Coca-Cola defends aspartame's safety in diet soda

Coca-Cola is out with a new ad defending its use of artificial sweeteners in its soda.

One ad will run next week in the Chicago Tribune.

Coca-Cola hopes to reassure diet soda drinkers that NutraSweet, also known as aspartame, is safe.

Critics blame sugary drinks for contributing to the country's obesity rates.

Coke hopes the ads will help declining sales of diet soda.