Sucking Lemons: Bitter Foods May Reduce Asthma Attack Risk

If asthma attacks are playing havoc with your wellbeing, try eating more bitter foods. This is according to research from scientists at the University of Massachusetts Medical School, who have found that the substances in some foods, which give them their bitter flavours, can also act to reverse the contraction of airway cells. Known as bronchodilation, your body needs this reversal to treat airway obstructive diseases such as asthma and chronic obstructive pulmonary disease (COPD), and so these new findings could pave the way for new treatments for such diseases.

The taste receptor cells bundled in your taste buds are responsible for mediating your sense of taste. Once thought to only exist in the tongue, scientists now know that these receptor cells are actually expressed in various cell types throughout your body, including the airway. It is here that bitter taste receptors exist in your airway’s smooth muscle cells, and they work by relaxing the cells when they have been exposed to bitter-tasting substances. If you have an asthma attack, this means that your smooth muscle cells contract excessively, which causes your airways to narrow, leading to breathing difficulties.

However, the new discovery that bitter substances can relax these smooth muscle cells indicates that it may be possible for them to halt asthma attacks. Further, this finding, published in the open access journal PLOS Biology, could lead to even better treatments, as the researchers noted that the relaxation effects of bitter tastes on these cells is quite fast, and  experiments in mice suggest that the effects are even stronger than anything currently available for treating asthmatic wellness.

Until now it was not known exactly which mechanism allowed bitter taste receptor activation to relax muscle cells, and so Dr. Ronghua ZhuGe and his colleagues looked at the effect of bitter substances on the contraction of airways and in single isolated cells, in order to unravel these mechanisms. An asthma attack allows calcium to flow into the cell from open membrane channels, and this is what causes cells to contract specifically. Therefore, Dr ZhuGe and colleagues determined that bitter substances work by shutting down these calcium channels.

Kevin Fogarty, director of the Biomedical Imaging Group in the Programme in Molecular Medicine at UMMS, and a co-author of the study, explained, ‘Once the channels are closed, the calcium level returns to normal and the cell relaxes. This ends the asthma attack.’ Dr ZhuGe added, ‘With this new understanding of how bitter substances are able to relax airways, we can focus our attention on studying these receptors and on finding even more potent bitter compounds with the potential to be used therapeutically to end asthma attacks.’