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. Solgar is currently unavailable on Amazon (checked 2026-09-08) — Thorne is the one you can buy today.
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 | Unavailable on Amazon (checked 2026-09-08) | Check price → |
Thorne's price is a live Amazon buy-box figure ÷ pack serving count. Solgar's Amazon listing was removed as of 2026-09-08; its price/serving figures above are the last verified label data, not a live price. 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
Solgar was the lower-cost pick for the same 25 mg chelated bisglycinate if you weren't subject to drug testing — but it is currently unavailable on Amazon (checked 2026-09-08), so there's no live listing to buy it from.
Choose Thorne — it's the one currently buyable, and if you compete in a tested sport you also get NSF Certified for Sport verification. If you don't need the certification, the premium mainly buys the ability to actually purchase this comparison's iron today.
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. Last verified $0.15/day, but the Amazon listing was removed (checked 2026-09-08).
Same 25 mg bisglycinate, NSF Certified for Sport. $0.27/day.
As an Amazon Associate we earn from qualifying purchases. We rank by verified label data and cost per day, never commissions.
The evidence · Iron
What the published reviews of Iron concluded
- Effects of Oral Iron Supplementation on Blood Iron Status in Athletes: A Systematic Review, Meta-Analysis and Meta-Regression of Randomized Controlled Trials. · Sports medicine (Auckland, N.Z.), 2024
“Increase in serum ferritin concentration after OIS was evident in subjects with initial pre-supplementation serum ferritin concentration ≤ 12 µg/l, while only minimal, if any effect, was observed in subjects with higher pre-supplementation serum ferritin concentration.”
- Iron supplementation in pregnancy. · The Cochrane database of systematic reviews, 2000
“Iron supplementation appears to prevent low haemoglobin at birth or at six weeks post-partum. There is very little information on pregnancy outcomes for either mother or baby.”
- Does Iron Supplementation Improve Performance in Iron-Deficient Nonanemic Athletes? · Sports health, 2018
“The evidence is equivocal as to whether iron supplementation in IDNA athletes improves athletic performance. Supplementing athletes with ferritin levels <20 μg/L may be more beneficial than supplementing athletes with higher baseline ferritin levels.”
- Systematic review and meta-analysis: what is the evidence for oral iron supplementation in treating anaemia in elderly people? · Drugs & aging, 2015
“Oral iron raises haemoglobin levels in elderly people with iron deficiency anaemia by 0.35 g/dL after 4-6 weeks, but it is unclear if this results in tangible health benefits.”
Method: PubMed searched in humans for systematic reviews and meta-analyses with Iron in the title; these 4 of the 38 that qualified are shown with the authors’ own conclusion quoted rather than summarised. What it cannot tell you: whether Iron will work for you — each of these reports an average across trials published 2000–2024, and null findings are shown here as readily as positive ones.
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. Solgar is currently unavailable on Amazon (checked 2026-09-08), so Thorne is the one you can actually buy there right now.
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.