Rooibos (Aspalathus linearis) facilitates an anti-inflammatory state, modulating IL-6 and IL-10 while not inhibiting the acute glucocorticoid response to a mild novel stressor in vivo

- Rooibos consumption is associated with an anti-inflammatory outcome.
- Rooibos decreased IL-6 and increased IL-10 levels in vivo.
- Rooibos limits glucocorticoid synthesis in H295R cells independent of IL-6 and IL-10.
- Rooibos inhibition of basal GC biosynthesis does not prevent an acute stress response.
- Data underline Rooibos as a functional food in reducing risk for chronic disease.

Rooibos is rich in polyphenols with a high anti-oxidant capacity, modulating adrenal steroidogenesis while also influencing cytokine levels. The aim of this study was to investigate Rooibos' immuno-modulating properties, given the interdependence of inflammatory and oxidative stress systems, together with the regulatory function of cytokines in steroidogenesis. Rooibos did not prevent an adequate corticosterone response in rats, with corticosterone and deoxycorticosterone levels significantly increased after 1 hr restraint. IL-6 levels decreased in Rooibos-treated rats while IL-10 (P < 0.05) and IL-10:IL-6 ratios (P < 0.01) increased. Rooibos inhibited glucocorticoid production more significantly in forskolin-stimulated than in basal H295R cells (corticosterone and deoxycorticosterone, P < 0.00001; 11-dehydrocorticosterone, P < 0.01), independent of IL-6 and IL-10. Rooibos therefore modulated the inflammatory response basally and during acute stress. While Rooibos affects steroid hormone biosynthesis, maintaining beneficial glucocorticoid levels and possibly achieving better long-term outcome in terms of glucocorticoid sensitivity, the ability to respond to acute stressors is unlikely to be compromised.