Although consuming iron on an empty stomach assists with its absorption, it is not recommended due to the adverse side effects such as nausea and diarrhea with this regime. Taking iron before retiring to sleep will enable good absorption while minimizing the gastro-intestinal side effects.

Thank you Alison for the response. Keeping aside the adverse effect part of it, is there any scientific study or Cochrane review that suggests better absorption of IFA before meals?

Better to be used after or within the meal in patient with GIT irritation, usually this is a common symptom. But the absorption is increased if given in empty stomach. Please refer to this link of Kazung Clinical Pharmacology page 585

http://file.zums.ac.ir/ebook/188-Basic%20and%20Clinical%20Pharmacology%2012th%20Edition=Bertram%20Katzung%20Susan%20Masters%20Anthony%20Trevor=007.pdf