While some supplements are designed to be taken with food, it’s usually recommended that you take it on an empty stomach, says Gans. “Iron is absorbed best on an empty stomach with a little vitamin C, like a glass of orange juice, because vitamin C helps your body take in the iron more efficiently,” she explains.
Collingwood specifically recommends taking your iron an hour or two before a meal for best results.
But if your iron supplement bothers your stomach, Gans says it’s fine to take it with a small meal. “Just try to avoid dairy with it,” she says. (The calcium in iron may interfere with absorption.)
Along with dairy products, Gans points out that these foods and drinks can mess with iron absorption and shouldn’t be taken at the same time as your supplement:
Calcium supplementsCoffeeTeaHigh-fiber foods
“Calcium competes with iron, and fiber can bind to it, making it harder for your body to absorb,” Gans explains. “It’s best to take iron at a different time than those foods.” (Coffee and tea contain polyphenols and tannins that can interfere with absorption, Collingwood says.)