EFFECT OF BLACK TEA DRINKING ON BLOOD-LIPIDS, BLOOD-PRESSURE AND ASPECTS OF BOWEL HABIT

Thirty-one men (47 (SD 14) years) and thirty-four women (35 (SD 13) ye ars) took part in a 4-week randomized cross-over trial to compare the effect of six mugs of black tea daily v. placebo (water, caffeine, mil k and sugar) on blood lipids, bowel habit and blood pressure, measured during a run-in period and at the end of weeks 2, 3 and 4 of the test periods. Compliance was established by adding a known amount of g-ami nobenzoic acid (PABA) to selected tea bags, and then measuring its exc retion in urine, Mean serum cholesterol values during run-in, placebo and on tea drinking were 5.67 (SD 1.05), 5.76 (SD 1.11) and 5.69 (SD 1 .09) mmol/l (P = 0.16). There mere also no significant changes in diet , LDL-cholesterol, HDL-cholesterol, triacylglycerols, and blood-pressu re in the tea intervention period compared with placebo, Compared with placebo, stool consistency was softened with tea (P = 0.04), and no o ther differences were found in bowel habit, Results were-unchanged whe n fifteen 'non-compliers', whose PABA excretion indicated that fewer t han six tea bags had been used, were excluded from the analysis, and w hen differences between run-in and tea periods were considered separat ely for those who were given tea first or second.