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Journal ArticleAging cell·Aug 2026

A Probiotic Fixed Blood Sugar in Old Male Mice, But Did Nothing for Females

Key Insight

This early mouse work suggests probiotic benefits for blood sugar may differ by sex.


Older male mice had much worse blood sugar control than females, and they were also low on citrulline (an amino acid made partly by gut bacteria). Feeding them a probiotic called Lactiplantibacillus plantarum AS21 for six months reshaped their gut bacteria, restored citrulline, and improved blood sugar handling. Females, who were already metabolically fine, saw almost no change. Giving citrulline directly produced similar benefits, including more GLP-1 release.

Disclaimer: Research summaries are provided for informational purposes only and do not constitute medical advice. Always consult a qualified healthcare professional before making changes to your health routine.