To reap the health benefits of tea you need to drink three cups a day, according to Simon Gibbons, Professor of Phytochemistry at the University of London School of Pharmacy.

He suggests drinking one cup in the morning, one at midday and one in the evening.

'You must leave the tea (whether a bag or leaf) to steep for at least five minutes to allow the hot water to extract the plant material,' he says.

There are four main types of tea leaves - black (including English Breakfast and Earl Grey), green, white and Oolong. They all contain antioxidants that have a host of health benefits. And herbal infusions, which do not contain tea leaves, also have many health-giving properties.

Adding milk prevents our bodies from accessing the valuable antioxidant qualities in the tea due to the proteins it contains - but adding sugar does not have the same effect.

CUTS STROKE RISK

A 15-year study in the Netherlands found a strong link between regular consumption of tea made with black tea leaves drunk without milk and reduced risk of stroke.

Researchers concluded that the flavonoids (nutrients with anti-oxidant properties) found in high concentrations in black tea helped reduce the production of LDL, the 'bad' cholesterol that can cause arteries to narrow, increasing the chance of stroke or heart attack.

A study in the USA found that five servings of black tea per day reduced LDL cholesterol by 11 per cent. The flavonoids also improve the functioning of blood vessels.

AIDS DIGESTION

Green tea - made from unprocessed tea leaves - helps keep your digestive system regular. It stimulates intestinal muscle contractions, thereby moving food through the system. It can also help with weight loss: green tea has been found to block the absorption of bad fats by up to 30 per cent.

Peppermint tea is also beneficial. Herbalist Sebastian Pole, of Pukka Herbs, explains: 'The essential oils in mint help to relax tension in the digestive system to help you digest your food better.' They prevent the intestinal muscles from cramping and allow digestive gases to pass easily.

Ginger tea is said to relieve nausea and is commonly recommended for morning sickness. Fennel tea is good for constipation, flatulence and colic.

BRAIN FUNCTION

Black tea can help you concentrate. A study at the University of Northumbria found that caffeine and L-theanine in black tea leaves improves cognitive skills. In a test, those who drank two cups performed better than those who drank placebo tea.

A study by scientists at Imperial College found that those who drink more than 100ml of tea (or coffee) a day appeared to have a 34 per cent lower risk of being diagnosed with a glioma, the most common type of brain tumour.

ANTI-CANCER

Tea contains polyphenols, antioxidants that can stop cancer cells growing. Tea has about eight to ten times the polyphenols found in fruits and vegetables. Green tea is especially high in polyphenols.

A recent study in Taiwan found that drinking one cup of green tea a day can reduce the risk of lung cancer, particularly for those carrying a certain gene. It is also thought to slow the progress of prostate cancer and to reduce the risk of stomach cancer.

Daniel Rook, of Chash Tea, recommends Oolong tea as it has even more polyphenols than either black or green. However, drinking tea too hot, at 70C or more, can raise the risk of throat cancer.

BOOSTS IMMUNE SYSTEM

A study at Harvard University used blood tests to compare the immune function of tea drinkers with that of non-tea drinkers and found that those drinking five or six cups of black tea a day had an enhanced immune system.

Chemicals known as alkylamines that are found in tea are also present in some bacteria and parasites. It is thought that by drinking tea we prime our immune cells to recognise these alkylamines and be ready to fight them.

The polyphenols in tea also strengthen our defences against certain bacteria and may help improve metabolism and skin health.

Ginger tea is thought to have anti-inflammatory properties and can stimulate circulation. It also has an a n a l g e s i c effect - one study found that, if taken at the onset of a migraine, it can help to relieve pain.

INSOMNIA AND ANXIETY

Its caffeine content - although lower than that of coffee per serving - means that black tea should be avoided near bedtime. Most herbal teas, however, do not contain caffeine.

Insomnia is often caused by - or causes - anxiety so herbs with calming properties are ideal. Chamomile has long been used to promote sleepiness as it contains chrysin, a chemical believed to relieve anxiety and promote drowsiness, and tryptophan, an amino acid known for its tranquillising effects.

Lavender tea - made from dried lavender flowers - relaxes and soothes both mind and body. Basil tea - made from shredded basil leaves - is also said to have sedative qualities.

DENTAL HEALTH

Although drinking black tea - particularly without milk - can discolour teeth, it can also protect them as the polyphenols reduce plaque formation and protect against bacteria that cause gum disease and cavities.

White tea and green tea also give protection from these bacteria. Fruit teas are acidic and can erode tooth enamel.

'It would be a good thing if more young people drank tea as it has so many health benefits,' says Ursula Arens, a registered dietician.

'It is fantastic for rehydrating, has no calories and is better for your teeth than fruit-based drinks. Tea gets ten out of ten for healthiness.'

Read more: www.dailymail.co.uk/health/article-1351421/Go-tea-total-Youll-likely-brain-tumour-stroke-better-able-fight-infection.html#ixzz1ColRVBv3