Green tea every day: what large cohort studies showed

Key points

Green tea is one of the simplest rituals doctors discuss: water, leaves and a couple of minutes of pause. In large cohorts of hundreds of thousands of people in Asia, those who drink 1-3 cups a day died less often from any cause and from heart and vessel disease, and 2-3 cups were associated with a lower stroke risk. In trials the drink itself slightly lowers total cholesterol. All this is association, not a promise, but it fits nicely with the fact that tea is pleasant, has no sugar and easily replaces a sweet drink.

Length of life: a large Asian cohort

The largest analysis pooled 12 Asian cohorts (Japan, China, Korea, Singapore): the green tea calculation included 477,192 people in total, all groups together from non-drinkers to people drinking five cups or more, followed for 6.5 to 22.7 years, with 94,744 deaths. Compared with non-drinkers, 1-3 cups a day were associated with a 9% lower risk of death from any cause: HR 0.91 (0.86-0.96) in men and HR 0.91 (0.86-0.95) in women (Shin S Int J Epidemiol 2022. PMID 34468722^[1]).

The risk of death from heart and vessel disease at 1-3 cups was 15% lower in men (HR 0.85; 0.80-0.91) and 12% in women (HR 0.88; 0.80-0.96). Among those drinking 5 cups or more the link looked stronger still: 21% in men and 22% in women (Shin S Int J Epidemiol 2022. PMID 34468722^[1]). In men the link with overall mortality was the same at any amount of tea, so no single "best" number of cups can be singled out.

Stroke: the Japanese cohort

A large Japanese cohort followed 82,369 people aged 45 to 74 for 13 years, during which 3,425 strokes occurred. Those who drank 2-3 cups a day, compared with people who seldom drink tea, were associated with a 14% lower stroke risk (HR 0.86; 0.78-0.95), and those who drank 4 cups or more with 20% lower (HR 0.80; 0.73-0.89) (Kokubo Y Stroke 2013. PMID 23493733^[2]).

This is a case where a household habit looks very "Mediterranean": tea instead of a sweet drink, a cup after a meal, a cup in the middle of the day.

Cholesterol: a small plus from the drink

A review of randomised trials separately counted the subgroup in which green tea was drunk as a beverage. In the drink subgroup total cholesterol was lower by 0.07 mmol/L (2.8 mg/dL) on average, 9 trials. LDL ("bad") did not change significantly, nor did "good" cholesterol or triglycerides (Xu R Nutr J 2020. PMID 32434539^[3]). So tea will not replace work on diet, but it is a small, measurable plus.

How to drink green tea

Brew loose tea or a teabag in a mug with hot but not boiling water, and drink it warm. It tastes better and is gentler on the throat. A simple rule: let the tea stand for a couple of minutes and take the first sip when it no longer burns your lips. If you are in a hurry, add a splash of cold water or pour the tea into a wide cup: it cools faster that way.

A simple plan for the day: a cup in the morning after breakfast, a cup in the middle of the day instead of a sweet drink, a cup after lunch or dinner. Three cups is within what was studied and is not burdensome at all. For work it is handy to take a thermos of brewed, slightly cooled tea: a cup is always at hand, and the sweet drink from the vending machine is not needed.

Tea also works well as a substitute. If you now drink sweet fizzy drinks, packet juice or coffee with syrup during the day, one or two cups of green tea in their place take a portion of sugar out of the day and ask for nothing in return. So the habit is not about "one more chore" but a simple swap that comes easily.

Brewing needs no special skill either. Put the tea in a mug or teapot, pour over hot water, wait a couple of minutes and drink. If you brewed it too long and it turned bitter, next time just shorten the time and let the water cool a little. Many people like to sip tea slowly without hurry: it is a small pause that is calming in itself.

It helps if tea becomes part of the rhythm of the day: a morning cup while planning the day, a cup in the middle of the day on a walk or by the window, an evening cup with a book. Such anchors help you remember the habit, and after a couple of weeks it settles without effort. Choose loose tea with a clear ingredient list, so that it contains only tea, without flavourings or sugar. If you want variety, change the types of tea and the ways of brewing: different teas taste different, and the habit will not get boring.

How to use it

• Guide from the cohorts: 1-3 cups a day; the link with benefit is also seen at more cups.
• Drink the actual drink: loose tea or a teabag without sugar.
• Use it to replace sweet drinks, not to add on top of them.
• Drink it warm: let the tea cool a little.
• If evening tea disturbs your sleep, move it to the first half of the day.

Who should see a doctor first

Green tea does not replace prescribed treatment for heart disease, blood pressure or cholesterol. If a doctor has limited your caffeine, you are pregnant or breastfeeding, or you have insomnia, anxiety or rhythm disorders, discuss the number of cups with a doctor. If you take prescribed treatment, discuss diet at your appointment.

Bottom line

Green tea is a simple habit with several pluses at once: it is associated with lower mortality and lower stroke risk in large cohorts and, as a drink, slightly lowers total cholesterol. One to three cups a day, without sugar and warm, is an easy way to make the day calmer and healthier.