Third-Party Tested Inositol 2026: Which Are NSF Certified
Of the 14 myo-inositol products we checked, 3 are on a public testing list. Ovasitol and Wholesome Story are on NSF/ANSI 173. Momentous Inositol is on NSF/ANSI 173 and NSF Certified for Sport. We found none on USP or the Informed lists.
By Erin Rose Updated October 20, 2026 How we score
Our recommendation
Buy Ovasitol
It is on NSF/ANSI 173, which checks that the label is accurate and that contaminants stay under set limits. Its label gives 4 g a day. Of the tested products, it costs the least: $0.96 a day at list price.
Buy on Amazon- Prefer capsules? Wholesome Story Myo & D-Chiro Inositol is on the same list, for $1.86 a day.
- Drug-tested for sport? Momentous Inositol is also on NSF Certified for Sport.
- Want the lowest cost? Micro Ingredients has the same amounts as Ovasitol for $0.45 a day, but it is not on a list.
On a testing list (3)
An outside program checked each of these and lists it by name. Tap a badge to see the list.
-
Our pick
Ovasitol Inositol Powder
2 g of myo-inositol and 50 mg of D-chiro-inositol a scoop (40:1). Its label says 2 scoops a day, which is 4 g.
$0.96 a day for 4 g
Buy on Amazon -
Capsules on the same list
Wholesome Story Myo & D-Chiro Inositol
2 g of myo-inositol in 4 capsules (40:1). Its label says 4 a day; NSF’s listing gives 8 (4 g).
$1.86 a day for 4 g
Buy on Amazon -
Also screened for sport
Momentous Inositol
NSF Certified for SportNSF/ANSI 173
0.9 g of inositol in its 2-capsule serving, so it costs the most for 4 g.
$2.22 a day for 4 g
Buy on Amazon
Cost is for 4 g of myo-inositol a day at each brand’s own list price (October 13, 2026); Amazon’s can differ. NSF/ANSI 173 also lists Codeage Liposomal Ovarian Inositol+, a powder blend with other ingredients, and Chiral Balance D-chiro-inositol, which is not myo-inositol. We do not score them.
Ask your doctor first if you are pregnant, breastfeeding or trying to get pregnant, if you take lithium or valproate, or if you take a prescription medicine such as metformin or another diabetes medicine.
Not on any testing list (6)
We also score Micro Ingredients; Nutricost; Zazzee Pregnositol; Pure Encapsulations; Fairhaven Health; Jarrow 750 mg. We found none of them on NSF/ANSI 173 or the 4 other lists we searched. That does not mean a product failed a test: brands pay to join. But no outside group is checking it for you. 5 more we checked could not be scored, and none of them is on a list either. See them ranked in the best myo-inositol, and priced in myo-inositol cost per dose.
What each list checks
| List | What it checks | Myo-inositol on it |
|---|---|---|
| NSF/ANSI 173 | That what is in the product matches the label, with no undeclared ingredients or unacceptable levels of contaminants. | Ovasitol, Wholesome Story, Momentous |
| NSF Certified for Sport | Label claims plus banned substances. NSF says products are tested for 280+ banned substances. By lot. A listing can name the certified lots; some say “All”. | Momentous |
| USP Verified | Ingredient identity and amount, purity, and manufacturing quality. Product certification, with audits. | No myo-inositol we score (checked September 22, 2026) |
| Informed Sport | Banned substances, at LGC's anti-doping laboratory. Every batch, before it is released to market. | No myo-inositol we score |
| Informed Choice | Banned substances, at LGC's anti-doping laboratory. Samples bought from retail at least monthly and blind tested. | No myo-inositol we score |
NSF/ANSI 173, NSF Certified for Sport and both Informed lists were searched on October 13, 2026. USP Verified was last checked on September 22, 2026. Testing tells you what is in the tub, not whether it works for you.
“Tested” on a label is not a listing
Several myo-inositol stores say “tested” without naming a lab or posting a report. Micro Ingredients says “3rd party lab tested”; Nutricost says “Tested by Independent, ISO-Accredited Laboratories”; Zazzee says “Tested by Confirmed FDA Lab.” A claim like that may be true, but you cannot check it. A listing on a public testing list you can. “Made in an NSF-registered facility” means the factory passed an audit, not that NSF lists the product.
How to check your own tub
- Find the lot number. It is usually stamped on the bottom of the tub or near the seal.
- Search NSF’s list at info.nsf.org by company name (Ovasitol is listed under Theralogix), or nsfsport.com for Certified for Sport.
- Match the product name and form (powder or capsule) to the listing, not just the brand.
Questions people ask
Which myo-inositol supplements are third-party tested?
Three. Ovasitol and Wholesome Story Myo & D-Chiro Inositol are on NSF/ANSI 173. Momentous Inositol is on NSF/ANSI 173 and NSF Certified for Sport. We found none on USP Verified, Informed Sport or Informed Choice. NSF/ANSI 173 also lists Codeage Liposomal Ovarian Inositol+ (a powder blend) and Chiral Balance D-chiro-inositol (D-chiro only), which we do not score. Micro Ingredients and Nutricost say “tested” on their stores, but name no lab.
Does "third-party tested" on a label mean anything?
On its own, no. The phrase has no legal definition, and a brand can print it after one test. Ask two things. Is the exact product on a certifier’s list that you can look up? Or does the brand post a lab report with a lot number you can match to your tub? A listing you can look up beats a claim.
Is Wholesome Story inositol NSF certified?
Yes. NSF/ANSI 173 lists Wholesome Story “Myo & D-Chiro Inositol” capsules, with 8 capsules as the daily serving (checked October 13, 2026). NSF also lists its powder and its versions with folate and vitamin D3.
Sources
- Public testing lists searched October 13, 2026: NSF/ANSI 173 (info.nsf.org, company and trade-name search), NSF Certified for Sport (nsfsport.com), Informed Choice and Informed Sport (wetestyoutrust.com). USP Verified (quality-supplements.org), September 22, 2026.
- Brand testing claims: each brand’s own store page, read October 13, 2026. Prices: each brand’s own one-time list price, October 13, 2026. We quote no Amazon prices.