Zinc, copper and iron concentrations in the plasma and diets of lactating Nigerian women.

Zinc, copper, iron, protein and energy intakes of 232 lactating women (consuming self-selected diets during the first 3 months post-partum) were computed from food intake values obtained using a 3 d dietary-recall method. Non-pregnant, non-lactating women (100) served as controls. Blood samples of subjects were also analysed for packed cell volume and haemoglobin concentrations as well as for plasma Zn, Cu and Fe levels by atomic absorption spectrophotometry. Except for Fe, intakes of all nutrients measured were significantly lower than recommended dietary allowances for lactation. Daily mean (and SD) Zn, Cu, Fe (mg), protein (g) and energy (MJ) intakes for lactating women were 8.2 (1.6), 1.6 (0.5), 29.0 (5.8), 52.4 (9.2) and 10.21 respectively. There was a significant intercorrelation between the different nutrients in the diet. Mean (and SD) plasma Zn, Cu and Fe concentrations (micrograms/l) during the first 3 months of lactation were 666.0 (76.0), 1290.0 (150.0) and 730.0 (185) respectively. These values were significantly (P less than 0.05) lower in the case of Zn and Fe and higher in the case of Cu than those of non-pregnant, non-lactating women. Maternal plasma levels of the trace elements also varied significantly with nutritional status as indexed by haemoglobin status. Correlation analysis between dietary and plasma trace element concentrations was significant for Zn (r 0.26, P less than 0.0001) and Fe (r 0.17, P less than 0.05). Dietary protein intake was significantly correlated with plasma Zn (r 0.18, P less than 0.005) and Fe (r 0.12, P less than 0.05). While maternal weight, arm circumference and skinfold thickness measurements tended to decrease with increase in the period of lactation, growth performance of entirely breast-fed babies was satisfactory as at the 12th week post-partum.