Adult women who consume two or more sugary drinks per day may double their risk of developing colon cancer before age 50, a new study suggests. The analysis of more than 20 years of data from the Nurse's Health Study II (NHSII) finds that women who consumed sugary beverages had a 16% risk increase per serving/day for early-onset colorectal cancer compared to women who had less than one serving a week, according to the results published in the journal Gut. In a subset of women with dietary data from when they were 13-18 years old, each serving per day increment of sugary drinks consumed in the teen years was associated with a 32% increase in early onset colorectal cancer risk. "We generally found that women who drink two or more sugar sweetened beverages per day have more than twice the risk of developing colorectal cancer compared to those who do not," said Yin Cao, an associate professor in the division of public health sciences at Washington University School of Medicine in St. Louis. "Adolescents who drink sugar sweetened beverages can have a 32% increased risk of early onset colorectal cancer. But we also found that replacing sugar sweetened beverages with other beverages, such as coffee or reduced fat milk, reduced the risk." It's not yet known exactly how sugary drinks might increase the risk of colorectal cancer but there are some emerging theories, Cao said. "One is that sugar sweetened beverages are a source of metabolism dysregulation and inflammation," she added. "There is also an emerging hypothesis coming from animal studies that high fructose corn syrup, which is the primary sweetener in these beverages, can induce tumor growth independent of metabolic syndrome." To explore whether sugary beverages might impact the risk of early onset colorectal cancer, Cao and her colleagues turned to the NHSII, an ongoing prospective cohort study of 116,429 U.S. female registered nurses who were aged between 25 and 42 at enrollment in 1989. Biennially, participants self-reported detailed information on demographic, lifestyle, and medical history. Dietary intake was assessed using a validated, semi-quantitative food questionnaire (FFQ) approximately once every four years. Cao and her colleagues focused on 95,464 women with validated food intake data gathered every four years, including 109 who developed early onset colorectal cancer during the 24 years of NHSII follow-up. A subset of 41,272 women also had reported beverage intake at ages 13-18 in a 1998 questionnaire. Overall, the current study found that women who consumed higher levels of sugar sweetened beverages tended to be less physically active, and more likely to use NSAIDs, to consume red and processed meat, and to have a lower endoscopy due to indications. They were also less likely to take multivitamins and had lower intake of alcohol fiber folate and calcium as well as a poorer quality of diet. After adjusting for potential confounding factors, the researchers found that compared with women who consumed less than one serving per week of sugar-sweetened drinks in adulthood, those who consumed two or more servings per day had a greater than two-fold likelihood of early colorectal cancer (relative risk 2.18). When the researchers looked at the subset of women who reported teen patterns of sugary drink consumption, they found that adolescent sugar sweetened beverage consumption was also associated with a higher risk of early onset colorectal cancer after adjusting for potential confounding factors in adolescence (RR 1.32). The researchers also explored the impact on adults of replacing one serving per day of sugar sweetened beverage with an equivalent amount of other beverages, and found a lower risk of early onset colorectal cancer with substitutions of coffee (RR 0.82), reduced fat milk (RR 0.65), or total milk (RR 0.64). The new study highlights the importance of environmental factors when it comes to the risk of colorectal cancer, said Dr. Daniel Labow, executive vice chair of the department of surgery in the Mount Sinai Health System in New York City. "It doesn't mean if you drink sugary drinks you're going to get colorectal cancer," Dr. Labow said. "But clearly there is some association with this population. Maybe they are doing other things that raise their risk. Sugary drinks may imply a less healthy diet." Dr. John Rhee, a medical oncologist/hematologist at UPMC Hillman Cancer Center in Pittsburgh, Pennsylvania, wasn't surprised to find that sugary drink consumption could be detrimental to health. "I think this study underscores the importance of eating healthy," Dr. Rhee said. "When it comes to colorectal cancer, there are risk factors you can't control, like genetics or IBD, and factors that can be changed, such as diet, exercise and smoking. Those are all modifiable. And it's important to communicate to patients that they can lessen their risk by changing their habits." —Linda Carroll Source
