The health benefits of tea – and how much to drink
Rishi Sunak is rarely spotted without a cup of tea. Alongside various other tactics he’s employed to win over the country, it’s thought that always appearing with a cup of tea in hand is a “secret weapon” to appear relatable - a strategic attempt to appear as a ‘man of the people’. It’s true that us Britons are – and always have been – a nation of tea drinkers. In fact, a third of us imbibe between 4-5 cups a day. Tea comes from the Camellia sinensis plant and is often blended with other plants for different flavours, such as Earl Grey or chai. Whatever blend you choose, there are surprising health benefits to be found in your humble cup of tea.
Antioxidant properties (and why you don’t have to drink it black to benefit)
“Tea is rich in polyphenols – natural bioactive plant compounds – that have antioxidant effects in the body,” says Dr Carrie Ruxton, a dietician from the Tea Advisory Panel. “Getting enough antioxidants in the diet from fruit, vegetables, wholegrains and drinks is important for fighting the effects of ageing and modern lifestyles which cause damage to cells (via oxidation of cell membranes).”
Green or black tea – containing antioxidants and compounds that may help reduce inflammation in the body – is commonly seen as superior for our health, but don’t worry if you can’t bear it without a drop of the white stuff.
“It is a health myth that adding milk to tea reduces the health effects of a cup of tea,” says Dr Ruxton. “Research studies have found inconsistent results for aspects like antioxidant effects or polyphenol levels in the blood. This is because polyphenols in tea are not absorbed in the small intestine but are acted on by gut bacteria in the colon. As a result, there is no evidence that adding milk has a negative impact on the health benefits of tea. In fact, for women, adding milk to your tea provides other health benefits as it will add to calcium intakes which protect bone density”.
Supports heart health
“Tea is good for the heart on a couple of levels,” says Ruxton. “The polyphenols, specifically flavan-3-ols – part of the flavonoid family – have positive effects on vascular function, which helps blood flow more easily through blood vessels, making them more elastic and reducing blood pressure. A lower blood pressure helps to reduce our risk of stroke and heart attack (myocardial infarction).”
Gunter Kuhnle is a professor of nutrition and food science at the University of Reading. He says that the flavanols, found in tea, have been shown to reduce the risk of heart disease so much that there is even a recommendation by the American Academy of Nutrition and Dietetics to consume 400-600 mg per day.
“We tried to convert this into normal foods – and that’s roughly three cups of green or eight cups of black tea a day,” says Prof Kuhnle.
Drinking three cups of black tea a day for six months significantly lowered blood pressure by 2-3 mmHg, it was found in a clinical trial. This is the equivalent effect on blood pressure of losing 2-3 kilos of weight.
Ruxton says the polyphenols may also aid heart health by helping to lower “bad” LDL cholesterol, and when Harvard University carried out a large survey on tea drinkers, it found that people who have at least 3-4 cups a day are less likely to have a heart attack.
May improve gut health
We’ve all become increasingly aware of the importance of gut health – but not all of us fancy drinking kefir or kombucha. Happily, a tea bag is much cheaper and will also bring some benefits to our bellies.
Several natural foods are prebiotic, meaning they promote healthier species of bacteria in the gut, says Ruxton, and tea – both green and black – is one of these special foods.
“Having a healthy gut microbiota has been linked with a lower risk of constipation, inflammatory bowel disease and respiratory infections, as well as a more balanced immune system.”
She explains this is because the polyphenols in tea are mostly not digested in the upper intestine, they instead pass through to the colon (large intestine) where they are broken down by the gut bacteria for food.
“The ‘friendly’ bacteria in the gut tend to be the ones that prefer to use polyphenols, and so regular tea drinking promotes these species.”
Lowers blood sugar
Daily consumption of tea has been linked with a lower risk of Type 2 diabetes. A study in Nutrition Research reported that people drinking more than four cups daily had a 17 per cent reduced risk of developing Type 2 diabetes. The effects of tea may be due to the polyphenols which promote the uptake of glucose by cells and have anti-inflammatory and anti-oxidant effects.”
May reduce the risk of cancer
There are more than 100 different types of cancer, and of course some are not preventable. But even so, the polyphenols found in black tea may help slow the development of certain types of cancer and promote cancer cell death.
“Large observational studies suggest that people who regularly consume green or black tea have a lower risk of cancer, particularly bowel cancer,” says Ruxton. There are no clinical trials in humans to prove a causal effect, she admits, so we can’t tell whether tea drinkers have healthier lifestyles (for instance they drink less alcohol and more fruit and vegetables) or “whether tea is having anti-cancer effects which have been suggested in animal and cell studies”.
But tea drinking has also been linked in studies with a lower risk of oral cancer, and cancers of the breast, ovaries, lungs, and thyroid.
Interestingly, a study found that those drinking the highest amounts of green tea specifically had a 22 per cent reduced risk of endometrial cancer.
Helps us concentrate
When we need to focus and feel more alert, coffee is normally our go-to beverage. But don’t overlook the boost tea offers – and it is less likely to give you the jitters.
“Tea contains around 40-50mg of caffeine, which is half the amount found in coffee,” says Ruxton.
“Caffeine is well known for promoting memory, alertness and concentration. However, tea is uniquely high in an amino acid called ‘L-theanine’ which works in combination with caffeine to produce a feeling of ‘calm concentration’.
“This has been proven by studies which have found that L-theanine lowers stress and improves mental focus under challenging working conditions”.
Can improve sleep
Herbal tea infusions containing camomile have long been linked to a good night’s sleep, but interestingly, studies by the Tea Advisory Panel (TAP) found that two cups of even regular tea can aid sleep quality – perhaps because the ritual of drinking it relieves stress.
The active compounds in tea that could help send us to the Land of Nod include polyphenols, L-theanine, theaflavins, thearubigins and gamma-aminobutyric acid (GABA). Both L-theanine, an amino acid, and GABA have direct effects on the brain, helping to activate pathways that lower stress and create calm and relaxation.
Promotes mental well being
“Flavanols have been shown to improve cognitive function, and there is some data from a larger study that support this,” says Prof Kuhnle. But in terms of improving mental health, he suspects that the social aspect of making tea and sitting together to drink is probably the biggest thing at play here – which is certainly important for our emotional wellbeing and mood. It’s been proven many times, after all, that happier people live longer.