Rw. Li et al., FUNCTIONAL CONSEQUENCES OF IRON SUPPLEMENTATION IN IRON-DEFICIENT FEMALE COTTON MILL WORKERS IN BEIJING, CHINA, The American journal of clinical nutrition, 59(4), 1994, pp. 908-913
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.