From VOA Learning English, this is the Health Report.
A new study has found evidence of aggressive behavior in children who drink four or more servings of soft drinks every day. Information for the study came from the mothers of 3,000 5-year-olds.
Researchers asked the women to keep a record of how many servings of soft drinks their children drank over a two-month period. The women were also asked to complete a checklist of their children's behavior.
The researchers found that 43 percent of the boys and girls drank at least one daily serving of soda, 4 percent of the youngsters had four or more sodas to drink every day.
Shakira Suglia is with Columbia University's Mailman School of Public Health in New York City. She worked on the study with researchers from the University of Vermont and Harvard University School of Public Health. She says they found that children who drank the most soda were more than two times as likely as those who drank no soda to show signs of aggression.
"For the children who consumed four or more soft drinks per day, we see an association between aggressive behaviors, attention problems and withdrawn behaviors."
The aggressive behaviors included destroying possessions belonging to others, taking part in fights and physically attacking people.
Shakira Suglia says the researchers identified the link after they considered socio-demographic factors like the child's age and sex. They also considered other possible influence, such as whether the boys and girls were eating sweets or giving fruit drinks on a normal day. In addition, the researchers examined parenting styles and other social conditions that might be taking place in the home.
Doctor Suglia says it's not clear why young children who drink a lot of soda have behavior problems.
"We can't prove that this is a direct cause and effect relationship, having said that, there are a lot of ingredients in soda, a lot of ingredients that have not been examined in relation to behavior."
A substance often found in soft drinks is caffeine, which helps to make people feel energized.
Doctor Suglia suggests that caffeine could be causing the 5-year-olds to be more aggressive. The research is part of a large study called the Fragile Families and Child Wellbeing Study, it follows 5,000 poor mothers and their children in 20 American cities.
Earlier studies of young adults have found the highest sugar levels in those who carry weapons and show signs of negative social behaviors.
And that's the Health Report from VOA Learning English.