Milk and Diabetes

Abstract

Type 1 diabetes is based on autoimmunity, and its development is in part determined by environmental factors. Among those, milk intake is discussed as playing a pathogenic role. Geographical and temporal relations between type 1 diabetes prevalence and cow’s milk consumption have been found in ecological studies. Several case-control studies found a negative correlation between frequency and/or duration of breast-feeding and diabetes, but this was not confirmed by all authors. T-cell and humoral responses related to cow’s milk proteins were suggested to trigger diabetes. The different findings of studies in animals and humans as well as the potential underlying mechanisms with regard to single milk proteins (bovine serum albumin, β-lactoglobulin, casein) are discussed in this review. In contrast to type 1 diabetes, the etiology of type 2 diabetes, characterized by insulin resistance is still unclear. In a population with a high prevalence of type 2 diabetes, the Pima Indians, people who were exclusively breastfed had significantly lower rates of type 2 diabetes than those who were exclusively bottlefed. Studies in lactovegetarians imply that consumption of low fat dairy products is associated with lower incidence and mortality of diabetes and lower blood pressures. In contrast, preference for a diet high in animal fat could be a pathogenic factor, and milk and high fat dairy products contribute considerably to dietary fat intake. Concerning milk fat composition, the opposite effects of various fatty acids (saturated fatty acids, trans-fatty acids, conjugated linoleic acid) in vitro, in animals and in humans have to be considered.

• type 1 diabetes
• type 2 diabetes
• metabolic syndrome
• milk
• breastfeeding

• BB rat=bio-breeding rat
• BLG=β-lactoglobulin
• BSA=bovine serum albumin
• CM=cow’s milk
• GAD=glutamate decarboxylase
• GLUT-2=glucose transporter-2
• HLA=human leukocyte antigen
• IAA=insulin autoantibodies
• ICA=islet cell antibodies
• ICA69=islet cell antigen 69 (=p69)
• IgA, IgG=immunoglobulins
• NOD-mouse=non-obese diabetic mouse
• PCA=parietal cell antibodies
• Tep69=T-cell epitope 69

Key teaching points:

• Type 1 diabetes is an autoimmune disease which is in part determined by environmental factors

• Case-control studies on infant feeding practices and detection of immune reactions against cow’s milk proteins led to the hypothesis that cow’s milk consumption is causally related to diabetes development; however, the findings supporting this theory have not been confirmed by other authors

• Intervention studies in humans seem to be necessary to define clearly a potential risk of CM consumption in infants

• The etiology of type 2 diabetes, characterized by insulin resistance and hyperinsulinemia, is still unclear

• Bottle-feeding in infancy has been discussed as being involved and certain constituents of CM could be related to diabetes development in adults

• On the other hand, lactovegetarian diets seem to be protective with respect to the development of the metabolic syndrome, and certain fatty acids have been shown to have beneficial effects on glucose tolerance in diabetic animals

Key teaching points:

• Type 1 diabetes is an autoimmune disease which is in part determined by environmental factors

• Case-control studies on infant feeding practices and detection of immune reactions against cow’s milk proteins led to the hypothesis that cow’s milk consumption is causally related to diabetes development; however, the findings supporting this theory have not been confirmed by other authors

• Intervention studies in humans seem to be necessary to define clearly a potential risk of CM consumption in infants

• The etiology of type 2 diabetes, characterized by insulin resistance and hyperinsulinemia, is still unclear

• Bottle-feeding in infancy has been discussed as being involved and certain constituents of CM could be related to diabetes development in adults

• On the other hand, lactovegetarian diets seem to be protective with respect to the development of the metabolic syndrome, and certain fatty acids have been shown to have beneficial effects on glucose tolerance in diabetic animals