On Friday, Pepsi announced that it would remove the artificial sweetener aspartame from all diet sodas sold in the US and replace it with sucralose.

The reason? Flagging sales. According to the Wall Street Journal, consumer surveys had showed "the presence of aspartame to be the number one reason that Americans are scaling back on diet colas."

Yet this trend appears to be driven by a widespread — and largely unfounded — fear the public has about the dangers of aspartame. This move might be good for Pepsi's business. But it probably won't help dispel any of the myths about artificial sweeteners as carcinogens that have persisted for decades.

Aspartame does not appear to cause cancer

Aspartame has been studied for more than 30 years, and there's no good evidence suggesting it causes cancer in humans. The European Food Safety Authority recently completed one of the most thorough risk assessments of aspartame ever done, looking at all the available research evidence.

Its conclusion? "Following a thorough review of evidence provided both by animal and human studies, experts have ruled out a potential risk of aspartame causing damage to genes and inducing cancer." The researchers found that aspartame does not harm the brain or nervous system, or affect behavior or cognitive function in children or adults.

Similarly, the National Cancer Institute found that artificial sweeteners, including aspartame, don't appear to cause cancer. Whatever fears people might have of the chemicals, the NCI noted, likely come from early rat studies that uncovered links between artificial sweeteners and bladder cancer. Yet subsequent studies determined that these results apply only to rats, and large-scale human studies have never found good evidence of an association.

Aaron Carroll, an evidence-based pediatrician and health commentator, had a nice summary of some of the science and hype behind aspartame over at CNN.

Aspartame was first approved for use in 1981, but it wasn't until 15 years later that health concerns showed up. In 1996, a research paper showed that there had been a recent increase in brain tumors and hypothesized that this might be due to aspartame. Mind you, it didn't prove that was so. But the potential link was all the media needed to go crazy. TV shows, magazine articles, and newspapers all questioned whether the artificial sweetener was safe. Further work using data from the National Cancer Institute showed that the increase in brain tumors really began in 1973, long before aspartame was introduced. Moreover, the increases in incidence of cancer were seen primarily in the elderly, which as a group, was not the major consumer of diet soda. And there's more. A randomized, double-blind, placebo-controlled trial showed that aspartame didn't affect memory, behavior or mood. And a study published in 2006 followed more than 285,000 men and almost 190,000 women and couldn't detect any relationship between aspartame and brain or blood cancer.

There have been studies suggesting that artificial sweeteners may disrupt the microflora in the gut, and that suggests drinking diet sodas is correlated with weight gain. (Update: Read more about that here.) But that research certainly doesn't single out aspartame as being any better or worse than any other sweetener.

Susan Swithers, a professor at Purdue University who has studied artificial sweeteners, told Vox, "My take on the human data is that you can find a paper that said anything you want it say."

Pepsi is responding to consumer demand — not science

In light of the evidence, Swithers suggested people take a common-sense approach to all sweeteners — artificial and "natural" — and consume them in moderation.

"Our food supply has become hyper-sweetened," she said. "We saw a huge increase in use of caloric sweeteners emerge 30 years ago in response to fact that we thought fat was going to kill us. Now, manufacturers have tried to replace that with artificial sweeteners to deal with the way our palates have been adjusted.



"The advice I give: we need to cut back on all the sweeteners we’re using."

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