Minerals
Iron — timing, dose & interactions
Carries oxygen in hemoglobin and myoglobin. Supplement only if you have documented low iron — excess iron is harmful, and absorption is tightly regulated by hepcidin.
Timing
When to take it
Best absorbed on an empty stomach in the morning, when the iron-regulating hormone hepcidin is lowest. Take with a small snack if it upsets your stomach.
Dose note. Adult UL for elemental iron. Higher doses are often prescribed short-term for deficiency — follow your clinician.
Interactions
Iron with other supplements
Iron + Calcium
Calcium reduces iron absorption from the same meal
Iron + Zinc
Zinc and iron compete when taken together without food
Iron + Curcumin
Curcumin binds iron
Iron + Vitamin C
Vitamin C boosts non-heme iron absorption
Iron + Caffeine
Coffee and tea reduce iron absorption
Iron + Green Tea Extract
Green tea catechins block iron absorption
Iron + Psyllium Husk
Fiber can reduce iron absorption
Safety
Medications & health conditions
Iron reduces levothyroxine absorption. Iron binds levothyroxine in the gut and can lower thyroid hormone levels. Keep it at least 4 hours away from your thyroid medication.
Iron blocks absorption of these antibiotics. Iron binds tetracycline and quinolone antibiotics in the gut, which can make the antibiotic less effective. Take the antibiotic at least 2 hours before or 4–6 hours after iron.
Do not take iron with iron overload. Supplemental iron worsens iron overload and organ damage.
Buying guide
What to look for on the label
Iron
- Iron bisglycinate (gentler on the stomach)
- Check the label for elemental iron, not the salt weight
FAQ
Common questions
When is the best time to take Iron?
On waking. Best absorbed on an empty stomach in the morning, when the iron-regulating hormone hepcidin is lowest. Take with a small snack if it upsets your stomach.
Should Iron be taken with food?
Iron is best absorbed on an empty stomach. Best absorbed on an empty stomach in the morning, when the iron-regulating hormone hepcidin is lowest. Take with a small snack if it upsets your stomach.
Can you take Iron with Calcium?
Not at the same time — take them at least 2 hours apart if you are supplementing iron to correct a deficiency. Take iron in the morning on an empty stomach and calcium with dinner. Separate by at least 2 hours.
Can you take Iron with Zinc?
Better apart — separate by about 2 hours, especially if taken on an empty stomach. Take iron on an empty stomach in the morning and zinc with a later meal.
Can you take Iron with Curcumin?
Probably fine for most people, but separate them if you are treating low iron. If you are iron-deficient, keep curcumin at least 2 hours away from iron.
Can you take Iron with Vitamin C?
Yes — taking them together can increase absorption, though it isn't required for iron supplements to work. Optional: take them together. More important for plant-based diets than for iron supplements.
Sources