Effects of rooibos (aspalathus linearis) extract on dryness of mouth, eye and skin in human: A randomized, double-blind, placebo-controlled study

Objective We investigated effects of food containing rooibos (Aspalathus linearis) extract including eriodictyol-6-Oglucoside (E6CG) on dryness of mouth, eye, and skin in human in a randomized, double-blind, placebo-controlled, crossover trial. Methods Thirty healthy adults with subjective dryness of multiple parts in mouth, eye, and skin were randomly devided into 2 groups and then instructed to intake either 100 mg of rooibos extract (0.21 mg of E6CG) or placebo for 2 weeks, respectively. The subjective dryness indices using the visual analog scale and the objective indices based on saliva flow rate, tear volume, and stratum corneum moisture content were evaluated before and after intake of the foods. This study was registered with UMIN Clinical Trials Registry as UMIN 000029492. Results Rooibos extract intake significantly improved the subjective dryness of mouth (P= 0.019), eye (P=0.006) and skin (P=0.030) and the objective indices of saliva flow rate (P= 0.045), tear volume (P=0.012) and stratum corneum moisture content (P=0.004). Conclusions This clinical study demonstrated that rooibos extract intake improves dryness of mouth, eye and skin.