Inositol + PCOS: Benefits, Considerations, and Ideal Dosage

Inositol supplements are one of the most powerful natural strategies for improving PCOS. Why? 

Research has shown that inositol can help women with PCOS control blood sugar, improve insulin sensitivity and glucose metabolism, regulate hormone levels and menstrual cycle regularity, and improve egg quality and fertility. 

Most of these benefits relate back to inositol’s effect on insulin regulation. Like many of the most effective supplements available, inositol helps your body do what your body already knows how to do. 

Let’s get into the details: how inositol works for PCOS, whether you should try it, what to look out for, and what else you need to know. 

What Is Inositol?

Inositol is a type of sugar the body makes naturally. Sometimes referred to as vitamin B8 (although it’s not technically a vitamin), inositol plays an important role in the development and structure of cells and cell membranes, and helps to regulate insulin levels. (1) 

In addition to those that we naturally produce, inositols are found in certain foods and are available as supplements. Largely through its effects on insulin, inositol supplements may help to improve metabolic syndrome, certain mental health conditions, and polycystic ovary syndrome (PCOS). (2, 3, 4)

Types

There are nine different types of inositol that have been identified. But there are really only two kinds that are well-studied, understood to be bioavailable, and commonly found in supplements. 

We’ll focus on those two types here: myo-inositol (MI) and D-chiro-inositol (DCI). In the body, some MI is converted to DCI in response to insulin release. 

Food Sources

Inositol is found naturally in certain foods. However, to achieve the therapeutic benefits for PCOS, food sources alone are not likely to be sufficient (which is where supplements come in). 

Foods that are high in inositol include: 

Citrus fruits

Cantaloupe

Lima beans, navy beans

Almonds, walnuts

Organ meats

Benefits Of Inositol For PCOS

Inositol supplements have been shown to offer significant benefits for those with PCOS, including improved blood sugar levels and reduced insulin resistance, more balanced hormones, better menstrual cycle regulation, increased frequency of ovulation, improved fertility, and increased pregnancy rates. (5) 

Here are some of the top research-backed benefits of inositol for PCOS. 

Periods And Ovulation

Inositol can help to improve the irregular menstrual cycles and anovulation (cycling without ovulation) commonly experienced by women with PCOS. 

Missed periods and decreased ovulation, like other symptoms of PCOS, may be caused in part by insulin sensitivity and elevated levels of male sex hormones. Research has also shown that people with PCOS may have altered levels of myo-inositol and D-chiro-inositol in the ovaries. (6)

Inositol supplementation helps to correct these imbalances. Several studies have found reduced androgen levels and more regular ovulation and periods when women with PCOS take daily inositol supplements. (7) 

Inositol may be especially helpful for supporting ovulation when combined with folic acid. One study found that the combination of myo-inositol and folic acid led to improved ovulation and pregnancy rates compared to standard treatment with Metformin. (8) 

LISTEN: Female Hormone Imbalances + Your Mood, Supplements & Self-Compassion | Dr. Will Cole 

Fertility

Up to 80% of people with PCOS have challenges with fertility, but it’s absolutely possible to get pregnant if you have PCOS. (9) Inositol supplements can play an important role here, helping to reduce the size of polycystic ovaries, improve egg quality, and correct the imbalance of MI to DCI in the ovaries, all of which can improve the likelihood of pregnancy.  (10, 11)

A randomized controlled trial compared women with PCOS taking myo-inositol supplements to those taking the diabetes drug Metformin (which has become standard treatment for PCOS). Over a 6 month period, women taking inositol achieved a natural pregnancy rate of 30%, compared to 18% for those taking Metformin. (12) 

How does this work? One of the reasons why females with PCOS often experience infertility is because of egg quality. Specifically, women with PCOS produce less mature eggs than those without – and this has been linked to lower levels of myo-inositol in the ovaries. (13) 

By supplementing with inositol, many women are able to achieve a better balance of MI to DCI, helping to improve ovulation, egg quality, and fertility. 

It’s important to take a supplement with the right balance of MI to DCI, however, as too much DCI can have the opposite intended effect– high levels of DCI can reduce absorption of MI, and negatively impact egg quality. (14) I’ll get a bit deeper into this balance and the right ratio to supplement with further down.  

Reduced Risk Of Gestational Diabetes

Women with PCOS have been shown to have an increased risk of high blood sugar or diabetes that develops during pregnancy (gestational diabetes). (15) 

Supplementing with a combination of inositol and folic acid (along with any other prenatal vitamins or supplements that your practitioner may recommend) has been shown to help manage blood sugar levels and reduce the risk of gestational diabetes (GD) and preterm birth associated with GD. (16) 

Of course, it’s always important to speak with your healthcare provider before introducing any new supplements while you’re pregnant. 

Weight Management

While weight loss is not typically the primary reason inositol treatment would be recommended for PCOS, supplementation may help some people lose weight, likely as a result of improved blood sugar control. (17) 

There have also been some reports of weight gain while taking inositol supplements for PCOS. This is uncommon, and may be caused by something unrelated to inositol. It’s also possible that some people gain weight because their bodies are metabolizing myo-inositol differently. 

Insulin Sensitivity And Decreased Diabetes Risk

Many PCOS patients deal with insulin resistance (or impaired insulin sensitivity), which occurs when the body’s cells don’t respond properly to the insulin released by the pancreas. 

This leads to blood sugar dysregulation, and forces the pancreas to release more and more insulin (hyperinsulinemia). Over time, this can lead to the development of type 2 diabetes. 

Several studies have shown that inositol supplementation is just as effective as or even more effective than Metformin when it comes to improving insulin resistance and blood sugar regulation. (18, 19) 

So how does it work? 

Inositol has been shown to act as a secondary messenger between the inside and outside of cells, helping cells become more responsive to insulin, and therefore improving blood sugar regulation. (20) Essentially, the body is thought to call on inositol when our primary insulin signaling system fails to get the job done. 

Maybe unsurprisingly given the above, insulin resistance has been linked to lower than usual levels of D-chiro-inositol in the body. (20) By taking inositol supplements, in an appropriate ratio of myo-inositol to D-chiro-inositol to match the body’s natural balance, many people with PCOS are able to improve insulin sensitivity. (21) 

Is Inositol Better Than Metformin?

Multiple studies have compared the effects of inositol supplements to the effects of the pharmaceutical drug Metformin for women with PCOS, and have generally found that inositol supplements are as effective as or even more effective than Metformin. (22) 

This is true when it comes to ovulation, fertility and pregnancy rates, and glucose control for women with PCOS. 

This is great news, especially for those who prefer more natural treatment options. Inositol also has a much better safety profile and lower risk of side effects compared to Metformin (the latter of which is more likely to cause digestive distress, fatigue, dizziness, and other adverse effects). 

Just remember to always speak with your doctor before discontinuing a prescription medication such as Metformin and/or introducing a new supplement like inositol. 

Sometimes your practitioner may also recommend adding inositol to your treatment plan but continuing to take Metformin. Again, this shouldn’t be done on your own – combining a blood sugar lowering medication with a blood sugar regulating supplement may lead to hypoglycemia and other concerns.  

Side Effects And Considerations

Inositol supplements are generally thought to be safe, and generally cause few to no side effects. Possible side effects may include mild diarrhea, nausea, or abdominal pain, but these are uncommon and typically only occur with very high doses. (23) 

Arguably the most important consideration when it comes to inositol supplements is the ratio of MI to DCI. Taking too much D-chiro-inositol without balanced amounts of myo-inositol can actually negatively affect hormone levels, PCOS symptoms, and fertility. The right ratio for most people seems to be 40:1 MI:DCI, however, it’s best to work with a practitioner who can help you make sure you’re getting the right balance here.  

Ideal Dosage

When you’re considering inositol supplements for PCOS, you’ll want to look at the ratio of the two main types of inositol as well as the total dosage. 

The ideal daily dosage for most people is thought to be approximately 2000 mg of myo-inositol combined with 50 mg of D-chiro-inositol. For some people, a higher dose of both may be recommended, but generally still at the ratio of 40 MI to 1 DCI. 

This 40:1 MI to DCI ratio is in line with the body’s natural healthy ratio, and has been shown to be the most effective for improving PCOS overall. (24) But again, always speak with a practitioner about the best plan for you. 

It’s usually best to take inositol supplements just before a meal. Inositol may also be especially effective when combined with folic acid, especially for improving fertility.

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Finding The Right Supplement Plan For You

Inositol, like other supplements, is most effective when used as part of a comprehensive, personalized, holistic wellness protocol. A functional medicine practitioner can help to answer any other questions you may have about inositol, develop the right supplement, dietary, and overall health plan for you, and support you throughout your journey with PCOS.

As one of the first functional medicine telehealth clinics in the world, we provide webcam health consultations for people around the globe.