As a parent have you frowned or watched in disgust as your kids stuff a handful of mud into their mouths while playing? Well you can relax, the next time this happens. For research suggests that eating mud or clay could actually be good for the stomach. Dining on dirt, or geophagy, is common among many cultures and has been reported in almost every country in the world. Researchers at Cornell University in New York studied more than 480 cultural by missionaries, plantation doctors and explorers and found that earth acts as a shield against ingested parasites and plant toxins. People may also crave dirt because it provides nutrients they lack such as iron, zinc, or calcium, the research found. Dr Sera Young, who led the study, said the first written account of human geophagy comes from Hippocrates more than 2,000 years ago.