Black tea versus Green tea

         The differences - The benefits


       Both black and green teas are derived from the green leaves of a plant with the botanical name Camellia sinensis.  Black tea is made when green tea leaves are spread out for a number of hours in the presence of warm air in order to greatly reduce their moisture content.  The leaves are then mechanically broken up into small pieces and spread out in cool humid air where oxygen (oxidation) begins to break down components of the leaves resulting in the leaves turning brown to black in color.  The leaves are then dried and made ready to be used as tea. 

       Green tea is largely made by initially steaming the freshly harvested leaves to limit their oxidation which allows them to retain their green color. The length of the steaming process has a significant effect on the color and quality of the tea. The longer the steaming time, the more easily the cellular membranes of the tea leaves break down during later processing. This affects the color, taste and fragrance of the finished product.  After steaming, the leaves are “rolled” to give them their desired shape and then they are quickly dried.  

       While all black and green tea comes from Camellia sinensis, there are differences in nutritional components, fragrance and taste due to the time of the year the leaves are picked, the soil and environmental conditions under which the tea is grown and different processing methods.  For example, Oolong tea is neither strictly a black tea nor a green tea as it tends to be more oxidized than green tea but less oxidized than black tea. Oolong teas will vary in levels of oxidation from 8% to 80%.  This results in a rather wide range of color and taste for oolong teas.

       White tea is made from very young budding green tea leaves that have white hair like structures on the unopened buds, thus the name “white tea.”  This tea is harvested in the early spring and has minimal processing.  Matcha is a green tea made into a powder from tea leaves grown for about three weeks in the shade before being harvested. This shade growth increases the production of an amino acid called theanine and also increases the caffeine content of the tea. Some sencha green teas are also partly shade grown.  Some green teas are roasted after being steamed and dried. Bancha is a roasted green tea that has a distinct flavor.

       Both black and green teas contain a number of beneficial compounds called polyphenols.  Polyphenols are a class of nutrients found in many foods and act in the body as antioxidants. Antioxidants reduce and neutralize the action of oxidation which is a breakdown process that leads to the production of free radicals.  Free radicals are molecular abnormalities that produce cellular damage.  While both black and green tea contains polyphenols, green tea has been shown to be a richer source of some of these nutrients. 

       Green tea has been shown to have about 30 percent polyphenols by weight. This includes significant amounts of a class of polyphenols called catechins of which the catechin EGCG (Epigallocatechin Gallate) has been shown to be very beneficial.

       In a study published in 2005 in the American journal Cancer Research, it was shown that EGCG inhibited cancer by blocking the enzyme dihydrofolate reductase (DHFR) which acts as a catalyst to cancer growth.  EGCG was found to be as effective as the anti-cancer drug methotrexate, a drug long used for treating a variety of cancers but also having a number of negative side effects. 

       In a 1998 study reported in the publication Cancer Letters, it was found that EGCG was effective in inducing apoptosis (programmed cell death) in prostate cancer.  A recent study published in Cancer Prevention Research found that EGCG inhibited the progression of prostate cancer.  In another study, researchers at Louisiana State University gave daily doses of 3200 mg of green tea extract containing EGCG to 26 men, aged 41 to 72 years who had been diagnosed with prostate cancer.  After 34 days, there was a significant decrease in a number of markers associated with prostate cancer.

       In addition to prostate cancer, EGCG has been shown to have protective effects against a variety of other cancers and has also been found to be protective for a number of other health problems including Alzheimer's and Parkinson's disease.  Various studies show EGCG and other catechins found in green tea have protective effects on neurons in the brain.

       This being said, it must be noted that black tea, while low in EGCG, is richer in the polyphenols, thearubigins and theaflavins.  These two polyphenols, which are produced when tea leaves are oxidized, have been linked to reduced risk of high cholesterol, diabetes, Parkinson’s disease, osteoporosis, cancer and kidney stones.  According to a report from the National Institutes of Health, black tea was found to significantly reduce the overall risk of developing Parkinson’s disease. A 2013 study found that black tea was effective in reducing the risk of prostate cancer.

       It should be noted that both black and green tea contains caffeine. According to the Linus Pauling Institute, black tea contains 42 to 72 milligrams of caffeine per cup while green tea contains 9 to 50 milligrams per cup.  Both black and green teas are available in decaffeinated formats.  Decaffeination does not appear to reduce the presence of polyphenols.

       Of interest is a British study that found when brewing black tea at or near the boiling point (90°C, or 194°F), there is a dramatic boost in its antioxidant content.  This same research found that tea bags can prevent the extraction of polyphenols called flavonoids and adding milk can block black tea’s antioxidant effects.  This research did not reveal whether this applies to green tea. 

       At Milk ‘N Honey we carry a variety of both green and black teas.  Our teas come in tea bags, loose tea and also decaffeinated formats. We also carry a product from the Life Extension Company called “Mega Green Tea Extract.” This product is standardized to contain 98% polyphenols including 45% EGCG per capsule. It is made from decaffeinated green tea.  Another product from Life extension we carry is “Theaflavin Standardized Extract.” This product features 350 milligrams of black tea extract per capsule standardized to 25% theaflavins. The black tea used to make this product is not decaffeinated. Each capsule of this product contains around 8 milligrams of caffeine, the amount found in about a 1/8 cup of brewed caffeinated green tea.