Tea & Health FAQ

What makes tea a healthy beverage?

Compounds naturally present in tea called polyphenols, which function as antioxidants. Antioxidants are chemicals that fight free radicals in the body, which can cause cellular damage and chronic disease such as heart disease and stroke.\

What are the nutritional benefits of tea?

Tea composition varies with climate, season, horticultural practices, and variety. Polyphenols are the most important component in tea, as they constitute approximately 36% of the dry weight of tea. Other components of fresh green leaf include caffeine, protein and amino acids, carbohydrates, lipids, vitamins, and minerals.

Green and black tea have similar chemical make-up. The primary difference between the two types lies in the chemical changes that take place during their production. In black tea the plant polyphenols are oxidised and this is prevented in the manufacture of green tea.

One of the most important groups of polyphenols in tea is the catechins in green tea and theaflavins and thearubigens in black tea. A variety of physiological effects have been attributed to tea catechins which are currently best known for their antioxidant activities.

Black tea is all-natural (non-flavoured) and contains no additives. It is virtually calorie-free (1 calorie per 100 ml) and sodium free and is therefore a suitable beverage for individuals on calorie-reduced or low sodium diets. Tea includes fluoride, traces of vitamins A, K, C, B carotene and B vitamins. Daily consumption of 650ml of tea (approx. 3 ½ cups) provides:

• Over half of the total intake of dietary flavonoids
• Nearly 16% of the daily requirement of calcium
• Almost 10% of the daily requirement of zinc
• Over 10% of the folic acid need
• Around 9%, 25% and 6% of vitamins B1, B2 and B6 respectively.

Is green tea better than black tea?

Both green tea and black tea are made from the tender shoots of the tea plant (Camellia sinensis). The differences in the final product are due to the different methods employed in the processing of the tender shoots. In black tea the predominant class of water soluble polyphenolic compounds in tea shoots known as catechins is converted to theaflavins and thearubigins during processing, while in green tea it remains unchanged. This is the major difference in the composition of green tea and black tea and the composition of other components are similar. Most of the beneficial properties of tea are due to the presence of high amounts of these polyphenolic compounds in tea. Research carried out so far indicate that polyphenolic compounds in both green tea and black tea have similar beneficial effects. Hence regular consumption of green or black tea will have similar benefits.

How many cups of tea should I drink to get the required health benefits?

Tea could be considered as a part of a healthy diet as it provides beneficial effects in addition to hydrating the body. Therefore, tea is a beverage which is suitable to obtain part of the daily requirement of fluids. Antioxidant activity of the polyphenols in tea has been recognised as the most significant beneficial activity of tea. Regular consumption of tea is important to obtain a regular supply of polyphenols. Hence, consumption of four cups per day could be considered as an adequate amount to obtain the beneficial effects of tea.

Does fresh tea have more health benefits than not-so-fresh tea?

Most of the health benefits in tea are due to the presence of flavonoids. If tea is not stored properly after processing into made tea, the flavonoid content could deplete with time reducing the health benefits. Proper packaging after processing could preserve the flavonoids for two to three years with very little decrease in the compounds that influence the health benefits.

How much caffeine is there in tea?

The human body requires a certain amount of caffeine and research indicates that up to 10 – 12 cups of tea daily will not have any detrimental effect on the body. The species or the variety of the tea plant determines content of caffeine in tea, as it is a genetic feature. The variety of Camellia sinensis that is grown in Sri Lanka has caffeine levels of approximately 2.5 – 4%. However, the distribution of caffeine in the plant depends on the part of the plant it is derived from.

For example:

• Bud 4.7%
• First leaf 4.2%
• Second leaf 3.5%
• Third leaf 2.9%
• Upper stem 2.5%
• Lower stem 1.4%

How much caffeine is considered safe?

The Food Guide to healthy eating recommends caffeine consumption in moderation. According to the current findings for most people an intake of caffeine up to 400-450 mg per day does not increase the risk of heart disease, hypertension or have an adverse effect on pregnancy or the foetus. This level of caffeine is equivalent to approximately 10 to 12 cups (170 ml) of tea per day.

As explained by Prof. T. W. Wickramanayake (Ph D Glasgow, Visiting Research Fellow Glasgow, Wisconsin and California) the pharmacologically active dose of caffeine is 200 mg and the acute fatal dose is about 10,000 mg. Those who drink more than 5 cups of coffee or 9 cups of tea are regularly consuming 5% of the fatal dose. The T 1/2 of caffeine is about 3 hr. It is excreted quickly in urine as 1-methyl uric acid.

Prof. Wickramanayake also states the following: “There is a positive association between myocardial infarction and heavy coffee consumption, whereas the correlation between infarction and heavy tea drinking is negative. In rats and rabbits maintained on atherogenic diets, caffeine increases serum lipid concentrations and therefore the incidence of atherosclerosis. Coffee has the same action but not decaffeinated coffee. Tea has the opposite effect to caffeine alone or caffeine in coffee. Similar results have been reported in a study of human subjects with and without heart ailments. Russian scientists have demonstrated that a course of tea consumption improved the condition of atherosclerotic patients. The alleged adverse effects of caffeine are apparently eliminated in tea either by a modification of its activity by other constituents, or by the opposing action of some anti-atherosclerotic constituent.”

Does green tea have the same caffeine level as black tea?

Green tea, as well as Oolong tea and Black tea, are all produced from the herb Camellia sinensis. They all contain the same amount of caffeine. Caffeine content in a cup of tea is 2.5% to 4%, which is about a third of that in coffee. It is claimed that 80% of the caffeine in tea remains unabsorbed by the human body. Thus Green tea, Oolong tea and Black tea may taste different, but the caffeine content is the same.

How much of caffeine is there in tea in comparison to coffee?

The amount of caffeine in a cup of tea or coffee could vary due to many reasons such as the variety of tea or coffee, method of processing, brewing, etc. However, in general, coffee contains higher amounts of caffeine than tea. An average cup of tea could contain 15 – 60 mg of caffeine while in coffee it could be 60 – 150 mg of caffeine.

Both tea and coffee contain the methylated xanthines, caffeine, theophylline and theobromine. Brewed coffee is said to have the highest caffeine content among those dietary items containing caffeine – approx. 100 mg per cup. In comparison, a 300ml bottle of cola has 30-60mg caffeine and approx. 37mg caffeine is found in a 56g dark chocolate bar. There are a wide variety of drug products that contain caffeine – typically 200 mg per tablet or capsule (pharmacologically active dose of caffeine). A cup of tea has approx. 28 – 44 mg caffeine (FDA 1980).

If I brew my tea for longer, will that increase the caffeine content?

Caffeine extraction times could vary in different types of tea. However, in most commercially available teas, caffeine is extracted quickly. Around 80% of caffeine in tea is extracted in the first minute of brewing and by 3 minutes around 90% of caffeine is extracted. Longer brewing will therefore, only slightly increase the amount of caffeine in the brew.

The quantity of caffeine in tea, on dry solids basis, is more than the quantity of caffeine in an equal weight of dried coffee beans. However, as a result of getting more cups of tea from a unit quantity of black tea than from an equal quantity of ground coffee beans, the quantity of caffeine per cup of tea is less than the caffeine in an equal cup of coffee.

Excessive caffeine is said to have adverse effects on the human system and brewed tea has only half the caffeine levels in brewed coffee. However, it is important to note that research proves that the presence of caffeine in tea does not produce unhealthy results due to its combination with tea polyphenols.

If I add milk to my tea will that reduce the health benefits of my tea?

Most of the beneficial properties of tea are due to the presence of high amounts of polyphenolic compounds in tea. When a cup of tea is consumed these polyphenols have to be absorbed from the digestive tract into the blood stream to impart the beneficial effects. Research carried out to find the absorption of polyphenols in tea with and without milk indicate that addition of milk does not alter the absorption of polyphenols. Therefore, addition of milk does not reduce the health benefits of tea.

Does tea affect hydration?

As brewed tea contains almost 98% water, it makes a healthy contribution to the delay fluid balance. Tea contains no additives or artificial colours. Research indicates possible antioxidant benefits so drinking tea can be a calorie-free way to increase intake of dietary antioxidants.

Maintaining optimal fluid balance is important to support optimal health. Due to its high water content, tea is a particularly good beverage choice for keeping one’s body well hydrated.

Does tea have a diuretic effect?

There is no reason to believe that tea promotes fluid loss. Rather there are many reasons to believe that tea is a valid beverage choice in helping to maintain fluid balance.

The diuretic effect can be attributed to the caffeine present in tea and coffee. Caffeine increases diuretic action on the kidneys, increasing urinary volume and sodium extraction as a result of a decrease in the tubular re-absorption of sodium and water. Coffee contains a higher content of caffeine compared to tea. Research has shown that a 170ml (6-oz) serving of tea contains, on average 34mg of caffeine in comparison to 99mg of caffeine in 170 ml serving of brewed coffee. Thus the diuretic effect of coffee is greater compared to tea.

Can green tea aid weight loss?

Long-term consumption of tea catechins could be beneficial against high-fat diet-induced obesity and type II diabetes and could reduce the risk of coronary disease. Further research that conforms to international standards needs to be performed to monitor the pharmacological and clinical effects of green tea and to elucidate its mechanisms of action.

What is L-theanine?

An amino acid found in plants which was first referred to by Dr. R. L. Wickremasinghe in 1978 in the context of its influence on the quality of tea. Subsequent research conducted in Japan and elsewhere suggests that L-theanine facilitates relaxation and may benefit the regulation of blood pressure in humans, as well as mental clarity, concentration and the immune system. L-theanine is different to caffeine in producing a calming effect. It is the predominant amino acid component in tea and whilst the amount of L-theanine in tea depends on several factors – climate, soil and sunlight – clinical studies suggest that consuming 6-8 cups of tea a day would offer 200-400mg of L-theanine, whilst it is said to be effective in doses ranging from 50mg to 200mg.

Fresh tea in particular is likely to be rich in L-theanine and researchers recommend it, amongst other things, for coping with stress and also for increasing ‘life energy’.

Is regular tea consumption good for my immune system?

A Harvard Medical School study discovered that regular consumption of tea could boost the body’s defences against infection. A component in tea was found in laboratory experiments to prime the immune system to attack invading bacteria, viruses and fungi, according to a study in the Proceedings of the National Academy of Sciences.

A second experiment, using human volunteers, showed that immune system blood cells from tea drinkers responded five times faster to germs than did the blood cells of coffee drinkers. Researchers claim that the results give clear proof that five cups of tea a day sharpen the body’s disease defences. The study revealed a substance called L-theanine was isolated from ordinary black tea. L-theanine is broken down in the liver to ethylamine, a molecule that primes the response of an immune system element called the gamma-delta T cell – considered to be the first line of defence against bacteria, viral, fungal and parasitic infections.

The T cells prompt the secretion of interferon, a key part of the body’s chemical defence against infection. To further test the finding, the researchers had 11 volunteers drink five cups a day of tea, and 10 others drink coffee. Before the test began, they drew blood samples from all 21 test subjects.

After four weeks, they took more blood from the tea drinkers and then exposed that blood to the bacteria called E-coli. The immune cells in the specimens secreted five times more interferon than did blood cells from the same subjects before the weeks of tea drinking researchers claimed. Blood tests and bacteria challenges showed there was no change in the interferon levels of the coffee drinkers.

Does fluoride in tea have any implications on oral health?

Tea plants accumulate fluoride in their leaves. In general, the oldest tea leaves contain the most fluoride. Most high quality teas are made from the bud or the first two to four leaves—the youngest leaves on the plant. Brick tea, a lower quality tea, is made from the oldest tea leaves and is often very high in fluoride. Symptoms of excess fluoride (i.e., dental and skeletal fluorosis) have been observed in Tibetan children and adults who consume large amounts of brick tea. Unlike brick tea, fluoride levels in green, oolong and black teas are generally comparable to those recommended for the prevention of dental caries (cavities). Thus, daily consumption of up to one litre of green, oolong or black tea would be unlikely to result in fluoride intakes higher than those recommended for dental health. The fluoride content of white tea is likely to be less than other teas, since white teas are made from the buds and youngest leaves of the tea plant. It has been found that not only fluoride but the polyphenols in tea also act to reduce tooth decay. Recent studies have further revealed that tea inhibits the growth of other harmful microorganisms in the oral cavity.

Does tea affect the absorption of iron?

Tea flavonoids bind with iron, thereby decreasing its absorption. However, drinking tea between meals has no effect on iron absorption.

Iron is present in two forms in our diet. ‘Haem iron’ which is found in meat and fish and ‘non-haem iron’ found in dietary items from plant sources. The body better absorbs haem iron than non-haem iron. Between 15-35% of haem iron is absorbed, while 2-20% is absorbed of non-haem iron. Non- haem iron is generally modified by other dietary components.

Absorption of haem iron is not affected by tea. However, if tea is consumed with the meal, non- haem iron absorption is reduced (absorption is not completely stopped). Further, meat and fish contain relatively higher amounts of iron compared to dietary items from plant sources. Therefore, if your diet is rich in meat and fish, meal time tea consumption will not affect the body iron status. However, if your diet is mostly vegetarian and already marginal in iron supply, it is advisable to consume tea between meals.

Certain components in grain, fruit and vegetables as well as polyphenols in tea reduce the availability of iron to the body. However, studies have shown that tea only decreases iron absorption when it is consumed simultaneously with food containing non- haem iron. Moreover, the ability of tea polyphenols to decrease iron absorption is reduced by the presence of other dietary constituents particular ascorbic acid (known to increase absorption of non-haem iron) and milk. Therefore, in order to overcome any potential for reduced iron absorption, simply add milk or lemon to tea. If a meal contains milk, tomatoes, orange juice or ascorbic acid of any kind, these will also balance iron absorption in a meal where tea is consumed.

Can consumption of tea impact chronic disease?

Many in vitro studies have demonstrated the antioxidant properties of both black and green tea, as well as the antioxidant activity of the polyphenols in tea. Further studies have shown that these antioxidant components of tea are absorbed into the blood circulation from the digestive tract and act as antioxidants in body systems. These findings indicate that tea drinking helps to reduce common degenerative diseases such as the risk of heart disease, stroke and cancer.

Does drinking tea during pregnancy affect the foetus?

Questions surrounding caffeine intake and risk of miscarriage and health of the foetus continue to be raised by pregnant women.

A study published in the Journal of American Medical Association found no evidence that moderate caffeine use increases the risk of spontaneous abortions, growth retention or account for other factors. Another seven-year epidemiological study on 1,500 women examined the effect of caffeine, during pregnancy as well as on subsequent child development.

Caffeine consumption equivalent to approximately 3 ½ to 5 cups of tea per day had no effect on birth weight, birth length and head circumference of the baby. Follow-up examinations at age’s eight months, four and seven years also revealed no effect of caffeine consumption on the child’s motor development or intelligence.

Pregnancy hampers caffeine metabolism. For example, in non-pregnant women the breakdown of half of the caffeine takes an average of 2.5 – 4.5 hours, 7 hours during mid-pregnancy and 10.5 during the last few weeks of pregnancy. As caffeine retention is longer during pregnancy, women sensitive to caffeine may be affected. As a result, a moderate consumption of approximately 3 – 4 cups a day, is recommended for women during pregnancy.

Can consumption of tea be good for memory as a person grow older?

Many research studies have been conducted to find out whether tea components could improve the cognitive function (all mental abilities and processes related to knowledge, which includes: attention, memory, judgment and evaluation, reasoning, problem solving, decision making, and comprehension etc.). These studies have found that tea components especially caffeine and theanine could improve the cognitive function. Further, research studies have shown that tea components may have beneficial effects on Alzheimer’s disease which is a prevalent disease of the elderly. However, from the studies carried out so far it is difficult to conclude whether tea consumption would actually improve the memory in old age.

How much theophylline, a compound known to have an effect on easing asthma is contained in a cup of tea?

Theophylline is an alkaloid derived from tea which acts as a mild bronchodilator. In brewed tea, trace amounts of theophylline are present; only around 1 mg/L which is significantly less than a therapeutic dose. Tea has classically been used to treat mild asthma and bronchitis although other potent anti-asthma medications are available with more therapeutic benefit, tea may be beneficial for mild respiratory problems and is safe, even for children. But tea should not be used as a medication for asthma. The difference in the quantity of theophylline between green and black tea is insignificant.

Does teabag filter paper contain epichlorohydrin?

There have been a number of statements on selected websites that use of teabag filter papers can have health effects as they are made with, or coated with, epichlorohydrin which is considered to be a potential carcinogen. The statements are at best ill-informed and misleading and the statement that epichlorohydrin is used to coat the paper is incorrect. The filter paper materials we use are fully compliant with relevant legal requirements and good practice guidelines for papers which are in direct contact with food.