Iron requirements increase in adolescence because of the
greater muscle mass and blood volume associated with the growth
spurt. In addition, females require even greater iron because of
the onset of menstruation. Iron is found in foods such as red
meats, grains, and vegetables. Adolescents may have trouble
reaching the iron requirement if their caloric intake is low,
because iron in foods is not absorbed well by the body. They may
require an iron supplement.