Gut microbiota modulation and inflammation mitigation in a murine model through a hull-less and purple grain barley genotype†

Barley, increasingly recognized for its health benefits, contains bioactive compounds like beta-glucans and (poly)phenols. Newly developed purple barley varieties, enriched with anthocyanins, offer potential gut health benefits. This study examined the effects of a hull-less, purple-grain barley genotype, consumed as whole-grain or isolated fractions (bran and endosperm), on gut microbiota and inflammation in a murine model. Fifty male and female BALB/cB&J mice were assigned to five diets over six weeks: standard diet (SD), rice diet (RD), whole-grain barley (WGB), anthocyanin-rich barley bran (BB), and beta-glucan-rich endosperm (PG). The BB diet triggered anti-inflammatory signals as it reduced IFN-γ and IL-4 in females, lowered TNF-α in both sexes, and decreased C-Reactive Protein (CRP) in males compared to SD. The PG diet improved gut barrier integrity by lowering LPS-binding protein levels. Barley-based diets enhanced gut microbiota diversity, particularly, by increasing beneficial bacteria like Lactobacillus, Lachnospiraceae UCG-001, and Akkermansia. Notably, BB and PG elicited stronger effects than WGB, suggesting that grain fractionation modifies the food matrix, potentially enhancing the bioaccessibility and bioavailability of key bioactive compounds. These results underscore the benefits of purple barley-derived fractions in promoting gut health and reducing inflammation, supporting their potential role to protect against inflammation-related conditions.