ORIGINAL ARTICLELipid metabolism in trained rats: Effect of guarana (Paullinia cupana Mart.) supplementation
Introduction
Guarana (Paullinia cupana Mart. var. sorbilis), a sprawling shrub or woody vine, found in northern Brazil,1 is widely used as a flavouring for soft drinks, and in the composition of a variety of dietary supplements throughout the world. It is claimed to have stimulant and ergogenic properties and to be of therapeutic value for a variety of conditions, showing alleged antidiarrheic, diuretic, and antineuralgenic properties.2, 3 Guarana has been shown to have an antioxidant effect,3 to inhibit platelet aggregation,4, 5 and to have a gastroprotective action.6 In Brazil, the use of guarana by athletes is widespread, with claims of performance improvement, and it has also been adopted as a supplement in the diet of racing horses.7 Guarana and Ma Huang mixtures are commercialized as weight reducing supplements, and seem to effectively promote fat loss in overweight subjects,8 despite considerable adverse effects.9
The role of changes in lipid metabolism in the anedoctal weight loss induced by guarana consumption has never, to our knowledge, however, been previously investigated. The existing studies assume that the effects of guarana equal those of caffeine, what is not necessarily true.
Guarana seeds contain caffeine (2.5–5%), theobromine and theophylline (small amounts), and tannins (up to 16%).10 Although the methylxantine content of guarana may explain many of the effects attributed to the plant, some studies demonstrated that treatment of rats with caffeine in similar doses to those found in guarana fails to induce many of the responses observed after guarana supplementation.2 It was thus suggested2, 3 that tannins could play a part in these responses to guarana supplementation.
The aim of this study was to examine the effects of guarana supplementation upon tissue lipid metabolism in rats receiving different doses of aqueous extract of guarana (GE), and compare the results with those presented by animals whose diet was supplemented with decaffeinated guarana extract (DG), hence isolating the influence of the methylxantine content from that of other components present in the extract. Trained rats were included in the study as to allow the comparison of the effects of exercise and supplementation upon lipid metabolism. An intermittent exercise training protocol was chosen, since anecdotal evidence shows frequent consumption of guarana is common (67%) among male teenager (14–18 years-old) volleyball and other court sports players in Brazil.
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Materials
Solvents, buffer reagents, and Tween 20 were purchased from LABSYNTH (Brazil); palmitoyl CoA, carnitine, albumin, lipid standards, and solvents for HPLC and mass spectrometry from the Sigma Chemical Co., USA. 14C-oleate and 3H-carnitine were purchased from Amersham, UK.
Guarana powder (batch GUAR04/01, P. cupana HBK, Sapindacea) was the kind gift from Santos Flora Ervas Medicinais Ltd. (Brazil).
Obtainment and analysis of guarana extracts
One litre of an ethanol:water solution (6.6:3.4 v/v) was added to each 2 kg of guarana crude powder and
Results
Guarana supplementation with the higher dose studied caused, after 14 days, the decrease of the total intake of food (Table 3), which was not found when the decaffeinated extract was supplemented. Although the total weight gain in the same period was not significantly changed by treatment with whole GE, both doses of DG induced lower weight gain in the period as compared with controls, despite the lack of difference in food consumption. Training reduced the weight gain rate of all groups. Water
Discussion
Guarana (Paullinia cupana) consumption is increasing in the world, as it takes part in the composition of many commercial dietary supplements,28 as a weight loss-promoting adjuvant.8 In Brazil, GE has been also used as a stimulant and in the therapeutics of depression, fatigue, and migraine.29
Although caffeine is considered to be the active component of guarana, there is evidence that its other components may also be involved in the response to supplementation.2, 3 Although there is extensive
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