Iron supplements, compared
3 products we’ve reviewed list iron as a key ingredient. Here’s what it does, what the research uses — and how much each product actually contains.
What it is
Needed to make hemoglobin, which carries oxygen in the blood. People who menstruate, are pregnant or eat no meat are most likely to fall short.
What the research uses
Adults need 8–27 mg a day depending on sex and life stage. The upper limit for adults is 45 mg a day.
Keep iron supplements away from children — accidental overdose is dangerous.
Educational information, not medical advice. Talk to a healthcare professional before starting a supplement, especially if you are pregnant, nursing or take medication.
Every product, dose by dose
| Product | Iron per serving | Form | Score |
|---|---|---|---|
 NSF Certified for Sport | 25 mgIron (as Ferrochel ferrous bisglycinate chelate) | Capsule | 8.6 |
 | 18 mgIron (as ferrous fumarate) | Tablet | 8.0 |
 USP VerifiedNon-GMO Project VerifiedClean Label Project | 8 mgIron (as ferrous bisglycinate) | Capsule | 7.5 |
Amounts are per serving as printed on each label. “Not disclosed” usually means the ingredient sits inside a proprietary blend.
Questions people ask
How much iron do studies use?
Adults need 8–27 mg a day depending on sex and life stage. The upper limit for adults is 45 mg a day.
Which iron supplement scores highest?
In our reviews, Thorne Iron Bisglycinate scores highest at 8.6/10, followed by Centrum Adults Multivitamin (8.0) and Ritual Essential for Women 18+ (7.5). Scores weigh efficacy, quality, value, experience and transparency — not just the dose.
How much iron is in these products?
It varies by product and serving size — for example Thorne Iron Bisglycinate (25 mg), Centrum Adults Multivitamin (18 mg), Ritual Essential for Women 18+ (8 mg). The table above lists the amount per serving for every product we've reviewed.