The short‐term effects of black pepper (Piper nigrum) and rosemary (Rosmarinus officinalis) on sustained attention and energy and fatigue mood states in young adults with low energy

Abstract

The aim was to test if black pepper (2 grams) or rosemary (1.7 grams) improved sustained attention, motivation, or feelings of mental energy and fatigue. Outcomes were measured in 40 low‐energy adults before and 60‐ and 90‐minutes after consumption of capsules containing black pepper, rosemary or a placebo (3.1 grams flour). Sustained attention was measured using a 16‐minute dual task in which single digit numbers were presented every second on a screen and the participant performed both a primary task (detection of three successive, different odd digits) and a secondary task (detect the number 6). Feelings of energy and fatigue were measured using the vigor and fatigue subscales of the Profile of Mood States and visual analog scales (VAS). ANOVAs showed non‐significant Condition X Time effects for motivation, also measured with a VAS, and the intensity of energy and fatigue feelings. Time‐varying ANCOVA, controlling for motivation, showed no significant effects on the primary or secondary task outcomes of: correct responses, errors, speed of response and signal detection sensitivity. It is concluded that black pepper and rosemary, consumed in capsule form, in the doses used and while wearing a nose clip to block olfactory effects, do not induce a short‐term improvement in sustained attention, motivation to perform cognitive tasks, or feelings of mental energy and fatigue in young adults with low energy.