Iron deficiency is the most common nutrient deficiency in women worldwide. But many iron supplements cause terrible GI side effects — constipation, nausea, dark stools. We rank the gentlest and most effective iron supplements available in 2024.
Why We Reviewed Roundup
Iron bisglycinate (chelated iron) is substantially better tolerated than iron sulfate (the cheap form in most supplements) and has comparable or better absorption in studies. Choosing the right form eliminates most side effects.
✅ Pros
- Iron bisglycinate: gentle on digestion
- Essential for premenopausal women
- Energy and cognitive improvements when correcting deficiency
❌ Cons
- Iron should only be supplemented if deficient (get tested)
- Can inhibit zinc and other mineral absorption
- Overdose risk — keep away from children
Key Ingredients
- #1 Thorne Iron Bisglycinate (gentlest)
- #2 Fergon (ferrous gluconate)
- #3 Spatone Liquid Iron (food-based)
- #4 Garden of Life Vitamin Code Iron
- #5 Slow Fe (ferrous sulfate — avoid if sensitive)
Who Is This For?
Premenopausal women with heavy periods, vegans/vegetarians, endurance athletes (high iron losses), and anyone diagnosed with iron deficiency anemia.
Check Current Price on Roundup
Find gentle, bioavailable iron supplements through our recommended links.
View Best Price →Price & Value
Gentle iron: $15–$25/month. Very affordable.
Our Verdict
Always get blood work before supplementing iron. If you need it, choose iron bisglycinate. Thorne Iron Bisglycinate is our top pick for tolerability. We give it a N/A/5 and recommend it for premenopausal women with heavy periods, vegans/vegetarians, endurance athletes (high iron losses), and anyone diagnosed with iron deficiency anemia.