Editorial introduction Thus far the efforts of the international agencies to prevent anemia in developing countries have focused mainly on iron supplementation in pregnancy, although efforts are increasing to promote iron fortification of cereal flours that can benefit the entire population. It has become increasingly apparent that pregnancy is too late a stage for intervention to prevent iron and folate deficiencies. Women who enter pregnancy with moderate to severe anemia are likely to remain iron deficient during pregnancy, even with iron supplementation. Iron deficiency should be prevented in women of childbearing age, particularly adolescent girls, who are at the highest risk of anemia. Costa Rica has a much better nutrition and health status than most other developing countries [1]. Its levels of anemia reported in the following paper are remarkably low. Still, more than half of the adolescent girls in this Costa Rican study had anemia and low folate intakes. This is a strong reminder of the importance of preventing these deficiencies in adolescent girls in all countries in order to improve pregnancy outcomes, as recommended by the UNICEF/UNU/MI technical workshop [2]. Folate supplementation in pregnancy is too late to prevent the increase in congenital neural tube defects associated with this deficiency. Hence the recommendation for increased fruits and vegetables in the diet is a sound one. This would provide not only folate, but also ascorbic acid and vitamin A, which improve the absorption of iron. To provide at least a basic level of protection for most of the population, the fortification of wheat flour with iron and folate should be given a high priority, as recommended by the UNICEF/UNU/MI technical workshop [2]. The value of this measure has been most recently demonstrated on a national scale in Venezuela [3].