The group, led by Caroline Roduit of Children's Hospital at the University of Zurich, had considerable overlap with the researchers who reported two years ago that the mother's exposure to farm animals before birth reduced the incidence of eczema. Both studies were based on data from the Protection against Allergy--Study in Rural Environments (PASTURE) project.
The authors say that, in the existing scientific literature, there is no consistent evidence that avoiding food allergens during pregnancy or infancy prevents allergies later. Because they conducted this study, it would seem they believe the opposite: that exposing kids to allergens could lead to tolerance and therefore fewer allergies. And eczema often has an allergic component, although it's sometimes difficult to classify the precise type of reaction that a patient has to a food.
The authors considered data from 1041 children, seeking to correlate the variety of foods fed eaten with whether the children developed eczema (not whether they developed food allergies). They reported an inverse correlation: the more foods eaten, the less eczema in the children. Here's Figure 2, the key graphic.
|Looks to me like the first two foods make the most difference. After that, the curve is essentially flat.|
Four interesting features stand out in the paper:
1) the authors observe that it is very hard to study the connection between food and eczema before a child is one year old, because if a child has symptoms of eczema early, or if one or both of the parents has allergies, the child tends to be given very few foods in addition to breast milk. So a naive researcher might immediately conclude that giving a kid only one or two foods leads to eczema. To be rigorous, the authors restricted their study to children who developed eczema after the first year.
2) yogurt, according to this data, is a special case. If a child eats yogurt, and very few other foods, it appears to reduce the odds of developing eczema to 40% of what they were to begin with. That may be because the yogurt bacteria somehow provide a probiotic effect in the gut.
3) the six major food groups that the authors consider as independent are vegetables and fruits; cereals; meat; bread; yogurt; and cake. (Cake is a separate food group in Europe?) I find this odd, given that bread and cake are made from cereals and the three groups must contain very similar allergens.
4) Europeans apparently give their children very few soy-based foods. North Americans must have been influenced by Asian cuisine and include tofu and soy sauce in their diets more than they used to. Or maybe it just looks that way because I live in the Pacific Rim.
I wouldn't make any radical changes to my kids' diet based on this paper, but you can't do any harm feeding them yogurt.