Dietary factors may have role in development of CRC
Factors related to diet, including fiber and alcohol intake, were associated with the development or prevention of colorectal cancer, according to study results.
“Several systematic reviews with meta-analysis of prospective observational studies have summarized evidence for the associations between dietary factors and the incidence of [colorectal cancer (CRC)],” Nathorn Chaiyakunapruk, Pharm D, PhD, from the department of pharmacotherapy at The University of Utah, and colleagues wrote. “However, to date, there has been little synthesis of the strength, precision and quality of this evidence in aggregate.”
Investigators searched the literature for studies that explored the association of dietary patterns, specific foods, food groups, beverages, macronutrients and micronutrients with the incidence of CRC. They included only meta-analyses of prospective observational studies with a cohort study design. Then, they graded the evidence of the association as convincing, highly suggestive, suggestive, weak or not significant.
Researchers identified 45 meta-analyses comprising 109 associations between dietary factors and CRC in their study. Of those studies, 35 were nominally statistically significant, whereas 17 associations demonstrated large heterogeneity between studies, and 11 had small study effects.
Chaiyakunapruk and colleagues determined that five (4.6%) associations had convincing evidence, two (1.8%) were highly suggestive, 10 (9.2%) were suggestive, 18 (16.5%) were weak and 74 (67.9%) had no evidence for an association.
Researchers found convincing evidence for an association between intake of red meat (high vs. low) and alcohol (four or more drinks per day vs. zero or occasional drinks) with the incidence of CRC. Additionally, they found an inverse association between higher vs. lower intake of dietary fiber, calcium and yogurt with CRC risk. These associations remained after sensitivity analyses.
“Emerging evidence supports a possible role for overall dietary patterns that, in totality, emphasize habitually consuming fruits, vegetables, grains and low-fat dairy and reducing red met and alcohol intake,” Chaiyakunapruk and colleagues wrote. “More research is needed on specific foods for which evidence remains suggestive, including other diary products, whole grains, processed meat and specific dietary patterns.”