A short-term, randomized, controlled, feasibility study of the effects of different vegetables on the gut microbiota and microRNA expression in infants

The complementary diet influences the gastrointestinal (gut) microbiota composition and, in turn, host health and, potentially, microRNA (miRNA) expression. This study aimed to assess the feasibility of altering the gut microbial communities with short-term food introduction and to determine the effects of different vegetables on the gut microbiota and miRNA expression in infants. A total of 11 infants were randomized to one of the following intervention arms: control, broccoli, or carrot. The control group maintained the milk diet only, while the other groups consumed either a broccoli puree or a carrot puree on days 1–3 along with their milk diet (human milk or infant formula). Genomic DNA and total RNA were extracted from fecal samples to determine the microbiota composition and miRNA expression. Short-term feeding of both broccoli and carrots resulted in changes in the microbiota and miRNA expression. Compared to the control, a trend toward a decrease in Shannon index was observed in the carrot group on days 2 and 4. The carrot and broccoli groups differed by weighted UniFrac. Streptococcus was increased on day 4 in the carrot group compared to the control. The expression of two miRNAs (i.e., miR-217 and miR-590-5p) trended towards decrease in both the broccoli and carrot groups compared to the control, whereas increases in eight and two different miRNAs were observed in the carrot and broccoli groups, respectively. Vegetable interventions differentially impacted the gut microbiota and miRNA expression, which may be a mechanism by which total vegetable intake and variety are associated with reduced disease risk.