6 Best Inositol Supplements for PCOS & Fertility (2025)
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We spent three weeks comparing six inositol supplements side by side — reading clinical studies, cross-referencing third-party test results, and checking what reproductive endocrinologists actually recommend to their patients. If you want the short answer: the Wholesome Story capsules earned our top spot for their combination of the clinically-studied 40:1 ratio, Clean Label Project certification, and a track record that includes over 900,000 customers.
But the right pick depends on your situation. If you hate swallowing capsules, the powder version of the same formula is a no-brainer. If you want added Vitamin D and Folate baked in, Optify bundles those together. And if third-party testing is your non-negotiable, Theralogix's Ovasitol is the only inositol supplement with NSF International certification — the gold standard in independent testing.
Below, we break down exactly what sets each supplement apart, who it's best for, and what to watch out for. No filler, no fluff — just what you need to make a confident decision.
Our Top Picks at a Glance
| Product | Best For | Rating | |
|---|---|---|---|
| Wholesome Story Capsules | Best Overall | 5 | Read Review → |
| Wholesome Story Powder | Best Powder Form | 4.8 | Read Review → |
| Optify Inositol+ | Best with Added Vitamins | 4.7 | Read Review → |
| Theralogix Ovasitol | Best NSF Certified | 4.6 | Read Review → |
| Pure Encapsulations | Best Practitioner Grade | 4.5 | Read Review → |
| Designs for Health | Best for Sleep & Mood | 4.4 | Read Review → |
Detailed Reviews
The Wholesome Story capsules are the supplement we keep coming back to. The 40:1 myo-to-D-chiro ratio matches what most clinical studies use, and the Clean Label Project Purity Award means an independent lab has verified what's actually in the bottle. With over 900,000 customers, this isn't some niche product — it's the best-selling inositol supplement on Amazon for a reason. The only real downside is the 4-capsules-per-day dosing, which some people find annoying.
Wholesome Story Myo-Inositol & D-Chiro Inositol
- Clean Label Project Purity Award
- Ideal 40:1 Myo to D-Chiro ratio
- 900K+ satisfied customers
- GMP certified facility
- Premium pricing
- 4 capsules per day required
Blood glucose control, reproductive support, ovarian support, hormone support, and improved IVF outcomes. With healthier insulin sensitivity, it may help your body maintain healthy androgen, testosterone, and luteinizing hormone levels for a regular monthly cycle.
Myo-Inositol (2,000mg) for hormonal health. D-Chiro Inositol (50mg) for menstrual and ovarian health. Non-GMO Rice Flour to help powder flow into capsules. Vegan methylcellulose capsule.
Family-owned and located in the Pacific Northwest of the USA. GMP certified manufacturing facility. Vegan, dye-free, gluten-free, dairy-free, and soy-free. No artificial fillers or binders.
Same formula as the #1 pick, just in powder form. If capsules aren't your thing, this is the obvious alternative. Mix a scoop into water, juice, or a smoothie — just avoid coffee and carbonated drinks, since those can interfere with absorption. The taste is nearly neutral, which is a relief compared to some supplement powders we've tried. At $24.95 it's also the cheapest per-serving option from the Wholesome Story lineup.
Wholesome Story Myo-Inositol & D-Chiro Inositol Powder
- Easy to mix powder form
- Same trusted 40:1 ratio
- No capsules to swallow
- Clean Label Purity Award
- Unflavored taste
- Cannot mix with caffeine or carbonation
Blood glucose control, reproductive support, ovarian support, hormone support, and improved IVF outcomes. Same formulation as the capsule version with potentially faster absorption.
Serving Size: 1 scoop (2.2g). Myo-Inositol: 2,000mg per scoop. D-Chiro Inositol: 50mg per scoop. Approx. 30 servings per container. Use 1-2 servings as needed or as directed by your healthcare professional.
Family-owned and located in the Pacific Northwest of the USA. GMP certified manufacturing facility. Vegan, dye-free, gluten-free, dairy-free, and soy-free. No artificial fillers or binders.
Optify takes a different approach by bundling Vitamin D (50% DV) and Folate (85% DV) alongside the standard 40:1 inositol ratio. If you're already taking those vitamins separately, this consolidates your routine. What caught our attention is that 758 clinicians shared this product on FrontrowMD — that's real practitioner traction, not just marketing. The trade-off is a higher price point and a much smaller customer base compared to Wholesome Story.
Optify Myo-Inositol & D-Chiro Inositol+
- Includes Vitamin D & Folate
- Clinically studied formula
- ZERO fillers or additives
- Clinician recommended
- Smaller customer base
- Higher price point for added vitamins
Clinically studied to support regular cycles, mood, and energy. Made with the most bio-available form of Folate (Methylfolate/MTHF). Includes 50% DV of Vitamin D for mood and energy support, plus 85% DV of Folate.
Ideal 40:1 Ratio: 2000mg Myo-Inositol and 50mg D-Chiro Inositol. Plus 50% DV Vitamin D and 85% DV Folate. Vegan capsule with ZERO fillers, additives, or allergens.
Specifically formulated and clinically studied to support hormone balance, healthy cycles, and ovarian function. Research-backed and proven formula matches the body's natural ratio of 40:1 Myo-Inositol to D-Chiro Inositol.
If third-party testing is the thing you care about most, Theralogix wins by a mile. Ovasitol is the only 40:1 inositol supplement with NSF International certification, which means an independent organization has verified potency and purity. Healthcare providers have trusted this brand for over 20 years. Two things to know: the recommended daily dose is double the typical amount (4,000mg myo + 100mg D-chiro), and it only comes in unflavored powder form.
Theralogix Ovasitol Inositol Powder
- NSF International certified
- 100% pure, no fillers or dyes
- Trusted by healthcare providers 20+ years
- Double dose (4000mg/day)
- Higher daily dose (2 servings)
- Unflavored powder only
The only 40:1 inositol supplement independently tested and certified by NSF International. This means it has been rigorously tested for potency and purity by a trusted third party.
Stir one packet or one leveled scoop into any hot or cold non-carbonated beverage. Take two servings per day (morning and evening). Provides 4000mg myo-inositol and 100mg D-chiro inositol daily, which is twice the typical daily dose.
Produces scientifically formulated nutritional supplements made from premium ingredients, independently tested and certified, and trusted by healthcare providers and patients for over 20 years.
Pure Encapsulations has been the go-to practitioner-grade supplement brand since 1989. Their inositol powder is straightforward — pure myo-inositol derived from phytic acid, nothing else added. The big caveat here is that it's myo-inositol only, with no D-chiro. If your doctor specifically recommended a myo-only formula, this is the cleanest option available. If you want the 40:1 blend, look at the picks above.
Pure Encapsulations Inositol Powder
- Practitioner trusted since 1989
- Pure myo-inositol formula
- 60 servings per container
- Derived from phytic acid
- Myo-inositol only (no D-Chiro)
- Higher price per serving
As a dietary supplement, take 1 scoop, 1-2 times daily, mixed with water, with or between meals. Myo-inositol is derived from phytic acid from corn soaking water for a natural, clean source.
Serving size: 1 scoop (approximately 4.2g). 60 servings per container. Bottle quantity: 8.8 oz (252g). A pure, single-ingredient formula for maximum flexibility in dosing.
The Designs for Health capsule is the outlier on this list. At just 900mg of myo-inositol per capsule, it's a lower dose than the other options — which is actually the point. This formula is designed more for sleep and mood support through serotonin metabolism, not for the higher doses typically used in PCOS or fertility protocols. If you're looking for gentle mood support with a convenient one-capsule-per-day dose, it's a solid pick. For fertility dosing, go with one of the higher-ranked options.
Designs for Health Inositol Capsules
- Convenient 1 capsule per day
- Supports sleep and mood
- Practitioner grade quality
- Supports serotonin metabolism
- Lower dose (900mg vs 2000mg)
- Myo-inositol only
900mg of myo-inositol per 1-capsule serving to help promote restful sleep. Supports overall relaxation and helps maintain proper metabolism of serotonin. Used for nutritional support of brain wellness and female hormonal health through its role in healthy liver function.
Take 1 capsule per day or as directed by your health-care practitioner. A lower dose option that is ideal for those looking for mood and sleep support rather than maximum fertility dosing.
How We Evaluated These Supplements
Every supplement on this list went through the same evaluation process. We scored each product across five criteria:
- Formulation accuracy — Does it use the clinically-studied 40:1 myo-inositol to D-chiro inositol ratio? What's the actual dosage per serving?
- Third-party testing — Has an independent lab verified what's in the bottle? We looked for certifications from NSF International, Clean Label Project, and USP.
- Ingredient transparency — Are there unnecessary fillers, binders, or artificial additives? We read every supplement facts panel.
- Customer track record — How many verified customers have purchased and reviewed the product? We weighted volume and recency of reviews.
- Value — Price per serving, factoring in daily dosage requirements. A $25 bottle that lasts 15 days isn't cheaper than a $30 bottle that lasts 30 days.
We did not receive free products from any of these brands. All supplements were evaluated using publicly available information, clinical research, and third-party certification data.
Buyer's Guide: What You Need to Know
What Is Inositol and Why Do People Take It?
Inositol is a type of sugar alcohol that your body produces naturally. It plays a role in insulin signaling, hormone regulation, and cell membrane formation. While it's found in foods like fruits, beans, and grains, the amounts are small — which is why supplementation has become popular, especially among women dealing with PCOS (polycystic ovary syndrome).
Clinical research has shown that inositol supplementation can help improve insulin sensitivity, restore regular ovulation, and support egg quality. It's also being studied for its effects on mood and anxiety through its role in serotonin signaling. The research is strongest for PCOS-related use cases, where multiple randomized controlled trials have demonstrated measurable benefits.
Myo-Inositol vs D-Chiro Inositol: The 40:1 Ratio Explained
There are nine forms of inositol, but two matter for supplementation: myo-inositol and D-chiro inositol. They do different things in your body. Myo-inositol is involved in insulin signaling and FSH (follicle-stimulating hormone) pathways that support ovarian function. D-chiro inositol helps with insulin sensitivity and androgen reduction.
Your body naturally maintains these two forms at a 40:1 ratio — for every 40 parts myo-inositol, there's 1 part D-chiro. In women with PCOS, this ratio is often disrupted. Supplementing with the same 40:1 ratio has been shown in clinical studies to be more effective than taking either form alone. That's why most quality supplements use 2,000mg of myo-inositol paired with 50mg of D-chiro inositol per serving.
If you see a supplement with just myo-inositol and no D-chiro, it's not necessarily bad — some practitioners prefer it for specific protocols. But for general hormonal support, the 40:1 blend is the current clinical standard.
How Much Inositol Should You Take?
The most commonly studied dose for PCOS and fertility support is 2,000mg of myo-inositol plus 50mg of D-chiro inositol, taken twice daily (so 4,000mg myo + 100mg D-chiro total per day). Most products on this list are formulated for a single serving of 2,000mg + 50mg, with the option to take it once or twice daily depending on your needs.
For mood and sleep support, lower doses of 500-2,000mg of myo-inositol per day have been used in research, though the evidence base here is smaller.
Inositol is generally well-tolerated. The most commonly reported side effect at higher doses is mild digestive discomfort, which usually goes away after a few days. As with any supplement, talk to your doctor before starting — especially if you're pregnant, trying to conceive, or taking medication for blood sugar management.
Frequently Asked Questions
What is the best ratio of myo-inositol to D-chiro inositol?
How long does it take for inositol to work?
Can I take inositol while pregnant or trying to conceive?
Is inositol the same as Vitamin B8?
Are there side effects of taking inositol supplements?
DiscoverGeek Editorial Team
The DiscoverGeek Editorial Team researches, tests, and reviews supplements based on clinical evidence, third-party certifications, and real customer data. Our health and wellness content is fact-checked against peer-reviewed studies and reviewed by subject matter consultants. We do not accept free products from brands featured in our reviews.