Long Life May Be Your Cup of (Green) Tea
By Kathleen Doheny
HealthDay Reporter
Adults who drank at least five cups of the brew daily had a lower risk of cardiovascular death and death from all other causes, except cancer, than those who drank less than one cup a day, according to a research team from Tohoku University in Sendai, Japan.
They published their findings in the Sept. 13 Journal of the American Medical Association.
While many laboratory and animal studies have suggested that green tea protects against illness, its effect in humans has been less clear.
"Only four epidemiological studies [in people] have been conducted to date," said lead researcher Dr. Shinichi Kuriyama.
And those studies "included small sample sizes, and the results were inconsistent," he added.
However, "our study includes far more participants -- 40,350 -- than the previous studies," Kuriyama said. "I think our study would provide strong evidence regarding the benefits of drinking green tea in humans on cardiovascular disease."
"To be more definitive, we need a randomized trial," said Chyu. He said his lab's animal studies have found that green tea does have cardio-protective effects, especially if consumption commences before the onset of hardening of the arteries.
For those who might want to "go green" for health, "I'd probably take a neutral position right now," Chyu said.
"Tea is not harmful, that we know," he said. If you're a tea drinker, continue, Chyu said. If not, be aware that the habit probably needs to be long-term before you reap any real health benefit.
"I don't think I'd recommend people drink large quantities of green tea," added Dr. Robert Vogel, professor of medicine at the University of Maryland Medical School in College Park.
Like Chyu, he stressed that the study only showed an association, not any direct cause-and-effect. However, he said green tea consumption is certainly preferable to drinking beverages such as non-diet sodas, which are loaded with sugar.
U.S. government health agencies have so far backed away from recommending green tea as a health aid. Earlier this year, a U.S. Food and Drug Administration review of the available data found no evidence to support companies' claims that green tea eases cardiovascular risk. The agency released a similar statement in 2005, noting a lack of evidence that green tea fights cancer.
Experts at the U.S. National Cancer Institute have also reviewed data from human trials focused on tea's cancer-preventing effects but said the studies offered conflicting results. The NCI is funding its own rigorous studies on the subject, however.
The study's lead author was much more enthusiastic.
"I personally drink green tea, two or three cups per day," Kuriyama said. "On the basis of our study results, I would like to recommend the drinking of green tea at least one cup per day."
But Kuriyama added that the tea should not be steaming hot. "Drinking green tea at high temperature may be associated with increased risk of esophageal cancer and mortality," he said, citing two published studies.
2006-09-21
04:28:47
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