Iron supplements treat iron deficiency anemia and low iron stores. Iron supplement guide covers forms, dosing, absorption optimization, and managing side effects. Discuss with healthcare provider before starting.
Common iron forms
- Ferrous sulfate: Cheapest, most studied. 65 mg elemental iron per 325 mg tablet
- Ferrous gluconate: 36 mg elemental iron per 324 mg. Better tolerated by some
- Ferrous fumarate: 33 mg elemental iron per 100 mg
- Iron bisglycinate: “Gentle” form; may absorb better; more expensive
- Heme iron polypeptide: Better absorbed; more expensive
Dosing
- For deficiency: 65-200 mg elemental iron daily
- Recent evidence supports every-other-day dosing for better absorption
- 3-6 months to replenish stores
- Recheck ferritin at 3 months
Optimizing absorption
What helps:
- Vitamin C (orange juice, supplement)
- Take on empty stomach (when tolerated)
- Heme iron sources from food
What hinders:
- Coffee, tea (tannins)
- Calcium (separate by 2 hours)
- Antacids and PPIs
- Grain phytates
Every-other-day dosing
Recent research suggests:
- Iron raises hepcidin, blocking absorption of subsequent doses
- Every-other-day dosing allows hepcidin to fall
- Better absorption per dose
- Often better tolerated
Managing side effects
- GI upset: take with food (less absorbed but more tolerable)
- Constipation: increase fiber, water; consider stool softener
- Black stools: normal, harmless
- Nausea: reduce dose, switch form, take with food
When to consider IV iron
- Severe deficiency requiring rapid correction
- Oral intolerance
- Malabsorption
- Inflammatory conditions affecting oral iron utilization
Frequently Asked Questions
What’s the best iron supplement?
Ferrous sulfate well-studied and cheap. Bisglycinate gentler if intolerant.
Should I take iron daily or every other day?
Recent evidence supports every-other-day. Discuss with provider.
Why does iron cause GI upset?
Common side effect. Various strategies to reduce.
Should I take iron with vitamin C?
Yes, increases absorption.
How long until iron deficiency resolves?
Anemia: weeks. Stores: 3-6 months.
The bottom line on iron supplements
Address deficiency confirmed by labs. Multiple forms; ferrous sulfate cheap and effective. Every-other-day dosing emerging best practice. Vitamin C helps absorption.