Overview
Black tea is made from the leaves of Camellia sinensis — the same plant used for green, white, and oolong tea — but unlike those, its leaves are fully oxidized (withered, rolled, and exposed to air for several hours) before drying. This oxidation turns the leaf dark and produces the tea’s characteristic reddish-brown color, malty or brisk flavor, and higher caffeine content relative to less-oxidized teas. Assam (India, bold and malty), Darjeeling (India, lighter and floral), Ceylon (Sri Lanka, bright and citrusy), and Earl Grey (black tea scented with bergamot oil) are among the best-known styles.
Active compounds and evidence
Oxidation converts much of the catechin content found in green tea into theaflavins and thearubigins, the polyphenols responsible for black tea’s color and body. A cup of black tea typically supplies roughly 40–70 mg of caffeine, depending on steep time and leaf amount.
Observational studies and meta-analyses associate regular black tea consumption with modestly lower risk of cardiovascular disease, and some randomized trials show small, short-term improvements in flow-mediated dilation (a marker of blood vessel function) after black tea intake. The Harvard T.H. Chan School of Public Health’s Nutrition Source summarizes tea, including black tea, as a beverage with consistent (though not dramatic) associations with cardiovascular benefit, likely related to its flavonoid content. As with most nutrition epidemiology, these are associations rather than proof of causation, and effect sizes are modest.
Safety and contraindications
- Caffeine sensitivity: Black tea’s caffeine content, while lower than coffee, can still affect sleep, anxiety, and heart rhythm in sensitive individuals; the FDA generally references 400 mg/day caffeine as a reasonable upper limit for healthy adults.
- Iron absorption: Tannins in black tea can reduce absorption of non-heme (plant-based) iron when consumed with meals; people with iron-deficiency anemia are often advised to drink tea between meals rather than with them.
- Pregnancy: Caffeine intake during pregnancy is generally advised to stay under 200 mg/day (ACOG guidance); black tea should be counted toward that total.
How it’s typically prepared
Steeped in freshly boiled water (200–212°F) for 3–5 minutes; milk is traditional in some regions and binds some tannins, producing a smoother taste.
Sources
- Harvard T.H. Chan School of Public Health — Tea
- USDA FoodData Central
- FDA — Spilling the Beans: How Much Caffeine Is Too Much?
Clinically reviewed by Dr. Shilpa Thakur. Last reviewed 2026-07-20. Educational information, not medical advice; consult a qualified clinician about caffeine intake if pregnant, breastfeeding, or managing a heart condition.