Safety and stress-reducing effects of rosemary extract: an open-label trial and randomized double-blind crossover study

This study comprised two trials that evaluated the safety and anti-stress effects of rosemary extracts containing rosmarinic acid and diterpenes. Study I was a 4-week, single-arm, open-label safety trial involving 22 healthy adults who consumed high doses of the rosemary extract daily. No clinically relevant adverse events or abnormal laboratory findings were observed, thus confirming its safety. Study II was a randomized, double-blind, placebo-controlled, crossover trial with 40 participants that assessed psychological and physiological stress markers. After four weeks of rosemary extract intake, significant improvements were found in trait anxiety scores measured using the State-Trait Anxiety Inventory and heart rate variability, as indicated by a decreased low-frequency/high-frequency ratio. Additionally, a single dose administered before the mental workload test significantly reduced state anxiety scores. No significant differences were observed in salivary cortisol levels or visual analog scale scores between the groups. These results suggest that rosemary extract is safe for consumption and may effectively reduce chronic and acute stress in healthy individuals. These findings support the use of rosemary extract as a natural dietary supplement for stress management.