Functional effects of rosmarinic acid on gut health and epigenetic regulation in antibiotic-free poultry diets.

Rosmarinic acid (RA), a bioactive polyphenol found in Salvia officinalis and other Lamiaceae herbs, has attracted attention for its functional feed application in animal nutrition. RA supplementation positively influences growth efficiency, liver antioxidant status, and serum biochemical indices in broilers. Its antimicrobial and immunomodulatory effects promote health and productivity. Studies suggest benefits for gut health and meat quality; however, epigenetic regulation of RA in poultry is considered a minor future perspective, being mostly based on mammalian studies. Hypothesized impacts of RA on chronic disease prevention and as a microbiome-engineering agent require further investigation. This review explores the regulatory effects of RA on DNA methylation, non-coding RNAs (ncRNAs), and histone modifications, which influence gut microbiome structure, nutrient absorption, and immune function in poultry. It emphasizes RA's potential as a functional food for gastrointestinal health, metabolic regulation, and chronic disease prevention, alongside its use in antibiotic-free poultry feed for microbiome engineering. The review also discusses RA's effects on lipid metabolism and oxidative stress, highlighting its role in maintaining intestinal barrier health. Nevertheless, certain limitations must be acknowledged, as successful nutritional interventions depend on understanding individual variability, including genetics, metabolism, age, and health status. Tailored methodologies, such as micronutrition and genomic nutrition, can improve diet quality, promote nutrient absorption, and enhance overall animal health. A tailored feeding regimen focuses on selecting nutrients with proven benefits for key health outcomes, such as omega-3 fatty acids, which scientific evidence shows promote brain and heart health while reducing inflammation.