Guarana: Background. Actions
Guarana has been used bythe Amazonian Indians of South America for centuries to enhance energy levels, suppress appetite, increase libido and protect them from malaria. More recently, hot guarana beverages have been adopted bythe greater population as a tonic to enhance wellbeing, in much the same way coffee is drunk in Australia.
Brazilian cocoa, guarana gum, guarana paste, quarana, quarane, uabano, uaranzeiro, zoom
Botanical Name / Family
Paullinia cupana (family Sapindaceae)
Plant Part Used
Guarana seeds are a rich source of caffeine, containing 3-6% on a dry weight basis. Other major compounds include theobromine, theophylline, tannins, resins, protein, fat and saponins.
A review of the scientific literature reveals that guarana itself has only recently been the subject of clinical studies. As such, studies pertaining to caffeine are sometimes used to explain the herb’s action, an approach that presupposes the other constituents are either inactive or of such weak effect they need not be recognised. Although this approach is convenient and provides us with some understanding of the herb’s pharmacological effects, the results of three recent clinical studies suggest that guarana’s effects on cognitive function are due to more than its caffeine content.
Although guarana has not been clinically investigated for its effects on the CNS there is a great deal of evidence to show that caffeine is an antagonist of the adenosine receptor, which produces a net increase in CNS activity because the inhibitory action of adenosine is blocked. This results in the release of a variety of neurotransmitters (e.g. noradrenaline, acetylcholine, dopamine, and the GABA/benzodiazepine system).
INHIBITS PLATELET AGGREGATION
Guarana inhibits platelet aggregation both in vitro and in vivo. Decreased thromboxane synthesis may in part explain this activity.
MAY INCREASE GASTRIC ACID SECRETION AND DELAY GASTRIC EMPTYING
This has been demonstrated in a clinical study using a herbal combination known as ‘YGD’, which contains yerbe mate (leaves of Ilexparaguayenis), guarana (seeds of Paullinia cupana) and damiana (leaves of Turnera diffusa var. aphrodisiaca). Whether stand-alone treatment with guarana will produce similar effects is unknown.
Guarana has been shown to be chemoprotective in a mouse hepatocarcinogenesis model. The herb was found to reduce the cellular proliferation of preneoplastic cells.
In vitro data has demonstrated the antibacterial and antioxidant effects of the ethanolic extract of guarana, thought to be due to the phenolic compounds. Guarana was shown to be effective against many pathogens of the digestive tract including Escherichia coll, Salmonella typhimurium and Staphylococcus aureus. This adds weight to the traditional use of guarana for diarrhea.
RELATING TO CAFFEINE CONTENT
Although these have not been tested for guarana directly, the caffeine content, which is well absorbed from the herb, may cause mild dilation of the blood vessels; an increase in blood pressure, renin and catecholamine release, urine output, metabolic rate, lipolysis, respiration, intestinal peristalsis; and inhibition of CYP1A2. Caffeine also possesses thermogenic properties.