Coca-Cola Artificial Sweetener Ad: New Coke Ads Defend Safety of Aspartame We're going to turn to the big, new campaign from coca-cola. The debate over artificial sweeteners head-on, with an ad that no-cal sweeteners are a healthy alternative to sugar. Diet coke is declining in sales. So, coke's fighting back. Reporter: Exactly. The new ads look more like public service announcements than the flashy marketing campaigns that we're accustomed to. But make no mistake. These are part of a concerted effort by coca-cola, to bring consumers back to diet drinks. It's not your typical diet drink ad. No special cans of soda glist glistening in the sun. The world's number one beverage company, coca-cola, this morning, rolling out full-page ads, touting the idea that diet drinks can help people manage their weight. The ads site scientific studies. 200 over the last 40 years. The company says supporting the safety of aspartame, the artificial sweetener used in the diet coke. Coke is getting in front of this. They're getting proactive. They're defending aspartame, which is the biggest diet sweetener used in the u.S. And it's used in their biggest diet products. Reporter: But coca-cola isn't just playing defense. Today, we'd like people to come together on something that concerns all of us, obesity. Reporter: Earlier this year, the company rolling out a two-minute commercial in the wake of a national debate about serving sizes, childhood obesity and public health. If you eat and drink more calories than you burn off, you'll gain weight. Reporter: But now, it may be the health of coke and its competition on the line. Sales of soda have been dropping most of the last decade, with diet drinks falling even faster. Just last year, diet coke, down 3%. Diet pepsi, down twice that. For decades, consumers in the u.S. Basically had one choice. And that was carbonated soft drinks. But teas have come on strongly. Bottled water. Sports drinks have gotten popular. Reporter: Coke, hoping to remind consumers this morning, even with all those alternatives, nothing beats the real thing. And coke isn't just defending aspartame. Along with pepsi, both companies are working to come up with a drink that uses natural, low-calorie sweeteners. They're trying to defend themselves here against a totally different market. There are more options. People are going organic. They're going all-natural. And coca-cola and pepsi are playing catchup. We'll see if it works. We turn to the 15-year-old boy who was denied a heart