Tea is Britain’s favourite drink — and now research suggests it could also protect your heart and brain.

Large studies now suggest that both black and green tea are linked with a lower risk of stroke and dementia.

The benefits aren’t identical, but both types of tea appear to support long-term brain and heart health.

What the research shows

One of the largest studies so far came from the UK Biobank in 2021, which followed more than 365,000 adults — most of them black tea drinkers.

Those who had around 3–5 cups of tea a day were less likely to suffer from stroke or dementia later on. And when tea was combined with coffee — about 2–3 cups of each per day — the benefits were even bigger: a 32% lower risk of stroke and a 28% lower risk of dementia compared with non-drinkers.

A 2023 review pooling data from over 410,000 people backed this up.

Tea drinkers overall had a 29% lower risk of dementia, including a 12% lower risk of Alzheimer’s and a 25% lower risk of vascular dementia — the type linked to poor circulation in the brain.

The picture is similar worldwide. In Asia, where green tea is the norm, drinking 3–4 cups a day is tied to nearly a 30% lower chance of stroke.

In Europe, where black tea is more common, studies show comparable protection. Taken together, reviews suggest that every extra 3 cups of tea a day may cut the risk of stroke by about 13%, no matter which type you drink.

Green tea vs. black tea — what’s the difference?

• Green tea is less processed, keeping higher levels of certain natural compounds (catechins) that have been closely studied for effects on memory, cholesterol, and circulation. Many Japanese studies showing reduced dementia risk are based on green tea.

  
  

• Black tea is fully processed, creating different compounds (theaflavins and thearubigins). These still act as powerful antioxidants. In the UK, where black tea is by far the most common, studies still find protective links with stroke and dementia.

  
  

• Shared benefits: Both black and green tea provide flavonoids that help blood vessels, circulation, and brain health.

How tea might protect your brain and heart

Researchers believe tea’s benefits are linked to the plant compounds it contains. These compounds may:

1. Keep blood vessels flexible

   
   

   • Tea helps the lining of blood vessels stay healthy, so they can widen and carry blood more easily.

   • This reduces the chance of clots, the main cause of most strokes.

   
   

2. Help control blood pressure

   
   

   • Regular tea drinking can bring blood pressure down slightly.

   • Even small reductions matter across a whole population because they lower rates of stroke and heart disease.

   
   

3. Protect against “furring up” of arteries

   
   

   • Green tea, in particular, may lower “bad” LDL cholesterol and stop it turning harmful.

   • This slows the build-up of fatty deposits that clog arteries and restrict blood flow.

   
   

4. Act directly in the brain

   
   

   • Some tea compounds can cross into the brain. There, they reduce inflammation, improve blood flow, and help brain cells communicate.

   • These changes may help slow memory decline.

   
   

5. Protect brain tissue

   
   

   • Brain scans suggest people who drink more green tea have fewer small scars in brain tissue — changes linked with a higher risk of dementia later in life.

     
     

6. Boosting brain cell “housekeeping”

   
   

   • A recent lab study found that the green tea compoundEGCG, when combined with vitamin B3, helped ageing brain cells restore energy and clear away damaging protein buildup—something that might, down the line, inform ways to support brain health in later life

How much tea to drink?

• 3–5 cups per day seems to be the sweet spot in most studies.

• Brew for 3–5 minutes for maximum benefit. Longer brewing releases more helpful compounds. One study found adding milk did not block absorption.

• Milk or no milk? Some small trials suggest milk may reduce short-term effects, but long-term UK studies (where most people add milk) still show benefits. The bigger issue is sugar, not milk.

• Caffeine: A mug of tea has around 75 mg caffeine. Most adults can safely have up to 400 mg/day. Pregnant women should keep caffeine to 200 mg/day or less (about 2–3 mugs of tea).

NHS guidance

The NHS counts tea and coffee (black or green, with or without caffeine) towards the recommended 6–8 cups of fluid a day. Decaf tea still contains flavonoids, so it’s a good choice if you’re sensitive to caffeine.

Key message:

Both black and green tea are linked with better heart and brain health. Green tea shows stronger evidence in dementia studies, while black tea has clear benefits in stroke and circulation research. Drinking 3–5 cups a day — brewed properly and without sugar — is a simple, everyday habit that may help support long-term health.