Tag Archives: Black Tea’s Effects on Blood Pressure: Randomized Controlled Trial

The new issue of *Archives of Internal Medicine* (vol. 172, #2) includes an article: “Effects of Black Tea on Blood Pressure: A Randomized Controlled Trial.”

The authors are Jonathan M. Hodgson, PhD; Ian B. Puddey, MD; Richard J. Woodman, PhD; Theo P. J. Mulder, PhD; Dagmar Fuchs, PhD; Kirsty Scott, BSc; & Kevin D. Croft, PhD.

Here’s how the article begins:


High blood pressure (BP) is a leading risk factor contributing to the global burden of disease.

Small changes in BP due to dietary modification may have a significant impact on the prevalence of hypertension and risk of cardiovascular disease.1

Tea is a popular beverage worldwide and is usually the major source of population flavonoid intake, often providing more than half of total intake.2

There is mounting evidence that tea and its flavonoids can make an important contribution to vascular health.3

However, the effects of regular consumption of black tea on BP remain unclear.

Our objective was to assess the effects of regular black tea consumption (3 cups/d) for 6 months on 24-hour ambulatory BP.

Another excerpt: “Men and women aged 35 to 75 years, who were regular tea drinkers, with a body mass index of 19 to 35 (calculated as weight in kilograms divided by height in meters squared) and a daytime ambulatory SBP between 115 and 150 mm Hg at screening were recruited from the general population.”

Another excerpt: “Compared with placebo, regular ingestion of black tea over 6 months resulted in lower 24-hour SBP and DBP. ”

Another excerpt: ” Significant differences in BP were also observed for daytime and nighttime BPs separately, but effects on the overall 24-hour BP were mainly driven by daytime BP (Figure and eTable).”

Another excerpt: “A large proportion of the general population have BP within the range included in this trial, making results of the trial applicable to individuals at increased risk of hypertension.”

Another excerpt: “There are a number of potential mechanisms for BP lowering by black tea. Hypertension and endothelial dysfunction are integrally related, and endothelial dysfunction may be an early marker for BP changes. A recent meta-analysis found that tea consumption can improve endothelial function,6 and we have previously shown that tea flavonoids can augment nitric oxide status and reduce plasma concentrations of endothelin-1.7 This could contribute to reduced vascular tone and lower BP. Another possible mechanism involves effects of tea flavonoids to alter body weight and/or visceral fatness. A recent meta-analysis suggests that green tea and its flavonoids–many of which are structurally similar to black tea flavonoids–together with caffeine can reduce body weight and abdominal fatness.8}

One final excerpt: “In conclusion, our study has demonstrated for the first time to our knowledge that long-term regular consumption of black tea can result in significantly lower BPs in individuals with normal to high-normal range BPs.”

Courtesy of Ken Pope. Article available on: http://archinte.ama-assn.org/cgi/content/full/172/2/186?etoc