Increasing obesity in U.S. children and adolescents is now associated with a rise in allergic disease. Results are now in on the analysis of the National Health and Nutrition Examination Survey for 2005-2006 (reference below.) The data suggest that obesity and allergy may be linked to inflammation.
Obesity and Allergy Increase in Young
The increase in childhood obesity in the US population has been dramatic over the last two decades, from about 5% in 1980 to 20% in 2005. During that same time, allergic response to skin tests has almost doubled in children from 22% to 42%. The association between obesity and allergy has been tentative and a large study was designed to determine if inflammation was the link between obesity and allergy.
Allergy Measured by IgE antibodies
Allergy results from the production of a class of antibodies, immunoglobulin type E (IgE), in response to a non-self protein or carbohydrates, i.e. allergens, such as the surface protein of ragweed pollen or dust mite feces. The IgE molecules are released from lymphocytes and circulate in the bloodstream until they are bound to special receptors on the surface of mast cells. The mast cells are located on mucous membranes where they typically come in contact with invading pathogens, or in the case of allergies, with airborne particles or food. Allergens binding to IgE/receptors complexes triggers mast cells to release histamine and produce runny eyes and sniffles of allergies.
Measuring the IgE levels specific to particular allergens can be done indirectly by skin tests or by direct analysis of IgE in blood serum. Thus, high serum IgE is an indication of an intense allergic response to a potential allergen.
Inflammation Measured by C-reactive Protein
Inflammation can be observed as swelling, reddening, and pain. Severe local infections can also cause the release of some acute response proteins, such as C-reactive protein, from the liver. So, elevated serum C-reactivity can be used as a measure of chronic inflammation.
Allergy Increases with Obesity and Inflammation
The medical literature suggests that obesity (BMI), allergy (IgE) and inflammation (C-reactive protein) are related, and a recent study attempted to shed light on those relationships in children. Data from the National Health and Nutrition Examination Survey for 2005-2006, were analyzed and the key findings were:
- Allergies are more prevalent among obese and overweight children.
- Obesity is associated with chronic inflammation.
- Allergy is also associated with inflammation.
Does Inflammation Cause Obesity and Allergy?
These results suggest some causal relationships that are being actively examined in clinical studies. Inflammation appears to be the foundation for the development of allergy, as well as many degenerative diseases. Fat cells produce inflammatory hormones. A major question is whether inflammation precedes obesity or obesity leads to inflammation and allergy. In either case, it seems obvious that prevention of childhood obesity, inflammation and allergy will be based on an anti-inflammatory diet and lifestyle/exercise.