(NaturalNews) Physical exercise can decrease the risk of developing lung cancer by up to 45 percent in former smokers, while proper diet can decrease it even further, according to research presented at the American Association for Cancer Research's Sixth Annual International Conference on Frontiers in Cancer Prevention Research in Philadelphia.Researchers studied 3,800 non-Hispanic white women and men using a pairing system that sorts people according to smoking status. Therefore, smokers with lung cancer would only be compared to smokers without lung cancer, with the same pairing taking place for former smokers and those who have never smoked. Researchers compared those who had not developed lung cancer based on a variety of factors including exposure to secondhand smoke, dust exposure, family cancer history, personal respiratory history, diet and exercise.Exercise was determined based on whether the participants gardened or not. According to researcher Michele Forman, "gardening is one of the few activities that people with lung cancer report doing."Former smokers who gardened reduced their lung cancer risk by 45 percent, while current smokers who gardened reduced their risk by 33 percent. Former smokers who gardened and who also ate four or more salads per week reduced their risk by 67 percent. Among current smokers, the risk reduction from both gardening and high salad intake was 71 percent.According to Forman, salad consumption "is a marker for consumption of many vegetables.""We are trying to understand what components of lifestyle can reduce lung cancer risk in people who have quit smoking, which has been a neglected field of study," Forman said. She noted that further research is needed to make sure that exercise from gardening is actually the cause of the correlation, rather than gardening being associated with some other risk-reducing factor, such as low alcohol consumption.