Black tea - helpful or harmful? A review of the evidence

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European Journal of Clinical Nutrition (2007) 61,

3-18.

Review

Black tea - helpful or harmful? A review of the

evidence E J Gardner, C H S Ruxton and A R Leeds

Abstract

Objective: To consider whether consumption of black

tea has a positive or negative impact on health.

Design: Databases were searched for relevant

epidemiological and clinical studies published between

1990 and 2004.

Results: Clear evidence was found for coronary heart

disease (CHD), where an intake of 3 cups per day

related to risk reduction. The mechanism could

involve the antioxidant action of tea polyphenols.

While experimental models have suggested that

flavonoids attenuated cancer risk, epidemiological

studies failed to demonstrate a clear effect for tea,

although there is moderate evidence for a slightly

positive or no effect of black tea consumption on

colorectal cancer. Studies on cancer were limited

by sample sizes and insufficient control of

confounders. There is moderate evidence suggestive of

a positive effect of black tea consumption on bone

mineral density although studies were few. There is

little evidence to support the effect of tea on dental

plaque inhibition but evidence to support the

contribution of tea to fluoride intakes and thus

theoretical protection against caries. There was no

credible evidence that black tea (in amounts typically

consumed) was harmful. Normal hydration was

consistent with tea consumption when the caffeine

content was <250 mg per cup. A moderate caffeine

intake from tea appeared to improve mental

performance, although sample sizes were small. There

was no evidence that iron status could be harmed by

tea drinking unless populations were already at risk

from anaemia.

Conclusions: There was sufficient evidence to show

risk reduction for CHD at intakes of 3 cups per day

and for improved antioxidant status at intakes

of one to six cups per day. A maximum intake of eight

cups per day would minimise any risk relating to

excess caffeine consumption. Black tea generally had a

positive effect on health.

Sponsorship: The Tea Council. The authors confirm that

the sponsors played no role in the writing of this

review.

Abstract with links to FREE full-text at:

http://www.nature. com/ejcn/ journal/v61/

n1/abs/1602489a. html