Los Angeles, Dec 8: Green tea, enjoyed by millions for its numerous health benefits, may have adverse effects if taken in high doses, a new study in fruit flies suggests.
Researchers at the University of California, Irvine (UCI) discovered that excessive consumption of green tea adversely affected development and reproduction in fruit fly populations.
It is unclear whether overconsumption could have the same impact on humans, but the findings suggest caution when using green tea, or any natural product, in high doses, researchers said. Nutraceuticals such as green tea, while growing in popularity, are largely unregulated, they said.
A UCI team led by Mahtab Jafari, associate professor of pharmaceutical sciences, investigated the effects of green tea toxicity on Drosophila melanogaster development and reproduction.
Embryos and larvae were subjected to various doses of green tea polyphenols. The researchers found that larvae exposed to 10 milligrammes of green tea were slower to develop, were born smaller and exhibited a dramatic decline in the number of emerged offspring.
Ten milligrammes of green tea made the flies more susceptible to starvation and heat stress but protected them against dehydration. Female offspring showed decreased reproductive output and a 17 per cent reduction in lifespan while males were unaffected.
Ten milligrammes of green tea caused morphological abnormalities in reproductive organs, such as testicular and ovarian atrophy, researchers said.
Researchers found that in other tests with mice and dogs, green tea compounds in large amounts dramatically reduced body weight and, in mice, negatively affected embryo development.
"While green tea could have health benefits at low doses, our study and others have shown that at high doses, it may have adverse effects," said Jafari, who led the study. Jafari believes that high doses of green tea may cause 'too much' apoptosis, or cell death. The study was published in the Journal of Functional Foods.