A New Study on Artificial Sweeteners and Cancer Risk

According to findings from Nutri-Sante, a population-based observational study conducted in France, people who consume more sweeteners than the usual average, particularly aspartame and acesulfame, have an overall cancer risk over 8 years that is 13% higher than that of people who do not consume these sweeteners. PLOS Medicine published the study, which reported that high aspartame consumption was associated with a 22% higher overall cancer risk and a 15% higher risk of obesity-related cancers compared with no consumption.

Charlotte Debras and colleagues from the French National Institute of Health and Medical Research and Sorbonne Paris Nord University wrote: “Our findings do not support the use of artificial sweeteners as safe alternatives to sugar in foods or beverages and provide important new information to address debates about their potential adverse health effects. Consistent with various in vivo/in vitro studies, results from the NutriNet-Sante cohort study suggest that artificial sweeteners found in many food and beverage brands worldwide are associated with increased cancer risk.”

Dietitian Duane Mellor, a lecturer at Aston University Medical School, commented to the UK Science Media Centre: “This study does not prove or suggest that we should give up artificial sweeteners or diet drinks and return to using sugar.” However, the study suggests that artificial sweeteners are not ideal replacements for sugar and bring their own potential risks, just as sugar does. The ideal answer is probably to avoid both, but this may not appeal to most people who like at least a little sweetness. Turning to diet fizzy drinks when looking for alternatives for drinking water or other fluids may therefore not be a healthy approach.

An Important Analysis Requiring Careful Interpretation

Another expert, Assistant Professor John L. Sievepiper of the Departments of Nutritional Sciences and Medicine at the University of Toronto in Ontario, Canada, said: “I think this is an important analysis, but the results need careful interpretation. Large observational studies like this, assessing exposure to low-calorie and no-calorie sweeteners in relation to obesity-associated chronic diseases, are at risk of reverse causation. This is a well-recognized caveat among researchers. Reverse causation is possible because many people consuming low-calorie or no-calorie sweeteners (aspartame and acesulfame-K are the most common) use them as a weight-loss strategy. People who are already overweight therefore often choose these artificial sweeteners, and excess weight and obesity themselves may actually be what increases cancer risk.”

According to Sievenpiper, the key concern in the current study is the difficulty of separating signals from low-calorie and no-calorie sweeteners from obesity itself and from signals for sugar and calories in this analysis. Subgroup analyses would help address some of these concerns.

Conflicting Results

Debras and colleagues wrote that recent epidemiological and animal studies on the possible link between artificial sweeteners and cancer risk have produced conflicting results, and that information on consumption of specific types of artificial sweeteners and artificially sweetened foods and beverages is lacking. In the ongoing NutriNet-Sante study, they aimed to investigate associations between artificial sweetener intake (total and the most common types: aspartame, acesulfame-K, and sucralose) and cancer risk (overall and the most common types—breast, prostate, and obesity-related cancers).

“Obesity-related cancers, as defined by the World Cancer Research Fund, are cancers in which obesity is one of the causal risk (or protective) factors, regardless of participants' body mass index (BMI): colorectal, stomach, liver, oral, laryngeal, pharyngeal, esophageal, breast (with opposing associations before and after menopause), ovarian, uterine, and prostate cancers.”

Regarding the current study, Sievenpiper said that “obesity increases breast cancer risk in postmenopausal women but, conversely, appears protective in premenopausal women.”

Details of the NutriNet-Sante Study

The ongoing NutriNet-Sante study began in 2009 to investigate relationships between diet and health in the French population. Between 2009-2011, 102,865 people enrolled. Artificial sweetener consumption was determined from repeated 24-hour dietary records including sweetener brand names. Women made up 79% of participants. Mean age was 42 and median body mass index was 24 kg/m2.

Most participants did not consume artificial sweeteners (63%); the remainder were classified as low consumers (18.5%) or high consumers (18.5%). During an average follow-up of 7.7 years, 3,358 participants were diagnosed with cancer (982 breast, 403 prostate, and 2023 obesity-related cancers). Median age at diagnosis was 60.

After adjustment for age, sex, education, physical activity, smoking, BMI, height, weight gain during follow-up, diabetes, family history of cancer, number of 24-hour dietary records, baseline calorie intake, and intake of alcohol, sodium, saturated fatty acids, fiber, sugar, fruit and vegetables, whole grains, and daily products, high consumers of artificial sweeteners had a higher overall cancer risk than nonconsumers. After adjustment for all variables, participants with high aspartame and acesulfame-K consumption had increased overall cancer risk compared with nonconsumers. High aspartame consumers had a higher risk of breast and obesity-related cancers than nonconsumers.