Unit 2: Health Effects of Complementary Feeding

During the complementary feeding period infants have an increased risk for gastrointestinal and respiratory tract infections as infants are exposed to microbial pathogens present in food and fluids (Michaelsen et al. 2003). In developing countries, children under 2 years of age experience an average of three to five episodes of diarrhea per year. In some countries, the rate is six to eight episodes per year (Dewey & Mayers 2011). See Lesson 8: Complementary Feeding in Developing Countries for specific information regarding infection in developing countries.

Breastfeeding has been associated with a reduced risk of infections in infancy, however data on the effects of the timing of complementary feeding on infections in infancy is limited and inconsistent (Agostoni et al. 2009).

The Millennium Cohort Study in the UK which assessed the effects of complementary food and breastfeeding compared to formula feeding on the risk for infection during the first 8 months of life, confirmed that there is a protective effect of breastfeeding on infectious diseases, but no effects on the age of introduction of complementary foods (Quigley et al. 2007). Other studies in the UK have suggested that an introduction of complementary foods before the age of 3 months may increase the risk of gastrointestinal diseases and respiratory tract infections whilst introduction after 4 months of age had no effect on the risk of infections (EFSA Panel on Dietetic Products Nutrition and Allergies (NDA) 2009).