The effects of iron and folate on serum zinc status in a cohort of pregnant wome

The effects of iron and folate intakes, from diet and supplement sources, on serum zinc levels were examined in 128 subjects who participated in the Diana Project, a prospective cohort study of factors thought to affect fertility and reproductive outcomes in women. Average daily intakes of folate and iron from diet prior to and during pregnancy were assessed using monthly Food Frequency Questionnaires. Average daily intakes of folic acid and iron from supplements prior to and during pregnancy were assessed by a monthly questionnaire. Data on potentially confounding dietary and supplement intakes were also collected.;Non-repeated measures regression analyses revealed no significant relationships between nutrient intakes of folic acid and iron, from diet or supplements, and serum zinc levels prior to pregnancy. In both repeated and non-repeated univariate regression analyses, folic acid supplements were found to be positively related to serum zinc levels between, but not within, subjects during pregnancy while iron supplements were found to be positively related to serum zinc between subjects only during the third trimester, and within subjects when averaged over pregnancy. Both non-repeated and repeated multivariate regression analyses showed that when the supplements were adjusted for each other, folic acid supplements became more strongly, positively related to serum zinc levels between subjects while iron became negatively (nonsignificantly) related to serum zinc both between and within subjects. Repeated measures multivariate analysis showed that an interaction occurred between iron and folate supplements, which was positively related to serum zinc levels between subjects, but was not significantly related within subjects. Iron was found to increase serum zinc levels in the middle and highest tertiles of folic acid supplement intake but to decrease serum zinc in subjects in the lowest tertile of folic acid supplement intake.