The relationship between tea and heart health is one of the most consistently studied in nutritional epidemiology. Since the 1990s, researchers in Japan, the Netherlands, the UK, and China have produced converging evidence: regular black tea consumption correlates with meaningfully reduced cardiovascular risk.
The Flavonoid Mechanism
Black tea contains a class of polyphenols called theaflavins and thearubigins — compounds created during the oxidation process that turns green tea into black tea. These compounds have a specific affinity for the endothelium (the lining of blood vessels).
When theaflavins bind to endothelial cells, they:
- Increase nitric oxide production — relaxing blood vessels and reducing pressure
- Reduce LDL oxidation — preventing the formation of arterial plaques
- Inhibit platelet aggregation — reducing clotting risk
The flavonoid content of masala chai is not reduced by adding milk — this was a major concern in older research that has since been resolved. Multiple studies confirm that milk does not bind with tea polyphenols in a way that reduces their bioavailability.
The Three-Cup Studies
Two large European studies — the Zutphen Elderly Study (Netherlands) and the EPIC-Norfolk cohort (UK) — both found that people who drank 3–4 cups of black tea daily had approximately 10% lower rates of heart disease compared to non-tea drinkers.
Three cups of black tea contains approximately 200–300mg of flavonoids. A standard serving of masala chai falls squarely in this range.
The Indian Paradox
India has one of the highest rates of black tea consumption in the world, alongside one of the highest rates of cardiovascular disease. This is not a contradiction — cardiovascular disease in India is strongly linked to dietary patterns (high refined carbohydrate intake) and genetic factors, both of which override the modest protective effect of tea.
This does not mean chai is not beneficial. It means chai is one useful element in a broader wellness picture — not a cure, but a daily habit that tips the balance in the right direction.
“Drink your three cups not because science guarantees you will live forever, but because it is a pleasant way to take care of yourself.