Oolong tea may have secret cancer-fighting properties, a new study suggests.
According to estimates by the American Cancer Society, more than 250,000 women in the United States developed breast cancer in 2017, and more than 40,000 died as a result.
In this context, researchers are still in need of more effective prevention and treatment strategies. Moreover, given the side effects of chemotherapy, the need for nontoxic alternatives is also dire.
With these aims in mind, scientists have investigated the potential benefits of green tea for breast cancer and found that certain compounds have anti-cancer effects. However, few studies have examined other types of tea and their role in breast cancer prevention.
Now, a study looks at the potential benefits of oolong tea. Chunfa Huang, Ph.D., who is an associate research professor in the department of internal medicine at Saint Louis University in Missouri, led the new research.
Huang and colleagues published their findings in the journal Anticancer Research.
Oolong tea damages breast cancer cells
Huang and team examined the effect of oolong tea extract on six breast cancer cell lines, which included ER-positive, PR-positive, HER2-positive, and triple-negative breast cancer cells.
The researchers treated these cells with different concentrations of green, oolong, black, and dark tea extracts.
Huang and team examined the viability of the cells and measured the DNA damage and cleavage, as well as any other changes in the morphology of the cells.
The extracts of green and oolong tea stopped the growth of all types of breast cancer cell. In contrast, black and dark tea extracts had no effect on the cells. Huang and team conclude:
"Oolong tea, same as green tea, can induce DNA damage and cleavage, play an inhibitory role in breast cancer cell growth, proliferation, and tumorigenesis, and [it has] great potential as a chemopreventive agent against breast cancer."
Oolong tea drinkers and breast cancer risk
Additionally, the scientists examined annual cancer registry data from China and the Fujian province and found that people in the latter area were 35 percent less likely to have breast cancer and 38 percent less likely to die from it compared with the national average.
They also noted that people who consumed large amounts of oolong tea on a regular basis were 25 percent less likely to develop breast cancer compared with the average incidence in the Fujian province and 50 percent less likely compared with the national average.
Finally, compared with the national average, high consumers of oolong tea were 68 percent less likely to die prematurely.
"It is clear that more study is needed," Huang says. However, "[t]he lower incidence and mortality in regions with higher oolong tea consumption indicate that oolong tea has great potential for its anti-cancer properties."
"From our results," concludes Huang, "oolong tea, much like green tea, plays a role in inhibiting breast cancer cell growth, proliferation, and tumor progression."