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Nature Made vs Thorne Iron (2026)
Disclosure: We earn commissions on purchases made through our links. This never influences our scores. Editorial policy
The Verdict
These two tie on our rubric - both post a 94 execution score on our 0-100 scale - but they suit different buyers. Nature Made is far cheaper (about $0.02 per dose versus Thorne's $0.27), carries USP Verification, and delivers a high 65mg ferrous sulfate dose ideal for correcting diagnosed deficiency. Thorne's bisglycinate is gentler on the stomach and NSF Certified for Sport. In our view, choose Nature Made for maximum value and deficiency correction if you tolerate ferrous sulfate; choose Thorne if standard iron upsets your stomach and you want the gentle chelated form.
Nature Made Iron 65mg (Ferrous Sulfate)
Nature Made
Thorne Iron Bisglycinate
Thorne
Head-to-Head Comparison
| Category | Nature Made Iron 65mg (Ferrous Sulfate) Nature Made | Thorne Iron Bisglycinate Thorne |
|---|---|---|
| Brand Score | 94/100Winner | 94/100 |
| Dosing & Form | 25/25Winner | 25/25 |
| Purity | 22/25 | 25/25Winner |
| Value | 25/25Winner | 21/25 |
| Transparency | 22/25 | 23/25Winner |
| Cost/Day | $0.02Winner | $0.27 |
| Dose/Serving | 65mg | 25mg |
| Form | ferrous sulfate tablet | ferrous bisglycinate chelate capsule |
| Third-Party Tested | ✓ Yes | ✓ Yes |
| Proprietary Blend | No | No |
Why This Comparison Matters
Nature Made and Thorne take opposite approaches to iron. Nature Made uses ferrous sulfate - the high-dose, low-cost, USP Verified standard that doctors most often recommend for correcting deficiency, but which can cause GI upset. Thorne uses iron bisglycinate, the gentle chelated form that trades a bit of cost for much better tolerability. This is the classic ferrous-sulfate-versus-bisglycinate decision.
Ferrous sulfate is cheap and effective at raising iron levels, and its 65mg dose is what many deficiency protocols call for. Bisglycinate is easier on the stomach at a lower elemental dose. The right pick depends on your tolerance and your goal.
We scored both on evidence, quality, cost per dose, and transparency.
Detailed Score Breakdown
Nature Made Iron 65mg (Ferrous Sulfate)
Nature Made
65mg elemental iron as ferrous sulfate (325mg ferrous sulfate = 65mg elemental iron). Ferrous sulfate is the most extensively studied iron form in clinical medicine with decades of RCT evidence. The dose aligns with standard clinical prescribing for iron-deficiency anemia. Included here for direct comparison with bisglycinate options.
USP Verified - independently tested for purity, potency, and disintegration. This is the highest certification a supplement can carry in the US, and Nature Made earns it here.
$0.02/day - by far the cheapest option in this comparison. A 365-count bottle provides a year of treatment-dose iron for under $10. The cost-per-milligram gap between ferrous sulfate and bisglycinate is substantial.
Full ingredient disclosure. Ferrous sulfate form and elemental iron amount both clearly stated on label. USP Verified seal. Straightforward formulation with standard tablet excipients, all disclosed.
Included as a comparison reference point. USP Verified and extremely cheap. The catch: ferrous sulfate causes GI side effects (nausea, constipation) in 30-70% of users. If you tolerate it, it is equally effective to bisglycinate at a fraction of the cost. If you do not tolerate it, bisglycinate is the answer.
Thorne Iron Bisglycinate
Thorne
25mg elemental iron as ferrous bisglycinate chelate - a well-studied chelated form with strong clinical evidence for efficacy and tolerability
NSF Certified for Sport - verified free of 270+ banned substances and tested for label accuracy. Thorne manufacturing exceeds FDA cGMP standards. The gold-standard certification in the supplement industry.
$0.27/day at 25mg (one capsule). At a therapeutic 50mg dose, about $0.53/day. Premium pricing is justified by NSF Certified for Sport status.
Fully disclosed label. Iron form specified as bisglycinate chelate. No proprietary blends. Minimal excipients. NSF certification seal displayed.
NSF Certified for Sport makes this the top choice for competitive athletes and anyone prioritizing certification rigor. Clean capsule with minimal excipients.
How We Compared These Products
Every product in our database is scored on four equally-weighted pillars: dosing accuracy and form quality, purity verification (third-party testing), cost per clinically effective dose (not cost per pill), and label transparency. Each pillar is worth 25 points for a total of 100.
Cost per effective dose is calculated using the clinically studied dose from published research, not the manufacturer's suggested serving. If a product requires multiple servings to reach the dose used in clinical trials, that cost is reflected in the value score.
For a full explanation of our scoring methodology, see our methodology page. Prices were last checked on the dates listed for each product and may have changed.
Frequently Asked Questions
Is Nature Made or Thorne iron better?
It depends on your stomach and your goal. Both score 94 on our 0-100 rubric. Nature Made uses high-dose ferrous sulfate (65mg), is USP Verified, and costs far less (about $0.02 per dose) - ideal for correcting diagnosed deficiency if you tolerate it. Thorne uses gentle iron bisglycinate, which is much easier on the stomach but costs more. Choose Nature Made for value and deficiency correction, Thorne if standard iron causes GI upset.
Is iron bisglycinate really gentler than ferrous sulfate?
Generally yes. Iron bisglycinate is a chelated form that is absorbed with less free iron irritating the gut, so it typically causes less constipation, nausea, and stomach upset than ferrous sulfate at comparable elemental doses. The tradeoff is cost - bisglycinate products like Thorne's run more per dose. If ferrous sulfate has caused problems for you, the gentler form is often worth the premium.
More Iron (Bisglycinate) Comparisons
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FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. Dietary supplements are not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare professional before starting any supplement regimen.