L - more than 60 times the concentration of caffeine in cola beverages. The product was not sold as a drink in a supermarket but as a tonic in a health food shop. The seeds contain between 3.6 per cent and 5.8 per cent caffeine. The substance is named after the Guarani Amazonian tribe that originally used the seeds to brew a drink. Such products are widely available at pharmacies and natural food outlets, and are marketed as 'natural sources of energy'.
Caffeine is a natural alkaloid methylxanthine.
It relaxes smooth muscle, stimulates skeletal muscle, has a weak diuretic action and its metabolic effects include hypoglycaemia. The toxic effects of caffeine include vomiting and abdominal pain as well as CNS symptoms including agitation, altered conscious state, rigidity and seizures. Most deaths associated with caffeine intoxication have occurred after overdose with diet pills and stimulants and most have occurred in young patients without known underlying heart disease. Consumers beware The authors Marianne Cannon, Clive Cooke and James McCarthy said there is an obvious potential for lethal overdose with the growing use of guarana-based products containing high levels of caffeine. The case also shows the need for medical practitioners to be familiar with the more widely used 'natural remedy' substances and their toxicological profile.