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Inositol usually refers to Myo-inositol, a small molecule structurally similar to glucose that is involved in cellular signalling. It appears to be an effective anxiolytic at higher doses, and is quite effective in treating insulin resistance and PCOS with standard doses.

Our evidence-based analysis on inositol features 189 unique references to scientific papers.

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Summary of Inositol

Primary information, health benefits, side effects, usage, and other important details

Inositol is a word that collectively refers to molecules with a similar structure, a collection of nine stereoisomers. While the term 'inositol' is used commonly with dietary supplements, it usually refers to a specific stereoisomer called myo-inositol. Inositols are pseudovitamin compounds that are falsely said to belong to the B-complex family, and are found in most foods but in highest levels in whole grains and citrus fruits.

Myo-inositol shows the most promise as a dietary supplement for promoting female fertility, restoring insulin sensitivity in instances of resistance (type II diabetes and polycystic ovarian syndrome being the most well investigated), and for reducing anxiety as well. Due to the mixed benefits to insulin resistance and fertility, myo-inositol is considered a good treatment for PCOS in women.

It also holds some promise as an anti-depressant (although not as impressive as its anxiolytic and anti-panic effects) and against some other conditions associated with anxiety such as panic disorders and binge eating. It is relatively ineffective for schizophrenia and autism, and has failed in treating PTSD despite its anti-panic effects.

In part because of its benefits to fertility and PCOS, as well as the anxiolytic effects potentially helping symptoms of PMS (dysphoria and anxiety mostly), myo-inositol is sometimes referred to as a general female health supplement. At times, the anti-depressant effects associated with this supplement seem to only work in females with males having no benefit.

It is a very safe supplement to ingest, and all side-effects associated with myo-inositol are merely mild gastrointestinal distress from high doses. High doses (usually in the 12-18g range) are required for any neurological effects while lower doses (2-4g) are sufficient for fertility and insulin sensitizing effects.

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How to Take

Recommended dosage, active amounts, other details

For the treatment of polycystic ovarian syndrome (PCOS), myo-inositol is taken in the range of 200-4,000mg once daily before breakfast; the higher dose seems to be used more often and seems more effective.

Neurological usage of inositol tends to require higher doses, and while antidepressant effects have been noted as low as 6g at times the standard dose is between 14-18g daily.

If using a soft gel formulation rather than powdered myo-inositol, then only 30% of the same dose is required to be equivalent. This would mean the 14-18g range for psychopharmacological effects is now reduced to 4.2-5.4g of myo-inositol soft gels.

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Human Effect Matrix

Unlocked for Examine members

The Human Effect Matrix summarizes human studies to tell you what effects Inositol has on your body, how much evidence there is, and how strong these effects are.

Full details are available to Examine members.
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
grade-a Notable Very High See all 14 studies
Supplementation of inositol in the range of 200-4,000mg daily appears to be effective in improving fertility in women with PCOS, while doses in the 2,000-4,000mg range appear effective in improving testosterone levels and insulin sensitivity.
grade-b Notable Very High See all 4 studies
There appears to be a decrease in anxiety symptoms associated with high dose inositol, and it has been noted to be comparable to fluvoxamine in potency.
grade-b Notable Very High See all 9 studies
In women with PCOS, inositol (typically 2000 mg once or twice daily) can significantly increase ovulation and fertility rates.
grade-b Notable High See all 3 studies
Chronic ingestion of high doses of inositol (18g) is associated with reductions in panic attack frequency to a level greater than the reference drug fluvoxamine; acute usage does not appear effective.
grade-b Minor Moderate See all 9 studies
Blood glucose can be reduced in women with PCOS secondary to treating that condition.
grade-b Minor Very High See all 6 studies
There may be a slight decrease in blood pressure in women with PCOS who are having it treated with inositol therapy.
grade-b Minor Very High See all 8 studies
There appears to be a reduction in depressive symptoms associated with inositol supplementation, although it is less potent than the benefits of inositol on anxiety and panic attacks.
grade-b Minor Very High See all 5 studies
An increase in circulating HDL-C is seen in women with PCOS getting inositol therapy
grade-b Minor High See all 7 studies
Secondary to treating symptoms of PCOS, fasting insulin concentrations are fairly reliably reduced.
grade-b Minor High See all 12 studies
Insulin sensitivity appears to be reliably improved following the treatment of PCOS in women.
grade-b Minor Very High See all 4 studies
There may be a small decrease in triglycerides associated with supplementation of inositol to women with PCOS
grade-b Minor High See all 7 studies
Decreases in body weight have been noted in women with PCOS, as inositol is effective in treating PCOS. They seem to influence leaner and overweight women more than obese women.
grade-b - Very High See all 3 studies
At the dose that showed anti-depressant effects, inositol failed to improve any symptoms associated with schizophrenia.
grade-c Minor - See study
An increase in adiponectin has been noted in women with PCOS
grade-c Minor - See study
Symptoms of bulimia and binge-eating in diagnosed women have been significantly improved with high dose inositol therapy (18g daily)
grade-c Minor - See study
There may be a reduction in oxidation associated with PCOS when the condition is being treated by inositol
grade-c Minor Very High See 2 studies
The limited evidence on the topic suggests that supplementation of inositol throughout pregnancy can reduce the risk of developing gestational diabetes by half.
grade-c Minor Very High See all 3 studies
The amount of insulin secreted in response to orally ingested glucose is attenuated after supplementation of inositol to insulin resistant persons
grade-c Minor Moderate See 2 studies
Myo-inositol supplementation appears to be effective in reducing dysphoric and depressive symptoms during PMS
grade-c Minor - See study
Lithium-induced psoriasis is reduced with supplemental inositol at 6g daily. Inositol may only be effective in this particular scenario
grade-c Minor - See study
Although a small decrease, there appear to be benefits to OCD symptoms associated with high dose inositol supplementation
grade-c Minor Very High See all 4 studies
A small decrease in total cholesterol has been noted with supplementation of inositol in women with PCOS
grade-c - - See study
Electroconvulsion therapy induced amnesia is not prevented with oral administration of 6g myo-inositol preloaded for five days
grade-c - - See study
No adverse effects to the liver during human toxicology testing.
grade-c - Moderate See 2 studies
The preliminary evidence at this point in time using scyllo-inositol has failed to find a significant therapeutic benefit and myo-inositol shows a nonsignificant trend for improvement based on preliminary evidence.
grade-c - Very High See 2 studies
Although a beneficial effect cannot fully be ruled out, the best evidence currently available does not support a significant role for inositol in the treatment of bipolar disorder.
grade-c - - See study
Despite the notable improvements in general panic disorders and anxiety, the lone study specifically looking at PTSD failed to find any significant benefits of inositol therapy.
grade-d Notable - See study
Although this may only apply to acne in women with PCOS, supplementation of normal doses of myo-inositol can abolish acne in over half of subjects within 3-6 months.
grade-d Minor High See all 3 studies
A decrease in LDL-C has been noted alongside other improvements in lipid parameters.
grade-d Minor Moderate See 2 studies
An increase in choline plasmalogen has been noted with myo-inositol oral ingestion, which is thought to underlie the reductions in LDL-C seen in persons with metabolic syndrome only.
grade-d Minor - See study
Although much more evidence is required in humans, there has been a high rate of regression seen with lung dysplasia in smokers due to ingestion of 18g Myo-inositol
grade-d Minor Very High See 2 studies
The hair growth associated with high androgen levels in women (hirsutism) appears to be reduced secondary to reducing androgens in women with PCOS or hyperandrogenemia
grade-d - - See study
No significant influence on C-reactive protein concentrations even in persons with metabolic syndrome.
grade-d - - See study
The preliminary evidence on autism does not support a role for inositol therapy

Studies Excluded from Consideration

Note: Studies in the above table include Myo-inositol, epi-inositol, and D-chiro-inositol. Usage is mostly myo-inositol, but if any discrepancies exist it will be made not of in the study description

  • Confounded with the usage of serotonin reuptake inhibiting drugs[1]

  • Used alongside D-chiro-inositol[2][3]

  • Confounded with the inclusion of folic acid (which was not also used as a placebo)[4]

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Things to Note

Is a Form Of

Other Functions:

Primary Function:

Also Known As

Myoinositol, Cyclohexanehexol, 1, 2, 3, 4, 5, 6-cyclohexanehexol

Do Not Confuse With

D-pinitol (structurally related)

Goes Well With

  • D-chiro-inositol (augments myo-inositol's efficacy in treating PCOS)

  • Melatonin (may be additive towards female fertility)

  • Phytic acid (synergistic with phytic acid's anticancer effects in vitro)

  • Lithium (moderate doses of myo-inositol can reduce the peripheral side-effects of lithium without affecting central effects)

  • Superloading myo-inositol may be required for neurological effects

  • If the supplement is labelled 'inositol' and a stereoisomer is not specified, it likely refers to isolated myo-inositol

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Click here to see all 189 references.