Inositol: Benefits, Side Effects and Dosage

People with PCOS have an increased risk of gestational diabetes (GD), which is diabetes that develops in pregnancy. A study published in 2019 concluded that people with PCOS have a two-fold higher risk of developing GD than those without PCOS.

6 Things to Know About Taking Inositol for PCOS

Renita White, MD, FACOG, is a board-certified obstetrician/gynecologist. She practices at Georgia Obstetrics and Gynecology, and cares for women all over the metro Atlanta area in Georgia.

Table of Contents
Table of Contents

Treating polycystic ovary syndrome (PCOS) with vitamin-like substances called inositols —a type of sugar in the body—has shown promising results. They are used to help people with PCOS control blood sugar and increase their chances of becoming pregnant.

Read on to learn more about how taking inositols can help treat PCOS.

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Inositol Improves Insulin Resistance

Inositols are a kind of sugar the body makes. They help balance chemicals that control your blood sugar and fertility. They also affect your metabolism, which is the process of turning the food you eat into energy.

Many people with PCOS are insulin resistant. Their bodies make insulin but aren’t able to use it effectively. This increases the risk of diabetes, infertility, obesity, and high cholesterol.

Inositols make molecules involved in the body’s response to insulin. Researchers say inositols may be part of the body’s messaging system when the usual insulin signaling system fails.

Does Inositol for PCOS Make You Gain Weight?

It depends on the individual. Imbalances in your levels of inositols are associated with weight changes, including weight loss and weight gain. Studies have found these weight changes are linked primarily to how myo-inositol (MI) is metabolized in the body. For many people with PCOS, inositol-based therapies may lead to weight loss.

Inositols From Food and Supplements

You can get inositols by eating healthy foods such as:

Fruits: Cantaloupe, grapefruit, other citrus fruits
Beans: Lima, navy
Grains: Brown rice, whole wheat
Nuts: Almonds, walnuts

You can also buy inositol food supplements, pills, or powders you mix with water. Inositol supplements are generally well-tolerated.

Inositols MI and DCI Benefits For PCOS

There are nine forms of inositol, but the two that have the biggest impact on PCOS are myo-inositol (MI) and D-chiro-inositol (DCI). Normally, MI is converted to DCI.

MI/DCI Supplements

It is important to note that MI:DCI ratios vary in different body tissue, but in the ovary, healthy females have a ratio of approximately 100:1. PCOS patients tend to have a much higher level of DCI and very low levels of MI, leading to an abnormally low MI:DCI ratio of 0.2:1.

Combined therapy with MI and DCI is more effective than taking either inositol alone. Specifically, research shows a 40:1 MI/DCI ratio is best for restarting ovulation in people with PCOS.

MI and DCI in a 40:1 ratio may be more effective than metformin. One study found people with PCOS who took the 40:1 MI/DCI supplement had significantly better ovulation and pregnancy rates (46.7% vs. 11.2%) than those who did not take the supplement.

Two grams, twice a day, is currently considered the optimal inositol for PCOS dosage. The best time to take inositol is just before eating.

MI to DCI and Fertility

PCOS is a common cause of infertility. Up to 80% of people with PCOS experience infertility challenges.

People with PCOS have an imbalance of MI to DCI in their ovaries.

This can affect:

Periods: People with PCOS can have irregular periods or no periods at all. Treatment with inositols has been shown to help improve insulin sensitivity and reduce male hormone levels in females with PCOS. This helps restore periods.
Ovulation: People with PCOS might not ovulate every month or at all. Researchers have linked this to having too little MI and too much DCI in the ovaries.
Egg quality: Eggs can’t mature unless there is a high enough level of MI in the follicular fluid. Females with PCOS have been shown to produce less mature eggs than females without the disorder. Researchers have linked this to having too little MI in the follicular fluid, which surrounds the eggs within the ovaries.

Inositols can help restore ovulation and improve oocyte (immature egg) quality. But researchers say that taking the correct formulation is essential because high doses of DCI negatively affect oocytes and prevent the body from absorbing MI.

MI Used to Treat Gestational Diabetes

People with PCOS have an increased risk of gestational diabetes (GD), which is diabetes that develops in pregnancy. A study published in 2019 concluded that people with PCOS have a two-fold higher risk of developing GD than those without PCOS.

Side Effects and Cautions

You may feel tempted to try using inositol supplements on your own. That’s not a good idea. Taking too much DCI, for example, can lower your estrogen levels and increase male hormone levels.

Estrogen has several benefits, like protecting bones and preventing breast cancer. Increasing testosterone levels in females already at risk of infertility also isn’t wise.

Additionally, inositol for PCOS has been linked to hair loss as well as excessive hair growth. Some people with PCOS also experience acne, which can be treated with other medications.

If your healthcare provider agrees and you decide to try inositols, you may need to be extra careful of what you eat and drink. Some artificial sugars and sugar alcohols weaken the benefit of these supplements.

Dosing Variations

Some food supplement companies continue to sell supplements with varying MI/DCI ratios. One review found that the MI to DCI ratio in PCOS products can range from as little as .04-to-1 to as high as 104-to-1. Some supplements contain only DCI, while others contain additional substances such as vitamins and artificial sugars. There’s no evidence to show these ingredients help.

Summary

Inositols are sugars the body makes that help regulate insulin and cholesterol levels. Two types of inositols help treat PCOS: MI and DCI.

You can get inositols by eating certain foods or taking food supplements. If you’re struggling with infertility, a 40 to 1 MI to DCI supplement ratio appears to be the most helpful. This ratio has also been shown to help lower insulin and cholesterol levels with PCOS.

A Word From Verywell

Research into using combinations of inositol supplements to treat PCOS is very promising. It’s also inexpensive compared to some other infertility treatments. If you have PCOS, ask your healthcare provider if it could benefit you.

19 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

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Centers for Disease Control and Prevention. PCOS (Polycystic Ovary Disease) and Diabetes.
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Inositol: Benefits, Side Effects and Dosage

Although it’s often referred to as vitamin B8, inositol is not a vitamin but rather a type of sugar with several important functions. It influences the action of insulin and may aid mental health and metabolic conditions, including diabetes.

Inositol, sometimes referred to as vitamin B8, naturally occurs in foods such as fruits, beans, grains and nuts ( 1 ).

Your body can also produce inositol from the carbohydrates you eat.

However, research suggests that additional inositol in the form of supplements may have numerous health benefits.

This article takes a detailed look at the benefits, recommended dosages and potential side effects of inositol supplements.

Though often referred to as vitamin B8, inositol is not a vitamin at all but rather a type of sugar with several important functions.

Inositol plays a structural role in your body as a major component of cell membranes ( 2 ).

It also influences the action of insulin, a hormone essential for blood sugar control. In addition, it affects chemical messengers in your brain, such as serotonin and dopamine ( 3 , 4 ).

It has been estimated that a typical diet in the US contains around 1 gram of inositol per day. Rich sources include grains, beans, nuts and fresh fruits and vegetables ( 1 ).

However, supplemental doses of inositol are often higher. Researchers have studied the benefits of doses up to 18 grams per day — with promising results and few side effects.

Summary

Inositol is a type of sugar that helps provide structure to your cells. It also affects the hormone insulin and the function of chemical messengers in your brain.

Inositol may help balance important chemicals in your brain, including those believed to affect your mood, such as serotonin and dopamine ( 4 ).

Interestingly, researchers have found that some people with depression, anxiety and compulsive disorders have lower levels of inositol in their brain ( 5 , 6 ).

Though more research is needed, several studies suggest that inositol has the potential to be an alternative treatment for mental health conditions. It also seems to have fewer side effects than traditional medications ( 4 ).

Panic Disorder

While research is still limited, inositol supplements may be helpful for treating panic disorder, a severe form of anxiety.

Those with panic disorder experience frequent panic attacks, which are sudden feelings of intense fear. Symptoms include rapid heartbeat, shortness of breath, dizziness, sweating and a tingling or numb sensation in the hands (7).

In one study, 20 individuals with panic disorder took either an 18-gram inositol supplement or a common anxiety medication every day for 1 month. Those taking inositol had fewer panic attacks per week, compared to people taking the anxiety medication ( 8 ).

Similarly, in a 4-week study, individuals experienced fewer and less severe panic attacks when taking 12 grams of inositol per day ( 9 ).

Depression

Inositol may improve symptoms of depression, but research has had mixed results.

For example, an early study demonstrated that taking a 12-gram inositol supplement every day for 4 weeks improved symptoms in people with depression ( 10 ).

In contrast, subsequent studies were unable to show any significant benefits ( 11 ).

Overall, there is not enough evidence yet to say whether inositol has a true effect on depression.

Bipolar Disorder

As with the other mental health conditions, research on the effects of inositol and bipolar disorder is limited. However, the results of preliminary studies seem promising ( 12 , 13 ).

For example, a small study in children with bipolar spectrum disorders showed reduced symptoms of mania and depression when a combination of 3 grams of omega-3 fatty acids and up to 2 grams of inositol were taken daily for 12 weeks ( 12 ).

In addition, studies suggest that 3–6 grams of inositol taken daily may help reduce symptoms of psoriasis caused by lithium, a common medication used to treat bipolar disorder ( 14 , 15 ).

Summary

Though more research is needed, inositol shows potential as an alternative treatment option for mental health conditions, including panic disorder, depression and bipolar disorder.

Polycystic ovary syndrome (PCOS) is a condition that causes hormone imbalances in women, which may lead to irregular periods and infertility. Weight gain, high blood sugar and undesirable cholesterol and triglyceride levels are also concerns with PCOS (16).

Inositol supplements may improve PCOS symptoms, particularly when combined with folic acid.

For instance, clinical studies suggest that daily doses of inositol and folic acid may help reduce levels of triglycerides in the blood. They may also improve insulin function and slightly lower blood pressure in those with PCOS ( 17 , 18 , 19 ).

What’s more, preliminary research found that the combination of inositol and folic acid may promote ovulation in women with fertility issues from PCOS ( 20 , 21).

In one study, 4 grams of inositol and 400 mcg of folic acid taken daily for 3 months induced ovulation in 62% of treated women ( 20 ).

Summary

Inositol may help reduce blood triglyceride levels, improve insulin function, lower blood pressure and promote ovulation in women with polycystic ovary syndrome (PCOS).

Clinical studies suggest inositol supplements may be beneficial for those with metabolic syndrome ( 21 , 22 ).

Metabolic syndrome is a group of conditions that raise your risk of chronic disease, including heart disease and type 2 diabetes.

Specifically, five conditions are associated with metabolic syndrome ( 23 ):

Excess fat in the stomach area
High levels of triglycerides in the blood
Low “good” HDL cholesterol levels
High blood pressure
High blood sugar

In a year-long clinical study in 80 women with metabolic syndrome, 2 grams of inositol taken twice daily reduced blood triglyceride levels by an average 34% and total cholesterol by 22%. Improvements in blood pressure and blood sugar were also seen ( 24 ).

Amazingly, 20% of the women taking inositol supplements no longer met the criteria for metabolic syndrome by the end of the study ( 24 ).

Summary

Inositol may help control metabolic risk factors by helping lower blood triglyceride levels, blood pressure and blood sugar. It may also improve cholesterol levels.

Some women experience high blood sugar during pregnancy. This condition is called gestational diabetes (GDM) and complicates up to 10% of pregnancies in the US every year ( 25 , 26 ).

In animal studies, inositol has been directly related to the function of insulin, a hormone that regulates blood sugar levels ( 27 , 28 ).

Only a limited number of studies are available on the supplement and GDM in humans. However, some suggest that a combination of 4 grams of myo-inositol and 400 mcg of folic acid may be helpful in preventing GDM when taken daily throughout pregnancy ( 29 , 30 , 31 ).

However, more research is needed, as other studies have not shown the same effects ( 32 ).

Summary

Inositol may help prevent high blood sugar levels during pregnancy when taken in combination with folic acid, but more studies are needed to confirm this effect.

Inositol has been studied as a potential treatment option for many conditions.

Besides those already mentioned, research suggests inositol may be helpful in the following conditions:

Respiratory distress syndrome: In preterm infants, inositol appears to be helpful for treating breathing issues from underdeveloped lungs ( 33 ).
Type 2 diabetes: A preliminary study suggests that inositol and folic acid taken daily for 6 months may aid blood sugar control in people with type 2 diabetes ( 34 ).
Obsessive-compulsive disorder (OCD): A small study suggests that 18 grams of inositol taken daily for 6 weeks may reduce symptoms of OCD ( 35 ).

Summary

Inositol is a potential treatment option for preterm infants with respiratory distress syndrome. It may also aid blood sugar control in people with type 2 diabetes and may reduce symptoms of obsessive-compulsive disorder.

Inositol supplements seem to be well-tolerated by most people.

However, mild side effects have been reported with doses of 12 grams per day or higher. These include nausea, gas, difficulty sleeping, headache, dizziness and tiredness ( 36 ).

Up to 4 grams of inositol daily has been taken by pregnant women in studies without adverse effects, though more research is needed in this population ( 37 , 38 ).

There are also not enough studies to determine the safety of the supplements while breastfeeding. However, breast milk seems to be naturally rich in inositol ( 39 ).

In addition, it’s unclear whether inositol supplements are safe for long-term use. In most studies, inositol supplements were only taken for a year or less.

As with any supplement, talk to your doctor before taking inositol.

Summary

Inositol supplements are associated with very few and only mild adverse effects. More research is needed to determine its safety in pregnant and breastfeeding women as well as in long-term use.

There are two main forms of inositol used in supplements, namely myo-inositol (MYO) and D-chiro-inositol (DCI).

Though there is no official consensus on the most effective type and dosage, the following have appeared to be effective in research studies:

For mental health conditions: 12–18 grams of MYO once daily for 4–6 weeks ( 8 , 9 , 10 , 13 ).
For polycystic ovary syndrome: 1.2 grams of DCI once daily, or 2 grams of MYO and 200 mcg of folic acid twice daily for 6 months ( 17 , 20 ).
For metabolic syndrome: 2 grams of MYO twice daily for one year ( 23 ).
For blood sugar control in gestational diabetes: 2 grams of MYO and 400 mcg of folic acid twice daily during pregnancy ( 29 , 30 , 31 ).
For blood sugar control in type 2 diabetes: 1 gram of DCI and 400 mcg folic acid once daily for 6 months ( 34 ).

While these inositol doses appear to be helpful for certain conditions in the short-term, more research is needed to determine if they’re safe and effective over longer periods.

Summary

There is no official consensus for recommended doses of inositol. Dosage and type of inositol supplement vary depending on the condition.

Research suggests that inositol may aid people with mental health and metabolic conditions, such as panic disorder, depression, bipolar disorder, polycystic ovary syndrome, metabolic syndrome and diabetes.

It appears to be safe for most people and cause only mild if any side effects in daily doses up to 18 grams.

While your diet likely contains small amounts of inositol, taking a supplement may prove beneficial for some.

Always discuss the use of supplements with your healthcare provider first.

How we reviewed this article:

Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available.

Inositol: Benefits, Side Effects and Dosage

6 Things to Know About Taking Inositol for PCOS

Inositol Improves Insulin Resistance

Does Inositol for PCOS Make You Gain Weight?

Inositols From Food and Supplements