Researchers at the University of Oxford’s Cancer Epidemiology Unit, in collaboration with international institutions, have made significant findings regarding the relationship between diet and colorectal cancer risk. Their study, based on data from 542,778 women in the United Kingdom, has revealed a positive association between alcohol consumption and colorectal cancer risk, as well as a protective effect of calcium and dairy-related foods.
Colorectal cancer is the third most common cancer worldwide, with nearly 2 million new cases reported in 2022. While incidence rates are higher in high-income countries, they are on the rise in lower-income regions as well. Studies have shown that dietary and lifestyle changes, such as those observed in migrants adopting the habits of high-risk countries, can play a crucial role in the development of colorectal cancer.
Certain nutrients, foods, and beverages have long been suspected of influencing colorectal cancer risk, including known carcinogens like alcohol and processed meat. However, there has been a lack of comprehensive data on how specific dietary components impact the risk of developing colorectal cancer.
In their study, titled “Diet-wide analyses for risk of colorectal cancer: prospective study of 12,251 incident cases among 542,778 women in the UK,” published in Nature Communications, researchers aimed to address these uncertainties using a large-scale, diet-wide analysis. The participants were drawn from the Million Women Study, a cohort of middle-aged women in the UK who completed detailed dietary questionnaires covering 97 dietary factors. Over an average follow-up period of 16.6 years, 12,251 women were diagnosed with incident colorectal cancer.
The study employed multivariable models that adjusted for various demographic, lifestyle, and clinical factors. A targeted genetic analysis was also conducted using data from several research consortia. The results confirmed the carcinogenic nature of alcohol and red/processed meats, with every 20 grams of daily alcohol consumption increasing the risk of colorectal cancer by 15% and every additional 30 grams of red/processed meat intake raising the risk by 8%.
On the other hand, calcium emerged as a protective factor against colorectal cancer, potentially due to its role in binding gut bile acids and reducing exposure to carcinogens in the colon. Consuming an additional 300 milligrams of calcium per day was associated with a 17% reduction in colorectal cancer risk. Dairy milk, yogurt, and other calcium-rich foods were also linked to a decreased risk, with calcium being the primary driver of this association.
In addition to calcium, several other dietary components were found to be associated with a lower risk of colorectal cancer. Whole grains, breakfast cereal, fruits, leafy greens, vitamin C, and other nutrients were all linked to a reduced likelihood of developing colorectal cancer. However, these protective effects were somewhat diminished when other lifestyle and dietary factors were taken into account.
Further analyses excluded the possibility of reverse causation and showed consistent results across different subsites of colorectal cancer. The study highlights the need for more research to understand the protective mechanisms of calcium and the potential health implications of high calcium intake.
In conclusion, this study sheds light on the intricate relationship between diet and colorectal cancer risk, emphasizing the importance of making informed dietary choices to reduce the risk of developing this prevalent form of cancer. More information on this study can be found in the publication in Nature Communications.
