Do you recommend vitamin C supplementation with PO iron in patients with iron deficiency?

Vitamin C supplementation is unnecessary. Taking the iron with a glass of orange juice away from food and especially coffee optimizes absorption. That being said vitamin C does no harm. See vonSiebenthal et al eClinical Works 2023 (Lancet publication), Benson et al, Lancet Haem 2025 or Auerbach et a...

Vitamin C can theoretically reduce iron to the ferrous form, making it easier to absorb. I have added Vitamin C in some who do not seem to be responding well to oral iron. Anecdotally, I have not found that to be particularly helpful

Some patients read about this effect and ask if they can take it. ...

For better absorption of iron, an acidic environment is preferred, especially if patient is taking a proton pump inhibitor. Thus, additional vitamin C would be helpful in converting iron to the ferrous state.