Assessment of Complementary Feeding of Canadian Infants

With the recent recommendation from Health Canada to extend exclusive breast-feeding to 6 months of age there has arisen concern about what is the best solid food to introduce at that time. Traditionally solids were introduced in Canada at 4-6 months and usually iron-fortified rice cereal was the first food of choice. New recommendations from Health Canada include meat as a potential first food as well as other iron fortified foods. This has lead to uncertainty of both public health officials and parents about the optimal introduction and choice of solids after exclusive breastfeeding.

In addition to meeting iron needs with the first solid food choice, the investigators are concerned about the possible generation of reactive oxygen species (ROS) in the gut of the infant fed traditional iron fortified cereals. Infant cereals are fortified at 25-30 mg iron per 100 g dry-weight. Absorption of the non-heme electrolytic iron ranges from 5-10% so that most of the residual iron enters the colon. Normally excess iron is sequestered by a variety of mechanisms in the body, but there is no such system for the sequestering of iron in the gut lumen. The investigators have shown that providing iron supplements to adults where the majority of the iron is unabsorbed passes through the digestive tract can lead to the generation of ROS in the colon. These effects are seen in adults receiving 1 mg/kg/day supplemental iron. By 5-6 months of age infants consuming iron fortified cereals will receive the same dose and are likely producing ROS in their digestive tract. This may cause inflammation and make infants more susceptible to disease. The investigators think that meats and infant cereals with phenolic antioxidants available from fruits will likely reduce the generation of ROS in vivo. Therefore the investigators wish to determine if traditional and newly recommended first foods are safe from a free radical and inflammatory perspective.

HYPOTHESES:

1. Consumption of infant cereals with iron will increase ROS generation in the gut 2. Consumption of infant cereals with iron and fruit will decrease ROS in the gut 3. Consumption of meat will not generate ROS 4. Consumption of iron fortified cereals or meat will maintain iron status during infancy