Heavy consumption of sugary drinks during adolescence and adulthood is associated with an increased risk of developing colorectal cancer in women under age 50, found a study in the BMJ's journal Gut.
Drawing on date from Nurses' Health Study II, the research, led by Washington University School of Medicine, provides support for public health efforts that encourage people to reduce the amount of sugar they consume.
"Colorectal cancer in younger adults remains relatively rare, but the fact that the rates have been increasing over the past three decades — and we don't understand why — is a major public health concern and a priority in cancer prevention," said senior author Yin Cao, an associate professor of surgery and of medicine in the Division of Public Health Sciences at Washington University. "Due to the increase in colorectal cancer at younger ages, the average age of colorectal cancer diagnosis has gone down from 72 years to 66 years. These cancers are more advanced at diagnosis and have different characteristics compared with cancers from older populations.
"Our lab is funded by the National Cancer Institute (NCI) and the National Comprehensive Cancer Network to identify risk factors, the molecular landscapes, and precision screening strategies for these cancers so that they can be detected earlier and even prevented," said Cao. "In past work, we have shown that poor diet quality was associated with increased risk of early-onset colorectal cancer precursors, but we have not previously examined specific nutrients or foods."
Compared with women who drank less than one 8-ounce (237ml) serving per week of sugar-sweetened beverages, those who drank two or more servings per day had just over twice the risk of developing early-onset colorectal cancer, meaning it was diagnosed before age 50. The researchers calculated a 16% increase in risk for each 8-ounce serving per day. And from ages 13 to 18, an important time for growth and development, each daily serving was linked to a 32% increased risk of eventually developing colorectal cancer before age 50.
Sugar-sweetened drink consumption has been linked to metabolic health problems, such as type 2 diabetes and obesity, including in children. But less is known about whether such high-sugar beverages could have a role in the increasing incidence of colorectal cancer in younger people. Like early-onset colorectal cancer rates, consumption of such drinks has increased over the past 20 years, with the highest consumption level found among adolescents and young adults ages 20 to 34.
The researchers analysed data from the Nurses' Health Study II, a large population study that tracked the health of nearly 116,500 female nurses from 1991 to 2015. Every four years, participants answered surveys that included questions about diet, including the types and estimated amounts of beverages they drank. Of the total participants, over 41,000 also were asked to recall their beverage habits during their adolescence.
The researchers identified 109 diagnoses of early-onset colorectal cancer among the nearly 116,500 participants.
"Despite the small number of cases, there is still a strong signal to suggest that sugar intake, especially in early life, is playing a role down the road in increasing adulthood colorectal cancer risk before age 50," said Cao. "This study, combined with our past work linking obesity and metabolic conditions to a higher risk of early-onset colorectal cancer, suggests that metabolic problems, such as insulin resistance, may play an important role in the development of this cancer in younger adults."
With the increasing rates in mind, the American Cancer Society has recently lowered the recommended age for a first screening colonoscopy to 45, down from the previously recommended age 50 for people at average risk. Those with additional risk factors, such as a family history of the disease, should start even earlier, according to the guidelines.
Since the study only included female nurses, most of whom were white, more work is needed to examine this link in people of more diverse races, ethnicities and genders.
While sugar-sweetened beverages were linked to an increased risk of early-onset colorectal cancer, some other drinks – including milk and coffee –were associated with a decreased risk. This observational study can't demonstrate that drinking sugary beverages causes this type of cancer or that drinking milk or coffee is protective, but the researchers said that replacing sweetened beverages with unsweetened drinks, such as milk and coffee, is a better choice for long-term health.
A report in The Guardian warns that some scientists not involved in the work said the findings were tentative because only 109 women who enrolled in the study were diagnosed with early onset bowel cancer, and among them only 16 reported drinking more than a pint of sugary drinks a day. Eating red and processed meat, a diet low in fibre, smoking, drinking alcohol and being overweight have all been found to raise the risk of the disease, and these can be hard to fully account for, they said.
“We just can’t be sure whether the observed association between sugary drinks and bowel cancer under the age of 50 is one of cause and effect,” said Kevin McConway, an emeritus professor of applied statistics at the Open University.
But again, some scientists believe more studies are needed to confirm the effect. “The analysis is based on only six cases of cancer found in this group. This is too small to draw any strong conclusions,” said Dr Carmen Piernas, a nutrition scientist at the University of Oxford. Duane Mellor, a dietitian at Aston University, said that while reducing sugary drink intake might lower the risk of bowel cancer, it may have little effect without also improving lifestyle and overall diet.
Sugar-sweetened beverage intake in adulthood and adolescence and risk of early-onset colorectal cancer among women
Authors: Jinhee Hur, Ebunoluwa Otegbeye, Hee-Kyung Joh, Katharina Nimptsch, Kimmie Ng, Shuji Ogino, Jeffrey A Meyerhardt, Andrew T Chan, Walter C Willett, Kana Wu, Edward Giovannucci, Yin Cao.
Published in Gut, 2021
Objective Sugar-sweetened beverage (SSB) consumption had substantially increased across successive US birth cohorts until 2000, and adolescents and young adults under age 50 years have the highest consumption. However, the link between SSBs and early-onset colorectal cancer (EO-CRC) remains unexamined.
Design In the Nurses’ Health Study II (1991–2015), we prospectively investigated the association of SSB intake in adulthood and adolescence with EO-CRC risk among 95 464 women who had reported adulthood beverage intake using validated food frequency questionnaires (FFQs) every 4 years. A subset of 41 272 participants reported beverage intake at age 13–18 years using a validated high school-FFQ in 1998. Cox proportional hazards models were used to estimate relative risks (RRs) with 95% CIs.
Results We documented 109 EO-CRC cases. Compared with individuals who consumed <1 serving/week of SSBs in adulthood, women who consumed ≥2 servings/day had a more than doubled risk of EO-CRC (RR 2.18; 95% CI 1.10 to 4.35; ptrend=0.02), with a 16% higher risk (RR 1.16; 95% CI 1.00 to 1.36) per serving/day increase. Each serving/day increment of SSB intake at age 13–18 years was associated with a 32% higher risk of EO-CRC (RR 1.32; 95% CI 1.00 to 1.75). Replacing each serving/day of adulthood SSB intake with that of artificially sweetened beverages, coffee, reduced fat milk or total milk was associated with a 17%–36% lower risk of EO-CRC.
Conclusion Higher SSB intake in adulthood and adolescence was associated with a higher risk of EO-CRC among women. Reduction of SSB consumption among adolescents and young adults may serve as a potential strategy to alleviate the growing burden of EO-CRC.
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