Inositol is a supplement that has gained popularity amongst those with PCOS and/or insulin resistance.
This article will cover all the ins and outs regarding inositol and its potential benefits for improving your health.
What is inositol?
Inositol is a type of sugar (specifically a sugar alcohol) found in some foods and produced by your body. There are different types of inositol, but the most common ones used in supplements are myo-inositol and D-chiro-inositol. Inositol is sometimes referred to as vitamin B8, but it’s not technically a vitamin.
Some foods contain natural inositol, such as whole grain bread, wheat bran, dried prunes, cantaloupe, beans, peas, almonds, and peanut butter.
Inositol supplements contain much higher doses of inositol compared to foods. If you want to reap the potential benefits of inositol in terms of insulin resistance and PCOS, then supplements are the best and more efficient route.
How does inositol work?
When taken in higher amounts, inositol positively impacts insulin resistance and polycystic ovary syndrome (PCOS) symptoms. PCOS is often caused by insulin resistance, but some people with PCOS don’t have insulin resistance.
Myo-inositol and D-chiro inositol have insulin-mimetic properties, which means they act similar to insulin. Myo- and D-chiro inositol have been studied for their ability to improve insulin sensitivity and are often recommended for women with PCOS to reduce symptoms.
Insulin is a hormone secreted by your pancreas. It helps lower blood glucose levels. Insulin resistance is a condition where your body doesn’t respond to insulin effectively and/or doesn’t produce enough insulin.
Insulin resistance is the leading cause of type 2 diabetes. Some signs of insulin resistance include:
- A waist circumference of >35 inches in women or >40 inches in men
- Dark, velvety patches of skin (acanthosis nigricans)
- Extreme thirst or hunger
- Feeling hungry even after a meal
- Increased or frequent urination
- Tingling sensations in hands or feet
- Feeling more tired than usual
- Frequent infections
- High blood sugar or insulin levels in blood work
Inositol also has beneficial impacts on hormone levels associated with PCOS. It can also help induce ovulation in women who don’t ovulate regularly. We’ll cover the specific ways PCOS impacts hormone levels in the next section.
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6 benefits of inositol
Below we share six health benefits of inositol.
1) Promotes more regular ovulation
One of the symptoms of PCOS is irregular ovulation. Ovulation is when your body releases an egg from your ovary. If the egg is fertilized by sperm, pregnancy occurs.
If your body doesn’t ovulate, you can’t become pregnant, and you will have long cycles with fewer periods than is considered healthy.
The standard “textbook” perfect menstrual cycle is considered 28-days long, with ovulation occurring around day 14 of the menstrual cycle. Longer cycles can still be considered normal and healthy.
However, some women with PCOS have very long cycles, which can last several months or longer.
Irregular ovulation can cause infertility, requiring fertility treatment and ovulation induction through prescription medications like Clomid or Letrozole.
A study was conducted on 50 women with insulin-resistant PCOS who weren’t ovulating (1). After administering myo-inositol, 29 of the 50 women ovulated (62%). Of the women who ovulated, 38% became pregnant.
According to another study, myo-inositol caused 16 out of 23 (70%) women with PCOS to ovulate compared to the placebo (4 out of 19, or 21%) (2).
Inositol might be a good alternative to promote ovulation before pursuing more advanced infertility treatments like the use of Clomid or Letrozole, or in-vitro fertilization (IVF).
Finally, myo-inositol may help promote oocyte (a developing egg) maturity, which can boost your odds of conceiving if you’ve struggled with PCOS-related infertility (3).
2) Reduces blood glucose levels
High blood glucose levels are a sign of insulin resistance and can lead to type 2 diabetes. If you have insulin-resistant PCOS, you might find that you have elevated blood sugar levels in the form of high fasting blood sugar, an abnormal reading after an oral glucose tolerance test, high random blood sugar, or high hemoglobin A1c (a blood test that estimates your average blood sugar over the last 60-90 days).
Inositol supplementation helps reduce blood glucose levels by improving insulin sensitivity independent of body weight (6). That means that inositol might help reduce high blood sugar levels in both lean and overweight individuals.
Metformin is a popular drug used to treat high blood sugar levels. According to a study, myo-inositol and metformin have similar positive effects on insulin levels, fasting blood sugar, and hormone levels associated with PCOS (7).
3) Reduces insulin levels
High insulin levels are a sign of insulin resistance. As your body becomes less efficient at responding to insulin, your pancreas will try to pump more insulin to help lower high blood sugar levels. As a result, higher insulin levels are found in people with insulin resistance.
In a review of 20 randomized control trials, inositol supplementation was shown to reduce fasting insulin levels and improve glucose tolerance (6).
4) Benefits women with lean PCOS and those without insulin resistance
Most women with PCOS are considered overweight or obese, which might be partly due to insulin resistance. Women who are considered lean can also develop PCOS, though it’s less common.
According to a study on 20 lean women with PCOS (or “lean PCOS”), administering D-chiro-inositol resulted in a significant (73%) reduction in free testosterone, induced ovulation in 60% of the women, lowered systolic and diastolic blood pressure, and reduced triglyceride levels (4).
In women without insulin-resistant PCOS, inositol may still be beneficial. A blend of myo-inositol and D-chiro-inositol helped induce ovulation in 79% of women with non-insulin-resistant PCOS (5). Among seven of those women who were trying to conceive, six of them achieved pregnancy.
5) Might lower your risk of diabetes
High blood glucose levels due to insulin resistance increase your risk of prediabetes (borderline diabetes) and type 2 diabetes. Regular inositol supplementation can help reduce blood glucose levels and hemoglobin A1c, indicating improved glucose metabolism.
Inositol use may improve your blood sugar levels enough that your risk of diabetes is lowered, so you might not need to rely on prescription blood sugar medications.
Insulin-sensitizing agents (substances or medications that improve insulin sensitivity) like inositol are beneficial in improving glucose metabolism and the metabolic profiles of women with PCOS (8).
6) Boosts sex hormone binding globulin (SHBG)
Sex hormone binding globulin is a type of hormone that impacts how much testosterone your body can use. Low levels of SHBG are associated with increased metabolic abnormalities in PCOS, such as insulin resistance and high blood lipid levels (9).
When administered for at least 24 weeks, myo-inositol caused a significant increase in SHBG, which might improve metabolic symptoms associated with PCOS (10).
Who might benefit from a myo-inositol supplement?
There are two main types of people who might benefit from a myo-inositol supplement:
Women with PCOS
PCOS is diagnosed if you meet at least two of three categories: having high androgen (male sex hormone, such as testosterone) levels, lack of or absent ovulation, and cysts on your ovaries as viewed on an ultrasound.
PCOS is a syndrome, which means diagnosing it isn’t as straightforward to diagnose compared to other health conditions. Your healthcare provider might need to rule out other potential causes of your symptoms before you receive a PCOS diagnosis.
Studies show inositol is effective at treating PCOS symptoms in both lean women and those considered overweight or obese, as well as people with and without insulin resistance.
Inositol comes with little risk of side effects, so it’s a reasonable option to consider trying regardless of the type of PCOS you have.
Those with elevated blood sugar levels (such as prediabetes)
If you have high blood sugar levels and either don’t need or don’t want to take pharmaceuticals, inositol is a good option to try. The benefits of inositol include improved insulin sensitivity and glucose metabolism, resulting in improved blood sugar and insulin levels.
If you aren’t experiencing a noticeable change in your blood sugar levels after several months of using inositol, it might not be effective as a sole treatment method to improve glucose metabolism.
If you have type 2 diabetes, you shouldn’t stop any existing treatment in favor of taking inositol before speaking with your healthcare provider.
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How often should I take inositol?
There are several options when it comes to inositol supplementation. To get the health benefits of inositol, you can choose myo-inositol, D-chiro-inositol, or a blend of both (usually in a ratio of 40 parts of myo-inositol per one part of D-chiro-inositol).
Inositol is available in capsule and powder form. The powder is relatively tasteless and can be mixed with most liquids, such as water or juice.
You can take inositol as often as the supplement label recommends. A popular inositol supplement with a 40:1 ratio suggests taking one scoop (containing 2,000 milligrams of myo-inositol and 50 milligrams of D-chiro-inositol) twice daily.
Inositol in capsule forms often suggest a dosage providing 2,000 milligrams of myo-inositol and 50 milligrams of D-chiro-inositol.
Inositol is generally well-tolerated. However, it might cause gastrointestinal symptoms in some people.
Inositol is a naturally-occurring sugar alcohol, which can cause symptoms like flatulence and nausea in some. Other potential side effects from taking inositol include dizziness, tiredness, and headache.
If you have a sensitive stomach, you might want to start with half of the recommended dose or split the total dose among two doses. Taking inositol with food might also help reduce any potential side effects.
Inositol has many potential health benefits. It can help improve glucose metabolism and insulin sensitivity, as well as promote healthy hormone levels and ovulation patterns among women with PCOS. Even if you don’t have PCOS, inositol might still be beneficial because it improves blood sugar levels and glycemic control.
Inositol supplements in the form of myo-inositol, D-chiro-inositol, or a blend of them at a ratio of 40:1, respectively, are widely available and generally very safe to take. If you have questions regarding inositol supplementation, reach out to a trusted member of your healthcare team.