Theories of Allergens in Down

Many people turn to down alternatives because of the fear that down causes asthma and allergies. There are two major theories for why down causes these conditions in some people. In one, the cause is blamed on tiny proteins in the down material itself. These proteins, when inhaled or ingested,

behave as "antigens" which are signs of germ invaders. Sensing them (mistakenly) to be foreign invaders, the body rallies an immune reaction causing sneezing, coughing, running eyes and noses. In the other, proteins not from the down but rather from tiny dust mites are blamed. Dust mites are microscopic creatures that live amongst humans, feeding off flakes of skin and other tiny organic material. These dust mites also secrete a protein that is thought to be the cause of reactions.

Medical Research

But is this line of belief really borne out by medical research? Unfortunately, the research is spotty because of the tremendous difficulty in studying something this. The difficulty lies in the fact that there are many kinds of down, as well as many kinds of household environments that have different propensities to be clean, as well as huge variation in the physiology of people and the behavior of their asthma or allergies toward the putative allergens.

Studies Show Mixed Results

However, it does seem that there are a few controlled studies that shed light in this direction. There have been two major conclusions in these studies. In one conclusion, synthetic bedding is shown accumulate and eventually contain even more of the suspected dust mite allergen that causes asthma and allergies. In the other conclusion, efforts to reduce dust mites using impregnable encasement (read: really sealed pillow cases!) showed modest to no effect on severity of asthma.

A Pillow Case

In the first study, researchers gave participants pairs of pillows: one filled with feathers, and the other with synthetic fill. The participants took the pillows home and put them next to each other. For three months they used the pillows as directed. At the end of three months, samples of fibers and dust were collected from the pillows. The researchers then looked for amounts of dust mite protein. This protein is called "Der p 1", for obscure reasons clearly. The researchers found that the feather pillows actually had 3 times less Der p 1 than the synthetics. THe point was that the synthetics seemed to accumulate more of the dust mite allergen! House dust mite allergen (Der p 1) accumulation on new synthetic and feather pillows.

A Study in Industrial Cleaning

In the second study, researchers (a different set this time) did a two part project. In the first project, they compared processed versus unprocessed feathers from bedding companies for the dust mite protein Der p 1. Processed feathers are washed with industrial methods. They showed that the processing removes virtually all traces of dust mite proteins, although it was true that dust mite proteins were found on the unprocessed, raw feathers. In the second part of the project, the researchers showed that there was very little accumulation of dust mite protein after 90 days. However, this study is inconsistent with the first which did show accumulation of der p 1.

Sources Clin Exp Allergy. 1999 Feb;29(2):182-5. Rains N, Siebers R, Crane J, Fitzharris P.
Ann Allergy Asthma Immunol. 2002 Jun;88(6):576-7.