Posted by Susan Lutfallah on June 6, 2009
Drinking black tea has been linked with reduced risk of heart disease in several studies – in fact, a number of these studies suggest that this benefit may be due to lowering of blood levels of low density lipoprotein (LDL) cholesterol (bad cholesterol). Unfortunately, elevated levels of LDL cholesterol are linked with heart disease.
However, the mechanism behind the beneficial effect of black tea in lowering LDL cholesterol levels was unclear – only recently have studies began to demonstrate that it is theaflavins, one of the complex flavonoids in black tea, which is responsible for this LDL-reducing effect.
Recently, researchers at the University College London and Unilever Research Colworth conducted the first randomized clinical trial on the effects of black tea on stress – overall, their results found that drinking black tea may reduce stress hormone levels (cortisol) and ease the burden of heart disease.
During the study, the researchers recruited 75 healthy young males and put them through a four-week “washout” period during which they were not allowed to consume tea, coffee, caffeinated beverages, dietary supplements, and many other substances. Subsequently, 37 of the men were given four cups of black tea per day for six weeks while the 38 members of the placebo group were given an identical-tasting caffeinated drink, with no active tea ingredients, for the same time period.
Afterwards, both groups were asked to perform stressful tasks – these included verbally responding to threats of unemployment and accusations of shoplifting while sitting in front of a camera. During the procedure, the researchers measured the cortisol, blood pressure and blood platelet levels of the subject, and also asked them to self-rate their stress levels.
According to the results, both groups showed significant increases in blood pressure, heart rate and subjective stress levels during the tasks.
However, 50 minutes after the tasks were complete, cortisol levels in the tea-drinking group had dropped by 47 percent compared to only 27 percent in the placebo group!
Additionally, the black tea drinkers showed lower blood platelet activation — which has been linked to blood clotting and subsequent heart attack risk — and a greater degree of relaxation after the tasks.
Posted in Black Tea | Tagged: black tea, chai tea, green tea, health tea, India, Japan, Japanese tea ceremony, loose leaf tea | Leave a Comment »
Posted by Susan Lutfallah on June 6, 2009
Polyphenols are components of the tea plant and the primary source of the health benefits in tea (e.g. antioxidant properties). Polyphenols undergo changes during the processing of the leaves. These changes result in the difference between black and green teas polyphenols and subsequent benefits.
Researchers have determined that the beneficial properties in green teas, primarily EGCG polyphenols, are easier to identify than the flavonoid polyphenols in black teas, which are known as thearubigins and theaflavins.
– Black teas contain more complex flavonoids then green teas; specifically thearubigins and theaflavins.
– Thearubigins and theaflavins are powerful antioxidants.
– Flavonoids, because of their complexity, do not absorb as quickly in the body and initially can be harder to identify (this is why most studies focused on green tea and EGCG polyphenols instead!)
Briefly, scientific reviewers took an in-depth look at epidemiological and clinical studies relevant to tea from 1990 – 2004. Overall, the review’s objective was to determine if consuming black tea has a positive or negative impact on health.
The review concluded;
– Drinking three cups of black tea per day for two weeks increased the concentration of flavonoids in the blood by about 25%.
– The consumption of flavonoids can lower the risk of coronary heart disease through a number of mechanisms.
– Tea flavonoids have also been shown to reduce low-density lipoprotein (LDL) cholesterol by 11.1%.
– Animal studies and in-vitro (e.g. test-tube experiments) studies both reveal positive effects of flavonoids which go beyond antioxidant capacity – that is, they induce an anti-inflammatory response.
This review of scientific research makes it clear that black tea is good for your health in general, and that black teas complex flavonoid polyohenols specifically can play an important role in daily antioxidant consumption and disease prevention. All-in-all, while green teas continue to steal the health-craze limelight, black tea belong center stage right alongside them!
Posted in Black Tea | Tagged: black tea, chai tea, green tea, health tea, India, Japan, Japanese tea ceremony, loose leaf tea, Matcha | Leave a Comment »
Posted by Susan Lutfallah on May 6, 2009
Black tea is a variety of tea that is more oxidized than the oolong, green, and white varieties – however, all four varieties are made from leaves of Camellia sinensis. Generally speaking, black tea is stronger in flavour and contains more caffeine than the less oxidized teas. Two principal varieties of the species are used: the small-leaved Chinese variety plant (C. sinensis sinensis), also used for green and white teas, and the large-leaved Assamese plant (C. sinensis assamica), which was traditionally only used for black tea.
In Chinese and Chinese influenced languages, black tea is known as “crimson tea”, which is perhaps a more accurate description of the colour of the liquid. In Chinese, “black tea” is a commonly used classification for post-fermented teas, such as Pu-erh tea. In the West, the expression “black tea” is also used to describe any cup of tea without milk (“served black”), similar to coffee served without milk or cream.
While green tea usually loses its flavour within a year, black tea retains its flavour for several years. For this reason, it has long been an article of trade, and compressed bricks of black tea even served as a form of de facto currency in Mongolia, Tibet, and Siberia into the 19th century.
The tea originally imported to Europe was either green or semi-oxidized. Only in the 19th century did black tea surpass green in popularity. Although green tea has recently seen a revival due to its purported health benefits, black tea still accounts for over ninety percent of all tea sold in the West.
Assam Black Tea
Assam is a black tea named after the region of its production; that is, Assam, India. Assam tea is manufactured specifically from the plant Camellia sinensis var. assamica (Masters) – in fact, this tea is known for its body, briskness, malty flavour, and strong, bright color.
Assam teas, or blends containing Assam, are often sold as “breakfast” teas – for example, English Breakfast tea, Irish Breakfast tea, and Scottish Breakfast Tea are common generic names.
Posted in Black Tea | Tagged: black tea, chai tea, green tea, health tea, India, Japan, Japanese tea ceremony | Leave a Comment »