Because of their size and relatively high fluid intakes, children consume more beverages per pound of body weight than adults. For this reason, it is important to be aware of what they eat and drink. Not only should you be aware of possible safety issues, but also if drinks they consume provide nutrients they need to grow.
Much of the concern about dangers of diet drinks has come from articles on the Internet. To determine if these concerns are valid, it is important to consider the results of well-controlled studies conducted by reputable scientists. Many studies have shown that popular sweeteners are safe. Aspartame is a well-studied sweetener and is marketed under brand names such as Equal® and NutraSweet®. Despite what you might read on the internet, laboratory testing, animal studies, population studies and human clinical trials have found no credible link between consumption of aspartame at levels found in the human diet and conditions related to the nervous system and behavior, nor any other symptoms or illness, including cancer. Based on these and other studies, the Food and Drug Administration has determined that the sweeteners in beverages currently sold are safe for adults and children.
The real problem with diet drinks for children is that they provide no nutrition and are not good for teeth. Children need calcium and vitamin D found in milk for healthy bones and teeth. They need vitamins found in 100% fruit juices for good health. Even when they do drink enough milk and get their vitamins from fruit and juices, soft drinks are still not recommended. According to the American Dental Association, even sugar-free soft drinks may increase the chance of tooth decay because they are acidic and cause teeth to erode. So, always use soft drinks (regular and diet) sparingly.