Abstract
BACKGROUND/OBJECTIVE: Paprika xanthophylls (PXs) have potent antioxidant properties and are believed to improve oxygen delivery (DO(2)) efficiency by enhancing red blood cell (RBC) deformability. This study investigated whether PX ingestion improves endurance performance and subsequently enhances cognitive function by improving brain microcirculation. METHODS: A crossover design was used to compare the effects of PX ingestion and a control condition in 21 healthy college students (18 males, 3 females). Each participant served as their own control, completing both conditions in a randomized order with a one-month washout period to eliminate any carryover effects. The participants underwent an incremental load test, a constant load test, the Trail Making Test Type B (TMT-B), and the Stroop test (ST). RESULTS: In the incremental tests, the PX group showed a significantly lower heart rate (p = 0.032) and higher exercise efficiency (EE) (p = 0.004). In the constant load test, heart rate was lower (p = 0.020), and EE was higher (p = 0.030). No significant between-group differences were found in the cognitive tests; however, the PX group showed significant improvements in the TMT-B (p = 0.034) and ST interference rate I (p = 0.040). CONCLUSIONS: It is speculated that PX intake may improve DO(2) efficiency, which could contribute to the observed enhancements in endurance performance and, in turn, positively affect cognitive function by optimizing the brain's oxygenation state. However, due to the absence of a placebo control group and unmeasured RBC deformability and cerebral blood flow, as well as a significant male predominance, this study's results should be interpreted with caution.