Dietary Medium-chain Fatty Acids and Risk of Incident Colorectal Cancer in a Predominantly Low-Income Population: A Report from the Southern Community Cohort Study

No prospective observational study has specifically examined the associations between dietary intakes of medium-chain fatty acids and the risk of colorectal cancer. To examine the association between dietary intakes of medium-chain fatty acids and colorectal cancer risk overall and by racial subgroups in a predominantly low-income US population. This prospective study included 71,599 eligible participants aged 40-79 who were enrolled in the Southern Community Cohort Study between 2002 and 2009 in 12 southeastern US states. Incident colorectal cancer cases were ascertained via linkage to state cancer registries which was completed through December 31, 2016. The dietary intakes of medium-chain fatty acids were assessed using a validated 89-item food frequency questionnaire. Multivariable Cox proportional hazards regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between intakes of medium-chain fatty acids and risk for incident colorectal cancer. Among 71,599 participants, 48,008 (67.3%) were Black individuals and 42,260 (59.0%) were female. A total of 868 incident colorectal cancer cases occurred during a median follow-up of 13.7 years. Comparing the highest to the lowest quartile, high intake of dodecanoic acid/lauric acid (C12:0) was associated with reduced risk of colorectal cancer among white participants (HR, 0.52; 95% CI, 0.30-0.91; P for trend =0.05), but not in Black individuals (HR, 0.92; 95% CI, 0.68 to 1.24; P for trend =0.80) in multivariable-adjusted models. No associations were found between intakes of hexanoic acid/caproic acid (C6:0), octanoic acid/caprylic acid (C8:0) or decanoic acid/capric acid (C10:0) and risk of incident colorectal cancer overall or within racial subgroups. In a predominantly low-income US population, an increased dietary C12:0 intake was associated with a substantially reduced risk of colorectal cancer only among white individuals, but not in Black individuals.