Researchers in Japan investigated whether paprika xanthophyll (PX) ingestion improved endurance performance and enhanced cognitive function by improving oxygen microcirculation.
“This could be a new nutritional strategy to concurrently boost both endurance performance and cognitive function,” they wrote in the journal Nutrients.
Paprika enhances oxygen delivery and endurance
The ability to perform well in endurance exercise is dependent on how efficiently the body can deliver and use oxygen, measured in maximal oxygen uptake (VO₂ max), anaerobic threshold and exercise efficiency (EE).
Red blood cell (RBC) deformability, the ability of red blood cells to change shape to deliver oxygen throughout the body, and microcirculation play a key role in oxygen use. When impaired, these factors can reduce oxygen diffusion and endurance capacity. Recent research has explored how antioxidant nutrients can improve oxygen delivery efficiency (DO₂)—how effectively inhaled oxygen reaches the bloodstream.
“Several studies on humans have shown that paprika xanthophyll (PX) found in red paprika possesses antioxidant properties similar to other xanthophylls, such as lutein and zeaxanthin,” the researchers wrote.
“Notably, capsanthin and capsorubin, which are the primary xanthophylls in red paprika, are considered to exhibit high scavenging activity against reactive oxygen species.”
Those pigments are also present in RBCs, which the authors noted suggests PX contributes to a reduction in oxidative stress and improved DO₂ efficiency. Furthermore, PX intake has been shown to reduce heart rate and oxygen consumption during exercise and improve EE. This may suggest an ability to enhance endurance performance through improved DO₂ efficiency, according to the researchers.
DO₂ efficiency may also impact cerebral microcirculation, as regions in the brain responsible for working memory, abstract reasoning, planning, cognitive flexibility and attention regulation depend on adequate oxygenation. However, the researchers noted that few previous PX studies have investigated brain effects.
Boosting physical and mental performance in recreational athletes
The researchers recruited 21 healthy students who all engaged in recreational sports but were not trained athletes to participate in the randomized crossover controlled trial with two conditions: control and PX supplementation separated by a one-month washout period.
Participants took one plant-based capsule daily with breakfast, containing 9 mg paprika xanthophylls—a branded extract by Japanese supplier Glico Nutrition —for one month.
During each condition, participants were assessed on physical and cognitive performance through a battery of tests.
Results showed improvements in physical performance with PX supplementation. Across both gradual intensity tests and steady workload tests, the PX group’s heart rate was lower, and participants used energy more efficiently.
The researchers noted that the PX supplementation appeared to optimize the quality of oxygen delivery rather than the total amount of oxygen delivered, as evidenced by improved physical performance without changing VO₂ peak. This was likely due to the antioxidants capsanthin and capsorubin in PX preserving deformability and supporting microcirculation, they explained.
In cognitive tests, no significant differences were found between groups; however, the PX intervention improved attention, cognitive flexibility, focus and ability to ignore distraction. The researchers noted that the results suggest that PX optimized DO₂ in brain regions with high oxygen demand, allowing better support for cognitive tasks during and after exercise.
“It is speculated, based on these findings, that PX intake may improve DO2 efficiency, possibly through the maintenance of RBC deformability and a reduction in blood flow resistance,” the researchers concluded. “Future research is needed to more clearly elucidate these mechanisms by directly assessing RBC deformability and localized cerebral blood flow.”
Source: Nutrients. doi: 10.3390/nu17172780. “Effects of Paprika Xanthophyll Intake on Endurance and Cognitive Function in College Students: A Crossover Randomized Controlled Trial”. Authors: Kim, D. et al.
