Does tea intake increase the risk of anemia? Evidence from a large prospective cohort and Mendelian randomization study

Abstract

<p>Tea consumption is avoided by some due to concerns about its potential to cause anemia. To clarify this impact, we assessed the association between tea intake and anemia in a Chinese prospective cohort study and by Mendelian randomization (MR). We analyzed associations of tea intake with anemia using data from the baseline (<em>N</em> = 30 085) and three subsequent follow-ups (the first: <em>N</em> = 17 898; the second: <em>N</em> = 10 435; the third: <em>N</em> = 5311) in the Guangzhou Biobank Cohort Study (GBCS). We also assessed the causal effect of tea intake on anemia, hemoglobin (Hgb) and hematocrit (Hct) using two-sample MR with summary statistics from relevant genome-wide association studies and the UK Biobank (<em>N</em> = 447 485). At the baseline, compared with never-drinkers, regular tea drinkers had higher levels of Hgb and Hct and a lower risk of anemia after adjustment for confounders (all <em>P</em> < 0.05; all <em>P</em> for trend ≤0.006). Prospectively, compared with never-drinkers, regular tea drinkers had higher Hgb (g L<small>⁻¹</small>) (<em>β</em> = 0.69; 95% CI, 0.28 to 1.10; <em>P</em> for trend <0.001) and Hct (%) (<em>β</em> = 0.30; 95% CI, 0.19 to 0.41; <em>P</em> for trend <0.001), but no significant difference in anemia risk (OR = 0.91; 95% CI, 0.82 to 1.02; <em>P</em> for trend = 0.071). MR analyses showed no association between tea intake and anemia, Hgb and Hct. Through triangulation of evidence using a Chinese cohort and genetics, tea consumption appears unlikely to impact anemia risk.<br></p>