FUNCTIONAL CONSEQUENCES OF IRON SUPPLEMENTATION IN IRON-DEFICIENT FEMALE COTTON MILL WORKERS IN BEIJING, CHINA

Eighty iron-deficient, nonpregnant female workers were randomly assign ed to ferrous sulphate (60 or 120 mg Fe/d) or placebo treatment for 12 wk. Energy expenditure was estimated during 3 d by heart rate (HR) re cording. Production efficiency (PE) was calculated as the ratio of pro ductivity to energy expenditure. In the iron-treated group mean hemogl obin (Hb) increased from 114 to 127 g/L (P < 0.001), mean serum ferrit in increased from 9.7 to 30.0 mug/L (P < 0.001), and mean free erythro cyte protoporphyrin decreased from 1.01 to 0.49 mumol/L (P < 0.001). M ean HR at work decreased from 95.5 to 91.1 beats/min (P < 0.001), whic h was inversely correlated with the change in Hb (r = -0.60, P < 0.001 ). PE increased significantly in the iron-treated group (P < 0.001) an d its change paralleled the change in Hb (r = 0.58, P < 0.001). The re sults show that iron supplementation enabled these women to do the sam e work at a lower energy cost.