Final answer:
The most common source of added sugar in the American diet is sweetened soft drinks, which have significant health implications when consumed excessively.
Step-by-step explanation:
The most common source of added sugar in the American diet is sweetened soft drinks. These drinks, which include energy drinks, flavored waters, fruit drinks, sports drinks, and sweetened coffee and tea, are often high in added sugars and low in other nutrients. While naturally occurring sugars are found in nutritious foods like fruits and some dairy products, added sugars are also introduced to enhance flavor, texture, or preservation. However, the excessive consumption of sugary soft drinks and other beverages with added sugars has been linked to an increase in health issues such as dental caries, obesity, Type 2 diabetes, and cardiovascular disease, emphasizing the need for mindful consumption.