Bee pollen in zebrafish diet affects intestinal microbiota composition and skin cutaneous melanoma development

Bee pollen is recommended as dietary supplement due to immunostimulating functions including antioxidant, anti-inflammatory and anti-carcinogenic properties. Nevertheless, the effectiveness of such properties is still not well understood. As diet can be associated with animal performance, microbiota modulation and potentially factor for cancer, this study aimed to analyze if bee pollen could influence growth, gut microbial and skin cutaneous melanoma development in zebrafish. Control diets based on commercial flakes and Artemia were compared with the same diet supplemented with bee pollen. Fish weight gain, increased length, intestinal bacteria metagenomics analysis, serum amyloid A gene expression and cutaneous melanoma transplantation assays were performed. Bee pollen affected microbiota composition and melanoma development. Differential abundance revealed higher abundance in the control group for Aeromonadaceae family, Aeromonas and Pseudomonas genus, A. sobria, A. schubertii, A. jandaei and P. alcaligenes species compared with pollen diet group. Pollen group presented higher abundance for Chromobacterium genus and for Gemmobacter aquaticus, Flavobacterium succinicans and Bifidobacterium breve compared with control group. Unexpectedly, fish fed with bee pollen showed higher tumor growth rate and larger tumor size than control group. This is the first study to report intestinal microbial changes and no protective cancer properties after bee pollen administration.