Study: Citrus Juice, Vitamin C Boosts Antioxidants in Green Tea

If you take lemon with your green tea you're probably giving your body an extra boost, according to a recent study from Purdue University. Citrus juice added to green tea caused more of the beverage's antioxidants to persist through simulated digestion. This suggests that adding vitamin C or citrus juices such as lemon, orange, and lime results in more available antioxidants at the absorption phase. Of all the juices tested, lemon had the most affect on antioxidant recovery.

The study's lead author and assistant professor of food science at Purdue University, Mario Ferruzzi, said the results were preliminary but encouraging. The antioxidants found in tea are catechins, which may be the source of the reported benefits of green tea. However, catechins become unstable in a non-acidic environment and less than 20 percent of the amount originally ingested remains after entering the intestines.

"Off the bat you are eliminating a large majority of the catechins from plain green tea," Ferruzzi said. "We have to address this fact if we want to improve bodily absorption."

Several additives that are commonly used with fresh brewed or ready made tea products, such as creamers, juices, and ascorbic acid, were tested during the study. Two of the most abundant kind of catechins were recovered six fold and thirteenfold, respectively, in ready to drink products that included ascorbic adid, or vitamin C. Vitamin C is used for flavor and to increase shelf life. In fresh brewed tea, the catechin levels recovered more fivefold with the addition of fresh citrus juice.

The data showed that citrus juice had a stabilizing affect greater than what was predicted by their vitamin C content. That suggests that other chemicals in citrus juice contribute to the improvement as well. Lemon juice was by far the most effective additive, causing 80% of the catechins to remain. Orange juice came in second place, with lime and grapefruit juices being the third and fourth most effective.

"If you want more out of your green tea, add some citrus juice to your cup after brewing or pick a ready-to-drink product formulated with ascorbic acid," Ferruzzi said.

Black tea, which is produced by fermenting green tea, has less cetchins but could also be enhanced with the addition of citrus of vitamin C, Ferruzzi said.

Catechins from green tea are an important class of antioxidants because studies have shown that they are able to detoxify toxic chemicals as well as inhibit cancer cell activity. They also stimulate immune strengthening enzymes. Current and planned studies will take the research further by looking at how metabolic factors influence whether the increased levels of catechins are actually able to be used by the body.

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Perdue University, Citrus Juice, Vitamin C Give Staying Power to Green Tea Antioxidants