Calcium Helps Block Effects of Lead, Researchers Say
Increasing calcium consumption may do more than strengthen your bones and teeth. For millions of American children and adults exposed to excessive lead, boosting calcium intake could sharply reduce the absorption of lead and its harmful effects, researchers say.
Besides urging the public to consume the minimum recommended daily allowance for calcium, preventive-medicine experts at the University of Medicine and Dentistry of New Jersey want manufacturers of fruit juices, cereal and baked goods to fortify their products with calcium, as a few already do.
The researchers say fortification would especially help protect children under 4, who put almost anything in their mouths and are at highest risk of permanent brain damage from lead exposure.
The sources? Mainly paint chips and dust. And, to a lesser extent, food and many consumer products, including some ceramics, glassware, leather craft items and vinyl toys and mini-blinds, particularly imported products.
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“Lead is present in the environment everywhere,” said John D. Bogden, professor of preventive medicine and community health at the university’s medical school in Newark.
“Milligram amounts of lead ingested over a period of a few months can cause problems,” particularly reduced intelligence and aggressive behavior in children, he said. In adults, lead poisoning can cause anemia, kidney disease and high blood pressure.
Bogden, the lead author of an article on the subject in the December issue of Environmental Health Perspectives, a journal published by the National Institutes of Health, said pregnant and nursing women also should increase calcium intake. Without enough, they can pass on to the baby some of the lead they have accumulated over the years in their bones, reducing the child’s intelligence and birth weight.
Calcium appears to sharply limit lead absorption in the gastrointestinal tract, so lead is excreted harmlessly rather than absorbed into the blood and accumulating in bones and organs.
Bogden recommends that children from 1 to 3 get at least 500 milligrams of calcium daily, children from 4 to 8 and adults over 50 get 800 mg, adults from 19 through 50 get 1,000 mg and children from 9 through 18 get 1,300 mg.
He and others warn that consuming more than 2,000 mg of calcium daily could cause problems in some people. An 8-ounce glass of milk contains 300 mg of calcium. Along with yogurt, cheese and ice cream, broccoli is a good source of calcium.
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Per capita U.S. milk consumption has been falling for two decades, and most Americans, particularly blacks, do not get enough calcium, which is crucial for bone-building and helping nerve, muscle and other cells signal to each other.
Dr. Howard Hu, associate professor of occupational and environmental medicine at Harvard School of Public Health, said that getting the government’s recommended daily minimum calcium intake is important for overall health, and probably a good strategy for reducing lead absorption.
“But it can only be thought of as an adjunct” to steps to reduce lead exposure in the first place, Hu said.
Those include avoiding exposure to products containing lead and making older homes safer by painting over old paint to prevent peeling and dust formation on window frames, or having professionals safely remove it.
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Lead levels in most Americans have fallen sharply over the last two decades, thanks to gradual removal of lead from gasoline, house paint, plumbing systems and food and beverage cans. But at least a few million children, and many adults, have dangerously high levels of lead in their blood. That’s because lead spread from auto exhausts decades ago remains in soil, and thus in the food supply. More than 64 million older homes, especially those built before 1950, have some lead paint.
Dr. Walter Rogan, an epidemiologist at the National Institute of Environmental Health Sciences, said many studies show people reporting high calcium intake in the past have low blood lead levels, but that doesn’t prove that calcium--rather than some other factor--is the cause.
That would require limiting calcium intake in some children with high lead exposure to compare them with children also exposed to lead but receiving at least the minimum recommended daily allowance, an unpopular, if not unethical, proposition.
Bogden and his collaborator at New Jersey Medical School, pediatrics professor Dr. James M. Oleske, and Dr. Donald B. Louria, chairman of preventive medicine and community health, note that studies on laboratory rats indicate sufficient calcium limits the bad effects of lead exposure.
Are food manufacturers likely to heed their call for calcium fortification?
David Kerr, executive director of the National Juice Products Assn., says a few major orange juice manufacturers began fortifying their juice with calcium in the last five years. Given fairly good sales to date, other orange juice processors are considering the idea, and he thinks “it’s an interesting concept for other juices” that don’t have such high nutritional value intrinsically.
At the National Food Processors Assn., spokeswoman Regina Hildwine said some breakfast cereals, breads and enriched flour are fortified with calcium, and some apple juice makers have approached her about trying it.
“From a public health standpoint, it’s a good idea,” she said. But the complicated chemistry of calcium compounds, along with stringent federal regulations on what can be added to processed foods, make calcium fortification very complicated for some foods, she stressed.
