as dosages go, a typical dose of Ovasitol includes 2000 mg of myo-inositol and 50 mg of D-chiro-inositol with the manufacturer recommending this amount be taken both morning and night. Inofolic Combi on the other hand provides half this amount in a standard serving with their capsules containing 1100 mg of myo-inositol and 27.6 mg of D-chiro-inositol.
While these two products dominate the PCOS inositol market, I have a preference for another product which I include in my recommendations where appropriate for people that complete my PCOS Inositol Quiz. This product contains 1500 mg of myo-inositol and 100 mg of D-chiro-inositol in each dose.
If you’re wondering if any of these products are better than the other, then the answer is no. When taking inositol supplements at these recommended levels, more is not necessarily better, and there doesn’t appear to be any medical reason to favor one over the other. As I described above in Myth 2 Busted, the relative ratio of 40:1 used by Ovasitol and Inofolic Combi is considered “arbitrary” and “has no reason to be considered preferable to other available formulations” (Sortino et al. 20179).
And if you find these specific products unaffordable (let’s face it, they’re the most expensive way to take inositol supplements), but you’d still like to try a combination of both types of inositol, you can also achieve the same results by buying them separately. Getting straight myo-inositol powder is really easy, and you can buy low dose (50 mg) D-chiro-inositol capsules separately as well.
15. Inositol Dosage PCOS Pro Tip 4: Assess Personal Efficacy
Another suggestion you might find helpful if you’re planning on taking inositol is to get yourself tested both before and after treatment. Wait 3 months if you’re taking a combined myo/D-chiro inositol supplement and wait 6 months if you’re going with just straight myo-inositol (see Pro Tip 1 to understand why). This will let you determine exactly how much benefit the supplements are giving you and will help you decide if it’s worth continuing.
Some of the tests worth considering include those relating to insulin sensitivity such as the oral glucose tolerance test, and a hormone panel that includes some or all of the following: luteinizing hormone, follicle stimulating hormone, estradiol, progesterone, androstenedione, 17-hydroxy-progesterone, insulin and testosterone.
Hopefully your physician can point you in the right direction here…
Inositol And PCOS: Side Effects And Safety
When it comes to side effects and safety, the general consensus seems to be that myo-inositol is a safe supplement to take given no clinically relevant adverse effects have been found in several human studies that looked at doses of 4000 mg per day throughout pregnancy (Regidor et al. 201642; Corrado et al. 201143; D’Anna et al. 201244).
It should be noted though that doses greater than 12000 mg per day may result in mild gastrointestinal side-effects such as nausea, flatulence and diarrhea (Carlomagno and Unfer 201145).
And as I’ve already mentioned in the section about fertility, care should be taken when using D-chiro-inositol when trying to conceive particularly if you don’t suffer from insulin resistance and/or hyperglycemia. Taking D-chiro-inositol alone, at high dosages, can adversely affect egg quality leading experts to warn against its use without screening for insulin resistance first (Vitagliano and Quaranta 201546).
How To Maximize The Benefits Of Inositol Supplements
While inositol can certainly improve your fertility, reduce unwanted hair and acne, have positive effects on your metabolic health, and even help with anxiety and depression, all of these outcomes simply reflect the predictable benefits of restoring a healthy hormone balance.
When we get our hormone balance right, all of our symptoms improve, but inositol supplements are only part of the solution for anyone who really wants to experience the full potential of what great health means.
In my view all of the positive benefits of inositol supplements are a reflection of the same mechanisms behind the scientifically proven diet and lifestyle recommendations for women with PCOS. And inositol can only bring you so far down that road. This is why the best way to get the most out of taking inositol is to also ensure you’re eating a PCOS friendly diet.
After seeing the results from tens of thousands of women who do my free 30-Day PCOS Diet Challenge since early 2016, I have seen the power of what a PCOS friendly diet can achieve.
So, my advice to you is to make sure to also focus on your diet if you’re taking inositol supplements and you want to see the best results possible.
Kym Campbell is a Health Coach and PCOS expert with a strong passion for using evidence-based lifestyle interventions to manage this disorder. Kym combines rigorous scientific analysis with the advice from leading clinicians to disseminate the most helpful PCOS patient-centric information you can find online. You can 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.
1Nordio M; Proietti, E. 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. EUROPEAN REVIEW FOR MEDICAL AND PHARMACOLOGICAL SCIENCES, 2012.
2Gerli, S.; Papaleo, E.; Ferrari, A.; et al. Randomized, double blind placebo-controlled trial: effects of myo-inositol on ovarian function and metabolic factors in women with PCOS. EUROPEAN REVIEW FOR MEDICAL AND PHARMACOLOGICAL SCIENCES, 2007.
2Genazzani, Alessandro D.; Santagni, Susanna; Ricchieri, Federica; et al. Myo-inositol modulates insulin and luteinizing hormone secretion in normal weight patients with polycystic ovary syndrome. JOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH, 2014.
5Dinicola, Simona; Chiu, Tony T. Y.; Unfer, Vittorio; et al. The Rationale of the Myo-Inositol and D-Chiro-Inositol Combined Treatment for Polycystic Ovary Syndrome. JOURNAL OF CLINICAL PHARMACOLOGY, 2014.
7Monastra, Giovanni; Unfer, Vittorio; Harrath, Abdel Halim; et al. Combining treatment with myo-inositol and D-chiro-inositol (40:1) is effective in restoring ovary function and metabolic balance in PCOS patients. GYNECOLOGICAL ENDOCRINOLOGY, 2017.
8Colazingari, Sandra; Treglia, Mariangela; Najjar, Robert; et al. The combined therapy myo-inositol plus D-chiro-inositol, rather than D-chiro-inositol, is able to improve IVF outcomes: results from a randomized controlled trial. ARCHIVES OF GYNECOLOGY AND OBSTETRICS, 2013.
10Heimark, Douglas; McAllister, Jan; Larner, Joseph. Decreased myo-inositol to chiro-inositol (M/C) ratios and increased M/C epimerase activity in PCOS theca cells demonstrate increased insulin sensitivity compared to controls. ENDOCRINE JOURNAL, 2014.
11Azziz, Ricardo; Carmina, Enrico; Dewailly, Didier; et al. Criteria for defining polycystic ovary syndrome as a predominantly hyperandrogenic syndrome: An Androgen Excess Society guideline. JOURNAL OF CLINICAL ENDOCRINOLOGY & METABOLISM, 2006.
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13Papaleo, Enrico; Unfer, Vittorio; Baillargeon, Jean-Patrice; et al. Myo-inositol may improve oocyte quality in intracytoplasmic sperm injection cycles. A prospective, controlled, randomized trial. FERTILITY AND STERILITY, 2009.
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16Ozay, Ozlen Emekci; Ozay, Ali Cenk; Cagliyan, Erkan; et al. Myo-inositol administration positively effects ovulation induction and intrauterine insemination in patients with polycystic ovary syndrome: a prospective, controlled, randomized trial. GYNECOLOGICAL ENDOCRINOLOGY, 2017.
17Papaleo, E.; Molgora, M.; Quaranta, L.; et al. Myo-inositol products in polycystic ovary syndrome (PCOS) treatment: quality, labeling accuracy, and cost comparison. EUROPEAN REVIEW FOR MEDICAL AND PHARMACOLOGICAL SCIENCES, 2011.
19Jamilian, Mehri; Farhat, Pegah; Foroozanfard, Fatemeh; et al. Comparison of myo-inositol and metforminon clinical, metabolic and genetic parameters in polycystic ovary syndrome: A randomized controlled clinical trial. CLINICAL ENDOCRINOLOGY, 2017.
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22Lagana, Antonio Simone; Barbaro, Luisa; Pizzo, Alfonsa. Evaluation of ovarian function and metabolic factors in women affected by polycystic ovary syndrome after treatment with d-Chiro-Inositol. ARCHIVES OF GYNECOLOGY AND OBSTETRICS, 2015.
24Unfer, V.; Carlomagno, G.; Rizzo, P.; 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. EUROPEAN REVIEW FOR MEDICAL AND PHARMACOLOGICAL SCIENCES, 2011.
26Pasch, Lauri; He, Steven Y.; Huddleston, Heather; et al. Clinician vs Self-ratings of Hirsutism in Patients With Polycystic Ovarian Syndrome Associations With Quality of Life and Depression. JAMA DERMATOLOGY, 2016.
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29Wu, Lindsay E.; Levina, Aviva; Harris, Hugh H.; et al. Carcinogenic Chromium(VI) Compounds Formed by Intracellular Oxidation of Chromium(III) Dietary Supplements by Adipocytes. ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 2016.
32Genazzani, Alessandro D.; Santagni, Susanna; Rattighieri, Erika; et al. Modulatory role of D-chiro-inositol (DCI) on LH and insulin secretion in obese PCOS patients. GYNECOLOGICAL ENDOCRINOLOGY, 2014.
41Unfer, Vittorio; Nestler, John E.; Kamenov, Zdravko A.; et al. Effects of Inositol(s) in Women with PCOS: A Systematic Review of Randomized Controlled Trials. INTERNATIONAL JOURNAL OF ENDOCRINOLOGY, 2016.
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46Vitagliano A, Quaranta M, ‘‘Empiric’’ inositol supplementation in normal-weight non insulin resistant women with polycystic ovarian disease: from the absence of beneﬁt to the potential adverse effects, ARCHIVES GYNECOLOGY OBSTETRICS, 2015.