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Moderate evidenceHeart & metabolic

Black Tea (brewed)

Regular black tea lowers blood pressure slightly in randomised trials, and large cohorts link 2 or more cups a day with modestly lower mortality. The effects are small and the mortality data are observational, but for an everyday drink the evidence is reassuring.

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What the science says

  • Small reduction in blood pressure Moderate evidence

    A meta-analysis of 11 placebo-controlled trials (378 participants, typically 4–5 cups a day) found black tea lowered systolic pressure by 1.8 mmHg and diastolic by 1.3 mmHg. A six-month randomised trial of three cups a day also found a small fall in 24-hour blood pressure. Most authors of the meta-analysis worked for a tea company, although no publication bias was detected.

  • Lower mortality with 2 or more cups a day Limited evidence

    In the UK Biobank, 498,043 adults followed for a median of 11.2 years, drinking 2 to 3 cups a day was associated with 13% lower all-cause mortality than drinking none, whatever the person's genetic speed of caffeine metabolism. A dose-response meta-analysis estimated about 1.5% lower all-cause mortality per daily cup. These are associations from observational data, not proof that tea causes the benefit.

  • Prevents heart disease or stroke Limited evidence

    No randomised trial has tested tea against cardiovascular events. The dose-response meta-analysis found about 4% lower stroke risk and 2% fewer cardiovascular events per daily cup, but rated the evidence low, and studies with a higher risk of bias showed bigger effects.

Dosage & safety

Studied doseThe blood pressure trials used about 3 to 5 cups a day, and the UK Biobank association appeared from 2 to 3 cups a day; a cup is about 236 mL. A cup of brewed black tea typically contains about 40–70 mg of caffeine. If you are short of iron, drink it at least 1 hour after meals rather than with them.
SafetySafe for most adults at usual intakes. Tea drunk with a meal cut non-heme iron absorption by about 37% in a stable-isotope study, and a 1-hour gap halved that loss, which matters for people with iron deficiency, vegetarians and pregnant women. Caffeine can disturb sleep and raise heart rate; keep total caffeine under about 200 mg/day in pregnancy and 400 mg/day for other adults. Tea drunk at 60 °C or hotter was linked to oesophageal cancer in a large cohort, so let it cool. Case reports describe skeletal fluorosis in people drinking several litres of strong tea every day for years.

How to take it

TimingAny time before mid-afternoon; the caffeine can disturb sleep later in the day.
With food?Between meals rather than with them if you are short of iron.
Worth knowingLet it cool to a comfortable drinking temperature rather than sipping it scalding hot.

Interactions

With medications

  • stimulant medication and high-dose caffeine products

    Additive caffeine effects: palpitations, anxiety and disturbed sleep. count black tea in your total daily caffeine

With other supplements

  • iron supplements and iron-rich meals

    Tea reduces non-heme iron absorption when taken at the same time. drink tea at least 1 hour after the meal or the supplement

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does black tea lower blood pressure?

A little. A meta-analysis of 11 placebo-controlled trials found black tea lowered systolic pressure by 1.8 mmHg and diastolic by 1.3 mmHg at about 4–5 cups a day (moderate evidence).

Is drinking black tea every day good for you?

Probably. In the UK Biobank, 2 to 3 cups a day was associated with 13% lower all-cause mortality than no tea. This is observational, so it shows association rather than cause (limited evidence).

How much caffeine is in black tea?

A cup of brewed black tea typically contains about 40–70 mg of caffeine. Keep total caffeine under about 400 mg/day for adults and 200 mg/day in pregnancy.

Should I drink tea with meals if I am low in iron?

No. Tea with a meal cut non-heme iron absorption by about 37% in a stable-isotope study; drinking it at least 1 hour after the meal halved that loss.

Scientific references

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