Pectin-rich dietary fiber from ripe papaya increases Lactobacillus abundance and reduces the formation of aberrant crypts in rats submitted to chemically-induced colorectal cancer

Pectins are a class of highly fermentable dietary fibers that modulate the gut microbiota, with biological effects that vary depending on ripening stage and molecular structure. This study investigated the impact of ripe and unripe papaya dietary fibers on gut microbiota composition in rats subjected to a chemically-induced colon carcinogenesis model. Male Wistar rats received AOM injections and were fed with regular chow, ripe papaya, and unripe papaya dietary fibers. After 10 weeks, aberrant crypt foci (ACF), short-chain fatty acids (SCFA) production, and intestinal microbiota composition were analyzed. Both pectins reduced the number of ACF with a single crypt, whereas only ripe papaya fiber intake reduced ACF with more than one crypt. Acetate production was higher in animals fed unripe papaya pectin, propionate increased for both pectins, and total SCFA was higher only in the unripe papaya compared to the AOM group. Ripe papaya pectin increased alpha and beta diversity of the microbiota, showing a profile similar to that of the negative control, whereas unripe papaya clustered closer to the AOM group. Ripe papaya pectin increased the abundance of several probiotic Lactobacillus species, while unripe papaya pectin increased Romboutsia abundance; the AOM treatment increased Mediterraneibacter. Overall, these results suggest that, depending on the ripening stage, papaya pectins can differentially modulate SCFA production and the microbiota profile, thereby contributing to the attenuation of early preneoplastic lesions in the colon.