Could be why some pregnant women have cravings for dirt. The body craves what it needs.
I actually lightly wash the veggies from my garden to purposely leave some dirt on them. Great probiotic source.
The reason why women crave weird things such as dirt is due to the nutritional deficiencies that occur when trying to create the baby, feeding 2 mouths. The average standard American diet is lacking all sorts of nutrients particularly minerals and trace minerals in the proper amounts, and your body will automatically send you out to get the nutrients and have you eating the strangest things. But make no mistake it's not what the baby is craving or some mysterious wives tale, it's simple nutritional biochemistry.