Fungal products in synthetic bedding may affect asthma

Synthetic bedding contains higher levels of fungal cell products than feather bedding, which may have a negative effect on asthmatics with respiratory problems according to a recent study by researchers at the University of Otago, Wellington.

The study, which has recently been published in the Journal of Asthma, confirms that synthetic bedding has much higher levels of fungi related beta glucan than feather bedding. This is the first study of its type in New Zealand and backs up similar evidence regarding synthetic bedding and fungi done overseas.

Beta glucans are non-allergenic components from the cell walls of fungi that can account for up to 60% of the weight of the cell. They are also present in large quantities in house dust.

This study follows earlier international evidence that shows house dust mites, known to affect asthmatics, are also more prevalent in synthetic compared to feather bedding.

"This study adds further strong evidence in a New Zealand setting that feather bedding is better than synthetics if you have asthma," says lead investigator Rob Siebers. "This is because beta glucan is pro-inflammatory and associated with lung function changes, including peak flow variability in children."

"There have already been a number of international studies that show synthetic bedding is associated with more asthma symptoms compared to feather bedding."

Rob Siebers’ research looked at 178 samples obtained from 35 floors, 35 mattresses, 35 duvets and 73 pillows. He says total beta glucan levels of synthetic pillows were two to three times higher than from feather pillows, although this just failed to reach statistical significance.

With duvets the beta glucan levels were much higher; seven to eightfold in synthetic duvets compared to feather. Allowing cats and dogs in the bedroom resulted in even higher levels in synthetic duvets. This effect was not seen in feather duvets. Similar results for synthetic duvets have been found in previous University of Otago studies for house dust mite infestation.

Mattresses older than five years also have about three times the amount of beta glucan compared to mattresses less than five years old.

Rob Siebers says that studies in Europe have shown that frequency of vacuuming has a dose-response relationship with beta glucan levels, and that older carpets are associated with higher levels. However this study did not show any significant relationship between lower beta glucan levels and vacuuming, airing the bedding and the age of a carpet.

The researchers say these results could be of importance to asthma patients as bedding items are in close proximity to airways, but further research is needed to determine what levels of beta glucan are associated with asthma and respiratory symptoms.

This study was funded by the University of Otago.

(Source: University of Otago: Journal of Asthma: August 2009)