Nowadays it often seems as if everything we eat or drink is bad for us in some way. Foods once considered healthy and nourishing contain, we are told, ingredients like carbohydrates, sodium and saturated fats which can cause dreadful diseases when consumed frequently or in excess. Every few days we hear, read or see on television news of some medical discovery exposing the harmful effects of yet another favourite food or beverage, now to be banished from the tables of health-conscious folk. The parade of bad news seems to have no end. So it comes as a relief to learn that one popular beverage, affordable and loved by billions of people around the world, is entirely beneficial and may in fact have preventive and curative health properties when consumed regularly. The beverage, of course, is tea.
Medical benefits have been claimed for tea for as long as it has been drunk. The origins of the ‘cuppa’ are lost to the ages, yet when we first hear of tea it is in a medicinal connection: a Chinese text, The Divine Farmer’s Herb-Root Classic, dating from around 250BC, recommends infusions of tea-leaves for the treatment of tumours, abscesses, bladder ailments and lethargy. Since then, generation after generation of medical authorities have sung the praises of tea; and today, a popular encyclopaedia lists no less than 22 separate claimed health benefits for the beverage, ranging from protection against HIV infection to the elimination of bad breath.
Extreme or bizarre claims must, of course, be taken with a grain of salt. Far more trustworthy are the benefits proclaimed or suggested by genuine scientific research. When subjected to chemical analysis, tea turns out to contain a number of ingredients whose health-promoting properties are well established. It is also nutritious: taken with milk, four cups of tea a day can provide:
• 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
The manganese and potassium in a cup of tea also helps maintain the body’s fluid balance.
Besides these ingredients, tea contains a unique amino acid, theanine, which has a relaxing effect on humans and also assists the natural immune response to infection. The modest amount of caffeine in tea also acts as a mild mood enhancer.
Perhaps the most significant health-promoting properties of tea lie in the antioxidants or ‘flavonoids’ it contains. Antioxidants are compounds that help remove harmful toxins from the bloodstream, and tea contains uniquely high concentrations of them. Research has shown that consuming such antioxidants can lower the risk of heart disease, strokes and cancer.
There are also indications that antioxidants in tea may help protect against Alzheimer’s disease and age-related memory impairment. Black and green tea both contain higher levels of antioxidants than common fruits or vegetables.
A Fluid Ounce (or Two) of Prevention
Even if we disregard extravagant, scientifically unsupported claims, the established health benefits of tea are numerous. Many of these benefits are preventive, suggesting that a few cups of tea a day can help stave off heart disease, diabetes, hypertension and many forms of cancer.
• Cancer prevention Animal and in vitro studies have shown that tea polyphenols may react directly with and neutralise chemical carcinogens, including those causing cancers of the skin, lungs, oral cavity, oesophagus, stomach, small intestine, colon, liver, pancreas, bladder, and prostate. In addition to the antioxidant ‘scavenging’ activity mentioned above, tea polyphenols may also alter enzymes involved in tumour formation, inhibit malignant cell proliferation and act against forms of bacteria that promote gastric cancers. According to some American studies, tea drinking may also protect against breast and ovarian cancers.
• Tea and heart disease Epidemiological studies have shown that regular tea consumption is linked to decreased risk from heart disease and stroke. While the data from different tests contains some inconsistencies, ‘meta-analyses’ comparing all the available population studies have tended to confirm the relationship, with regular and frequent tea drinkers showing risk levels up to 20% lower than those who do not, or rarely, consume it. Another study suggested that drinking three cups of tea a day reduces the risk of myocardial infarction by 11%.
• Tea and oral health Containing significant amounts of fluoride, tea can contribute considerably to daily fluoride intake, helping reduce tooth decay. Tea polyphenols may also inhibit the growth of bacteria which cause decay, or make them less harmful to the teeth. Recent research indicates that tea could also inhibit the growth of harmful micro-organisms that cause inflammation and oral diseases, including certain oral cancers.
• Tea and your digestion It has been found that consumption of tea can reduce the quantity of harmful microorganisms such as Enterobacteriacea found in the digestive tract, simultaneously increasing the number of beneficial ones and promoting digestive health.