A Daegu Lab Ties Rooibos's Aspalathin to Calmer Skin in Mice

Aspalathin, the flavonoid unique to rooibos among food plants, eased eczema-like skin inflammation in mice by blocking a specific immune signal, researchers at Kyungpook National University in South Korea reported.

The team, led by Sang-Hyun Kim of the university's pharmacology department, applied aspalathin to the skin of mice with induced atopic dermatitis. Treated mice showed less redness, less scaling, and thinner, less inflamed skin than untreated mice, the researchers said in Biomedicine and Pharmacotherapy.

Aspalathin makes up more than 40 percent of the flavonoid content in green, unfermented rooibos. The Daegu-based team traced its effect to a specific mechanism: aspalathin blocked activation of STAT6 and NFAT1, two proteins that drive the immune overreaction behind atopic dermatitis, in the mice's skin tissue and in isolated T cells, basophils, and keratinocytes. Treated mice also had lower blood levels of the antibodies IgE and IgG2a, two markers of immune activation the study tracked.

The study is a mouse model, not a clinical trial in people, and topical aspalathin is not an available treatment. Whether the same mechanism holds in human skin, and at what dose, is not something a mouse study can settle.

A topical dose painted on a mouse's shaved skin is not a cup of tea, and the Ministry will not confuse the two. What holds regardless is narrower and older than this study: there was never any caffeine in the cup to begin with, and a genuine antioxidant load, aspalathin included, has been there all along.

Sources: Yang et al., "Aspalathin, a key flavonoid in rooibos, restores STAT6-mediated immune dysregulation in atopic dermatitis," Biomedicine and Pharmacotherapy, vol. 184 (2025), DOI: 10.1016/j.biopha.2025.117926; PubMed record, PMID 39970731.