Systematic Review and Meta-Analysis of the Effect of Nutrients on Blood Lead Levels in Pregnancy

To synthesize experimental and nonexperimental research on the relationship between nutrients and blood lead levels in pregnant women. We also performed a meta-analysis on a subgroup of studies on calcium and blood lead levels.

PubMed, Embase, and CINAHL databases were searched in July 2019.

We included articles published in English in any year that reported the results of experimental or observational studies on the effect of nutrients on blood lead levels in pregnancy.

Three nurse reviewers extracted data and appraised the studies using tools from the Joanna Briggs Institute.

We included 28 studies from 16 countries. Study authors examined 14 distinct nutrients, with calcium being the most frequent. The metaregression included nine analyses of the effect of calcium on blood lead levels and showed a small but significant inverse relationship. The quality of evidence for the effect of calcium on lead levels was high. Eleven analyses were related to the effect of iron on blood lead levels. The quality of evidence was high, and we found mostly negative associations between iron intake and blood lead levels. The quality of evidence for the remaining nutrients was moderate, with few significant findings.

Targeted nutritional interventions may be beneficial for pregnant women with current lead exposure or a history of elevated lead levels, particularly those with calcium- or iron-deficient diets. More rigorously designed studies are needed in this area.