The acute effect of flavonoid-rich apples and nitrate-rich spinach on cognitive performance and mood in healthy men and women.
Level 2 - randomized trial
Individual randomized controlled crossover trial
PubMed 24676365 · doi:10.1039/c3fo60590f
What was done
In a randomized, controlled crossover trial, 30 healthy men and women received four energy-matched acute treatments: control, flavonoid-rich apple, nitrate-rich spinach, and combined apple plus spinach. Investigators measured circulating nitric oxide status via plasma S-nitrosothiols and other nitroso species (RXNO), as well as plasma, salivary, and urinary nitrate and nitrite levels. Cognitive function was evaluated using the Cognitive Drug Research computerized assessment battery alongside mood ratings.
What was found
Relative to control, all active treatments (apple, spinach, and apple plus spinach) resulted in higher plasma RXNO. Treatments containing spinach (spinach alone and apple plus spinach) produced statistically significant increases in plasma, salivary, and urinary nitrate and nitrite compared with control. No significant effect was observed on cognitive function or mood. The abstract reports directional findings without providing exact numerical values or effect sizes.
Why it matters
Flavonoids and nitrate acutely augment circulating nitric oxide biomarkers, but these acute biochemical shifts do not translate into immediate improvements in cognitive performance or mood in healthy adults.
Limits
The trial had a small sample size of 30 healthy participants and tested only acute single-dose effects, meaning chronic supplementation effects were not evaluated. The abstract provides no exact numerical data, p-values, or confidence intervals, and testing in healthy adults may be prone to cognitive ceiling effects.
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