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Visitor Questions
Q I have read that the decaf green tea has in fact lost a lot of the antioxidants during the process of taking the caffeine out. Is that right?

We have an FAQ that will answer your questions; read below to learn more. Lemon juice added to green tea may actually help improve the bioavailability of the antioxidants; we are not aware of any evidence that has shown the lemon juice will damage the antioxidants. We are also not aware of evidence to indicate that green tea polyphenols will decrease as the tea cools.

How does the nutrition analysis of regular green tea compare with decaffeinated green tea?

In general, decaffeinated green tea is simply a more processed form of the green tea that has not been decaffeinated. Like all foods, green tea will have its nutrient content reduced as it becomes more and more processed. It would be very rare for a processed food to contain the same amount of nutrients, or more nutrients, than a processed food. (The only exceptions would be artificially fortified or enriched foods that have had vitamins or other nutrients deliberately added back during the manufacturing process.)

All green teas undergo some processing since some form of heat is necessary to stop the oxidation processes that occur naturally with freshly picked tea leaves. However, this processing can be very minimal and can leave the vast majority of nutrients intact.

Decaffeination of green tea is not quite as simple. There are three basic ways in which caffeine gets removed from tea leaves.

In one method, compressed carbon dioxide (CO2) is combined with water to create a solution that will draw caffeine (and other substances) out from the leaves. Once the tea leaves have been soaked in this solution, they are removed, and the solution can then be passed through an activated carbon filter to remove the caffeine. The tea leaves can then be re-immersed in the solution so that some of the lost flavoring components can be restored. This method of green tea decaffeination is sometimes called the effervescence or CO2 method.

A second approach is to soak the leaves in water for an extended period of time to allow for the release of caffeine (and other substances) from the leaves, then to remove the leaves and add a chemical solvent like ethyl acetate to the caffeine-containing water. Once this solvent has extracted the caffeine, the tea leaves can be re-immersed in the water to allow the natural flavors (and other factors) to be restored.

A third approach is to use hot water alone as an agent for removing caffeine from the tea leaves. Approximately three minutes of boiling is sufficient to reduce the caffeine content of green tea leaves by about 80-85%.

The second method of decaffeination is definitely one I do not recommend since the tea leaves are returned to water that has trace (or higher) residues of ethyl acetate. Even though ethyl acetate can be a naturally occurring substance (it's present in several common fruits, for example), it's also a known toxin in high doses and at these high doses is known to disrupt activity in the liver, respiratory system, and central nervous system. The other two approaches—effervescence using CO2 or hot water alone—seem like lower risk approaches to me.

There is no question that some nutrients are lost from green tea in any decaffeination process. I've only seen two published studies in this area, however. I have been impressed by one very recent research study that showed very little loss (about 5%) of certain key phytonutrients (called catechins) from hot-water-decaffeinated green tea leaves. It's important to note, however, that this study involved fresh tea leaves that had been neither dried nor rolled. The researchers themselves pointed out that far more catechins were lost in the case of dried or dried/rolled tea leaves. Still, it's encouraging that at least in this one particular case, a decaffeination process could result in so little damage to these components.

These research results pointed in the same general direction as an animal study I found that showed significant skin protection from nutrients in water-decaffeinated green tea. In comparison with non-processed green tea, water-decaffeinated green tea lost about 16% effectiveness in protecting the skin cells of mice. I am uncomfortable trying to draw any conclusions about human consumption of decaf green tea from a single study on mice. But once again, it is encouraging to see results that point in the same general direction as the phytonutrient loss study that I described earlier.

For individuals sensitive to caffeine, or individuals simply choosing to follow a caffeine-free diet, water-decaffeinated green tea or effervescence-decaffeinated green tea makes good sense to me. There is definitely a nutrient loss that occurs in the decaffeination process, but the degree of loss seems like a good trade-off for individuals who need or choose to avoid caffeine.

References

  • Lianga H, Liang Y, Donga J, et al. Decaffeination of fresh green tea leaf (Camellia sinensis) by hot water treatment. Food Chemistry. 2007;101(4)4:1451-1456.
  • Wang ZY, Huang MT, Lou YR, et al. Inhibitory effects of black tea, green tea, decaffeinated black tea, and decaffeinated green tea on ultraviolet B light-induced skin carcinogenesis in 7,12-dimethylbenzanthracene-initiated SKH-1 mice. Cancer Res. 1994 Jul 1;54(13):3428-35.

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