Inositol is often called vitamin B8, but it’s not actually a vitamin. It’s a type of sugar that your body produces naturally and that you get from foods like fruits, beans, grains, and nuts.
So why take it as a supplement?
Research suggests inositol may help with conditions ranging from panic disorder to PCOS to metabolic syndrome. It influences insulin signaling and brain chemistry—two systems that affect a wide range of health outcomes.
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Available on the App StoreHere’s what the science says about inositol benefits, dosages, and side effects.
What is inositol?
Inositol is a sugar alcohol that serves as a major component of cell membranes throughout your body. It plays a structural role in nearly every cell you have.
Beyond structure, inositol affects two important systems:
Insulin signaling. Inositol helps insulin do its job of moving glucose into cells. This connection explains why it’s studied for blood sugar-related conditions.
Brain chemistry. Inositol influences neurotransmitters like serotonin and dopamine—the same chemicals targeted by many psychiatric medications.
A typical American diet provides about 1 gram of inositol daily from foods like citrus fruits, beans, whole grains, and nuts. Supplement doses range much higher—studies have tested doses up to 18 grams per day with few side effects.
Mental health benefits
People with depression, anxiety, and OCD often have lower inositol levels in their brains. This observation led researchers to test whether supplementing inositol could help.
A 2014 meta-analysis examined all randomized controlled trials on inositol for depression and anxiety disorders. The results were mixed—inositol didn’t show statistically significant effects across all conditions, but it did show a trend toward benefit in certain populations, particularly those with premenstrual dysphoric disorder.1
The strongest evidence is for panic disorder specifically.
Suggested read: Can Your Diet Affect Your Mental Health? Discover the Link
Panic disorder
Panic disorder involves recurring panic attacks—sudden episodes of intense fear with physical symptoms like rapid heartbeat, shortness of breath, and dizziness.
In clinical trials, inositol has performed comparably to conventional anxiety medications. One crossover study found that 18 grams of inositol daily reduced panic attack frequency and severity as effectively as fluvoxamine (a common SSRI), with fewer side effects.
Another 4-week study found that 12 grams daily significantly reduced both the number and intensity of panic attacks compared to placebo.
Depression
Results for depression are less consistent. Early studies showed promise with 12 grams daily improving symptoms over 4 weeks. But later studies failed to replicate these findings.
The meta-analysis noted a trend toward benefit that didn’t reach statistical significance—possibly because studies were small. Inositol may help some people with depression, but the evidence isn’t strong enough for a clear recommendation.
Bipolar disorder
Research is limited. Small studies suggest inositol combined with omega-3 fatty acids may reduce symptoms in children with bipolar spectrum disorders. Doses of 3-6 grams daily may also help manage lithium-induced psoriasis (a side effect of the common bipolar medication).
Inositol for PCOS
Polycystic ovary syndrome (PCOS) is one of the most studied applications for inositol. PCOS causes hormonal imbalances that can lead to irregular periods, infertility, weight gain, and insulin resistance.
The theory: since inositol influences insulin signaling, it might help address the insulin resistance that underlies many PCOS symptoms.
A 2024 systematic review examined 30 trials with over 2,200 women to update the international evidence-based PCOS guidelines. The findings were nuanced: while some studies showed benefits for ovulation and metabolic markers, the overall evidence was graded as “limited and inconclusive” due to study quality issues.2
That said, the guidelines note that myo-inositol may be a reasonable alternative for women who can’t tolerate metformin (the standard treatment for PCOS-related insulin resistance).
Suggested read: How to Lose Weight with PCOS: 13 Helpful Tips
Individual studies have shown:
- Ovulation improvement. In one trial, 4 grams of inositol plus 400 mcg of folic acid taken daily for 3 months induced ovulation in 62% of treated women.
- Better insulin function. Several studies show improved insulin sensitivity with regular inositol use.
- Reduced triglycerides. Some trials found lower blood triglyceride levels.
The two main forms used for PCOS are myo-inositol (MYO) and D-chiro-inositol (DCI). Most research uses myo-inositol alone or in combination with small amounts of DCI.
Metabolic syndrome
Metabolic syndrome is a cluster of conditions that increase your risk of heart disease and type 2 diabetes:
- Excess abdominal fat
- High triglycerides
- Low HDL (“good”) cholesterol
- High blood pressure
- High blood sugar
Because inositol affects insulin signaling, researchers have tested whether it can help address these metabolic risk factors.
One year-long study in 80 women with metabolic syndrome found impressive results with 2 grams of inositol twice daily:
- Triglycerides dropped by 34%
- Total cholesterol fell by 22%
- Blood pressure and blood sugar also improved
By the end of the study, 20% of participants no longer met the criteria for metabolic syndrome.
While these results are promising, they come from a single study. More research is needed to confirm whether inositol consistently helps with metabolic syndrome.
Gestational diabetes prevention
Gestational diabetes (GDM) affects up to 10% of pregnancies in the US. It occurs when blood sugar levels rise during pregnancy, creating risks for both mother and baby.
Some research suggests that inositol, taken throughout pregnancy, may help prevent gestational diabetes in women at high risk.
The typical protocol studied: 4 grams of myo-inositol plus 400 mcg of folic acid daily, started early in pregnancy.
Results have been mixed. Some trials show reduced GDM incidence, while others find no effect. The inconsistency may relate to different populations, timing of supplementation, or baseline risk factors.
If you’re pregnant or planning to become pregnant and concerned about gestational diabetes, discuss inositol with your healthcare provider. Don’t supplement during pregnancy without medical guidance.
Other potential benefits
Beyond the main conditions above, inositol has been studied for:
- Type 2 diabetes. Early research suggests inositol plus folic acid may help with blood sugar control in people with type 2 diabetes, though evidence is limited.
- OCD. One small study found that 18 grams daily for 6 weeks reduced obsessive-compulsive symptoms. More research is needed.
- Respiratory distress in preterm infants. Inositol appears to help with breathing issues in babies with underdeveloped lungs.
These applications require more research before recommendations can be made.
Side effects
Inositol is generally well-tolerated, even at high doses.
Potential side effects at doses above 12 grams daily:
- Nausea
- Gas and digestive discomfort
- Headache
- Dizziness
- Fatigue
- Difficulty sleeping
Most people experience no side effects at typical doses (2-4 grams daily).
Pregnancy and breastfeeding: Studies have used up to 4 grams daily during pregnancy without reported adverse effects, but research is limited. Breast milk is naturally rich in inositol, but safety during breastfeeding hasn’t been well-studied.
Long-term use: Most studies lasted a year or less. Long-term safety data is lacking.
Talk to your doctor before starting inositol, especially if you’re pregnant, breastfeeding, or taking medications.
Dosage recommendations
Two forms of inositol are commonly used in supplements:
- Myo-inositol (MYO) – the most common and well-researched form
- D-chiro-inositol (DCI) – sometimes used alone or combined with MYO
Dosages vary significantly based on the condition being targeted:
| Condition | Dose | Duration |
|---|---|---|
| Panic disorder | 12–18g MYO daily | 4–6 weeks |
| PCOS | 2g MYO + 200mcg folic acid twice daily, or 1.2g DCI daily | 6 months |
| Metabolic syndrome | 2g MYO twice daily | Up to 1 year |
| Gestational diabetes prevention | 2g MYO + 400mcg folic acid twice daily | Throughout pregnancy |
| Type 2 diabetes | 1g DCI + 400mcg folic acid daily | 6 months |
Note that mental health doses (12-18 grams) are much higher than metabolic doses (2-4 grams). Start with lower doses and increase gradually if needed.
Most inositol supplements come as powder (easier for high doses) or capsules (more convenient for lower doses).
Bottom line
Inositol shows promise for panic disorder, PCOS, and metabolic syndrome—but the evidence quality varies.
For panic disorder, the research is fairly consistent: high doses (12-18 grams) appear to reduce panic attack frequency with fewer side effects than conventional medications.
For PCOS, results are mixed. International guidelines suggest inositol as a possible alternative to metformin for women who can’t tolerate metformin, but the evidence isn’t strong enough for a first-line recommendation.
For metabolic syndrome and gestational diabetes, early studies are encouraging but need replication.
Side effects are minimal at typical doses. If you’re considering inositol for any of these conditions, talk to your healthcare provider about whether it makes sense for your situation.
Mukai T, Kishi T, Matsuda Y, Iwata N. A meta-analysis of inositol for depression and anxiety disorders. Hum Psychopharmacol. 2014;29(1):55-63. PubMed ↩︎
Fitz V, Graca S, Mahalingaiah S, et al. Inositol for Polycystic Ovary Syndrome: A Systematic Review and Meta-analysis to Inform the 2023 Update of the International Evidence-based PCOS Guidelines. J Clin Endocrinol Metab. 2024;109(6):1630-1655. PubMed ↩︎
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