Women taking a calcium supplement could reduce the amount of lead passed to their fetus or nursing baby, according to a new study. Researchers found that lead levels in the blood were reduced by 16% in those women taking a calcium supplement.

The research stems from a known problem: pregnancy and breastfeeding mobilizes calcium which is stored in bone, sending it out into the blood stream where it is transferred to the baby. However, lead stored in the bone is also mobilized and is also transferred. Lead is known to be toxic, particularly to developing brains. The researchers wanted to find out if supplying extra calcium through supplements might reduce the amount of calcium – and therefore, lead – drawn from the bones at this critical time.

“All of us who live in the post-industrialization era have some lead in our bones,” says one expert. “Like it or not, we’ve been exposed to lead from gasoline, paint and other sources.”

Researchers from Mexico conducted a randomized, double-blind trial with 617 lactating women with an average age of 24. The women received either calcium carbonate (supplying 1,200 mg of elemental calcium per day) or a placebo. Blood samples were obtained at the outset, and at 3 and 6 months after the trial began. Bone lead levels were also measured. Blood lead was determined by graphite furnace atomic absorption spectroscopy.

The researchers found that women with higher bone lead levels who took the calcium supplements had an overall reduction of lead in circulating blood levels of 16.4%. They conclude that “among lactating women with relatively high lead burden, calcium supplementation was associated with a modest reduction in blood lead levels.”

Epidemiology 2003;14:206-212.