Does Diet Soda Truly Lead to Cancer?

By Neil Smith

Published on October 30, 2008

It's one of the oldest and most hotly debated questions facing nutritionists - does diet soda cause cancer? Diet soda has come under fire amidst criticism that aspartame, the sweetening agent in diet soda, leads to cancer in those who consume it. But is this true, or just the nutritional equivalent of an old wives' tale? The arguments on both sides of the debate are compelling for different reasons, and we won't try to definitively settle the issue here. Instead, we'll outline what those arguments are and let you decide for yourself.

The Arguments That Diet Soda Does Cause Cancer

There have been many arguments that the artificial sweeteners in diet soda do, in fact, cause cancer. Again, the alleged cancer-causing ingredient is aspartame, better known as NutraSweet®. A commenter on an article titled Is Diet Coke Bad for You? lays out the "aspartame causes cancer" argument as follows:

"Aspartame/Nutrasweet®'s breakdown products attack the bodies tissues and create Formaldehyde which builds up in the tissues forever. Remember the smelly, eye watering fumes from the frogs you dissected in school? They were preserved with Formaldehyde! Formaldehyde is thought to cause cancer. Aspartame/Nutrasweet® also breaks down to diketopiperazine [DKP] which is proven to cause Brain Tumors! Brain Tumors used to be rare. Several of the rats in the original study formed brain tumors during their Aspartame/Nutrasweet® exposure. The researchers surgically removed the tumors and returned the rats to the study and discounted the tumors."

Another web article titled Aspartame Study Reveals What Mainstream Media Don't Tell You: The Deadly Truth about Sweeteners condemns aspartame on similar grounds:

"A new study of the Cesare Maltoni Cancer Research Center of the European Ramazzini Foundation has not only confirmed but further reinforced the results of an earlier study by the same research institute that found the artificial sweetener Aspartame to cause cancers and leukemia in rats.

The earlier study was condescendingly dismissed by industry and by the European Food Safety Agency as well as US FDA, but evidence of the damage done by the sweetener does not seem to be going away. If anything, the scientific findings overwhelmingly suggest that there are real problems that can no longer be brushed under the carpet.

The new Italian study finds that Aspartame, in doses similar to those found in a modern diet, when given over the whole life span of rats, causes an increased incidence of cancers."

Similar websites and articles can be found all over the Internet. The basic position being argued in them is believed by many ordinary citizens as well, from casual soda drinkers to doctors and nutritionists. However, there are a growing number of people who believe that diet soda may not be as harmful or cancer-causing as some claim.

The Arguments That Diet Soda Does Not Cause Cancer

Until recently, studies investigating the cancer-causing properties of aspartame were conducted on rats. While this is commonplace in research science, the conclusions of experiments on rats are always subject to revision based on comparable tests of human beings. That's the position being argued by a new federal study which concludes, interestingly, that people who drink lots of diet soda are not more likely to get cancer.

According to MSNBC, the study was praised by consumer groups and carried out by reputable researchers independent of any funding or ties to industry groups. In the study, 340,045 men and 226,945 women were surveyed from 1995-1996, of which 2,106 developed blood-related cancers and 376 developed brain tumors. These numbers were not inordinately high given how many people were surveyed, and no link between aspartame and the cancers was found by the survey.

What Should You Do?

So, taking all this into account, should you be drinking diet soda? That's a question only you can answer, based on your own appraisal of the arguments above and your own thought processes. The old saying "everything is okay in moderation" is probably the best advice to follow. Downing five or six sodas a day probably isn't smart whether it has aspartame in it or not. On the other hand, the occasional can of diet soda isn't likely to harm a person who exercises, eats a healthy diet, and leads a generally healthy lifestyle.

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