Giving iron supplements to young kids who don’t have enough iron in their blood might help them do a little better on tests that measure how smart they are, especially in places where many kids are iron-deficient.

Giving iron pills to kids who aren’t anemic doesn’t seem to make them smarter, better at remembering things, or more focused — their brain skills stay about the same.

Giving kids iron supplements doesn’t reliably make them smarter or do better in school — even if their bodies absorb the iron, it doesn’t usually lead to noticeable improvements in how they think or learn.

Giving iron supplements to kids who don’t have enough iron in their blood might help them pay attention better and focus more, especially if they’re between 2 and 12 years old.

When kids under 7 don’t have enough iron in their blood, it can make it harder for them to think clearly and move smoothly, because their brains aren’t getting the right materials to grow and work properly.

When kids who don’t have enough iron in their blood take iron supplements for 3 months, they tend to do better on tests that measure how they think and learn.