The Early Development of the GI Tract and the Immune System
Thomas A. Kruzel, ND
Breast feeding and the introduction of solid foods during infancy have long been recognized by naturopathic physicians as being vital to the development of children’s immune systems, which ultimately translates to good health and well being throughout their lives. Much has been written about the quality of foods and availability of nutrients needed for growth, development, and maintenance of health.1 Naturopathic medicine, with its emphases on diet and nutrition, has long recognized that the early development of the gastrointestinal tract and its relationship to development of immunity sets the stage for how individuals deal with health challenges throughout the rest of their lives. Certainly, this is all the more important in light of recent findings of high levels of environmental toxins, increasing resistance of microorganisms to antibiotics, and ever-changing viral organisms that we will experience throughout our existences. Additionally, the added pressures of nutrient deplete and higher lectin-containing foods produced by corporate farming methods and genetically modified foods upon the gastrointestinal tract are only recently being recognized.
The benefits of breast feeding and its effects on immune system development have been extensively reviewed and will not be covered here. An excellent review article can be found on this subject in the recent Natural Medicine Journal.2 Breast feeding has a significant effect on the growth, development, and function of the epithelium and immune and nervous systems of the gastrointestinal tract and is an integral component of the infant’s innate defense system. Properties in breast milk, such as cytokines, lactoferrin, glycoconjugates, oligosaccharides, white blood cells, and immunoglobulins, help protect the developing infant’s GI tract from colonization by bacteria associated with necrotizing enterocolitis, as well as allergens. Antibodies found in breast milk have been shown to reflect the antigenic repertoire of the mother’s gastrointestinal and respiratory tracts. It has also been shown that while there is variation from mother to mother in the types of antibodies conveyed through breast milk, if the bacterial organisms are similar in both environments of mother and infant, then a greater specificity is achieved.3 All of these factors help to convey a selective advantage to beneficial organisms, such as bifidobacteria and lactobacilli, needed for GI tract and immune development in the infant. Additionally, the volume of the thymus has been found to be greater in breastfed infants than non-breastfed infants, which lends credence to the GI/immune system development connection.4