Source: Coca-Cola Enterprises.

Coca-Cola Enterprises (NYSE:CCE) admits aspartame is wreaking havoc with diet soda sales here in the U.S., but having sold off its North American operations several years ago, it's counting on the clean bill of health the European Food Safety Authority gave the artificial sweetener to keep its international consumers from similarly fleeing its beverages. 

"I wouldn't say we're immune to [aspartame issues in Europe], but I think we're in a better place," said the Coke bottler's chairman and CEO John Franklin Brock. "We're guardedly optimistic about the future."

Sales at Coca-Cola Enterprises fell 2.5% in the first quarter when accounting for currency fluctuations, while volumes dropped 1.5%, driven lower by Diet Coke volumes plunging 11% from the year-ago period. While that would also seem like an indictment of aspartame since it's used across its entire diet soda platform, volumes of Coca-Cola Zero, which also contains the artificial sweetener, actually rose more than 20% in the quarter, giving the executive his cause for hope.

Over the past five years, Coke Zero has enjoyed a 15% compounded annual growth rate even as Diet Coke tumbled. But consumer concerns over artificial sweeteners haven't translated the same overseas, and that's allowed the bottler to avoid a lot of the weakness Coca-Cola (NYSE:KO) witnessed here and is why management intends to continue making Zero a focus of its growth portfolio here and abroad.

Coke bought Coca-Cola Enterprises' North American business in 2010 for $12.3 billion, giving it direct control of about 90% of volume and apparently also 100% of the risk. Volumes of Coke's diet beverage have fallen for eight consecutive years, with the decline increasing over the past three. Last year, volume fell 6.8% according to Beverage Digest, while sales were off 6.9%. It's sold nearly 20% fewer cases of Diet Coke since 2007, while regular Coke was down by half that rate.

Coke tried to stem the tide by accelerating the use of the more natural sweetener stevia, first tested in Argentina and now being made more broadly available, but it hasn't helped stanch the bleeding of Sprite. Sales accelerated lower to 9.4% on a 9.2% drop in volume compared to its previous 6.4% decline on volumes that fell 7.3% before the switch to stevia was made in March 2013.

Coca-Cola Enterprises is still experiencing extreme sluggishness in the U.K. as volumes dropped 9% there compared to 3.5% growth on the Continent, and with the regulatory authorities giving aspartame their stamp of approval, the company is hoping that will be enough to keep the malaise from spreading across the Channel.

Shares of Coca-Cola Enterprises have risen 30% over the past year, and it trades at just 14 times estimated earnings, which management says should rise 10% from last year, though on a constant currency basis, earnings will be just 5% higher. Its dividend of $1 per share yields 2.2% currently. If it can avoid aspartame causing sales to go flat or even get the rest of its portfolio growing slightly like Coca-Cola Zero, the bottler may see its stock bubble up even higher.