The Centers for Disease Control and Prevention recommends a diet high in calcium, iron and vitamin C as a way of lowering children’s blood lead levels, but a review of studies has found little evidence that it works.

The C.D.C. recommends that children eat red meat for iron, two servings of fruit for vitamin C, and two daily servings of dairy products for calcium because “these foods may help keep lead out of the body.”

But a search of the literature, published in The Journal of Pediatrics, found only one study to show that dietary calcium helped reduce lead more than a placebo, and no studies to show that dietary calcium or vitamin C provide such a benefit.

A few studies of iron and calcium supplements showed mixed or negative results, and there is no study of vitamin C supplements that shows a benefit.

The author, Katarzyna Kordas, an associate professor of epidemiology at the University at Buffalo, said there is no harm in following the recommendations, since these foods are rich in nutrients.

“But,” she added, “it’s important not to rely on nutrition to protect children from lead exposure. There are no studies that show it will.”