Iron and folate in fortified cereals

Fortification of cereal-grain products was introduced in 1941 when iron and three vitamins were added to flour and bread. Ready-to-eat cereals were fortified at about the same time. These fortifications have contributed to increased dietary iron intake and reductions in iron deficiency anemia in the US. In 1996, FDA finalized rules for fortification of specific enriched cereal-grain products with folic acid. This measure was instituted to increase the folate intakes of women of child-bearing age and thereby reduce the risk of having a pregnancy affected with a neural tube birth defect. However, with recent increases in fortification, public health officials in the US are concemed that excess intake of specific nutrients such as iron and folic acid may result in toxic manifestations.

Our objective was to measure iron and total folate content in breakfast cereals and compare assay to label values for % Daily Value. We also determined by weight the amount of a ready-to-eat breakfast cereal adults would eat and compared this to the labeled serving size, for which the reference amount for this cereal per eating occasion was 1 cup or 30 g.

Twenty-nine breakfast cereals were analyzed for iron content using the bathophenanthroline reaction. Twenty-eight cereals were analyzed for total folate, utilizing a microbiological assay with tri-enzyme digestion. Serving size quantities were estimated in seventy-two adults who regularly ate breakfast cereal and were asked to fill a 16 or 22 cm round bowl with the amount of cereal that they would consume for breakfast.

When the labeled value was compared to the assayed value for iron content 21 of the 29 breakfast cereals were 120% or more of the label value and 8 cereals were 150% or more of the label value. Overall, analyzed values for iron ranged from 80% to 190% of label values. Analyzed values for folate ranged from 98% to 320% of label values. For 14 of 28 cereals, analyzed values exceeded label declarations by more than 150%. Bran-containing cereals contained the highest amounts of folate relative to their label declarations. The median analyzed serving size for the breakfast cereal was 47 g for females, 61 g for males with a combined median of 56 g as compared to the label value of 30 g.

Analyzed values of iron and folic acid in breakfast cereals were considerably higher than labeled values. For adults, the amount of cereal actually consumed was approximately 200% of the labeled serving size. When the quantity of cereal consumed is more than the labeled serving size and when the levels of iron and folate are higher than declared, the intake of both will be significantly greater than the labeled values. It will be important to continue monitoring serum ferritin and folate levels in NHANES IV, since daily consumption of breakfast cereals may contribute to excessive intakes of iron and folate.