The health health virtues

Appeared in China around the year 600 and has been drunk for millennia, tea has become a very popular drink, appearing in the most consumed drinks in the world. However, if we drink a lot, we know little or badly all our benefits.

All teas, whether white, green, black, Oolong come from a plant called Camellia sinensis. The differences are due to the degree of fermentation (enzymatic oxidation) of the leaves: in black tea this process is completely accomplished, while it is interrupted very early in green tea, by exposing the leaves to heat. The white and Oolong teas correspond to intermediate states.

All teas are however rich in flavonoids, compounds belonging to the large family of polyphenols. “” Flavonoids represent a third of the weight of the tea leaf, which is very high, when you consider that tea has practically no calories »Explain Professor Jeffrey Blumberg (Tofts University, Boston). The flavonoid content, and therefore the profits associated with it, varies considerably according to the production regions, varieties, the treatment of leaves and the way in which tea is infused. Despite everything, tea can be considered a drink favorable to health even if it should not expect miracles.

It is favorable to cardiovascular health

Tea contributes to the flexibility of the arteries and the fluidity of the blood. Epidemiological studies show that compared to non -drinkers, tea drinkers have less hypertension; Their risk of a vascular accident is reduced. In a double -blind controlled study, volunteers with hypertension drank a cup of black tea per day; Their diastolic and systolic pressures were lowered (1). These benefits have been maintained, even in the presence of fatty and sweet foods which tend to contract the blood vessels. Other studies have found similar results.

It is good for bone health

Several studies have observed the link between bone mineral density (a marker of the health of our bones) and tea consumption. In 2007, researchers reported that menopausal women who regularly drink tea seem to keep bones healthy for longer (2). Another study then followed a group of 171 menopausal women suffering from osteopenia (which precedes osteoporosis) which were assigned in double blind and randomly either to take 500 mg of green tea polyphenols, either to perform 3 sessions of one hour per week of Tai Chi, or both at the same time, or, to take a placebo, all for 6 months. At the end of the study, women who took green tea and/or who made Tai Chi saw their bone mineral density and their muscle strength increase (3), two parameters that could protect fractures. Tea would act by reducing oxidizing stress and inflammation, which is caused by a loss of bone mass and muscle mass.

It could improve your intellectual performance

Regular consumption of tea (3 to 4 cups per day) is associated with a lesser decline in intellectual performance with age (4). Although researchers do not know with certainty which substance (s) of tea would be responsible for these effects, they strongly suspect the flavonoids of being responsible for it, via an improvement in cerebral blood flow. The benefit would be identical to that of coffee but without the negative effects of caffeine which can cause sleep disorders (5).

He could protect from cancer

Several observation studies have shown that tea consumers were less likely to develop cancer (6, 7). This benefit would be proportional to the dose consumed with a decrease in risk that can reach 41 % for people who drink 10 cups per day compared to those who drink less than 3. The anticancer properties of tea have also been highlighted during laboratory studies (8) and seem to concern more particularly green tea, thanks to its polyphenols. Black tea, more consumed in Europe, seems less protective. Regular consumption of green tea would be particularly protective of colon cancer and probably skin cancer (9, 10) but also lung, prostate and breast cancers (11).

For Professor Alice Bender (American Institute for Cancer Research) however, “In experimental studies, tea compounds appear very promising to fight cancer. They act as antioxidants, slow down the growth of tumors and promote the death of cancer cells. But evidence in humans are still too limited to draw firm conclusions on the risk of cancer. »»

It helps the patients of hemochromatosis

Hemochromatosis is a disease characterized by an iron overload of the organism then causing often irreparable lesions at the level of the organs. The main treatment consists in carrying out phlebotomies (bleeding) to eliminate surplus iron. A clinical study has shown that tea consumption during meals decreases the absorption of iron and thus makes it possible to space the sessions of phlebotomies, then improving the quality of life of the patients (12).

He can help lose weight (modestly)

The compounds of tea activate thermogenesis, that is to say all the mechanisms that allow the maintenance of our body temperature and lead to “burn” reserve fats. Caffeine slightly increases thermogenesis and destocking of fats, but ” The Association Caféine-Flavonoids du tea (catechins) is much more effective in promoting energy expenditure and fat oxidation, even if the effect remains limited, or 100 calories eliminated per day, the equivalent of 1.3 kg lost in 3 months “, According to the Rick Hursel (University of Maastricht, Netherlands). This additional energy expenditure can help lose a little weight as shown by several studies, especially in size (13, 14).

Read : Does green tea make you lose weight?

There are also food supplements that combine green tea polyphenols (epigallocatechine gallate or ECGC) and caffeine, but they are not recommended for children, pregnant women and when there is a cardiovascular risk factor.

Furthermore, there is no fairly significant evidence of the effects of tea on feelings of hunger and satiety, studies remaining still contradictory on this subject (15).

It can be useful against type 2 diabetes

Tea consumption can be a promising strategy for preventing and treating diabetes and complications by regulating the absorption and metabolism of glucose, controlling the level of postprandial glucose and improving insulin resistance. Indeed, the consumption of black tea seems to significantly reduce the level of glycated hemoglobin in diabetic patients, as for green tea it could help to compensate for diabetes induced by a diet too rich in fat (16).

He protects the liver

The hepatotector effect of tea is the result of its action on oxidative stress. By improving the antioxidant defense system, by inhibiting inflammation, it manages to block the destruction of liver cells, to regulate the metabolism of lipids, to prevent hepatic steatosis and fibrosis. In a study, the consumption of green tea extract in people with fatty liver disease has reduced abnormally high transaminases in this type of disease (16).

He is an ally against stress

Regular consumption of tea could help to recover more easily and quickly from a period of stress. Certainly, the ritual and the generally soothing context in which tea is consumed helps. However, studies confirm the relaxing effect of tea (17). On a panel of black tea consumers, cortisol levels, stress hormone, falls 53 % an hour after stress, against 73 % in people who did not drink tea.

But where do these soothing virtues come from? Tea contains an amino acid called L-Théanine which can help reduce stress and anxiety by reducing cortisol and increasing the activity of a calming neurotransmitter called GABA. According to an article of Pharmacology Research From 2019, the daily consumption of 200 to 400 mg of L-Théanine (the equivalent of 8 to 16 cups of tea), would have beneficial effects to fight against stress and anxiety (18).

To read on this subject: I resist stress better

It acts favorably on the intestinal microbiota

It is the tea polyphenols that have a positive impact on the composition of the microbiota by acting as prebiotics (fibers that nourish good bacteria in the intestine). Their ability to influence the presence of good bacteria in the intestine could explain the multiple health health benefits, including its slimming action. Tea polyphenols induce the proliferation of Bifidobacterium spp. and Lactobacillus/enterococcus spp. and inhibit the Bacteroides-Prévotella And Clostridium histolyticum (19).

It captures heavy metals

A study by Northwestern University (United States) reveals that tea captures heavy metals present in water such as lead or cadmium (20). This small “depollution” would be possible thanks to an adsorption effect linked to the large contact area with water.

“Our work highlights the unknown potential of tea consumption to passively contribute to the reduction of exposure to heavy metals in populations around the world,” said Vinayak Dravid, one of the study authors. However, “We do not suggest that everyone is starting to use tea leaves as a water filter”he specifies. Based on their experiences, researchers believe that tea preparation can eliminate about 15 % of drinking water lead, even high lead concentrations (10 ppm). This estimate only applies to a cup of “typical” tea, that is to say a cup of water and a sachet of tea infused for three to five minutes.

Researchers also found that cellulose sachets give better results than cotton or nylon, which absorb few contaminants.