Impact of tea drinking on iron status in the UK: a review.

BACKGROUND: The aims of this review are (1) to evaluate the literature on the likely impact of tea drinking on the iron status of different groups within the UK population and (2) to formulate targeted and evidence based advice on tea drinking in the context of iron nutrition in different groups of people.
METHOD: A literature search identified 35 references specific to the effects of black tea on iron absorption and iron nutrition plus one recent review article. Each study was assessed in terms of methodogical quality and relevance to the tea drinking patterns of the UK population.
RESULTS: There is clear evidence to show that tea drinking limits the absorption of nonhaem iron. However, there are few studies which have assessed the influence of tea drinking on indicators of iron status. There are no intervention studies and the conclusions reported in this review are based on 12 observational studies mostly from other countries. These studies have reported either significant negative correlations between tea drinking and blood indicators of iron status or more cases of anemia in tea drinkers compared with nontea drinkers. Many of the studies reviewed report additional relationships between iron status indices and other factors (both dietary and nondietary), highlighting the complexity of influences on iron absorption and iron status.
CONCLUSION: From the available evidence there is no need to advise any restriction on tea drinking in healthy people with no risk of iron deficiency. In groups at risk of iron deficiency the advice should be to drink tea between meals and to wait at least 1 h after eating before drinking tea.