Inositol (myo-inositol) supplementation shows promise in promoting female fertility and treating type 2 diabetes and polycystic ovary syndrome.
Studies also show its efficacy in treating depression, anxiety and panic disorders.
Inositol is a broad term used to describe a collection of nine naturally occurring molecules, or stereoisomers. Two stereoisomer’s in particular, myo-inositol and D-chiro0inositol, are being closely studied for their role in treating insulin-resistant conditions, such as type 2 diabetes and polycystic ovary syndrome (1).
Inositol helps treat polycystic ovary syndrome (PCOS). PCOS is a lifelong hormonal disorder affecting 1 in 10 women of childbearing age. It is associated with insulin resistance and excessive androgens, such as testosterone.
Women affected are at higher risk of developing several diseases and conditions such as diabetes, metabolic syndrome, heart disease and high blood pressure (2). PCOS is also one of the most common causes of infertility.
Researchers believe that myo-inositol and D-chiro-inositol act as second messengers for insulin, and a deficiency of these inositols contributes to the various characteristics of PCOS. Therefore, supplementation with myo-inositol and D-chiro-inositol therapy may help in alleviating metabolic, menstrual/ovulatory and cutaneous hyper androgenic features of PCOS (3).
Inositrol treats gestational diabetes. This type of diabetes develops during pregnancy and like other types of diabetes, affects how cells use glucose (4). Two separate studies show the benefit of myo-inositol supplementation.
In a two-year, prospective, randomized, open-label, placebo-controlled study , pregnant patients with a family history of type 2 diabetes were randomized to receive 2 g myo-inositol plus 200 μg folic acid or only 200 μg folic acid twice a day from the end of the first trimester.
Supplementation with myo-inositol significantly reduced the incidence of gestational diabetes as well as the delivery of macrosomia fetuses (babies born unusually large for their gestational age; gestational diabetes is one of the main risk factors) 5, 6.
In another study, pregnant women with gestational diabetes were randomized to receive 4 g of myo-inositol plus 400 μg folic acid daily, or only 400 μg folic acid daily. The study period lasted 8 weeks.
While fasting glucose, insulin and insulin resistance significantly improved in both groups, the improvement was greater in women treated with myo-inositol (7).
Inositol helps treat type 2 diabetes. In a recent pilot study, patients with type 2 diabetes took a combination of myo-inositol and D-chiro-inositol orally twice a day in addition to their glucose-lowering drugs. After three months, researchers found that supplementation was effective in lowering both fasting blood glucose and HbA1c levels.
An important aspect of this study is that it involved male participants. Most published studies up until this point have focused on women with conditions linked to insulin resistance.
While studies with larger sample sizes and randomized controlled trial designs are needed, researchers are optimistic that supplementation could be an alternative therapy to traditional insulin sensitizer glucose-lowering drugs, for both women and men (8).
Inositol has pro-fertility effects in women with PCOS. One of the complications of PCOS is a woman’s ability to conceive. The hormonal imbalance caused by PCOS interferes with the growth of eggs and ovulation (9).
The goal of a 2015 study was to evaluate the effectiveness of myo-inositol supplementation — alone or in combination with clomiphene citrate (a drug used to induce ovulation) — in stimulating ovulation and improving the pregnancy rate in non-ovulating women with PCOS and proven insulin resistance.
After supplementation with myo-inositol, ovulation was present in 61.7 percent of the women, and of those ovulating women, pregnancy occurred in 37.9 percent. During follow-up, a reduction of body mass index and insulin resistance was also observed (10).
Inositol improves symptoms of panic disorder. According to the Anxiety and Depression Association of America, approximately 6 million adults are affected by panic disorder (11). Only 70 percent of patients respond to treatment and many discontinue taking treatment drugs due to side effects.
A double-blind, controlled, random-order crossover study was carried out to compare the effect of inositol with the treatment drug fluvoxamine in panic disorder.
After one month of treatment with inositol (up to 18 g/day versus one month of fluvoxamine up to 150 mg/day), researchers found that inositol reduced the number of panic attacks per week by 4.0 compared with a reduction of 2.4 with fluvoxamine.
In addition, improvements on the Hamilton Rating Scale for Anxiety scores, agoraphobia scores and Clinical Global Impressions Scale scores were similar for both treatments. Unlike treatment with fluvoxamine, inositol did not cause nausea and tiredness (12).
These results are promising for those seeking a way to treat their panic disorder without experiencing troublesome side effects.
Inositol is efficacious in treating premenstrual dysphoric disorder. Premenstrual dysphoric disorder (PMDD) is a severe form of premenstrual syndrome (PMS), and can lead to depression and anxiety (13).
The results of a 2011 study showed a significant improvement in all three different scales used, including a reduction in the Daily Symptoms Records scale and an improvement in the Hamilton Depression Rating scale and Clinical Global Impression-Severity of Illness scale (14).
Inositol helps improve symptoms of bulimia and binge eating. In a double-blind crossover trial, 18 g of inositol performed significantly better than placebo on the Global Clinical Impression, the Visual Analogue Scale and the Eating Disorders Inventory.
Researchers of the study found inositol supplementation to be comparable to standard treatment with serotonin selective reuptake inhibitors (SSRIs) 15.
Studies show inositol to be well tolerated. A higher dosage of 12 g per day has been shown to cause mild gastrointestinal side effects such as nausea and diarrhea (16).
In another study, an oral dose of 18 g for 3 months was safe and well tolerated (17).
The proper dosage depends on the condition being treated. Many studies performed have shown that the efficacious dose for improving infertility in women with PCOS is 2000 mg myo-inositol twice a day along with 200 μg folic acid twice a day (18).
Antidepressant effects have been seen at dosages of 14-18g daily.
The proper dosage also depends on whether powder versus soft-gel formulation is used. Speak with a physician or other medical expert for guidance.
Inositol (myo-inositol) is a molecule that when taken in supplement form has been shown to improve female fertility and treat insulin-resistant conditions such as PCOS and type 2 diabetes. It has also shown promise in alleviating symptoms of depression, panic disorder, premenstrual dysphoric disorder, bulimia and binge eating.
Supplementation appears to be well tolerated with side effects are limited to mild gastrointestinal issues.