Innovation: Sometimes it’s in the Cup in Front of You


Richard Gray, a writer with the Daily Telegraph, wrote a byline a couple of days ago about recent re-discoveries of the potential health benefits of drinking tea made from the leaves of the coffee plant. I say “re-discovery” because, as his article notes, there were attempts in the 1800s to try to sell the idea. As so often happens, many things that seem new to us were known to our ancestors; sometimes to innovate we just need to look at history:

Once it was a simple question: Tea or coffee? Now, after a scientific breakthrough that choice will become rather less straightforward.

The scientists found that “coffee leaf tea” contained high levels of compounds credited with lowering the risk of heart disease and diabetes. The leaves were found to contain more antioxidants than normal tea – which is already renowned for its healthy properties – and high levels of a natural chemical found in mangos known to combat inflammation.

The researchers believe the leaves of Coffea plants, as they are known scientifically, have been largely overlooked due to high value placed on coffee beans, which are actually seeds inside cherries produced by the small green shrub. These contain far fewer of the healthy compounds.

The researchers at the Royal Botanic Gardens in Kew, London, and the Joint Research Unit for Crop Diversity, Adaptation and Development in Montpellier believe coffee leaves could provide a new, healthy drink to rival coffee and traditional green or black tea. The drink, which contains low levels of caffeine, has earthy taste neither as bitter as tea nor as strong as coffee.

Dr Aaron Davies, a coffee expert and botanist at Kew Gardens who helped conduct the research, said coffee leaf tea was popular among some locals in places like Ethiopia and South Sudan and there had even been an attempt to market it in Britain in the 1800s. “In, 1851 people were touting it as the next tea and there were all these reports at the time about its qualities. I spent some time in Sudan and met a village elder who made it every day – she would hike for a couple of hours to collect the leaves to make tea,” he said.

“What was surprising was how many antioxidants are in the coffee leaves. They are much higher than those in green tea and normal black tea. There were also very high levels of a substance called mangiferin in the leaves of arabica coffee plants. This chemical was first extracted from mangos but has had lots of healthy properties attached to it.”

Dr Davies found samples of coffee leaf tea in the Kew collections that date back nearly 100 years. At the time, coffee producers in Sumatra and Java, in modern-day Indonesia, had attempted to popularise coffee leaf tea in the UK and Australia. Reports at the time claim the drink could offer immediate relief from hunger, fatigue and had the ability to “clear the brain of its cobwebs”. It was also described as refreshing, although there were some who described it as undrinkable.

Tests on 23 species of coffee plant by Mr Davies and Dr Claudine Campa from the Joint Research Unit for Crop Diversity, Adaptation and Development showed that seven had high levels of mangiferin in their leaves. Arabica coffee leaves were found to contain the highest levels of mangiferin, which has been found to have anti-inflammatory effects while also reduce the risk of diabetes, blood cholesterol, and protecting neurons in the brain.

The results, published in the scientific journal Annals of Botany, showed that arabica also had the highest levels of antioxidants – higher than those found in tea or traditional coffee.

“What is amazing though is that there is so much work that goes on into the healthy properties of tea, but coffee leaves have been completely overlooked,” Dr Davies said.

The researchers admit, however, the impact of the compounds found in coffee leaves on the human body requires further research. Studies on tea has found it to be rich in similar antioxidants that are thought to be beneficial against heart disease, diabetes and even cancer, although work is still being conducted to prove the role they play in the human body, too.

The health benefits of compounds in coffee beans, however, are more controversial, with some studies showing contradictory findings, although it has been reported to reduce the risk of diseases like Parkinson’s disease, dementia and heart disease.

Coffee leaf tea is not yet widely available, but is sold by some health food shops. Master tea taster Alex Probyn, who runs his own tea blending business and also advises Marks and Spencers on tea, tried coffee leaf tea while on a trip to Ethiopia and tested a sample that we obtained by mail order from a health food shop in the United States. He said: “When I tried it in Ethiopia, it had a very fresh flavour, a bit like cut grass that is similar to what you would expect from a green tea. There is not any hint of coffee in there and most people would struggle to identify it from other leaves.

“The coffee leaves have quite a pungent and greenish character – they are bitter but not unpleasant. The sample that you have has a slightly menthol and eucalyptus taste that makes me think something else has been added to it to soften the bitterness. If I could find a source, I would use coffee leaves in my own blends as I think it offers something that is a little bit different. The difficulty may be that coffee growers will want the leaves to stay on their plants so they can produce good beans.”

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