Iron is one of the most essential of all nutrients. It is required for blood formation. Iron is the key nutrient for managing oxygen transport to cells. Pregnant women and girls, including teenagers, are most vulnerable to developing the deficiency. It is possible to have too much iron in the body, and this may be even more common than the deficiency. Iron tablets should only be taken for proven iron deficiency. Food sources of iron are the safest type to consume. Have a mirror handy when taking this test, since there are skin and nail signs of iron deficiency.