Effects of Paprika Xanthophyll Intake on Endurance and Cognitive Function in College Students: A Crossover Randomized...

Paprika xanthophylls (PXs) have potent antioxidant properties and are believed to improve oxygen delivery (DO₂) 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.

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).

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).

It is speculated that PX intake may improve DO₂ 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.