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Does sugar directly feed cancers, feeding their growth? The answer seems to be yes, at least in mice according to a study led by researchers at Baylor College of Medicine and Weill Cornell Medicine.
Their study, published in Science, showed that consuming a daily modest amount of high-fructose corn syrup—the equivalent of drinking about 12 ounces of a sugar-sweetened beverage daily—accelerates the growth of intestinal tumors in mice, independent of obesity.
“An increasing number of observational studies have raised awareness of the association between consuming sugary drinks, obesity and the risk of colorectal cancer,” said co-corresponding author Dr. Jihye Yun, assistant professor of molecular and human genetics at Baylor. “The current thought is that sugar is harmful to our health mainly because consuming too much can lead to obesity. We know that obesity increases the risk of many types of cancer including colorectal cancer; however, we were uncertain whether a direct and causal link existed between sugar consumption and cancer.”
Dr. Yun and her colleagues generated a mouse modeling early-stage colon cancer in which the APC gene is deleted. “APC is a gatekeeper in colorectal cancer,” Dr. Yun stated. “Deleting this protein is like removing the brakes of a car. Without it, normal intestinal cells neither stop growing nor die, forming early stage tumors called polyps. More than 90 percent of colorectal cancer patients have this type of APC mutation.”
Using this mouse model, the team tested the effect of consuming sugar-sweetened water on tumor development. The sweetened water was 25 percent high-fructose corn syrup, which is the main sweetener of sugary drinks people consume. High-fructose corn syrup consists of glucose and fructose at a 45:55 ratio.
When the researchers provided the sugary drink for the mice to drink at their will, they rapidly gained weight in a month. To prevent the mice from being obese and mimic humans’ daily consumption of one can of soda, the researchers gave the mice a moderate amount of sugary water orally with a special syringe once a day. After two months, the mice receiving sugary water did not become obese, but developed tumors that were larger and of higher-grade than those in model mice treated with regular water.
“These results suggest that when the animals have early stage of tumors in the intestines—which can occur in many young adult humans by chance and without notice—consuming even modest amounts of high-fructose corn syrup in liquid form can boost tumor growth and progression independently of obesity,” Dr. Yun said. In humans, it usually takes 20 to 30 years for colorectal cancer to grow from early stage benign tumors to aggressive cancers.
“This observation in animal models might explain why increased consumption of sweet drinks and other foods with high sugar content over the past 30 years is correlating with an increase in colorectal cancers in 25- to 50-year-olds in the United States,” said Dr. Cantley, a co-corresponding author and director of the Sandra and Edward Meyer Cancer Center at Weill Cornell Medicine.