Pagophagia

Pagophagia is a form of the disorder pica involving the compulsive consumption of ice or iced drinks. It has been associated with iron deficiency anemia, and shown to respond to iron supplementation, leading some investigators to postulate that some forms of pica may be the result of nutritional deficiency. Chewing ice may lessen pain in glossitis related to iron deficiency anemia. However, the American Dental Association recommends not chewing ice because it can crack teeth; instead ice should be allowed to melt in the mouth.

Folk wisdom (and some early investigators) maintained that pica reflected an appetite to compensate for nutritional deficiencies, such as low iron or zinc. Some forms of pica (as in pregnant women who are iron deficient) can be treated by supplementing the nutrient.

Later research has demonstrated that the substances ingested generally do not provide the mineral or nutrient in which patients are deficient. As the people start eating nonfoods, pica can also cause the nutritional deficiencies with which it is associated. In one case study, pagophagia was reported to cause iron deficiency anemia. At the same time, however, the researchers suggested that chewing ice may benefit stomatitis and glossitis. The nutrients obtained from nonfoods such as soil or ice will vary widely depending on geographic location. For example, ice made from hard water will contain more minerals, especially calcium and magnesium, but simply drinking the water will provide the same minerals.

Ice

Ice is water frozen into a solid state. Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaque bluish-white color.

In the Solar System, ice is abundant and occurs naturally from as close to the Sun as Mercury to as far as the Oort cloud. Beyond the Solar System, it occurs as interstellar ice. It is abundant on Earth's surface – particularly in the polar regions and above the snow line – and, as a common form of precipitation and deposition, plays a key role in Earth's water cycle and climate. It falls as snowflakes and hail or occurs as frost, icicles or ice spikes.

Ice molecules can exhibit up to sixteen different phases (packing geometries) that depend on temperature and pressure. When water is cooled rapidly (quenching), up to three different types of amorphous ice can form depending on the history of its pressure and temperature. When cooled slowly correlated proton tunneling occurs below 20 K giving rise to macroscopic quantum phenomena. Virtually all the ice on Earth's surface and in its atmosphere is of a hexagonal crystalline structure denoted as ice Ih (spoken as "ice one h") with minute traces of cubic ice denoted as ice Ic. The most common phase transition to ice Ih occurs when liquid water is cooled below 0°C (273.15K, 32°F) at standard atmospheric pressure. It may also be deposited directly by water vapor, as happens in the formation of frost. The transition from ice to water is melting and from ice directly to water vapor is sublimation.

Eating

Eating (also known as consuming) is the ingestion of food, typically to provide a heterotrophic organism with energy and to allow for growth. Animals and other heterotrophs must eat in order to survive — carnivores eat other animals, herbivores eat plants, omnivores consume a mixture of both plant and animal matter, and detritivores eat detritus. Fungi digest organic matter outside of their bodies as opposed to animals that digest their food inside their bodies. For humans, eating is an activity of daily living. Some individuals may limit their amount of nutritional intake. This may be a result of a lifestyle choice, due to hunger or famine, as part of a diet or as religious fasting.

Eating practices among humans

Many homes have a large eating room or outside (in the tropics) kitchen area devoted to preparation of meals and food, and may have a dining room, dining hall, or another designated area for eating. Some trains have a dining car. Dishware, silverware, drinkware, and cookware come in a wide array of forms and sizes. Most societies also have restaurants, food courts, and/or food vendors, so that people may eat when away from home, when lacking time to prepare food, or as a social occasion (dining club). At their highest level of sophistication, these places become "theatrical spectacles of global cosmopolitanism and myth." At picnics, potlucks, and food festivals, eating is in fact the primary purpose of a social gathering. At many social events, food and beverages are made available to attendees.