Vitamin D and Lead Poisoning

Vitamin D is the everything vitamin--or so it seems. Ample intake has been linked with fighting osteroporosis, cancer, diabetes, gum disease, muscle weakness, autoimmune disease--you name it. The rub: Few people really get ample intake.

It always seemed that more was better. But today I finally ran across a potential drawback to the sunshine vitamin.

It seems that for young children exposed to lead--and the nation's inner cities have many--increasing amounts of D are being linked to increasing body burdens of absorbed lead, a toxic heavy metal that can diminish IQ. To find out more, read the study in the April Environmental Health Perspectives. It was conducted by scientists at the University of Medicine and Dentistry of New Jersey (UMDNJ)-New Jersey Medical School (yes, the school's name really is that long).

John Bogden, an environmental health scientist and one of the study's authors, says the vitamin-lead link was not a surprise. Among its many functions, he notes, vitamin D helps the body absorb calcium. That's why lots of D is good for building strong bones and teeth. Unfortunately, the body responds to lead much as it does to calcium.

The researchers studied 142 low-income black and Hispanic children in Newark, N.J.. over a period of 6 to 7 months. All the kids were between the ages of 1 and 8 . The scientists measured vitamin D and lead in the children in winter and again in summer. Why? Upon exposure to sufficient sunlight, skin can make vitamin D. However, in Newark and other northern cities, sunlight is not strong enough in winter to trigger much if any production of D, so people are dependent on diet for this nutrient. And despite what food and dietary supplement manufacturers tell you, none are making products that are really rich in D. So, Bogden's group reasoned, children might show sharply lower vitamin D levels in winter.

And, in this study, they did.

The surprise, Bogden's group found, was that despite their living in the same neighborhoods and experiencing the same socioeconomic deprivation, Hispanic children in this study had little lead poisoning. For the purposes of this study, that was defined as lead concentrations of at least 10 micrograms per deciliter of blood. The black children, however--especially those 1 to 3 years old--had very high rates: about 12 percent in winter and 22 percent in summer.

The question, Bogden asks, is what underlies this strong ethnic difference? Is it housing? Diet? Access to sunlight? His group will be checking it out.

But the bigger problem, of course, is that these economically disadvantaged kids unwittingly face a Hobson's choice: a trade-off between compromised IQ and all of the health benefits that vitamin D offers.