Multi-ingredient energy dietary supplement with a small amount of caffeine modulates central and autonomic nervous...

Most research on the impact of neurostimulatory substances on brain function and human behavior focuses on the adverse effects of their high doses or long-term use. However, little is known about the impact of single doses that contain psychostimulants only in a small amount. Therefore, we investigated the acute effect of an energy dietary multi-ingredient supplement with a low amount of caffeine (55 mg) on the ANS in a double-blind, placebo-controlled study (47 participants, 27 women). Previously, we reported its impact on the activity of the CNS through changes in the resting state EEG (rsEEG) pattern and event-related brain potentials by reversing the fatigue-related brain activity. Here, we show that supplementation also influences the ANS through changes in heart electrophysiology. The supplement changed the PRQ and QTc intervals in the ECG signal. In addition, LF power changes were correlated with the changes in rsEEG, which we reported earlier. These findings show that a single dose of dietary supplementation with a much smaller dose of caffeine than in typical caffeinated products may still impact both the CNS and ANS. The results indicate that using such products before electrophysiological examinations in research, diagnostics, and treatment should be considered to control confounding factors. Finally, since the effects were elicited by an energy boost supplement in the mentally fatigued participants, it may be of special importance and enable translation into treatments related to attention, anxiety, mood, and memory disorders.