What supplements should female runners take?

Female runners may benefit from iron or calcium supplements, if their levels are low. Iron requirements for all female athletes may be up to 70% higher than the estimated average, due to blood losses from menstruation, hemolysis (foot strike and impact), increased iron losses in sweat and the GI tract and poor dietary iron intake [1,2]. Female athletes may also be at risk for low bone-mineral density due to poor calcium intake, which increases the risk of stress fractures. Menstrual dysfunction, low dietary calcium intake, restricted energy intake and disordered eating contribute to calcium deficiencies in women [1]. 

Since female runners are at a higher risk for iron deficiency anemia, they should get screened often. Supplements should only be taken under direction of a healthcare provider, as too much iron in the blood can be toxic.