Metabolic and physiological effects of ingesting extracts of bitter orange, green tea and guarana at rest and during treadmill walking in overweight males

Abstract

Objective: This study examined the acute effects of ingesting a widely used commercial formula containing extracts of bitter orange, green tea and guarana (Gx) on the metabolic rate and substrate utilisation in overweight, adult males at rest (study 1) and during treadmill walking (study 2). Subjects: Two different groups of 10 sedentary males with more than 20% body fat participated in studies 1 and 2. Design: In each study, subjects participated in two experimental trials during which they were given two 500 mg capsules containing either Gx or a placebo (P) in a counterbalanced double-blind manner. Doses of the main active ingredients were 6 mg of synephrine, 150 mg caffeine and 150 mg catechin polyphenols. Measurements: In study 1, subjects completed 7 h supine rest with baseline measures taken during the first hour, with expired gases, blood pressure, heart rate and venous blood being collected every 30 min for the remaining 6 h following ingestion of Gx or P. In study 2, subjects exercised for 60 min at 60% heart rate reserve following ingestion of Gx or P 1 h previously. Venous blood samples were collected twice at rest and at 5,10,15,20,30, 40, 50 and 60 min, with expired gas measurements taken at 4, 9, 14, 19, 29, 39, 49 and 59 min. In both studies, venous blood was analysed for NEFA, glycerol, glucose and lactate concentrations, while expired gases were used to calculate ATP production from carbohydrate and NEFA, as well as the total substrate utilised. Results and conclusion: The results did not show any significant effect of Gx ingestion on total ATP utilisation during 6 h rest or during 60 min treadmill walking. Changes were observed in the relative contributions of CHO and NEFA oxidation to ATP production in both studies, such that there was an increase in ATP production from CHO and a decrease from NEFA. The increase in CHO oxidation was shown to be as high as 30% at rest.

Metabolic response to green tea extract during rest and moderate-intensity exercise

“…Our results are also in line with a number of studies that have demonstrated increases in whole-body EE and fat oxidation during resting conditions following GTE supplementation [7,11,12]. However, a number of studies have reported no difference in FFA or glycerol concentrations despite changes in whole-body measures of fat oxidation [13,31,32]. In the current study, fat oxidation rates were not measured during the rest period.…”

Blood orange juice inhibits fat accumulation in mice

“…For example, administration of ascorbic acid was more effective in counteracting oxidative stress when provided through orange juice than when supplemented as a simple water solution. 32 A few studies have shown the lipolytic activity of another component of orange juice, synephrine, 33,34 an adrenergic compound that could have adverse health effects. 35,36 Nevertheless, no difference in the amount of synephrine was found between Moro and Naveline juices.…”

Effect of an Energy Drink on Physical and Cognitive Performance in Trained Cyclists

“…proprietary blend failed to demonstrate any metabolic shifts in obese men at rest or during moderate walking exercise at 60% of VO 2max (Sale et al, 2006). The dose of guaraná delivered in this study was not explicitly stated, though it was less than 1262 mg.…”

“…Guaraná is primarily marketed as a thermogenic aid and as a weight-loss supplement. Guaraná has been studied as a thermogenic supplement but usually in combination with other ingredients (Bérubé-Parent et al, 2005;Haller et al, 2005;Sale et al, 2006) and rarely has it been studied in exercising humans (Sale et al, 2006).…”