Many parents often complain of their toddlers and older children having persistent cravings for many inedible substances such as chalk, earth, and clay. This condition is popularly known as Pica, and is largely associated with iron deficiency. The desire to eat chalk, clay, or earth in particular, is known as Geophagy and doctors often attribute this with lowered calcium and mineral levels. Geophagy is common among animals and evidence suggests that this practice has been around within the human since the time of Homo Neanderthalensis. In many cultures this practice is well accepted. In India, pregnant women often express the desire to eat chalk to relive nausea. It is believed that chalk powder coats the GI tract and absorbs toxins to ease nausea.
Eating chalk is not harmful per se, but it must be avoided since one can run the risk of unnecessary infection from bacteria or worms. Sometimes one can develop a condition known as hypercalcemia, where the calcium levels in the blood rise beyond acceptable range.
Calcium, mineral and iron levels can be checked for by getting suitable blood tests. If the results are within the acceptable range then the habit could be purely psychological where a child or an adult indulging in the habit might be looking for emotional cushioning or mental comfort. Alternatively it could just be a phase where the particular taste is desired.
If the tests indeed indicate lowered calcium, iron and mineral levels, then one must consult a health practitioner and start with the suggested treatment. Usually the doctors prescribe a supplement of deficient element in tablet or syrup form. In addition you could include foods like milk, yogurt, spinach, beets, etc in your diet to meet with the daily requirement of calcium, iron and other minerals. It is important that you understand that the supplements are not a substitute for the corresponding elements. Rather they are meant for fulfilling short term deficiency. In general practice one must always eat a wholesome diet to fulfill daily nutritional needs.
Although Geophagy is a universal phenomenon, it is equally debated. While many believe it to be an evolved practice indicative of deficiency, others believe it to be a purely acquired psychological habit. In either case it is best to seek help if the habit persists for longer than a month. If the habit fades away on its own with a short time there is no need for undue concern.