Acute, dose-response effects of guayusa leaf extract on mood, cognitive and motor-cognitive performance, and blood pressure, heart rate, and ventricular repolarization.

2024-07-16
Journal of the International Society of Sports Nutrition 21(1)
- Nathaniel J Helwig
- Laura E Schwager
- Alexander C Berry
- Anna C Zucker
- Jacob S Venenga
- Samantha C Sterbenz
- Nathaniel D M Jenkins

PubMed: 39014963
DOI: 10.1080/15502783.2024.2379424

Study Design

Type: Randomized Controlled Trial (RCT)
Population: 25 adults (mean ± SD, age = 28 ± 7 y; 9 M/16 F)
Methods: Randomized, double-blind, placebo-controlled crossover trial; participants consumed 600 mg or 1200 mg GLE or placebo on three separate visits
Blinding: Double-blind
Funding: Unclear

Purpose

We conducted a randomized, double-blind, placebo-controlled crossover trial in young adults to examine the dose-dependent (600 mg versus 1200 mg), acute effects of consumption of an Ilex guayusa tea extract (GLE) on mood, cognitive and motor-cognitive performance, as well as its acute cardiovascular effects.

Methods

Twenty-five adults (mean ± SD, age = 28 ± 7 y; 9 M/16 F) completed familiarization and then three randomly ordered experimental visits where they consumed either 600 mg (GLE₆₀₀) or 1200 mg (GLE₁₂₀₀) GLE or placebo (PLA). Following supplement consumption, participants completed a mood state survey, assessments of perceived jitteriness, energy, and focus, and neurocognitive and motor-cognitive testing. Blood pressure (BP), heart rate, and QT interval length were determined before and after supplementation.

Results

GLE₆₀₀ significantly improved total mood disturbance (mean ± SE difference = -6.9 ± 2.6 au, p = 0.034), fatigue-inertia (-2.84 ± 0.89 au, p = 0.008), perceived energy (+13.00 ± 4.49 au; p = 0.02), motor speed (+4.52 ± 1.42 au, p = 0.008), and psychomotor speed (+7.20 ± 2.16 au, p = 0.005) relative to PLA. GLE₁₂₀₀ also improved psychomotor speed (+5.08 ± 2.16 ms, p = 0.045) and uniquely increased motor-cognitive performance as reflected by a decrease in reaction time (-0.106 ± 0.04 ms, p = 0.026) during a neurocognitive hop test. The effect of GLE on jitteriness was both dose- and sex-dependent. Jitteriness increased with increasing GLE dose in women only (p < 0.001). Both GLE₆₀₀ and GLE₁₂₀₀ similarly increased systolic and diastolic BP by 4-5 mmHg (p ≤ 0.022). Neither GLE₆₀₀ nor GLE₁₂₀₀ acutely influenced QTc length (p = 0.31).

Conclusions

The goal of GLE supplementation should be considered when selecting a dosing strategy. Lower dosages of GLE (e.g. 600 mg) appear to optimize cognitive and mood-related outcomes while limiting side-effects such as jitteriness in women, and higher dosages may be necessary (e.g. 1200 mg) to promote improvements in motor-cognitive performance.

Research Insights

Guayusa→Changed QT Interval Length
Neither GLE600 nor GLE1200 acutely influenced QTc length (p = 0.31)
Effect
Neutral
Effect size
Small
Dose
600 mg and 1200 mg
Guayusa→Improved Mood Disturbance
GLE600 significantly improved total mood disturbance (mean ± SE difference = -6.9 ± 2.6 au, p = 0.034)
Effect
Beneficial
Effect size
Small
Dose
600 mg
Guayusa→Improved Motor Speed
GLE600 significantly improved ... motor speed (+4.52 ± 1.42 au, p = 0.008)
Effect
Beneficial
Effect size
Small
Dose
600 mg
Guayusa→Improved Psychomotor Speed
GLE1200 also improved psychomotor speed (+5.08 ±
Effect
Beneficial
Effect size
Small
Dose
1200 mg
Guayusa→Increased Energy Levels
GLE600 significantly improved ... perceived energy (+13.00 ± 4.49 au; p = 0.02)
Effect
Beneficial
Effect size
Small
Dose
600 mg
Guayusa→Increased Jitteriness
Jitteriness increased with increasing GLE dose in women only (p < 0.001)
Effect
Harmful
Effect size
Small
Dose
600 mg and 1200 mg
Guayusa→Increased Systolic Blood Pressure
Both GLE600 and GLE1200 similarly increased systolic BP by 4-5 mmHg (p ≤ 0.022)
Effect
Harmful
Effect size
Moderate
Dose
600 mg and 1200 mg
Guayusa→Reduced Diastolic Blood Pressure
Both GLE600 and GLE1200 similarly increased diastolic BP by 4-5 mmHg (p ≤ 0.022)
Effect
Harmful
Effect size
Moderate
Dose
600 mg and 1200 mg
Guayusa→Reduced Fatigue-Inertia
GLE600 significantly improved ... fatigue-inertia (-2.84 ± 0.89 au, p = 0.008)
Effect
Beneficial
Effect size
Small
Dose
600 mg
Guayusa→Reduced Mood Disturbance
GLE600 significantly improved total mood disturbance (mean ± SE difference = -6.9 ± 2.6 au, p = 0.034)
Effect
Beneficial
Effect size
Moderate
Dose
600 mg
Guayusa→Reduced Reaction Time
a decrease in reaction time (-0.106 ± 0.04 ms, p = 0.026)
Effect
Beneficial
Effect size
Small
Dose
1200 mg

Adverse Events Reported

Guayusa→diastolic blood pressure increase
Both GLE600 and GLE1200 similarly increased systolic and diastolic BP by 4-5 mmHg (p ≤ 0.022).
Finding
Increased risk
Magnitude
increased by 4-5 mmHg
Significant
Yes
Guayusa→diastolic blood pressure increased
Both GLE600 and GLE1200 similarly increased systolic and diastolic BP by 4-5 mmHg (p ≤ 0.022).
Finding
Increased risk
Magnitude
increased diastolic BP by 4-5 mmHg
Significant
Yes
Guayusa→jitteriness
The effect of GLE on jitteriness was both dose- and sex-dependent. Jitteriness increased with increasing GLE dose in women only (p < 0.001).
Finding
Increased risk
Significant
Yes
Guayusa→systolic blood pressure increase
Both GLE600 and GLE1200 similarly increased systolic and diastolic BP by 4-5 mmHg (p ≤ 0.022).
Finding
Increased risk
Magnitude
increased by 4-5 mmHg
Significant
Yes
Guayusa→systolic blood pressure increased
Both GLE600 and GLE1200 similarly increased systolic and diastolic BP by 4-5 mmHg (p ≤ 0.022).
Finding
Increased risk
Magnitude
increased systolic BP by 4-5 mmHg
Significant
Yes
Guayusa→qtc interval prolongation
Neither GLE600 nor GLE1200 acutely influenced QTc length (p = 0.31).
Finding
No significant difference
Significant
No
Guayusa→qtc prolongation
Neither GLE600 nor GLE1200 acutely influenced QTc length (p = 0.31).
Finding
No significant difference
Significant
No