Green tea is consumed world wide for the benefit of the catechins it contains. Catechins are a class of chemical compounds with anti-oxidant and anti-inflammatory properties, as well as other healthy ingredients. It has been discovered by researchers at the University of Sao Paulo’s Public Health School that guarana is a worthy competitor as far as catechins are concerned. The seeds of this tropical shrub are used in fizzy drinks that are among the most popular in Brazil and over-the-counter supplements. Guarana contains more than 10 times the amount of catechins founds in green tea.
In a clinical trial with healthy human volunteers, it has demonstrated that guarana is a rich source of catechins and when properly absorbed, reduces the oxidative stress associated with the development of neurodegenerative and cardiovascular disorders
Other conditions as diabetes, cancer, inflammation and premature aging due to cell death, are associated with guarana. Above all, it has always been seen as a stimulant because of its high caffeine content. This study is featured in Food & Function and published by the Royal Society of Chemistry in the United Kingdom.
The two-stage study was conducted over one month. Volunteers were selected that were healthy, but slightly overweight, and with a moderately elevated risk of cardiovascular disease. They measured the baseline parameters on the first day and evaluated the same items again on day 15 after the implementation of a controlled diet. The participants were then asked to take guarana at home every morning before breakfast for the next fortnight. Bottles containing guarana seed powder were given to the volunteers and they were instructed to prepare a daily drink with the contents of one bottle in 300 ml of water.
The same volunteers’ blood tests were compared at different times to avoid influence of variability between individuals. The acute effect of guarana was measured one hour after the participants drank the solution on day 1 and day 15. Researchers assessed the extent to which guarana affected oxidative stress markers during the two-week intervention period. The tests performed showed an increase in oxidation resistance of the LDL in the blood samples taken from the volunteers after they drank guarana. Oxidative stress markers included oxidation of low-density lipoprotein or “bad” cholesterol. A cornet assay was also performed, analyzing DNA damage in individual cells due to various factors, including oxidative stress.
All the markers depended on the presence of catechins in the bloodstream. Improvement in the parameters they assessed was associated with a rise in the concentration of plasma catechins after guarana intake, showing that guarana was indeed responsible for this effect.
Tests showed increased glutathione peroxidase and catalase activity, both shortly after guarana ingestion, and on the following day. This suggests the bioavailability of guarana catechins is equal to or greater than that of green tea, cocoa and chocolate catechins. Their bioavailability was sufficient to have a positive effect on plasma anti-oxidant activity, protect erythrocyte DNA and reduce plasma lipid oxidation.
–Dr Fredda Branyon