Abstract 6451: 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 (SCCS)
Authors: Fan Lei , Zhu Xiangzhu , Chen Qingxia , Huang Xiang , Steinwandel Mark D. , Shrubsole Martha , Dai Qi 
Published: June 2023

Purpose: Previous studies have investigated medium-chain fatty acids (MCFAs) as a part of saturated fat intake and risk of colorectal cancer (CRC). However, unlike long-chain saturated fatty acids, MCFAs possess many unique properties, including inhibition of pro-carcinogenic bacteria, biofilm formation, and induction of apoptosis. Further, C12:0 has been consistently shown in vitro to exhibit the most potent anti-microbial properties in a dose-dependent manner compared to other MCFAs. Black Americans have the highest CRC incidence and mortality across all racial subgroups in the US. In a predominantly low-income population, we aimed to examine whether dietary intake of MCFAs is associated with a reduced risk of CRC overall and among racial subgroups.

Methods: The daily intake of total energy and individual nutrients, including MCFAs, was derived from a food frequency questionnaire. Multivariable-adjusted Cox regression was used to assess the associations between dietary intake of MCFAs and the risk of incident CRC during the 13.75-year follow up after adjustment for confounders.

Results: Among 71,599 eligible participants, 868 incident CRC cases were identified (622 Blacks, 220 Whites and 26 other racial groups). High intake of C12:0 was significantly associated with a reduced risk of CRC only in White participants in a dose-response manner (for highest VS lowest quartile: HR, 0.37; 95% CI, 0.17 to 0.80; P for trend =0.0068). This protective association primarily appeared in White participants at high risk of CRC, such as those aged 50 years or older, overweight or obese, ever smokers, or living in a neighborhood with greater deprivation. On the other hand, we did not find a significant association in Black participants (HR, 0.87; 95% CI, 0.59 to 1.27); P for trend =0.72). However, there was a marginal linear association in Black participants with the lowest deprivation index while the association disappeared among Black participants with higher deprivation index. Finally, we found from the NHANES 2005-2016, a representative sample of the US general population, that Black Americans had the lowest intake of MCFAs across all racial subgroups and, overall, intakes of MCFAs decreased with reducing poverty-income ratio. No associations were found between intakes of C6:0, C8:0, or C10:0 and the risk of incident CRC overall or within the racial group.

Conclusion: In this predominantly low-income population, increasing dietary C12:0 intake was associated with a substantially reduced risk of CRC only among White participants, but not in Black participants. This racial difference in associations may be because Black Americans consumed the lowest levels of MCFAs in all racial groups while a much higher proportion of Black participants had lactose intolerance and a lower proportion of them consumed lactose-free fermented foods.

Citation Format: Lei Fan, Xiangzhu Zhu, Qingxia Chen, Xiang Huang, Mark D. Steinwandel, Martha Shrubsole, Qi Dai. 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 (SCCS) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6451.