Effect of dietary resistant starch on the inhibition of preneoplasia in azoxymethane‐induced A/J mouse model (123.5)

Abstract

Colorectal cancer (CRC) occurrence is believed to be affected by diet and lifestyle factors. Resistant starch, a type of dietary fiber, is resistant to normal digestion in the small intestine and is instead available for fermentation in the larger intestine by gut microbes. Four starches, varying in digestibility resistance, were used: normal control cornstarch (CS), native high amylose cornstarch (HA7), high amylose complexed with octenyl succinic anhydride (OS‐HA7), and high amylose complexed with stearic acid (SA‐HA7). Preneoplastic lesions were induced in male A/J mice with azoxymethane (AOM), a known colon carcinogen, and saline was used as a control. Treatment groups of mice were fed one of the experimental diets for 10 weeks. Colons were collected and analyzed for common preneoplastic lesions aberrant crypt foci (ACF) and mucin‐depleted foci (MDF). It was hypothesized that the SA‐HA7 diet would provide the greatest inhibition of preneoplasia as it contained the greatest resistant starch content, allowing for greater fermentation and greater production of SCFA. Body weights were recorded weekly. The saline and AOM treated, OS‐HA7 fed mice were not significantly different in body weights at any week. The OS‐HA7‐AOM group, however, was significantly different from all other groups at weeks 7, 12, and 17. The mice fed the SA‐HA7 diet actually had the greatest number of ACF compared to the other diet groups. The HA7 diet had the lowest number of ACF but was not significantly different from the SA‐HA7 diet (p=0.09). No MDF were observed in any of the diet groups. The results from this study suggest that the SA‐HA7 diet may enhance preneoplasia rather than inhibit it if ACF are reliable biomarkers for CRC. Long term studies are needed to determine the impact of resistant starch on CRC.Grant Funding Source: supported by USDA‐AFRI