Iron helps the body create hemoglobin, which is needed for red blood cells to carry oxygen, Angela Martindale, celebrity nutritionist, says. If your hemoglobin levels are not high enough, you won’t make enough healthy oxygen-carrying red blood cells. This can lead to anemia, exhaustion and a weaker immune system that can’t fight off illnesses, she adds. “The body breaks down the iron […] also to create healthy and strong skin, hair and nails.”