Many people don't know exactly how much and what kinds of sugar are in their beverages, according to a new study. But people who are concerned about sugar tend to be better at avoiding it, researchers found, Fox News reports.

The confusion is understandable. Regular soft drinks and many fruit juice beverages and sports drinks are sweetened with added sugars such as sucrose or high fructose corn syrup, while 100-percent fruit juices only contain natural sugars. Milk has natural sugar too, even though it isn't sweet. Diet soft drinks may taste sweet, but they don't contain any sugar.

Gail Rampersaud studies nutrition and education at the University of Florida in Gainesville's Institute of Food and Agricultural Sciences. She said the new study was originally designed to see how consumers interpret drink labels.

Rampersaud and her colleagues surveyed 3,361 U.S. adults through an online questionnaire. They asked participants about their diets including non-alcoholic beverage consumption and quizzed them on types and amounts of sugar found in various beverages. They also asked about use of food labels and general nutrition and health knowledge.

People in the study reported drinking the most water - more than four cups every day, on average. They drank about two and a half cups per day of "other beverages" such as coffee and tea.

Further down the list were sugar-sweetened beverages, milk, diet drinks and 100-percent fruit juice and blends.

Most people - 96 percent - identified regular soft drinks as sugary. But only three quarters of them knew soft drinks contain added sugar, according to findings published in Nutrition Research.

Another 40 percent called 100-percent fruit juices sugary. Those juices only contain natural sugars and not added sugars.

More than one third of participants incorrectly thought milk contains no sugar. Less than one quarter correctly indicated that milk has natural sugar called lactose.

Not all sweet beverages should be avoided, Rampersaud said. Fruit juices, for instance, contain vitamins.