Dirty Dining Earns Respect From Scientists

Maybe Mom was wrong when she said you shouldn’t eat dirt. Two Canadian scientists tested soil in North Carolina, China and Zimbabwe and pronounced it nutritious.

There is a warning, however: Don’t eat dirt willy-nilly because it might be too dirty.

“The sticky point is, today, you don’t want contaminated soil,” said Susan Aufreiter, one of the researchers. “What with industry, you don’t know what’s in it.”

But there’s nothing like clean old dirt. The scientists found that subsoil in Stokes County, N.C., is rich in iron and iodine, beneficial for children and premenopausal women.

“It sounds a little bizarre, doesn’t it?” Aufreiter said. “There’s mental retardation in the world caused by a lack of those elements, so it’s not trivial.”

Dirt eating, especially among the poor, dates back to slavery. Clay lovers would look for a certain smell and texture and sometimes bake it before dining. The practice, called geophagy, has waned in recent years.

Aufreiter, a laboratory analyst at the University of Toronto, and William Mahaney, a York University geography professor, used “instrumental neutron activation analysis” to get a precise chemical breakdown of the soil.

They also found nutritional value in light, yellowish soil from China’s Hunan province (iron, calcium, magnesium, potassium and other minerals) and in red soil from Zimbabwe (kaolinite, the main ingredient in over-the-counter diarrhea remedies).

And why did they choose dirt from Stokes County?

Aufreiter knows someone from the county who ate dirt while growing up and brought her a sample. The person didn’t want to be identified in the study, which was reported in the current issue of the International Journal of Food Sciences and Nutrition, published in England.

In 1971, more than half the women surveyed in one rural Mississippi county said they had consumed clay. But when the same researchers sought out 10 of the dirt eaters in 1984, nine said they had given up the habit.

Leonard Hicks, the Stokes County agricultural agent, has tested soil for 17 years and said it does, indeed, include good stuff like phosphorus, iron and iodine.

“Plant needs and human needs are very similar,” he said.