Thursday, March 24, 2011

LabEvoEndo Journal Club: Laura Klein presents on food allergies

This semester I'm trying out something a bit new -- I've encouraged my students to do quick write-ups of the papers they present in journal club in a way they think would be suitable for a blog post. This is to share what we're up to and give my brilliant students a chance to show their stuff.

This first guest post of the LabEvoEndo Journal Club is by Integrative Biology Honors Senior Laura Klein. Laura's been in my lab since her sophomore year.

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Welcome, readers! This blog post will start a series of posts by undergraduate lab members about the topics that LabEvoEndo currently finds interesting and are discussing in our weekly lab meetings. Usually, these will be related to our own current research projects and will somehow tie into the broader goals of the lab.

The other week, I spent a lot of time looking at some Polish survey data related to food allergies and food intolerances that Dr. Clancy and I collected last summer. This led me to thinking about the health implications of food allergies, so this week’s lab meeting article is "Food allergies in children affect nutrient intake and growth” by Christie et al from 2002. As the authors from this article are all medical professionals, I also wanted to supplement this article with some information about the daily social stressors that food allergies can have on individuals or families, so we also read excerpts about The Impacts of Food Allergies on the Quality of Life’ from Fernandez-Rivas and Miles “Food allergies: clinical and psychosocial perspectives.”

To give you some background for the study, 6-8% of American children will develop food allergies in the first 3 years of life, which also happens to be a critical period for growth. Of children with food allergies, most will have a single allergy to cow’s milk, eggs, peanuts, what, soy, tree nuts, or fish. Previous studies have found that children with cow’s milk allergies have a lower height/age ratio, though they did not propose a mechanism for this trend. One possibility is that elimination diets in general may reduce the amount of macro or micro nutrients available in the diet.

In this study, Christie et al. compared 98 children with and 99 children without food allergies (all about age 4) to determine if food allergies and elimination diets impact the growth and nutrient intake of children with food allergies. All children who were diagnosed with an allergy had been following a food elimination diet. The BMI, height-for-age, and weight-for-age for all children was compared to the CDC’s Health Statistics Growth Charts, and individuals were classified as having ‘potential undernutrition’ (<25th percentile), ‘adequate nutrition’ (25th-75th percentile), and ‘potential overnutrition’ (>75th percentile). Parents also completed three days of dietary intake records, which were compared with recommended dietary allowances.

The authors found that more children with allergies were categorized as having ‘potential undernutrition’ as determined by height-for-age than children without allergies. Additionally, a large number of these children had two or more allergies. Because the article only focused on height-for-age despite collecting many other measurements, we were skeptical that food allergies were the sole cause having low height-for-age. Some possibilities that we discussed but the study did not control for included premature birth and genetic influences on height or growth rates.

Another study result that generated much discussion was that more than 25% of the children in both the control and allergy groups were not getting the recommended daily intake levels of calcium and Vitamins D & E. We thought this was problematic, not necessarily for the health of the children, but for how recommended daily intake levels are defined. Children with milk allergies who consumed supplementary fortified beverages were more likely to be meeting all of the intake recommendations than even children without any dietary restrictions. Considering this, are the current guidelines a reflection of realistic intake for small children?

In the discussion, the authors introduce the possibility that ‘catch-up’ growth during puberty. They suggest that this could be many food allergies disappear as children mature, so foods can be reintroduced into the diet. However, we also suggested that early teenagers are usually simply hungrier than toddlers (as anyone who has been in a high school cafeteria knows). Greater consumption of calories may provide greater energy sources for growth. Also, by puberty, people usually have more access to food because they are able to prepare it themselves. Both of these situations could contribute to more available energy that could be used for growth.

Finally, we wrapped up our discussion talking about how different kinds of elimination diets have biological and social impacts. For members of our group with food allergies and intolerances, especially ones like nuts or gluten, group dinners can be a challenge because hosts can be unsure what to prepare and may only have one or two ‘safe’ dishes. This related to a problem brought up in both articles- that parents with children newly diagnosed with food allergies may unnecessarily restrict many foods because they are unsure what will cause an allergic reaction. This could cause an artificially limited availability or nutrients or calories. And, to tie this back to an earlier point, as children grow up and learn what foods to avoid, their teachers and friends’ parents may give them more freedom to choose a range of foods that are acceptable, instead of limiting them to one or two ‘safe’ foods.

A good analogy to this situation might be someone who has just decided to adopt a vegetarian diet. Younger people may at first be so focused on avoiding meat that they don’t pay attention to the nutrition content of their food. For example, cheese pizza and grilled cheese are meat-free, but don’t provide all protein, vitamins, and minerals needed for a complete diet. Also, young people who still live at home may have less control over the types of food bought or prepared. As one former vegetarian in the group told us, to balance all the portions of your diet takes a lot of effort and planning. She said she had never been more aware of what she was eating, but that it took time to figure out how to achieve a good balance of nutrients.

Stay tuned for updates and about brains and hormones!


Christie L, Hine RJ, Parker JG, & Burks W (2002). Food allergies in children affect nutrient intake and growth. Journal of the American Dietetic Association, 102 (11), 1648-51 PMID: 12449289

Fernandez-Rivas, M, & Miles, S (2007). Chapter 1. Food allergies: Clinical and Psychosocial Perspectives Plant Food Allergens DOI: 10.1002/9780470995174.ch1

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