One 2005 study indicated soda and sweetened drinks are the main source of calories in the American diet and that of those who drink more sweetened drinks, obesity rates were higher.[19] Most nutritionists advise that Coca-Cola and other soft drinks can be harmful if consumed excessively, particularly to young children whose soft drink consumption competes with, rather than complements, a balanced diet. Studies have shown that regular soft drink users have a lower intake of calcium, magnesium, vitamin C, riboflavin, and vitamin A.[20]