By Lori Bricker, MS, RD
The other day I received the following questions in my email from a student doing a project on tea and health. I thought these sounded like fine questions, so I’m posting them with my answers here.
What is the main benefit of drinking tea? It’s really difficult to pick one thing. The research being done these days covers so many interesting topics, including heart disease, cancer, Parkinson’s disease, cognitive function, blood vessel function, mood, stress, weight loss, dental health — the list goes on and on. But not all of these studies have found definitive answers to our questions about tea and health, and sometimes even conflicting results are found. Much more research needs to be done to pin down the intricacies of how tea affects our bodies. So rather than focus on one benefit, I usually think of tea as a way to improve overall health and well-being. There are few people who can’t benefit in one way or another from drinking reasonable amounts of tea on a regular basis. Even one cup has been shown to offer some benefits. The other question that people always ask is whether green tea is better for you than black tea. It is becoming apparent that all kinds of tea are good for you: black, green, oolong, and white. (Herbal teas are not true “teas” in that they are not made from the Camellia sinensis plant – so those are really completely different topic.) I encourage people to drink all kinds if they like them, and if they only like one kind, then just drink that one. Drinking tea should not be a chore. It is a very pleasant activity, and that in itself may contribute to some of its effects on our mood and stress level.
Could you say that tea helps increase longevity? How so? Perhaps. There was a study published this year that found that Chinese men who drink more than 3 cups a day of tea have longer telomeres. Telomeres are part of our chromosomes. They are a repetitive piece of DNA located at the ends of our chromosomes, and each time a cell divides, a bit of this telomere gets sheared off and shortened. Telomeres protect our DNA from being damaged during cell division, much like the end of a shoelace protects the shoelace from unraveling. Once the telomeres are gone, our DNA is subject to degradation during cell division, and animal studies suggest this plays an important role in aging at the cellular level. (See this Wikipedia article for more detail about telomeres.) The mechanism by which tea might protect telomeres is not known at this time. Another recent study found a correlation between green tea intake and reduced death rate from all causes – there could be many different things at work here. If tea consumption can reduce the incidence or death rate of certain diseases, then that alone may increase longevity.
Are the downsides of caffeine enough to outweigh the positives of tea? It is generally agreed that, for most people, moderate caffeine consumption (up to 300 mg. per day) is harmless. Many people find that caffeine boosts mental clarity and alertness in a pleasing way. Tea contains, roughly, only 40 mg caffeine per 6 oz. cup, compared to brewed coffee at 100-150 mg., so you’d have to drink quite a bit more tea to get “too much” caffeine. Also, tea is unique in that it contains the amino acid L-theanine, which “significantly increases activity in the alpha frequency band which indicates that it relaxes the mind without inducing drowsiness” (Ref: http://highwire.stanford.edu/cgi/medline/pmid;18296328). This may explain why some people report tea calms them in spite of the caffeine content. Since caffeine is a cardiac stimulant, however, people with certain heart conditions should avoid caffeine, and excessive caffeine intake can cause restlessness, insomnia, and anxiety. Women should avoid caffeine throughout pregnancy and while nursing.
Are there any other negatives to drinking tea? There really aren’t any. The only possible downside is that it is hard to get a decent cup of tea at most restaurants, and you’re kind of left out when people are enjoying their coffee drinks. But it is delicious, inexpensive, enjoyable, and healthful. What more could you possibly want?
I find that the amino acid L-theanine in tea offsets the caffeine (theine) so that its negative effects are canceled out. Instead of the caffeine alone causing a stress response, there’s a relaxation response because of the theanine. Therefore the two complement one another.
I swiched from coffee (half caff) to tea over two years ago, without any drowsiness or caffeine withdrawal headaches at all–probably because I was still getting about 1/3 of my usual daily “dose”. About two weeks after switching, I woke up one morning and realized that I felt more rested than I’d felt in YEARS! All the coffee I was drinking–I think the caffeine overload kept my muscles from ever fully relaxing properly. I’ve also almost completely stopped “grinding” my teeth in my sleep. Overlooked benefits!