(NaturalNews) Asthma, cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD) are serious and even life-threatening conditions. However, these health problems share something with a usually minor infection -- the common cold. The connection? Rhinovirus (RV), a single-stranded RNA virus from thefamily, causes the majority of colds and RV is also known to trigger exacerbations of CF, asthma and COPD.But now University of Michigan at Ann Arbor scientists have found that a natural substance, the flavonoid quercetin, puts the brakes on the ability of RV to replicate. It also fights inflammation. According to their research just presented at the American Thoracic Society (ATS) 2010 International Conference held in New Orleans,That's great news not just for people looking for a possible cure for the common cold but especially for those suffering from conditions like COPD and CF that rob them of the ability to breathe. For example, COPD (which includes emphysema and chronic obstructive bronchitis) causes coughing, wheezing, shortness of breath, chest tightness, and other symptoms. According the National Heart, Lung and Blood Institute, COPD is a major cause of disability and the fourth leading cause of death in the United States. CF is an inherited chronic disease that affects the lungs and digestive system of about 30,000 children and adults in the US. It causes the body to produce a thick, sticky mucus that clogs the lungs and can lead to life-threatening lung infections.For their study, the University of Michigan research team decided to test quercetin on cells infected with RV. A phytochemical found in the skins of apples, red onions and other foods, quercetin is known to be a powerful antioxidant with antihistamine and anti-inflammatory properties. So the scientists hypothesized that quercetin might reduce the ability of RV to spark an inflammatory response. That's important because inflammation causes oxidative stress which can disrupt the function of epithelial cells (cells that line cavities and structures) inside airways, negatively impacting the ability to breathe.Their lab experiments with RV infected cells showed that the researchers were right. The results suggested that quercetin actually inhibited the ability of the virus to replicate. The flavonoid also appeared to reduce the RV-triggered immune system response that can cause cytokines (proteins that are secreted by specific cells of the immune system) to induce excess inflammation.the researchers stated.As NaturalNews has previously reported, evidence has been accumulating over the past several years that shows phytonutrients such as quercetin are powerful protectors of health ( https://www.naturalnews.com/027409_foods_meal... ). For example, the flavonoid may protect brain cells and help prevent dementia ( https://www.naturalnews.com/002509.html ). A study by University of South Carolina research found quercetin can boost exercise endurance, too ( https://www.naturalnews.com/026591_quercetin_... ).