Drinking lots of soda may increase the risk of violent behavior in teens, a new study suggests. Teens in the study who drank more than five cans of non-diet soda per day were significantly more likely to report behaving violently towards others, and more likely to report having carried a gun or knife in the past year, the researchers said. The results held even after the researchers took into account other factors that have been linked to violent behavior, including age, alcohol and tobacco use, and the frequency of family dinners. It's possible that the caffeine and sugar in the soda may directly affect teens' behavior, the researchers said. However, it's also possible that people who are violent have a penchant for soda. Additional research is needed to find the exact reason for the link. It's possible that an underlying condition, such as low blood sugar, may result in both high soda consumption and aggressive behavior, the researchers said. But even if soda consumption doesn't cause violent behavior, it may be a useful marker for aggressive, the researchers say.