Zinc and small babies

Oral iron and the bioavailability of zinc

The oral bioavailability of zinc was studied in nonpregnant adults before and 24 hours after two weeks of oral supplementation with iron and folic acid. Bioavailability was greatly reduced, and the shape of the plasma curves suggested that this was due to impairment of the intestinal absorption of zinc. The findings suggest that the reduced bioavailability of zinc occurs because of interelement competition in the bowel wall. This might induce zinc depletion.

Peripheral blood leucocyte zinc depletion in babies with intrauterine growth retardation

The zinc content of peripheral blood leucocytes from the cord blood of 63 normal and 20 preterm babies, and of 27 babies with evidence of idiopathic intrauterine growth retardation (IUGR) was measured. Leucocyte zinc depletion was present in babies with acute IUGR (IUGR babies compared with controls, mean 47.8 v 51.5 ng zinc/mg dry weight), but was especially severe in those with prolonged IUGR (mean 43.2 ng zinc/mg dry weight), while preterm babies were normal (mean 51.9 ng zinc/mg dry weight). We suggest that this fetal tissue zinc depletion is caused by maternal zinc depletion, and may reflect a reduction of whole body zinc status.

Trace elements in human seminal plasma and spermatozoa

Methodologies for the analysis of cadmium, copper, iron, lead, selenium and zinc in human seminal plasma and spermatozoa have been developed. Analyses were made directly in a dilution of seminal plasma or nitric acid digest of lyophilized cells using Zeeman-effect atomic absorption spectroscopy. Within-run coefficients of variation (CV's) for pooled specimens ranged from 0.5% to 9%. Between-run CV's ranged from 4% to 13%. Analysis of a seminal plasma specimen at 1/2, 1, 1 1/2, 3 1/2 and 5 hours post emission indicated that no change in seminal plasma trace element concentrations occurred on standing in contact with spermatozoa. Trace element concentrations were determined in specimens from patients undergoing infertility studies.

A prospective study of serial maternal serum zinc levels and pregnancy outcome

A prospective study of 878 pregnant women in Adelaide, South Australia, examined the relationship of maternal serum zinc concentration to pregnancy outcome. Blood samples were obtained at weeks 18 and 32 of pregnancy, and from the umbilical cord. Additional detailed data were obtained, via standardised antenatal interview and review of clinical records, on antenatal care, personal, behavioural, and sociodemographic characteristics, and, subsequently, on delivery and neonatal assessment. Maternal mid-pregnancy zinc status was negatively correlated, although very weakly, with duration of gestation and with birthweight (including, in particular, the 18 recorded cases of intrauterine growth retardation). This finding accords with recent suggestions that, in non-experimental human studies in populations in which frank zinc deficiency is absent, maternal serum zinc level may be an outcome, rather than a determinant, of fetal growth later in pregnancy. Low mid-pregnancy zinc levels were associated with increased risk of intrapartum haemorrhage. In general, the greatest risk of having some complication or abnormality of delivery or neonatal functional status occurred in pregnant women who had both an initially below-average, and subsequently decreasing, serum zinc concentration. This corroborates other recent research. While it might be inferred that above-average fetal growth, by depressing maternal zinc status, could itself impair delivery and neonatal functioning, our data indicate that these effects operated independently.