The main difference between black tea and green tea is the fermentation of the tea leaves. For black tea, leaves are picked and then allowed to wither; the leaves are rolled to release the juices and allowed to ferment and are oven-dried prior to packing. Green tea leaves are heated immediately after picking, then rolled, dried and packed. The fermentation process of black tea leaves impact the benefits the tea offers.
Certain studies have found that black tea is useful for certain conditions where green tea is not; the inverse is true also. However, there are a few health conditions where both green and black tea make a positive impact.
Stroke
In a study published in the "Journal of the American Heart Association," researchers showed that drinking at least 3 cups of green or black tea daily can significantly reduce the risk of stroke. Additionally, your risk of stroke decreases with the more black or green tea that you drink; drinking 3 cups of green or black tea daily can reduce your risk by 21 percent. If you drink an additional 3 cups, you can reduce your risk by an additional 21 percent.
Prostate Cancer
Black and green tea also share the benefit of slowing the growth of prostate cancer cells. In findings published by the "Federation of American Societies for Experimental Biology," researchers demonstrated that prostate cancer cells grew slower after the cancerous cells were placed in a container of blood serum of men who had consumed either black or green tea. The control was a blood serum of the men before they drank the tea.
Breast Cancer
Not all benefits of tea can be assigned to both black and green teas. A metaanalysis published in "Carcinogenesis" in 2006 explained that previous studies have shown that tea and tea polyphenols have anticarcinogenic properties when it comes to breast cancer. The ultimate results of the metaanalysis showed that those who consume green tea have a lower risk for breast cancer. Additionally, those who had late-stage breast cancer and drank black tea demonstrated a promoting effect on the breast cancer.
Colon Cancer
Although black tea accelerates breast cancer growth, it seems to reduce the risk of colon cancer. A study published in the journal "Carcinogenesis" showed that black tea extracts, not green tea extracts, can protect against certain kinds of colon cancer by a mechanism involving increased tumor cell death. A study published in the "American Journal of Cardiology" in 2004 showed that consuming black tea improves blood flow in the heart over consumption of caffeine.
References
- Stroke: Journal of the American Heart Association; Green, black tea can reduce stroke risk; Lenore Arab; February, 2009
- Carcinogenesis; Effects of black tea, green tea and wine extracts on intestinal carcinogenesis induced by azoxymethane in F344 rats; Caderni G., et al; 2000 Nov
- The American Journal of Cardiology; Black tea increases coronary flow velocity reserve in healthy male subjects; Hirata K; 2004 Nov
- Carcinogenesis; Green tea, black tea and breast cancer risk: a meta-analysis of epidemiological studies; Sun CL., et al; 2006 Jul
- Federation of American Societies for Experimental Biology; Green and black tea polyphenols consumption results in slower prostate cancer cell growth; Henning, Susanne, et al; April, 2004
- U.S. National Library of Medicine. Tempest in a Teapot: Tea & Politics & Health, Tea Types
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