Knip M, Virtanen SM, Seppä K, et al. Dietary intervention in infancy and later signs of beta-cell autoimmunity. N Engl J Med. 2010;363:1900-1908.
Double-blind, randomized, controlled trial consisting of 230 newborn infants with a first-degree relative with type 1 diabetes and HLA-conferred susceptibility to type 1 diabetes in 15 hospitals throughout Finland. The intervention group (113 infants) received casein hydrolysate formula and the control group (117 infants) received standard cow’s milk–based formula when breast milk was not available during the first 6–8 months of life. The control formula was composed of 80% intact milk protein (Enfamil) and 20% hydrolyzed milk protein.
Two hundred eight children remained in the trial and provided at least one blood sample during follow-up period; 17 of the casein hydrolysate group children and 33 in the control group developed at least one autoantibody. Casein hydrolysate formula was associated with a decreased risk of seroconversion to positivity for islet-cell antibodies, IA-2 autoantibodies, GAD autoantibodies, IA-2 Autoantibodies, and ZnT8 autoantobiodies. The development of 2 or more antibodies signals a risk of 50–100% development of type 1 diabetes over 5–10 years. Seven of the 113 children in the casein hydrolysate group and 9 of the 117 children in the control group developed type 1 diabetes (although this was not a primary endpoint of this trial).
With the incidence of type 1 diabetes rising faster than it has previously among children, food content in early childhood has been postulated to impact the risk of developing this disease later in life. In particular, early exposure to complex protein (found in cow’s milk–based formula) and shortened breastfeeding duration could be risk factors for beta cell autoimmunity. In this trial, researchers from the Trial to Reduce IDDM in the Genetically at Risk (TRIGR) project investigated the effect of early dietary intervention during infancy on genetically susceptible infants. This publication is a follow-up to a pilot study by the same group. It establishes “that it may be possible to manipulate spontaneous beta cell autoimmunity by dietary intervention in infancy.”1
The correlation between consumption of cow's milk and type 1 diabetes, as suggested by the above study, does hold some merit and may be one piece of the puzzle.
The results of this study do show fewer signs of beta-cell autoimmunity, up to 10 years, when infants are put on a highly hydrolyzed protein formula. The trial does not compare maternal breast milk to formula; although this comparison would be interesting, it is not considered ethical. In addition, the trial does not consider the impact of the dietary intervention on lifelong incidence of type 1 diabetes as the primary endpoint. Breast milk provides cytokines and growth factors that influence oral tolerance and provides immunological homeostasis and gut maturation. The immune-mediated impact of cow’s milk consumption was originally implicated by epidemiological and animal studies to correlate with later development of type 1 diabetes. However, the retrospective data on the relationship between cow’s milk and type 1 diabetes has been inconsistent. This theory is still quite controversial; not enough conclusive, prospective research is available to make a definitive statement on the relationship between cow’s milk and later development of diabetes. That said, the correlation between consumption of cow’s milk and type 1 diabetes, as suggested by the above study, does hold some merit and may be one piece of the puzzle. For this reason, whenever breastfeeding is not possible, clinicians should consider alternatives, particularly formulas that do not contain the complex proteins contained in non-hydrolyzed cow’s milk.