A key ingredient in the aroma from citrus fruits such as oranges and lemons appears to protect rats from the symptoms of asthma, new research shows. Study author Dr. Ehud Keinan explained that the citrus ingredient is called limonene, and it likely protects against asthma by “burning” inhaled ozone, which can increase inflammation in the lungs. Other scents - such as those emitted from pine trees, geraniums and roses - contain similar ingredients to limonene, Keinan said, which may help explain why asthma is much more common in urban areas that lack vegetation. “In rural populations, people are very much exposed to these compounds,” he said. The researcher, who is based at the Technion-Israel Institute of Technology in Israel, told Reuters Health that squeezing an orange peel releases liquid that contains a high concentration of limonene. He said he has heard stories of people who say they experienced relief from asthma and other lung diseases after spending time around limonene.
