You've likely seen the studies that argue green tea is a powerful brew of cancer-fighting antioxidants.

But new research shows that although green tea is high in catechins — antioxidants that have been shown to reduce the risk of chronic diseases like cancer and cardiovascular disorders — the amount of these substances that are available for absorption by the body are lower when they're consumed solely in tea.

The researchers believe that citrus juices and vitamin C protect catechins from oxidative damage in the intestine.
(CBC)

Under 20 per cent of catechins, which include EGC, EGCG, EC and ECG, remain after digestion, say the authors.

Scientists have discovered that mixing green tea with other substances, such as citrus juices, vitamin C and even soy milk and rice milk, increases the amount of the antioxidants that can be absorbed by the body.

The study is published in the November issue of Molecular Nutrition and Food Research.

According to Mario Ferruzzi, assistant professor of food science at Purdue University in Indiana, and the study's lead author, catechins break down in non-acidic environments, such as the intestines, leaving less than 20 per cent of the antioxidants to be absorbed after digestion takes place.

"We have to address this fact if we want to improve bodily absorption," he said in a release issued Tuesday.

Ferruzzi and his colleagues experimented by adding a variety of substances to green tea and then simulated digestion.

Citrus juices, including from limes, grapefruits, lemons and oranges, increased the levels of catechins by more than five times, with an 81 to 98 per cent recovery for EGC, 56 to 75 per cent for EGCG, 86 to 95 per cent for EC and 30 to 55 per cent for ECG.

Lemon juice was the most effective at preserving catechins in green tea, the study found.

Adding 30 milligrams of vitamin C to the green tea, increased recovery of the antioxidant ECG, EGCG, EC and ECG to 74 per cent, 54 per cent, 82 per cent and 45 per cent respectively.

The researchers believe that the juices and vitamin C protect the catechins from oxidative damage in the intestine. Juices also have fibre and polysaccharides that can protect the antioxidants, they theorize.

Green tea with 50 per cent cow's milk increased the amount of catechins to 52 per cent, soy milk raised it to 55 per cent and rice milk raised it to 69 per cent.