Two cups of popular drink slashes risk of stroke - just don't add one common ingredient

Since the 17th century, the United Kingdom has been one of the world's largest consumers of tea, with an average annual per capita supply of over 4lb.

For over 300 years, Brits have been offering each other a cup of tea in times of trouble, or even just to be polite. But it has now emerged that the humble cuppa does a lot more good than some of us had realised.

A large-scale research project has revealed that regular tea-drinkers have a reduced risk of strokes and heart problems. But only, the experts from China’s Nantong University found, if drinkers go without one popular addition.

The researchers studied the habits of 177,810 UK adults with an average age of 55, of whom 147,903 were regular tea drinkers. They found that the 68.2% of the study subject who didn’t take sugar in their tea derived significant health benefits from their regular brew.

Every person surveyed was in good health at the beginning of the 12-year study period, but by the end of the period, 15,003 of them were diagnosed with some form of of cardiovascular disease.

The research, published in the International Journal of Cardiology Cardiovascular Risk and Prevention showed that tea-drinkers were less likely to suffer heart problems, as long as they didn’t add sugar.

Researchers found that people who drank up to two cups of unsweetened tea a day were at significantly lower risk of heart failure - by around 21%.

They also had a 14% lower chance of having a stroke and were 7% less likely to be diagnosed with coronary heart disease.

The research found: "Drinking tea without added sweeteners may help preserve beneficial bioactive compounds, such as polyphenols, which are known for their antioxidant and anti-inflammatory properties.

"In contrast, both sugar and artificial sweeteners have been linked to insulin resistance and disruptions in metabolic function—factors that are strongly associated with an increased risk of cardiovascular disease."

Polyphenols – which are present in coffee, red wine and dark chocolate, as well as tea – are known to have significant health benefits. Several studies credit them with a variety of health benefits, particularly due to their antioxidant and anti-inflammatory effects.

The benefits include:

1. Antioxidant Protection

Polyphenols help neutralise free radicals, reducing oxidative stress, which can damage cells and contribute to aging and chronic diseases.

2. Anti-Inflammatory Effects

They modulate inflammatory pathways, potentially reducing chronic low-grade inflammation involved in diseases like arthritis, cardiovascular disease, and certain cancers.

3. Cardiovascular Health

Polyphenols are thought to improve endothelial function (important for blood vessel health), lower blood pressure and LDL cholesterol and inhibit platelet aggregation, reducing clot risk. They may reduce the risk of stroke and coronary artery disease

4. Blood Sugar Regulation

Some polyphenols improve insulin sensitivity and slow down carbohydrate digestion and absorption, helping to regulate blood glucose levels and reduce the risk of type 2 diabetes.

5. Neuroprotective Effects

Protect neurons from oxidative damage

May slow cognitive decline and lower risk of neurodegenerative diseases such as Alzheimer’s and Parkinson’s

Enhance brain plasticity and memory function

6. Gut Health Support

Polyphenols can act as prebiotics, promoting the growth of beneficial gut bacteria, and modulating gut microbiota composition—important for immunity, digestion, and even mood regulation.

7. Potential Cancer Risk Reduction

Certain polyphenols may inhibit tumour growth, angiogenesis (formation of new blood vessels feeding tumours), and cancer cell proliferation, although more human studies are needed.

8. Anti-Microbial Properties

Some polyphenols show activity against bacteria, viruses, and fungi, and may contribute to oral health (e.g., in tea or berries).

9. Skin Protection

Help protect skin from UV damage

Reduce signs of ageing and inflammation

May support wound healing through antioxidant effects