 We avoided dairy, gluten, and other allergenic foods with my youngest child, both while I was pregnant, and in his first few years. He breastfed exclusively for 6 months, and for a few years afterwards. He still developed diabetes. Got (hydrolyzed) milk?There has long been debate (and there are innumerable studies) about cow's milk and type 1 diabetes. The most recent study, published in late 2010, provides the best evidence yet that there is a link between cow's milk and type 1 diabetes. Published in the prestigious New England Journal of Medicine, the double-blind, randomized study assigned genetically at-risk infants to receive either regular cow's milk infant formula, or a a casein hydrolysate formula, when breastmilk was not available in the first 6-8 months of life. Over the next ten years, the children were analyzed for type 1 diabetes as well as type 1 related autoantibodies. The results were convincing: the children given hydrolyzed infant formula had a 50% lower risk of developing type 1 related autoantibodies by age 10. (Since this study did not include people from the general population, whether this intervention will work in people less genetically at risk of type 1 is not known). This study was part of a larger trial, the TRIGR (Trial to Reduce IDDM in the Genetically at Risk). TRIGR began in 2002 and is currently running in 77 centers in 15 countries to answer the question of whether weaning to a hydrolyzed formula will reduce the incidence of type 1 diabetes. The authors suggest that the hydrolyzed formula reduces gut permeability, and has a beneficial effect on gut flora (Knip et al. 2010).
Up until now, studies of cow's milk and type 1 diabetes have been conflicting. Many studies have found that cow's milk consumption is associated with an increased risk of type 1-related autoimmunity or type 1 diabetes (e.g., Kimpimaki et al. 2001; Wahlberg et al. 2006; Holmberg et al. 2007), while others have not (Norris et al. 2003; Ziegler et al. 2003; Virtanen et al. 2006; Savilahti and Saarinen 2009). The differences may involve differences in timing, differences in the studies, genetic background in certain populations, or even the type of milk.
On the latter point, briefly, the milk protein casein has different variations (A1 or A2) depending on the breed of cow. Laugesen and Elliott (2003) found that consumption of milk containing the A1 type of casein is associated with type 1 diabetes (breeds that produce A1 milk are more common in northern Europe, where type 1 incidence is higher). Merriman (2009) argues that this association is instead due to latitude and the protective effects of vitamin D.
Cow's milk contains bovine insulin, which is similar to human insulin, and can cause immune reactions in humans. Some researchers propose that an immune reaction to bovine insulin may spread to react with the body's own insulin, and eventually, in combination with other factors such as viruses, could result in an autoimmune attack against the insulin-producing beta cells, resulting in type 1 diabetes (Vaarala 2006). Mäkelä et al. (2006) have found evidence for this process in infants, finding that viral infections can enhance the immune response to insulin, induced by bovine insulin in cow's milk.
A recent study found that children who later developed type 1 diabetes had higher levels of cow's milk antibodies in infancy. The authors suggest that this finding may be due to increased gut permeability or delayed maturation of the gut immune system in the children who developed diabetes. Early exposure to cow's milk may be a risk factor for type 1 diabetes only in children who have a dysfunctional gut immune system. (All the children in this study were fed cow's milk formula for at least two months; also see the breastfeeding page) (Luopajarvi et al. 2008).
Interestingly, milk and milk products are good indicators of the level of contamination of persistent organic pollutants (POPs) in the food chain (Malisch and Dilara 2007). In a study of young Dutch children, dairy products were found to contribute about half of their level of their exposure to PCBs and dioxins (Patandin et al. 1999). Could this factor also play a role in the associations between cow’s milk and type 1 diabetes? This possibility has not been studied. Wheat and glutenGluten has been thought to play a role in the development of type 1 diabetes due to the association between type 1 and the autoimmune celiac disease: around 7% of people with type 1 diabetes have celiac disease (Narendran et al. 2005).
Interestingly, in a long-term study, children with celiac disease who had type 1 diabetes-related autoantibodies found that those antibodies gradually disappeared over two years after going on a gluten-free diet (Ventura et al. 2000). Similar to the bovine insulin in cow's milk, wheat also contains a protein that resembles another protein linked with the autoimmune attack in the pancreas (MacFarlane et al. 2003). Gluten has also been found to cause intestinal inflammation in people with type 1 diabetes (Auricchio et al. 2004). Ziegler et al. (2003) found that early introduction of gluten-containing foods (before 3 months of age) to be a risk factor for the development of type 1-associated autoimmunity in children with genetic risk of type 1 diabetes. Norris et al. (2003) found that exposure to any cereals before 3 months of age (and also after 7 months), led to a higher risk of developing autoantibodies in genetically susceptible children. The authors propose that perhaps the reason that later introduction of cereals could increase risk is that older babies are likely to be fed larger amounts of food. Indeed, the study confirmed that babies given cereals at 7 months or older were more likely to be given more servings per day of cereals in the first month of exposure as compared to the others. This study also found that if cereals were introduced while the child was still breastfeeding, the risk of autoimmunity was lower. Wahlberg et al. (2006) found that the combination of early cow's milk formula and late introduction of gluten increased the risk of autoimmunity in children. Based on the above research, doctors conducted a randomized intervention study to determine if delaying the introduction of gluten would prevent type 1 diabetes in children genetically at risk of the disease. They found that first introducing gluten at 6 months of age versus 12 months of age was safe, but did not change the risk of developing type 1 related autoantibodies, or type 1 diabetes (Hummel et al. 2011). SoySoy proteins have been shown to cause diabetes in animals. One human study from China found that infants given soy-based infant formula had double the risk of type 1 diabetes. It also found that more children with type 1 had been introduced to solid food before 3 months of age than children without diabetes (Strotmeyer et al. 2004). The bottom lineIt seems that introducing food before 3 months of age is problematic, perhaps because the intestine is still immature and unable to handle these foods. Indeed, Virtanen et al. (2006) found that introducing fruits, berries, and roots early (around 3-4 months of age) was associated with development of type 1 diabetes-related autoimmunity in genetically at-risk children.
For more information on why foods such as wheat and dairy might contribute to the development of type 1 diabetes, and the involvement of the gut immune system, see the diet and the gut page.
While all studies do not have consistent findings, we can still use them to help determine how to feed our babies. Parents could be careful introducing certain foods, especially wheat and cow's milk. Introduce them in small amounts, while breastfeeding, and not too early in life. Zeigler et al. (2003) suggest that ensuring compliance to infant feeding guidelines, such as not introducing solid foods to infants before 3 months of age, may help reduce the incidence of type 1 diabetes. World Health Organization (WHO) (http://www.unicef.org/) infant feeding guidelines call for exclusive breastfeeding for a full 6 months, the introduction of safe and complementary foods from the sixth month of life while breastfeeding continues, and then continued breastfeeding for up to 2 years of age or beyond. Only 5% of families of children with first degree relatives who have type 1 diabetes follow the WHO recommendations for infant feeding (Pflüger et al. 2010).
If formula feeding is necessary, then it is clear that using hydrolyzed formula reduces the risk of type 1-related autoantibodies in children genetically at-risk of type 1 diabetes. |