Iron is vital for red blood cells and their ability to carry oxygen, for energy turnover, and for muscle function. For those reasons, iron is highly important for athletes because iron deficiency anemia impairs your performance. Still, iron deficiency is quite common, especially in connection with endurance sports and menstrual bleeding. A plant-based diet and low stomach acid can also increase the risk of becoming iron-deficient. In a new review article that is published in Life, a group of scientists has looked at iron and iron supplementation and how it can affect athletic performance.