Pagophagia is the compulsive consumption of ice.
It has been shown to respond to iron supplementation, leading some investigators to postulate that pica is the result, not the cause, of nutritional deficiency (specifically, deficiencies of iron, zinc, magnesium, and phosphorus).
Folk wisdom (and some early investigators) maintained that pica reflected an appetite to compensate for some problem. Ice probably helps relieve some of the symptoms of low iron, including inflammation of the tongue and stomach.
Later research, however, has demonstrated no evidence that the substances ingested provide any nutrient or mineral in which patients are deficient.