Questions and Answers

What is an antioxidant?

Dietary antioxidants are compounds in the human diet that scavenge reactive oxygen species (ROS) and/or free radicals. This helps to reduce therisk of chronic disease. Reactive oxygen species (ROS) and/or free radicals are substances that can damage the body's DNA, carbohydrates and proteins.

What is the level of antioxidants in Tea?

Antioxidants in tea are known as flavonoids. On a serving basis, tea isone of the richest sources of dietary antioxidants.

How does this compare with fruit and vegetables?

Fruit and vegetables contain many essential nutrients and also containhigh antioxidant levels. Some research shows that tea has a much higher antioxidant activity than many vegetables.

Do all fruit/vegetables contain the same amounts of antioxidants?

No. The antioxidant content varies considerably.

What other foods/drinks contain antioxidants? Howabout coffee?

Red wine has been shown to have high flavonoid antioxidant activity – ie levels comparable with those of tea. Coffee also contains antioxidants, called chlorogenic acids, but these are different to the flavonoid antioxidants found in tea.

How many cups of tea are equivalent to one piece offruit?

It depends on the nature and size of the piece of the fruit and the strength of the cup of tea. 
Research is continuing in this area. Some of thecompounds in tea and fruit and vegetables are the same, however, some are different. It is not suggested that one should substitute tea for fruit andvegetables, but merely that tea may have benefits in its own right.

Can you substitute tea for fruit and vegetables?

No. Tea, fruit and vegetables contain not only antioxidants, but also avariety of other essential substances. A healthy diet is best achieved byconsuming a wide range of healthy foods.

How many cups of tea should we drink in a day toget the amount of antioxidants the body needs?

What are free radicals and what do they do?

Free radicals are unstable reactive substances, which can disrupt molecules in the body, and have been implicated in cancer and heart disease.

How are free radicals produced and where do they come from?

Free radicals are natural by-products of the body's metabolism, but canalso increase as a result of exposure to environmental influences such assmoking, radiation, air pollution and exposure to sunlight and through the ageing process.

Which types of cancers/heart disease do antioxidants protect against?

Research suggests that antioxidants might play a role in the prevention of a number of cancers and heart diseases. Population studies suggest that drinking tea can reduce the risk of cardiovascular disease and a number of studies have been undertaken to find out the mechanism by which this may occur.
One of these has been to investigate the effects of tea flavonoids on the formation of oxidized low density lipoprotein (LDL) that contributes to the narrowing of the arteries (arteriosclerosis). Although many studies have shown that tea flavonoids inhibit LDL oxidation, there is currently insufficient evidence to show that this also occurs in the human body. 
Atherosclerosis is also associated with endothelial dysfunction produced by oxidative stress and there is preliminary evidence from human studies that tea flavonoids can improve endothelial function.
Animal studies consistently demonstrate that tea flavonoids can reduce the number and size of tumors formed in the lung,stomach, skin, colon and oesophagus after animals are exposed to carcinogens.The results from human population studies are however inconclusive and much more work needs to be done on mechanisms and human studies to determine if tea compounds have a role in cancer reduction. Leading scientists worldwide are actively studying the health effects of tea and its components. As evidence continues to build via clinical trials and large scale population studies, the precise benefits will be more identifiable.

Hasn't a recent large scale Heart Protection Study,reported in the Lancet, failed to show any benefit from antioxidant supplements?

The findings of a Heart Protection Study, which was set up to provide substantial evidence, either for or against, the ability of antioxidant vitamins to prevent cardiovascular disease does not discount the belief that fruits and vegetables, or tea, are beneficial to health. Although the study showed that consumption of antioxidants does not provide any additional benefits over and above that of prescribed drugs, it is questionable whether it proved that antioxidant vitamins do not prevent heart disease. The current body of scientific evidence strongly supports the ability of antioxidant vitamins to confer a wide range of health benefits both to normal healthy individuals and those at high-risk of, or diagnosed with, a disease.

By how much do antioxidants reduce the risk of cancers/heart disease?

Although antioxidants are thought to reduce the risk of cardiovascular disease and certain cancers, the mechanism by which this occurs and the degree of risk reduction have yet to be determined.

Are there antioxidants in decaffeinated/fruit infusions/specialty tea/packet tea? How do they compare to ordinary tea?

Tea products are available in a number of forms including decaffeinated tea, fruit flavoured teas and specialty teas. These can be obtained in both loose and bag form. Where the major constituent of these products is tea(Camellia sinensis), they will all contain high levels of flavonoid antioxidants. Many infusions are not made from the leaves of the Camellia sinensis plant and are therefore not true teas. They are, however, often made from the plant parts (leaves, flowers, berries etc) and are likely to contain antioxidant compounds.

Does green tea contain more antioxidants than ordinary tea?

Both green and black teas are rich in flavonoid antioxidants. A group of flavonoids called catechins are the main antioxidants in the green tea. During the black tea processing, some of these green tea catechins form other flavonoid antioxidants called theaflavins and thearubigins. A number of product and preparation factors combine to make the total average antioxidant content of a serving of black tea (198mg / 200ml serving) higher than that for green tea (118mg / 200ml serving).

Are the flavonoids in green tea better than those inblack tea?

There is no evidence to show this to be the case. Although green and black tea contain different flavonoid antioxidants, research has shown a similar increase in plasma antioxidant content when green or black tea is consumed. Animal, population and clinical studies have shown the apparent health effects of green tea to be similarly derived from black tea.

Does the level of antioxidants depend on where the tea comes from?

Yes. There are comparatively small differences in the antioxidant levels present in different tea origins. However, the way in which the tea is prepared is the major determinant of the amount of antioxidants in each serving.

Do all brands of tea contain the same level ofantioxidants? Is one brand better than another?

Branded teas are usually a blend of different tea origins and will probably vary slightly in the type and amount of flavonoids they contain. The way in which the tea is prepared will determine the amount of antioxidants in each serving. The small differences in antioxidant content between brands will mean that one brand is not 'better' than another.

Do you get more antioxidants the longer you brewthe tea?

Yes. The length of time the tea is brewed, and also the amount ofagitation (stirring, dunking) of the brew, will increase the level of antioxidants extracted from the leaf.

Does the level of antioxidants reduce the older the tea is?

Provided the tea is properly stored, and is not exposed to excess moisture and/or light, there will be minimal change in the antioxidant level with age.

Does adding hot water affect the antioxidant level?

Freshly boiled water is required to extract the flavonoid antioxidants from the leaf into the infusion. The antioxidant level is not affected by the hot water.

Do the antioxidants get caught up in the tea bag? Is it better to have loose tea?

Loose-leaf tea infuses more efficiently than tea contained in a teabag, but the time the tea is brewed and the amount of agitation (stirring, dunking)of the brew, determine the level of antioxidants extracted from the leaf.

How do tea antioxidants work and what makes them more powerful than other types?

Antioxidants work by scavenging ROS and/or free radicals. The chemical structure of the flavonoids found in tea make them particularly suitable for this scavenging action. In addition, flavonoids prevent metals from promoting the production of ROS and/or free radicals.

How can tea be healthy for you when it contains tannins?

The compounds commonly referred to as tannins are the flavonoids that play an important part in tea's color and taste. Scientific research isstarting to indicate that these have positive health benefits.

How much scientific evidence is there? Is it conclusive evidence?

Research is ongoing. At present research suggests that antioxidants might play a role in the prevention of a number of cancers and heart diseases, but it is not conclusive. As evidence continues to build, via clinical trialsand large-scale population studies, the precise benefits will be more identifiable.

Why has this information only come to light now?

Tea long has been thought of as a health beverage, but it is only in recent years that scientists have begun to study tea flavonoids. The recent interest in flavonoids has been heightened by the growing weight of research into the benefits of antioxidants and the relationship between tea consumption and the reduced risk of heart disease and cancer.

Should I be letting my kids drink tea?

Yes, for healthy children on a balanced diet. However, for infants and toddlers with poor iron levels, there is the possibility that tea drinking could substantially reduce non-haem iron absorption. In this case, the child should not consume tea with its meal and should wait at least one hour after the end of a meal before drinking tea.

Are there vitamins and minerals in tea?

Tea contains minerals (especially potassium, manganese and zinc) but insignificant amounts of vitamins.

Can tea act as a pro-oxidant?

Although a few studies have been able to demonstrate pro-oxidantactivity in some circumstances, the weight of experimental evidence indicates that the suggested beneficial effects of tea are due to its action as an antioxidant.

Does milk negate the beneficial properties of tea?

The bulk of evidence continues to support the beneficial effects of tea,with or without milk.
 

PLEASE NOTE: The above Questions and Answers, have been sourced from the United Kingdom Tea Council. For further information on this organisation please visit www.tea.co.uk.