Tea, particularly green tea, has received widespread media coverage for studies revealing its health benefits but Professor Alan Crozier from the University of Glasgow says that the new findings show that coffee can also be considered a valuable source of antioxidants, supplementing those obtained from fruit and vegetables.
Research has already established the antioxidant activity of coffee and confirmed its antioxidant components - chlorogenic acid, also found in fruits, such as apples.
But Professor Crozier's research demonstrated for the first time the high bioavailability of such antioxidants when consumed in coffee.
Investigating the absorption of chlorogenic acid in the ileum, part of the small intestine, of volunteers, the researchers found that more than 75 per cent of the antioxidant had disappeared, being absorbed into the bloodstream before reaching the ileum.
The remaining 25 per cent would pass from the small to the large intestine where it may offer protection against colon cancer, Crozier told NutraIngredients.com.
"This is higher absorption than I've seen with other antioxidants," he said. "With green tea about 30 per cent of the antioxidants are absorbed altogether, but they shouldn't be regarded as competing with each other. More importantly it shows that all of these beverages are a useful supplement to the diet."
He cautioned however that producing such antioxidants in supplement form raises the risk of side effects as the natural ingredient is taken out of its normal matrix.
"It's important to eat a varied diet of fruit and vegetables so that your body can absorb a range of antioxidants. If you rely on supplements, with one tablet you could, for instance, be consuming the equivalent of 2 kilos of onions - not a very natural thing to do."
High doses of chlorogenic acid have been shown to raise concentrations of homocysteine in plasma, thought to be a marker for heart disease risk. But the antioxidant has also been shown to be a potent anti-inflammatory agent.
The findings were presented last week at the Society for Experimental Biology's annual meeting at Heriot-Watt University in Edinburgh and will be submitted for publication in a scientific journal.