Add green tea to the growing list of substances that activists will soon be calling an endocrine disruptor; a study has found that, rather than bring health benefits, as Big Tea proclaims, excessive consumption adversely affects development and reproduction in fruit fly populations.

Derived from the plant Camellia sinensis, green tea is popular worldwide for its purported brain and heart health and anticancer properties.
Nutraceuticals such as green tea, are popular among groups that distrust agricultural, medical, and energy science, but they are unregulated. 

A team 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 with the following results:

  • Larvae exposed to 10 milligrams of green tea were slower to develop, were born smaller and exhibited a dramatic decline in the number of emerged offspring.

  • Ten milligrams 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 percent reduction in lifespan; males were unaffected.
  • Ten milligrams of green tea caused morphological abnormalities in reproductive organs, such as testicular and ovarian atrophy.

Mahtab Jafari, associate professor of pharmaceutical sciences at University of California-Irvine,   believes that high doses of green tea may cause "too much" apoptosis, or cell death, though they did not evaluate mechanisms. "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." 

The Jafari group studies natural food products - herbs, spices and root extracts, for example - that people have ingested for centuries because of their alleged health benefits. 

"We are planning to continue to measure total consumption, evaluate metabolic pathways, and identify and quantify the metabolites of natural products in flies," Jafari said. "These experiments will enable us to have a better understanding of toxic doses in humans."

Jafari noted 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. 

The study results appear in the Journal of Functional Foods.