A diet-controlled clinical trial which attempts to provide estimates of the effect of black tea consumption on serum lipids under tightly controlled conditions, including a controlled diet. Mildly hypercholesterolemic individuals (total cholesterol levels between 4.9 and 6.7 mmol/L, 190 and 260 mg/dl), non-smoking, chronic disease-free individuals were enrolled in a 15-week, double blind, randomized crossover trial, during which they consumed a controlled low-flavonoid diet plus 5 cups of black tea or a tea-like placebo over two 4-week treatment periods.