Solgar vs Thorne Iron Bisglycinate 25 mg (2026)
Informational comparison of label data and cost — not medical advice. Prices are live per-serving figures; formulas are each brand’s published Supplement Facts.
Solgar Gentle Iron (Iron Bisglycinate) 25 mg and Thorne Iron Bisglycinate 25 mg deliver the same 25 mg of elemental iron as bisglycinate in a single capsule — the chelated form chosen specifically because it is gentler on the stomach than ferrous sulfate. The gap is certification: Thorne is NSF Certified for Sport, Solgar is not.
The numbers, side by side
| Solgar Gentle Iron (Iron Bisglycinate) 25 mg | Thorne Iron Bisglycinate 25 mg | |
|---|---|---|
| Form | Iron bisglycinate (chelated) | Iron bisglycinate (chelated) |
| Dose / serving | 25 mg | 25 mg |
| Serving size | 1 capsule | 1 capsule |
| Servings / container | 90 | 60 |
| Third-party cert | None | NSF Certified for Sport |
| Price | $12.95 | $16.00 |
| Cost / day | $0.15 | $0.27 |
| Buy | Check price → | Check price → |
Prices are live Amazon buy-box figures ÷ pack serving count, last reviewed August 1, 2026. Formula details are each brand’s published Supplement Facts panel.
The real difference
Both products use iron bisglycinate, a chelate in which iron is bound to two glycine molecules. That chelation is the whole point of the form: it is the reason bisglycinate is tolerated by people who cannot take ferrous sulfate without constipation or nausea. Both land at 25 mg of elemental iron per capsule, so the active ingredient and the dose are the same.
What separates them is NSF Certified for Sport, which Thorne carries and Solgar does not. That programme screens for 280+ substances banned in competitive sport on top of confirming label accuracy. If you are drug-tested, that is the difference. If you are not, you are paying a premium for a certification that does not change the iron.
Who each one is for
Choose Solgar if you want the same 25 mg chelated bisglycinate at a lower cost per capsule and you are not subject to drug testing.
Choose Thorne if you compete in a tested sport and need NSF Certified for Sport verification — the premium buys the certification, not a better-absorbed iron.
Before either iron is the one supplement worth testing before taking. Excess iron accumulates and is genuinely harmful. Ask for ferritin and transferrin saturation rather than supplementing on suspicion.
Our picks
25 mg chelated iron bisglycinate, no third-party certification. $0.15/day.
Same 25 mg bisglycinate, NSF Certified for Sport. $0.27/day.
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Frequently asked questions
Is Solgar or Thorne iron bisglycinate better?
Same active ingredient and dose — 25 mg of elemental iron as chelated bisglycinate in one capsule. Thorne adds NSF Certified for Sport; Solgar does not carry a third-party certification. Unless you are drug-tested, Solgar gives you the identical form and dose for less.
Why is iron bisglycinate gentler than ferrous sulfate?
Bisglycinate binds iron to two glycine molecules, which keeps more of it chelated through the gut rather than free. Free iron is what drives the constipation, cramping and nausea that make ferrous sulfate hard to tolerate. Both products here use the bisglycinate form.
Should I take iron without a blood test?
Generally no. Unlike most nutrients the body has no active route to excrete excess iron, so it accumulates. Supplementing without confirmed deficiency risks overload, and the symptoms people self-treat as low iron often are not. Ferritin plus transferrin saturation is the standard pair of tests.
Related
- Ferrous sulfate vs bisglycinate — why the form changes tolerability
- Iron dosage guide — RDA, deficiency doses, and timing
- All iron bisglycinate products — ranked by cost per dose
Sources
- NIH Office of Dietary Supplements. “Iron — Health Professional Fact Sheet.” ods.od.nih.gov
- NSF. “Certified for Sport” — what the programme tests. nsfsport.com
- Product labels and live Amazon pricing for both products, reviewed August 2026.