May 10, 2021 -- Drinking too many sugar-sweetened beverages in adolescence and young adulthood could partially explain the recent rapid rise in early-onset colorectal cancer — at least in women, according to a new study.

The study found that women who recalled drinking two or more of these drinks each day in adolescence had a twofold increase in the risk of colorectal cancer before the age of 50, compared to those who had only one such drink per week or less.

However, experts warn the findings are based on small numbers and do not prove a direct connection.

"Despite these limitations, this signal keeps appearing over and over again," said Marcus DaSilva Goncalves, MD, at the Meyer Cancer Center at Weill Cornell Medicine in New York City, who was not involved in the study.

"There is strong evidence in mice and supportive epidemiologic studies that back the link between fructose-containing sugars and obesity, diabetes, and certain cancers like” colorectal cancer, he said.

The issue is certainly of great interest. Colorectal cancer has been considered a disease of the elderly, but there has been a dramatic increase in recent years of cases in younger adults the United States as well as other high-income countries.

Details of the Findings

The study, published in Gut, analyzed data from an ongoing study of the health of nurses.

This analysis looked at the association of sugary drink consumption among 95,464 female registered nurses who between the ages of 25 and 42 years when they enrolled in the study and followed them for the development of early onset colorectal cancer, which was defined as starting before the age of 50.

Of those, 41,272 nurses were also asked about how many sugary drinks they normally had when they were 13 to 15 years old.

The nurses filled out food questionnaires every 4 years, which asked about soft drinks, fruit drinks, sports drinks, and sweetened tea beverages.

Information on potential risk factors was also collected, including family history of bowel cancer, lifestyle, regular use of aspirin or non-steroidal anti-inflammatory drugs and vitamin supplements.

Participants were also asked about their teenage health, including weight and lifestyle.

Over a a period of up to 24 years, researchers found 109 cases of colorectal cancer, and a 2.2-fold higher risk among women who reported drinking two or more sugary drinks per day, compared to those who reported drinking less than one per week.

The findings "reinforce the public health importance of limiting [sugary drinks] for better health outcomes," senior author Yin Cao, MD, from Washington University School of Medicine in St. Louis, said..

"While our sample size was limited and this finding requires further validation, it is important to note that 30% of US children and adolescents consume more than 1.5 servings of [sugary drinks] daily," he said in a statement.

However, experts reacting to this study on the UK Science Media Centre were less convinced by the research. "Overall, these findings should be considered as preliminary and exploratory until larger studies are done in other populations," said Carmen Piernas, PhD, nutrition scientist at the University of Oxford in England.

Piernas said an important limitation of the analysis is lack of power. " The absolute risk is very low. A related analysis reporting the increase in risk with each additional sugary drink serving per day is only borderline significant," she said.

Nevertheless, she also noted that "there is already strong evidence that consuming sugary drinks increases risk of weight gain and diabetes. Everyone should aim to minimize their consumption — this analysis does not change that advice."