After water, it is certainly the most consumed drink in the world. “Tea has its roots in the mists of time. Its origins can be traced back to China over 5000 years ago, before becoming a typical drink of Western civilization in modern times. Just think of the Anglo-Saxon countries known for the so-called ‘tea time’. There are numerous varieties of tea, different in flavour, aroma, color which can vary from white, to yellow, to green, to black, although they all derive from a single mother plant: the Camellia Sinensis. The processing methods to which the leaves are subjected, based on oxidation or fermentation processes, will then define the different types of tea”. Mauro Minelli, immunologist and professor of Fundamentals of dietetics and nutrition at Lum University.
“Among the beneficial substances contained in tea, the following should be mentioned first of all polyphenols which, in the green variety, are mainly represented by catechins, with particular reference to Epigallocatechin-3-gallate (EGCG); in black tea, however, theorubicins and theoflavins stand out. Well known – he continues – is the antioxidant power of polyphenols, capable of neutralizing the action of free radicals which, left to themselves, would over time lead to progressive damage to intracellular DNA, the integrity of which remains the basic element of our health. In this regard, studies conducted on cell lines and laboratory animals seem to confirm the ability of tea polyphenols to block the replication and reduce the invasiveness of tumor cells, thus protecting us from the risk of serious diseases”.
But tea contains other virtuous substances “including alkaloids such as caffeine which, in addition to stimulating our psychomotor activities, making us much more active and efficient throughout the day, also increase our ability to resist sleep and fatigue. Furthermore, caffeine is also able to implement the respiratory functions by stimulating the nervous center which modulates these functions – the immunologist points out – Other alkaloids present in tea are theophylline and theobromine which above all exert a relaxing action on the muscle tissue, generating bronchodilation and modulating the functions of the respiratory bile as well as the peristaltic activities of the intestinal walls”.
‘It is instead attributed to anti-inflammatory but also astringent activity.
“The tannins, other polyphenols contained in tea, are instead attributed anti-inflammatory but also astringent and anti-diarrheal activity, being able to regulate the functions of the intestinal glands – recalls Minelli – Tea is generally present in slimming diets as the antioxidant agents contained in the drink, by accelerating the metabolism of fats and sugars, contributes to keeping blood sugar and cholesterol levels within limits, which is why tea is considered a useful and profitable drink for the prevention of atherosclerosis and cardiovascular diseases”.
However, some limitations must also be remembered for tea as, “if consumed in excessive quantities, this noble drink can be associated with some undesirable effects, precisely due to those alkaloids, including caffeine, already previously mentioned. In fact, excessive tea consumption could generate tachycardia, nervousness, insomnia, agitation. Due to all these potential side effects, tea intake by children is therefore not recommended. Both green tea and black tea are also capable of inhibiting absorption of iron, generating negative effects on those people who suffer from an iron-deficiency anemic state”, warns the expert.
“Finally, tea is capable of interfering with the pharmacological action of some medicines, among which some chemotherapy drugs such as Bortezumib should be mentioned, whose therapeutic effects are strongly counteracted by some molecules present in tea leaves. Small precautions useful, however, to make tea consumption tasty and safe”, he concludes.
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