According to a study published in 2010 in the American Journal of Obstetrics and Gynecology a substance in green tea appears to significantly shrink the size of uterine fibroids.
Green tea extract can kill human leiomyoma (fibroid) cells in tissue cultures and can eradicate fibroid lesions in lab animals, according to Dr. Ayman Al-Hendy, director of clinical research at Meharry Medical College in Nashville, Tenn and colleagues - as published January 14th 2010 in the American Journal of Obstetrics & Gynecology.
Green tea comes from the same plant as black tea however green tea is made from the unfermented leaves and black tea from the fermented leaves. After harvest green tea does not go through any processes of fermentation and therefore contains or rather retains relatively high amounts of a substance called polyphenols which have anti-oxidant properties helping to combat cell damaging molecules called free radicals.
The most biologically active polyphenol in green tea is called epigallocatechin gallate or EGCG.
In the 2010 study published by the American Journal of Obstetrics and Gynecology varying doses of green tea derived EGCG were introduced into test tubes that contained cells of uterine fibroid tumours. They also gave mice oral doses of EGCG. Within as little as 24 hours the EGCG was shown to slow tumour growth and when fibroid tumours were measured at 4 - 8 week intervals they showed a medically significant decrease in both their weight and overall volume.
The study concluded that EGCG can effectively halt fibroid growth and trigger the death of fibroid cells in a test tube and in live animals.
Although these exciting study results came from tests on animals, clinical studies will soon be underway in human trials.
Concerns have been raised as to green tea’s toxic effect on the liver. A study published in The Journal of Nutrition in January 2009 found that consumption of high levels of green tea extracts did not affect markers of liver function in healthy men.
However the National Centre for Complementary and Alternative Medicine states that green tea extracts that contain EGCG or other active substances can potentially increase your risks for liver problems.
The green tea extract consumed in the 2010 study was approximately equivalent to consuming between 6 and 8 cups of green tea per day. Although a few previous studies using mice and isolated case studies suggested that green tea might increase the risk for liver problems. The study authors noted that it is likely these adverse liver reactions were at least partly due to other, unrelated factors, such as genetics or other health problems, and not simply green tea consumption.
Other studies suggest that green tea may even help to prevent liver damage. However, these benefits may only apply to the brewed drink form of green tea. Some evidence points to green tea extract supplements having a negative effect on the liver.
A 2006 review published in Liver Transplantation noted that commercially available green tea supplements may trigger acute liver toxicity. However, the report doesn't list doses or supplement concentrations.
So my advice would be to stick to drinking cups of brewed green tea and avoid the supplements as brewed green tea does appear to offer health benefits to the liver and potentially fibroids.
It is also important to note that tea (as well as coffee!) are heavily sprayed crops so try and buy organic green tea as this will help reduce your exposure to endocrine disrupting herbicides and pesticides.
Green tea also contains caffeine just like its black tea counterpart so consumption should be restricted to no more than 5 cups per day.
Preliminary research shows green tea may also lower your risk for certain types of cancer, lower your cholesterol and reduce your risk for Parkinson's disease, according to MedlinePlus.
Other potential benefits include reducing inflammation in inflammatory bowel disease, lowering your risk for diabetes and helping with weight loss, notes the University of Maryland Medical Center.
If you are pregnant or suffer from anemia, heart conditions, bleeding disorders, anxiety, osteoporosis, glaucoma or diarrhea, you should limit your consumption of green tea even further, since caffeine can worsen these conditions. Green tea may also interfere with certain medications, so you should speak to your doctor before taking green tea extract or drinking large amounts of green tea.