Mythbusters: Does This Cause Cancer?

Victoria Stern, MA


March 04, 2015

In This Article

Can Artificial Sweeteners Cause Cancer?"

What the science says: Fears about the potential carcinogenic effects of artificial sweeteners continue to persist, despite a compelling body of evidence showing that no such link exists.

Concerns emerged more than 40 years ago, after studies indicated that the artificial sweetener cyclamate might be linked to cancer, prompting the FDA to ban its use. These findings also compelled researchers to investigate the potential carcinogenesis of another popular artificial sweetener, saccharin.

In 1977, a study published in Science found an association between saccharin and bladder cancer in rats,[30] spurring the FDA to ban saccharin as well. The FDA lifted the ban, however, after thousands of people wrote letters of protest. But until concerns about saccharin could be resolved, the FDA maintained that all foods containing the sweetener must have a warning label stating that "Use of this product may be hazardous to your health. This product contains saccharin, which has been determined to cause cancer in laboratory animals."

Subsequent studies in rats continued to show an elevated risk for bladder cancer after the animals consumed very high doses of the sugar substitute,[31,32] but results in humans showed no clear evidence of an association.[33] In fact, experts soon found that the mechanism that led to cancers in rats was irrelevant in humans.[34] Specifically, when consumed in high doses, researchers discovered that saccharin changes the composition of rat urine, creating a precipitate. The precipitate can damage the cells lining the bladder, which in turn can promote tumor growth when the cells regenerate. This mechanism, however, is unique to rats.

In a monograph published in the late 1990s, a group of experts at the IARC analyzed the results of 17 case/control studies exploring the link between saccharin and bladder cancer in humans. The IARC concluded that "there is inadequate evidence [emphasis original] in humans for the carcinogenicity of saccharin salts used as sweeteners" and downgraded its original categorization of group 2B (possibly carcinogenic to humans) to group 3 (not classifiable as carcinogenic to humans).

In 2000, the National Toxicology Program of the National Institutes of Health removed saccharin from the list of potential carcinogens. In addition, further studies in humans have continued to find no evidence of a link between saccharin consumption and cancer risk.[35]

The data on the carcinogenic effects of other artificial sweeteners, such as aspartame, have formed the basis for similar conclusions. In 2006, researchers at the National Cancer Institute prospectively investigated the link between aspartame consumption and the risk for malignant brain cancer in 285,079 men and 188,905 women who were part of the NIH-AARP Diet and Health Study of retirees.[36]

Over 5 years, the researchers identified 1888 hematopoietic cancers and 315 malignant gliomas and found that higher levels of aspartame were not associated with an elevated risk for either cancer or their subtypes in both men and women. The authors concluded that their findings "do not support the hypothesis that aspartame increases hematopoietic or brain cancer risk."

In the past 10 years, newer-generation artificial sweeteners, including acesulfame potassium (ACK, Sweet One®, Sunett®), sucralose (Splenda®), and neotame (Newtame®), have become widely available. But before these sweeteners received FDA approval, the FDA performed more than 100 safety studies on each one. According to the National Cancer Institute, "The results of these studies showed no evidence that these sweeteners cause cancer or pose any other threat to human health."

What the expert says: "Although there has been a lot of negative press about artificial sweeteners, there is no evidence that artificial sweeteners cause cancer in humans," said Christine Zoumas, MS, RD, project manager of the Diet and Physical Activity Shared Resource at the University of California, San Diego, Moores Cancer Center.

When a food or color additive is developed, Ms Zoumas explained, it goes through dozens of toxicity, animal, and human studies before being approved. Aspartame, for instance, was first developed in 1965 but wasn't FDA approved until 1981, after undergoing testing for 16 years. Even then, the sweetener was only permitted as an additive in selected products while researchers continued to monitor its effects.

The FDA also establishes an acceptable daily intake for additives—the amount of a product a person can safely consume each day with no side effects, Ms Zoumas noted. For aspartame, for instance, the acceptable daily intake is 50 mg/kg of body weight. That means a 60-kg person can safely consume 3000 mg of aspartame per day, which is equivalent to about 136 packets of Equal or sixteen 12-ounce cans of diet soda.

"The testing for food additives in the United States is very rigorous," Ms Zoumas said. "If there was indeed a link between artificial sweeteners and cancer, these products would be off the shelves."

Verdict: No link.


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