Association between consumption of black tea and iron status in adult Africans in the North West Province: the THUSA study.

The association between black tea consumption and iron status was investigated in a sample of African adults participating in the cross-sectional THUSA (Transition and Health during Urbanization of South Africans) study in the North West Province, South Africa. Data were analysed from 1605 apparently healthy adults aged 15-65 years by demographic and FFQ, anthropometric measurements and biochemical analyses. The main outcome measures were Hb and serum ferritin concentrations. No associations were seen between black tea consumption and concentrations of serum ferritin (men P = 0.059; women P = 0.49) or Hb (men P = 0.33; women P = 0.49). Logistic regression showed that tea consumption did not significantly increase risk for iron deficiency (men: OR 1.36; 95 % CI 0.99, 1.87; women: OR 0.98; 95 % CI 0.84, 1.13) nor for iron deficiency anaemia (men: OR 1.28; 95 % CI 0.84, 1.96; women: OR 0.93; 95 % CI 0.78, 1.11). Prevalence of iron deficiency and iron deficiency anaemia was especially high in women: 21.6 and 14.6 %, respectively. However, the likelihood of iron deficiency and iron deficiency anaemia was not significantly explained by tea consumption in sub-populations which were assumed to be at risk for iron deficiency. Regression of serum ferritin levels on tea consumption in women <or= 40 years, adults with a daily iron intake <or= 5.80 mg and adults with ferritin levels <or= 26.60 microg/l, respectively, showed P values in the range of 0.28-0.88. Our findings demonstrate that iron deficiency and iron deficiency anaemia is not significantly explained by black tea consumption in a black adult population in South Africa. Tea intake was also not shown to be related to iron status in several sub-populations at risk for iron deficiency.