Ulcerative colitis (UC) is a chronic inflammatory gastrointestinal condition that poses significant public health challenges worldwide. A study indicated that the amino acid L-arginine (L-Arg) might alleviate UC symptoms, but the efficacy of prophylactic versus therapeutic use of this supplementation remains uncertain. To investigate this, researchers administered L-Arg to mice, either before or during the instigation of colitis via dextran sulfate sodium (DSS).
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The study involved five groups of male C57BL/6 J mice: a control group (CON), a DSS group, a continuous L-Arg group (Arg), a prophylactic group receiving L-Arg before DSS exposure (BeArg), and a therapeutic group receiving L-Arg during DSS exposure (DuArg). Results indicated that BeArg significantly reduced weight loss, disease activity index (DAI), and colon shortening compared to the DSS group, showing protective effects similar to those observed with full continuous L-Arg administration. The BeArg group also exhibited improvements in intestinal barrier integrity and a decrease in pro-inflammatory cytokine levels, compared to the DSS group.
Conversely, DuArg provided only modest clinical improvements, with limited effects on inflammatory responses and gut barrier dysfunction. Analyses of the gut microbiota revealed that both BeArg and continuous L-Arg supplementation effectively remodeled microbial community structures, while DuArg had minimal effects.
Overall, findings suggest that L-Arg supplementation can exert preventive effects against colitis, mainly through its modulation of gut microbiota, emphasizing the significance of timing in intervention strategies. Future research should investigate the underlying mechanisms further and consider the role of L-Arg in dietary strategies for UC management.