Amanda C Swart
University of Stellenbosch, South Africa
Title: Rooibos (Redbush) tea: a functional food that plays a protective role in lifestyle-associated metabolic diseases
Biography
Biography: Amanda C Swart
Abstract
Rooibos (Aspalathus linearis), also known as Redbush, is a South African herbal tea rich in polyphenols. Consumption is reported to modulate the immune system, enhance well-being, and to aid anxiety and stress. Stress activates the hypothalamic-pituitary-adrenal axis resulting in elevated glucocorticoid plasma levels. Glucocorticoids, cortisol and corticosterone, are responsible for maintaining homeostasis of the central nervous system, metabolism and immune function. Long-term exposure to elevated cortisol is associated with symptoms linked to metabolic diseases — metabolic syndrome, diabetes, insulin resistance, depression, and impairment of the immune system, amongst others, many of which result from a hormonal imbalance. We investigated the influence of Rooibos on steroid hormone production in forskolin- stimulated H295R cells, mimicking the stress response in a human adrenal cell model. An in vivo study conducted in male Wistar rats subjected to acute immobilization stress determined the effect of Rooibos on circulating steroid levels. The inhibitory effect of Rooibos on glucocorticoid biosynthesis and on the inactivation of cortisol, as well as on cytokine production was determined. Data showed that Rooibos inhibited glucocorticoid production while also favoring inactivation of glucocorticoids, lowering glucocorticoid plasma levels. Rooibos increased the secretion of IL10, an anti-inflammatory cytokine, while inhibiting IL6, a pro-inflammatory cytokine, in rat adrenal tissue. In H295R cells Rooibos modulated basal and forskolin-stimuated steroid production in the presence of these cytokines. These data suggest that Rooibos may serve as a functional food acting as a protective agent in clinical conditions associated with metabolic diseases.
