An umbrella review of 45 meta-analyses suggests there are links between dietary intakes and colorectal cancer risk. In this study recently published in JAMA Network Open, findings show that dietary fiber, calcium, and yogurt were associated with lower risk, whereas alcohol and red meat were associated with higher risk.
The study’s researchers investigated the quality of evidence regarding reported associations between dietary factors and colorectal cancer risk in publications found through searches of MEDLINE, Embase, and Cochrane Library sources. They rated the strength of each association based on set statistical criteria regarding the quality of evidence, using the following 5 categories: convincing, highly suggestive, suggestive, weak, or nonsignificant.
From searches that yielded 9954 publications, the researchers identified 45 eligible meta-analyses of prospective, observational data, which showed 109 associations between diet and the incidence of colorectal cancer. Of these associations, approximately one-third (32.1%) were considered nominally statistically significant at a level of P ≤.05.
The researchers considered the majority (67.9%) of reported associations to show no evidence of an association. Weak associations were found with 16.5%, while 9.2% were suggestive, 1.8% were highly suggestive, and 4.6% were supported by convincing evidence.
Associations that showed convincing evidence related to colorectal risk included lower risk with intake of dietary fiber, dietary calcium, and yogurt. Conversely, convincing evidence suggested red meat and alcohol consumption of 4 or more drinks per day were linked to greater colorectal cancer risk.
“Our findings largely support existing cancer prevention dietary guidance regarding increasing consumption of dietary fiber and dairy products and limiting intake of red meat and alcoholic beverages,” the researchers wrote in their report. They indicated that further research to evaluate particular foods for which evidence is currently suggestive of associations is needed.
Veettil SK, Wong TY, Loo YS, et al. Role of diet in colorectal cancer incidence: umbrella review of meta-analyses of prospective observational studies. JAMA Netw Open. 2021;4(2):e2037341. doi:10.1001/jamanetworkopen.2020.37341