Acute effects of Hibiscus sabdariffa on blood pressure and cognitive function.

Introduction: Hibiscus sabdariffa is well known for its blood pressure lowering properties, particularly in hypertensive individuals. To date, effects of hibiscus on cognitive performance have not been assessed, hence the current pilot study explored the acute effects of hibiscus consumption on cognitive performance and metabolic outcomes in overweight individuals.

Methods: Twenty participants aged 35 ± 2.8 years with a BMI of 30 ± 1.2 (kg/m²) were recruited to a randomised, placebo-controlled crossover study. Participants received either a hibiscus-containing beverage or an inert placebo alongside a high carbohydrate breakfast. Metabolic and cognitive measures were assessed across a 2-hour postprandial period.

Results: Consumption of the hibiscus drink significantly reduced postprandial glucose response compared to placebo after 30 and 45 min, with no change in blood pressure. Hibiscus consumption significantly attenuated the decline in delayed word recall on the visual verbal learning test. Additionally, there was a decrease in retroactive interference after hibiscus, suggesting that newly learned information interfered less with recall of previously learned information in comparison to placebo. Furthermore, non-significant improvements (p = 0.063) in executive function and pattern separation were observed following hibiscus consumption.

Conclusion: To summarise, this pilot study demonstrates that acute hibiscus consumption moderately affects aspects of memory and executive function, coupled with beneficial effects on postprandial glucose response. Further research is warranted to confirm these findings in larger sample sizes and to determine the effect of longer-term consumption of hibiscus on these outcomes.