Why Pepsi's decision to ditch aspartame isn't good for soda - or science

PepsiCo, the maker of Pepsi, Mountain Dew, and many other popular soft drinks, is changing the formula of one of its offerings for the first time in decades.

The company said Friday it will stop sweetening Diet Pepsi, Caffeine Free Diet Pepsi and Wild Cherry Diet Pepsi with aspartame, a controversial artificial sweetener. Beginning in August, the drinks will instead come sweetened with Sucralose, better known as Splenda, and acesulfame potassium, which is often called Ace K and is currently used in Coke Zero.

READ: Pepsi dropping sweetener aspartame from diet cola drinks

The move is a momentous one. Amid one of the most difficult stretches the diet soda business has seen, Pepsi is the first behemoth to acknowledge that big changes are needed to salvage sales. Coca Cola hasn't so much as hinted at the potential for a sweetener switch, despite shrinking demand for Diet Coke, the best-selling low-calorie soft drink in the world.

From a business perspective, the change is fairly intuitive — removing aspartame is the number one request from customers, according to Pepsi. Fears of aspartame first sprouted in the mid 1990s, roughly a decade and a half after the ingredient was approved by the FDA, and have only accelerated since.

But appeasing the public isn't the same as making a sound scientific choice.

There is actually no definitive evidence that consuming sugar substitutes such as aspartame causes any harm.

A 2006 study found no connection with aspartame consumption and the incidence of cancer. The National Cancer Association agrees: the group states rather clearly on its Web site that no such association has been proven. So does the NIH. And the European Food Safety Authority, in one of the most comprehensive considerations of aspartame's effects on the body, concluded that eating aspartame is "safe for human consumption."

Even Pepsi, as part of its announcement, acknowledged that there is no scientific basis for its formula rework.

"Decades of studies have shown that aspartame is safe, but the reality is that consumer demand in the U.S. has been evolving," Seth Kaufman, senior vice president of Pepsi, told Bloomberg. "The U.S. diet cola consumer has been asking and asking and asking for an aspartame-free great diet cola."

Pepsi (and other diet soda makers, for that matter) is in no position to ignore its customers. Sales of Diet Pepsi have plummeted by roughly 35 percent over the past 10 years.

Americans on the whole seem to be falling out of love with diet- and low-calorie soda in general — not aspartame in particular. Sales of low-calorie soft drinks have tumbled by almost 20 percent over the past five years in the United States, according to data from market research firm Euromonitor. Diet Coke and Diet Pepsi have been the biggest losers, but even Coca-Cola Zero has seen sales slow to a halt in recent year. Last year, the brand contracted for the first time, according to Eurmonitor.

But the problem with appeasing customers at the expense of science is that it sets a poor precedent. And in this case it's also unlikely to reverse Diet Pepsi's waning appeal.

What Pepsi's move will likely accomplish, more than anything else, is give credence to unfounded fears that aspartame is somehow more harmful or artificial than a lot of other sweeteners being used in products on supermarket shelves. That myth doesn't appear to be anywhere close to dying.