Strong negative association between intake of tofu and anemia among Chinese adults in Jiangsu, China

Background Anemia is prevalent in China. Tofu made from soybean is a popular food. Soybean is shown to have an affect on iron status. No study has examined the relation between tofu and iron status. Objective To investigate the association between tofu intake and anemia among Chinese adults. Design A cross-sectional household survey of 2,849 men and women aged 20 years and older (mean age 47.0 +/- 14.5 years), from a nationally representative random sample in Jiangsu province undertaken in 2002 (response rate 89%). Tofu intake was assessed by food frequency questionnaire. Nutrient intake was measured by 3-day weighed food records. Serum ferritin and hemoglobin were measured. Results The prevalence of anemia was 18.3% in men and 31.5% in women. Mean hemoglobin values increased by quartiles of tofu intake (men: 14.1, 14.0, 14.5, and 14.8 mg/dL [141, 140, 145, and 148 g/L]; women: 12.4, 12.5, 12.6 and 13.3 g/dL [124, 125,126, and 133 g/L]), and the prevalence of anemia decreased concomitantly. Comparing first and fourth quartiles of tofu intake, the prevalence of anemia was 23.9% vs 10.7% in men, and 38.1% vs 16.8% in women. Tofu intake was inversely associated with serum ferritin levels in women. In multivariate analyses, the odds ratio of anemia for men in fourth compared to first quartile of tofu intake was 0.30 (95% confidence interval 0.17 to 0.50), and the corresponding odds ratio for women was 0.31 (95% confidence interval 0.20 to 0.47). The association between tofu intake and anemia was independent of iron intake. Conclusions Tofu intake was associated with lower risk of anemia among Chinese adults in both sexes.