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Vitamin B8 (Myo-
Inositol)

Moderate study situation·7/10
A higher score indicates better study conditions, but not necessarily effectiveness.

A naturally occurring nutrient often used as a supplement for metabolic, reproductive, and mental health.

PCOSMale FertilityDepression / Mood EnhancementGlucose MetabolismAnxiety ReliefFemale FertilityHormone BalanceWeight Management
dose range
2–4 g
Divide daily dose into two (e.g., 2 g morning, 2 g evening) for better tolerability.
Consumption
Take with or without meals; mix powdered form in water or juice. For PCOS and metabolic benefits, 2–4 g/day. Higher doses (12–18 g/day) used for psychiatric conditions only under supervision.
Not fat-soluble.
Best time
Two divided doses with first and second meals for metabolic/fertility benefits. High-dose protocols require professional guidance.

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Description

Myo-inositol (formerly vitamin B8) is a sugar alcohol found abundantly in the human body and many foods. It plays a vital role in cell signaling, insulin sensitivity, and hormone balance. It is not an essential vitamin but is regularly used as a supplement, especially for PCOS, fertility, and some mental health conditions.

benefits
Main effects with level of evidence
Moderate
Note on evidence

Strong evidence supports use in PCOS and insulin resistance. Evidence for mental health benefits is mixed but promising in some studies.

Improves Symptoms of Polycystic Ovary Syndrome (PCOS)

Strong

Myo-inositol supplementation improves insulin sensitivity, restores ovulation, and regulates menstrual cycles in women with PCOS.

Particularly relevant for: Women with PCOS
S3 · PMC8896029: Myo-Inositol in PCOS ManagementS4 · Cochrane Review: Inositol for PCOS

Supports Female Fertility and Egg Quality

Moderate

May improve oocyte quality and increase pregnancy rates, including in women undergoing IVF.

Particularly relevant for: Women seeking fertility assistance
S4 · Cochrane Review: Inositol for PCOSS5 · PubMed: Myo-Inositol Safety and Efficacy

May Improve Sperm Quality in Men

Limited

Some studies suggest benefits for sperm motility and count, potentially aiding male fertility.

Particularly relevant for: Men seeking fertility support
S2 · Examine.com: Inositol

Supports Blood Sugar Control and Insulin Sensitivity

Moderate

Helps reduce fasting insulin and blood sugar in individuals with metabolic syndrome or insulin resistance.

Particularly relevant for: Individuals with insulin resistance or metabolic syndrome
S2 · Examine.com: InositolS3 · PMC8896029: Myo-Inositol in PCOS Management

Potential Mental Health Benefits

Mixed

High-dose myo-inositol may help reduce symptoms of anxiety, depression, and OCD, though evidence is mixed and more research is needed.

Particularly relevant for: Individuals with anxiety, depression, or OCD
S2 · Examine.com: InositolS5 · PubMed: Myo-Inositol Safety and Efficacy

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This information is for educational purposes only and does not replace medical advice.
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This website is for educational and informational purposes only and does not constitute medical advice or professional services. The information provided should not be used to diagnose or treat any health problem or disease. Persons requiring medical advice should consult a licensed physician.