Epigallocatechin gallate enhances sympathetic heart rate variability and decreases blood pressure in obese subjects: a randomized control trial

Abstract

This study aimed to investigate effects of epigallocatechin gallate (EGCG) on blood pressure (BP) and autonomic nervous system, indicated by 5-min heart rate variability (HRV) measurement in obese subjects, and determine correlations of BP with metabolic factors. In a double-blind, randomized controlled trial, obese subjects (n = 30) were randomly allocated to receive 150 mg EGCG (n = 15) or placebo (n = 15) twice a day without dietary restrictions. After 8-week EGCG treatment, systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) significantly decreased, while the low-frequency (LF) to high-frequency power (HF) ratio (LF/HF ratio) significantly increased (P < 0.05 all), indicating a shift toward sympathetic dominance, either directly or indirectly after BP lowering. SBP had positive correlations with obesity parameters, leptin, insulin, and insulin resistance but had a negative correlation with insulin sensitivity. DBP was positively correlated with age and HF in normalized unit, but negatively correlated with height and LF in ms². High-density lipoprotein cholesterol (HDL-C) was negatively correlated with SBP, DBP, and MAP reflecting its protective effect against elevated BP. In conclusion, the 8-week EGCG treatment decreased BP and increased the LF/HF ratio, reflecting increased sympathetic activity, either a direct EGCG effect or an indirect compensatory response following BP reduction.

Keywords: EGCG; HRV; Hormones; MAP; Metabolic; Obesity.

Fig. 1

The effect of EGCG treatment on time-domain heart rate variability. EGCG, Epigallocatechin gallate; SDNN, standard deviation of all NN intervals; SDSD, standard deviation of differences between adjacent NN intervals; RMSSD, the square root of the mean of the sum of the squares of differences between adjacent NN intervals; pNN50, percent of pNN50 count.

Fig. 2

The effect of EGCG treatment on frequency-domain heart rate variability. EGCG, Epigallocatechin gallate, VLF, power in the very low frequency range; LF ms², power in the low frequency range in ms²; LF nu, power in the low frequency range in normalized units; HF ms², power in the high frequency range in ms²; HF nu, power in the high frequency range in normalized units; LF/HF ratio, the ratio of LF ms² to HF ms², *P < 0.05.

Fig. 3

The summary of results. EGCG, Epigallocatechin gallate; BP, blood pressure; SBP, systolic blood pressure; DBP, diastolic blood pressure; MAP, mean arterial pressure; Sym., sympathetic; HRV, heart rate variability; LF nu, power in the low frequency range in normalized units; LF/HF ratio, the ratio of LF ms² to HF ms²; BMI, body mass index; % fat, fat percentage; HOMA-IR, Homeostatic Model Assessment for Insulin Resistance; HF nu, power in the high frequency range in normalized units; QUICKI, quantitative insulin sensitivity check index; HDL-C, high density lipoprotein cholesterol, LF power in ms², power in the low frequency range in ms², dotted arrows represent proposed mechanism, , positive correlations and regressions; , negative correlations and regressions; , first mechanism; , second mechanism.

Fig. 4

Allocation of subjects. The figure was adapted from a previous study under a Creative Commons license, which allows for use, sharing, adaptation, distribution, and reproduction with appropriate citation. BMI, body mass index; EGCG, Epigallocatechin gallate.