Colon and rectal cancers are on the rise in younger adults, although researchers aren’t sure why. A new study on women and diet suggests that sugar-sweetened beverages may play a role.
Colon cancer rates in people under the age of 50 have risen sharply in recent years. Compared to people born around 1950, people born around 1990 have twice the risk of colon cancer and four times the risk of rectal cancer.
While sugar-sweetened beverage sales have declined in recent years, the number of calories in sugary beverages rose dramatically between 1977 and 2001. During these years it rose from 5.1 percent of total calorie intake to 12.3 percent for 19 to 39 year olds and from 4.8 percent to 10.3 percent for children under 18 years of age. By 2014, those numbers were down, but 7 percent of the total calories consumed by Americans were still from sugary beverages.
The new study, published in the journal Gut, examined the association between colon cancer and sweet beverages in 94,464 registered nurses who participated in a prospective long-term health study between 1991 and 2015 between the ages of 25 and 42 years. They also examined a subgroup of 41,272 nurses who reported their sugary drink intake between ages 13-18.
The study included consumption of soft drinks, sports drinks, and sweetened teas. The researchers also recorded consumption of fruit juices – apple, orange, grapefruit, plum, and others.
Over an average follow-up period of 24 years, they found 109 cases of colon cancer among caregivers (the absolute risk of colon cancer in younger people is still low). But when compared to women who averaged less than an 80-ounce serving of sugar-sweetened beverages per week, those who drank two or more had more than twice the relative risk for the disease. Each additional serving of sweet drink increased the risk by 16 percent. One serving per day in adolescence was associated with a 32 percent higher risk, and replacing sugary drinks with coffee or low-fat milk resulted in a relative risk reduction of 17 to 36 percent. (They had no data on sugar-sweetened coffee.)
“I was very interested to see that the study was on women,” said Caroline H. Johnson, an epidemiologist at the Yale School of Public Health who has published extensively on the environmental risks of colon cancer but was not involved in the work . “The focus was mainly on the men. It will be interesting to see if it is confirmed in men. “
There was no association between the consumption of fruit juices or artificially sweetened beverages with early onset colon cancer. The analysis controlled several factors that may influence colorectal cancer risk, including race, BMI, menopausal hormone use, smoking, alcohol use, and physical activity.
The study only showed a connection, so it could not prove cause and effect. But Nour Makarem, assistant professor of epidemiology at Columbia Mailman School of Public Health, who was not involved in the research, said, “This is robust evidence, new evidence that higher soda intake is linked to higher risk of colon cancer . We know that sugar-sweetened beverages have been linked to weight gain, glucose dysregulation, etc., which are also risk factors. So there is a plausible mechanism underlying these relationships. “
The study’s lead author, Yin Cao, associate professor of surgery at Washington University School of Medicine in St. Louis, said metabolic problems like insulin resistance and high cholesterol, as well as inflammation in the bowel, could play a bigger role as a cause of cancer in the younger Population than the elderly, but the exact potential mechanisms are not yet understood.
“One hypothesis is that increased weight gain increases the risk,” she said, “but we have obesity controlled. Still, it could be one of the things that help. Studies in mice found that high fructose corn syrup contributed to cancer risk regardless of obesity.
“This is the first time sugar-sweetened beverages have been linked to early onset colon cancer,” she continued, “and this study has yet to be repeated. However, researchers and clinicians should be aware of this largely ignored risk factor for cancer at a young age. This is an opportunity to rethink the guidelines for marketing sugar-sweetened beverages and how we can help reduce consumption. “