New research reveals a cuppa is packed with antioxidants that can reduce the risk of heart disease and cancer. And freshly-brewed teas have 20 times the level of trendy bottled teas.Here are five fast facts about the benefits of a cuppa:
Tea up a top ticker: Scientists at King’s College London found three to four cups of tea a day can cut your chances of having a heart attack and keep bad cholesterol at bay.
Breast brew: Tea can also fight cancers – including breast cancer. A US study found the chances of developing a tumour dropped by 37% in women under 50 who drank three cups a day.
Tea
The whole tooth: Tea is a natural source of fluoride that can help protect against tooth decay and gum disease.
Coffee is good brew too: New research from Holland shows two to four cups a day can lower risk of heart disease and strokes by 20%.
Milk it: Had a curry? Add milk to your cuppa. A new study says drinking milk can cure garlic breath.
Green tea
Tea is a naturally refreshing drink and taken on its own it has no calories, so it’s the perfect drink to keep you feeling good. When taken with milk, as is the preference of 98% of the population, four cups of tea a day can provide you with significant amounts of the following nutrients:
* approximately 17% of the recommended intake for calcium
* 5% for zinc
* 22% for Vitamin B2
* 5% for folic acid
* 5% for Vitamins B1 and B6
Tea
A cup of tea also contains manganese, which is essential for general physical development, and potassium which helps to maintain your body’s fluid balance.
Caffeine is a naturally occurring substance found in the leaves, seeds or fruits of at least 100 different species worldwide and is part of a group of compounds known as methylxanthines.
Both green tea and black tea come from the leaves of the plant Camellia sinensis, however the processing that the leaves undergo to make the final tea is different. The leaves for black tea are fully oxidised while those for green teas are lightly steamed before being dried. Figure 1 outlines the processing of green and black tea in more detail.
Increasing evidence is highlighting the role antioxidants may have in helping to maintain your health in a variety of ways by opposing the action of free radicals. In addition to the well known antioxidants such as Vitamins C and E, there is growing research demonstrating the potential health maintainence effects of plant-derived antioxidants, polyphenols, found in fruits, vegetables, nuts, cereals and drinks such as tea.
Tea
Dental disease remains a significant problem in the UK with the vast majority of the population suffering with the consequences of this disease at some stage in their lives. It can result in acute pain, aesthetic problems and can increase the risk of tooth loss, which may have long-term effects on food intake resulting in impaired nutritional status and subsequent overall well being.
Iron has several vital functions in the body, it?s major role being as an Oxygen carrier in blood haemaglobin and muscle myoglobin. In addition, it is a component of many enzymes and is required for a number of metabolic processes.
On average, British people drink approximately 3 cups of tea a day with about 70% of the UK population drinking tea on a regular basis.
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“Psychologists have found that sweetened drinks make people less aggressive and argumentative,” according to the Daily Mail. The scientists behind the new research said a sweet drink could improve your ability to restrain your aggressive impulses during stressful meetings or commutes.
These findings come from a study where student volunteers drank lemonade sweetened with sugar or an artificial sweetener before performing stressful tasks, including preparing a speech to be read to a stranger. After the speech, some of the volunteers were provoked by being told that their speech was boring and disappointing. Those who had drunk the sugary lemonade responded to this provocation less than those who drank the artificially sweetened lemonade. The researchers suggested that this could be because the brain needs glucose for functions such as controlling behaviour.
This research used very controlled situations to provoke aggression, and it is not clear whether sugary drinks would have any effect on aggression in more stressful and complex real-life situations. Some people may feel that drinking a sugary drink makes them calmer, but they should be careful not to drink too many, as this could lead to tooth decay and weight gain.
Where did the story come from?
The study was carried out by researchers from the Universities of New South Wales and Queensland in Australia and was funded by the Australian Research Council. The study was published in the peer-reviewed Journal of Experimental Social Psychology.
The Daily Mail has reported on the research correctly and mentioned that drinking too many sugary drinks could harm your teeth. However, its headline and some of the text suggested that sugary tea may have an aggression-reducing effect, which was not specifically tested in the study.
What kind of research was this?
This was an experimental study looking at the effects of glucose consumption (a simple sugar) on aggression. The brain relies on glucose for its energy and it has been suggested that fluctuations in glucose affect ‘executive functioning’, the ability to control one’s actions. Low glucose levels have also been linked to higher levels of aggression. Therefore, the researchers were interested in finding out whether giving people glucose would reduce their levels of aggression.
The researchers in this study chose to randomly assign volunteers to receive either a sugar sweetened drink or artificially sweetened placebo drink. This process of randomisation should ensure that the groups are well balanced, and that any differences in their responses were due to the drink received.
Neither the participants nor the researchers were told which drink each person received. This should reduce the chance of a person’s beliefs about the effects of sugar influencing the results.
However, some people may have been able to detect that they were drinking an artificially sweetened drink. This could potentially affect their responses, particularly if they knew what the aim of the study was.
What did the research involve?
The researchers performed two experiments in which the undergraduate volunteers were given either lemonade sweetened with sugar, or lemonade with an artificial sweetener (the placebo). The levels of aggression displayed by the volunteers who consumed the two different drinks were then measured in aggression-provoking situations.
In the first experiment, 80 volunteers had their natural levels of aggression (called ‘trait’ aggression) assessed. They were asked to fast for three hours before the start of the study. After fasting they were randomly assigned to receive a sugary drink or not. The volunteers were then placed in a situation where an individual provoked them and they were given the chance to retaliate against the provoker by playing loud ‘white noise’ at them.
Specifically, after the drink, volunteers were given 10 minutes to write a two-minute speech on a given topic (e.g. life goals), which they were to present through a sham web conference to another ‘participant’. This participant was in fact an actor who also gave a pre-recorded two-minute speech. The volunteer then received written feedback on their speech supposedly from the actor, which suggested that it was boring and disappointing. They then participated in a test where they could deliver 25 blasts of white noise of variable length and loudness to the actor when prompted by a visual cue on the screen. The actor responded in kind with noise of increasing length and loudness.
The volunteer thought this was meant to be a test of speed of response to the visual cue. The length and loudness of the volunteer’s first noise blast was taken as a measure of their level of aggression towards the actor.
In the second experiment, 170 undergraduate volunteers were also randomised to drink a sugary or artificially sweetened drink, and to either be provoked by the actor or not. They could respond with one blast of white noise. Again, the researchers compared the length and loudness of the volunteer’s noise blast to assess their level of aggression towards the actor.
What were the basic results?
The researchers found that in the first experiment, those given the sugary drink were slightly less aggressive than those given the placebo drink, although this difference was not large enough to be statistically significant. The sugary drink reduced aggression in volunteers with high levels of natural aggression more than those with lower levels of natural aggression, while the placebo drink did not.
In the second experiment, volunteers were more aggressive if they had been provoked. The researchers found that the sugary drink did not affect levels of aggression in volunteers who had not been provoked. In those who were provoked, the sugary drink reduced levels of aggression compared to the placebo drink.
As in the first experiment, the sugary drink reduced aggression in provoked volunteers with high levels of natural aggression more than in those with lower levels of natural aggression. The researchers found that among those who were not provoked, people with high levels of natural aggression who drank the sugary drink were more aggressive than those who drank the sugary drink but had low levels of natural aggression.
How did the researchers interpret the results?
The researchers conclude that giving people sugar (glucose) can reduce aggression in response to provocation, even in people with high natural levels of aggression
Conclusion
This experimental study suggests that drinking a sugary drink may reduce aggression in response to provocation in the short term, particularly in people with higher levels of natural aggression. However, this study only looked at one measure of aggression in response to provocation in very controlled, artificial scenario. When interpreting this study it is important to remember that:
* it is not clear whether a glucose drink would have any effect an aggression in more complex and stressful real-life situations
* it is unclear whether any of the undergraduate volunteers in this study would be considered to have serious problems with aggression, or problems with aggression resulting from psychiatric diagnoses
* participants fasted for three hours before the study. It is not clear whether the sugary drink would have had the same effect if they had not been fasting
Some people may feel that drinking a sugary drink makes them calmer, but people should be careful not to drink too many as this could lead to tooth decay and weight gain.
“Two cups of tea a day cuts heart disease,” the Daily Express has reported. The newspaper says that tea contains “health boosting flavonoids” that can reduce the risk of heart disease by 11%.
The news is based on a study examining a selection of research on the potential heart benefits of both green and black tea. It concludes that regular consumption of any type of tea is likely to reduce the risk of cardiovascular disease, probably due to levels of substances called flavonoids that are found in tea. The authors suggest that the reduction in risk is the result of actions such as preventing clogging of the arteries and improving body weight.
However, this review should be seen as a “round-up” of some of the existing research as it was not a systematic analysis of the research, and therefore cannot provide firm evidence. As the authors of the review point out, we now need good quality studies directly looking at whether tea can prevent heart disease in humans.
Overall, it is unlikely that drinking tea can prevent heart disease in isolation from other factors, or redress the effects of a poor diet or unhealthy lifestyle. Adopting a balanced diet, doing regular exercise, consuming moderate amounts of alcohol, and not smoking are all important ways to help reduce the risk of heart disease.
Where did the story come from?
The review was carried out by researchers from the School of Medicine and Pharmacology at the University of Western Australia. There is no information about any external sources of funding. The study was published in the peer-reviewed journal Molecular Aspects of Medicine.
The review was reported in both the Daily Mail and Daily Express, whose reporting generally did not reflect the uncertainty of the study’s conclusions. For example, the Mail reported that three cups of tea a day can prevent cardiac problems, while the Express said drinking tea two or three times a day could reduce risk of the disease by 11%. These claims appear to be based on a 2001 analysis, which the reviewers considered to be flawed. The review actually suggests that this earlier research had several problems that undermine the certainty of the results.
Both newspapers also claim that drinking two cups of tea will provide as many antioxidants as eating five portions of vegetables. Although tea does contain antioxidants, the suggestion that it can be a substitute for the numerous health benefits of fruit and vegetables is not supported by this research.
The Express did however feature the views of an external expert advising that more research is needed and that tea cannot protect from the effects of a poor diet or lifestyle. Both papers report views from the Tea Advisory panel, which support the researchers’ conclusions. The Mail points out that the Tea Advisory Panel is funded by the tea industry.
What kind of research was this?
This was a non-systematic, narrative review looking at the potential health benefits of both green and black tea. It examined evidence from various studies, including animal models, population studies and some randomised controlled trials (RCTs). It included research on the effect of tea on a number of cardiovascular endpoints related to health, including atherosclerosis (clogged arteries), blood pressure and cholesterol reduction.
The authors point out that tea is such a common drink worldwide that any health effects could have a significant impact on public health. Both green and black tea, they say, are rich in flavonoids – anti-oxidant substances that are thought to have health benefits. They say that as little as two to three cups a day will supply a “major contribution to total flavonoid intake in most individuals”.
What did the research involve?
The researchers viewed and summarised 63 studies on the possible effects of green and black tea. They looked at population studies on the possible link between tea and heart disease, but they also summarised studies of potential associations between tea and a number of clinical endpoints associated with cardiovascular disease. These were atherosclerosis, function of the endothelium (lining of the arteries), blood pressure, oxidative stress, cholesterol reduction, inflammation, function of the blood platelets, levels of homocysteine, body weight and body composition, and type 2 diabetes.
The review did not state how the researchers identified and selected the studies to be included. This means we cannot be sure if any relevant studies were omitted, nor whether studies not included came to similar conclusions. Although researchers describe the evidence they found, they do not systematically examine the quality of studies that were included.
What were the basic results?
The main findings reported by the authors were as follows:
* population studies suggest that tea may reduce cardiovascular disease risk
* mouse studies suggest that tea can inhibit development of atherosclerosis (although the authors recognise that human studies are needed)
* RCTs suggest that tea can enhance nitric oxide levels and improve endothelial function (which has a role in cardiovascular disease)
* RCTs provide limited evidence that green tea might reduce body fat
* there is inadequate evidence about the effects of tea on oxidative stress, inflammation, blood platelet activation, blood pressure and risk of type 2 diabetes
How did the researchers interpret the results?
The researchers suggest that tea is likely to provide protection against cardiovascular disease. Green and black tea appear to have similar health benefits.
Conclusion
This review summarises a selection of the existing evidence on the associations between tea and aspects of cardiovascular health. It is not clear whether researchers included all the available evidence, how they selected their studies, or whether any other evidence came to similar conclusions.
As the authors imply, large randomised controlled trials are needed to look at any association between tea and the prevention of cardiovascular disease. Where diet is concerned, RCTs are difficult to design because of the difficulties associated with trying to isolate dietary factors. Also, they are expensive to set up.
Moderate consumption of whichever colour tea you prefer is unlikely to damage your health, and it may have some benefits, as this research suggests. However, it is well established that the best way to reduce the risk of heart disease is to follow a healthy diet and lifestyle, which involves regular exercise, reducing fat and salt intake, eating plenty of fruit and vegetables, and not smoking.