question: How is chewing ice related to iron deficiency?
comment: I found a study from 2014: "Potential explanations include activation of the dive reflex, which would lead to peripheral vasoconstriction and preferential perfusion of the brain or, alternatively, sympathetic nervous system activation, which would also increase blood-flow to the brain." & #x200B; So in 5 year old terms: They don't know, but maybe chewing ice makes people who lack iron more alert by sending extra blood to the brain, like a shock from jumping into cold water. People low on iron can pass out easily from their brains not getting enough oxygen from blood. Tricking the body into thinking its in cold water can send more blood to the brain. & #x200B; That still doesn't answer why people low on iron would *crave* chewing ice, since usually the "effect" isn't also the "cause". I also don't know how many people were in the study. & #x200B; This is just a guess though, no one knows for sure according to pubmed.
passages: 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.
   Hendy J, Warinner C, Bouwman A, Collins MJ, Fiddyment S, Fischer R, Hagan R, Hofman CA, Holst M, Chaves E, Klaus L, Larson G, Mackie M, McGrath K, Mundorff AZ, Radini A, Rao H,Trachsel C, Velsko IM, Speller CF (2018) Proteomic evidence of dietary sources in ancient dental calculus, Proceedings of the Royal Society B, 20180977
  
  Hendy J, Welker F, Demarchi B, Speller C, Warinner C, Collins MJ (2018) A Guide to Ancient Proteins, Nature Ecology and Evolution, 2, 791–799.
   Iron deficiency anemia tends to develop slowly; therefore the body has time to adapt, and the disease often goes unrecognized for some time. In severe cases, shortness of breath can occur. Pica may also develop; of which consumption of ice, known as pagophagia, has been suggested to be the most specific for iron deficiency anemia.
  
  Other possible symptoms and signs of iron-deficiency anemia include:
  
  Section::::Signs and symptoms.:Child development.
   BULLET::::- Increased loss of iron (usually through loss of blood).
  
  BULLET::::- Nutritional deficiency. This can result due to a lack of dietary iron or consumption of foods that inhibit iron absorption. Absorption inhibition has been observed caused by phytates in bran, calcium from supplements or dairy products, and tannins from tea, although in all three of these studies the effect was small and the authors of the studies cited regarding bran and tea note that the effect will probably only have a noticeable impact when most iron is obtained from vegetable sources.
   Section::::Mechanisms of iron regulation.:Cellular iron regulation.
  
  Section::::Mechanisms of iron regulation.:Cellular iron regulation.:Iron import.
   Since then, supplemental iron products, including Geritol, have been contraindicated because of concerns over hemochromatosis, and serious questions raised in studies for men, postmenopausal women, and nonanemic patients with liver disease, heart disease, type 2 diabetes, or cancer.
  
  Section::::Media sponsorships.
   Pagophagia
  
  Pagophagia (from Greek: "pagos", frost, + "phagō", to eat) is the compulsive consumption of ice or iced drinks.
  
  It is a form of the disorder pica. 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.
   BULLET::::- Neuropeptide Y also known as NPY is a hormone that encourages eating and decreases metabolic rate. Blood levels of NPY are elevated in patients with anorexia nervosa, and studies have shown that injection of this hormone into the brain of rats with restricted food intake increases their time spent running on a wheel. Normally the hormone stimulates eating in healthy patients, but under conditions of starvation it increases their activity rate, probably to increase the chance of finding food. The increased levels of NPY in the blood of patients with eating disorders can in some ways explain the instances of extreme over-exercising found in most anorexia nervosa patients.
   It is however, highly unlikely that iron deficiency anemia is a cause of either porotic hyperostosis or cribra orbitalia. These are more likely the result of vascular activity in these areas and are unlikely to be pathological. The development of cribra orbitalia and porotic hyperostosis could also be attributed to other causes besides an iron deficiency in the diet, such as nutrients lost to intestinal parasites. However, dietary deficiencies are the most probable cause.
   In longstanding cases and in patients who have taken iron supplementation or received numerous blood transfusions, iron overload may be a significant problem. This is a potential cause of heart muscle damage and liver disease. Measuring iron stores is therefore considered part of the diagnostic approach to hereditary spherocytosis.
   Commonly observed side-effects, occurring in 1 to 10% of cases, include stool discoloration, diarrhea, nausea, and dyspepsia. Uncommon side-effects, occurring in 0.1 to 1% of cases, include constipation, vomiting, stomachache, tooth discoloration, itchiness, and headache. As very rare side-effects, occurring in 0.1 to 0.01% of cases, allergic reactions have been observed.
  
  Section::::Dosage and administration.
  
  The preparation is available in various galenic formulations: syrup, drops, drinkable solution, film-coated tablets, and chewable tables. The syrup, drops, or drinkable solution are preferable for children. The preparation is dosed according to age. The following general dosage guidelines apply (for iron deficiency with anemia):
   Section::::Biological and pathological role.:Deficiency.
   Special case: ketoacidotic diabetes and iron availability
   Bronzing of the skin. This deep tan color, in concert with insulin insufficiency due to pancreatic damage, is the source of a nickname for this condition: "bronze diabetes".
  
  Section::::Causes.
   Originally, this was blamed on ungalvanised barrels used to store home-made beer, which led to increased oxidation and increased iron levels in the beer. Further investigation has shown that only some people drinking this sort of beer get an iron overload syndrome, and that a similar syndrome occurred in people of African descent who have had no contact with this kind of beer (e.g., African Americans).
  
  This led investigators to the discovery of a gene polymorphism in the gene for ferroportin, which predisposes some people of African descent to iron overload.
  
  Section::::Mechanism.:Genetics.
   Section::::Mechanisms of iron regulation.:Cellular iron regulation.:The storage iron pool.
  
  Iron can be stored in ferritin as ferric iron due to the ferroxidase activity of the ferritin heavy chain. Dysfunctional ferritin may accumulate as hemosiderin, which can be problematic in cases of iron overload. The ferritin storage iron pool is much larger than the labile iron pool, ranging in concentration from 0.7 mM to 3.6 mM.
  
  Section::::Mechanisms of iron regulation.:Cellular iron regulation.:Iron export.
   Many of these ions can inhibit iron absorption. Mutation of NRAMP2 in rodents leads to defective endosomal iron export within the ferritin cycle, impaired intestinal iron absorption and microcytic anemia. Symptoms of Mn deficiency are also seen. It is found in apical membranes of intestinal epithelial cells but also in late endosomes and lysosomes.
  
  Section::::NRAMP1.
   In an episode aired on October 15, 2009, the Dutch television show "", followed up one of Kellogg's Special K nutritional claims, namely the addition of iron. The show provided evidence that the iron was not nutritional ionic iron—as it occurs in natural foods like spinach—but was, in fact, metallic iron. A Kellogg's telephone help desk employee was not willing to discuss the ingredients of their products in general, claiming it was a company secret; although, in the show, the company was not confronted with the findings. The nutritional experts in the show agreed that metallic iron should not be part of a diet. Metallic iron is speculated to damage organs. After the airing, the Dutch food authority nuanced the claims made in the TV program, claiming there are no health risks. They also challenged the claim that the cereal could contain "shredded bites," and responded that iron powder is suitable for human consumption.
   Chewing gum assists oral irrigation between and around the teeth, cleaning and removing particles, but for teeth in poor condition it may damage or remove loose fillings as well. Dental chewing gums claim to improve dental health. Sugar-free chewing gum stimulates saliva production, and helps to clean the surface of the teeth.
  
  Section::::Food and drink.:Ice.
  
  Chewing on solid objects such as ice can chip teeth, leading to further tooth fractures. Chewing on ice has been linked to symptoms of anemia. People with anemia tend to want to eat food with no nutritional value.
  
  Section::::Food and drink.:Alcohol.
   After administration, the maximum absorption capacity is reached already after 30 minutes and continuously increasing absorption can be observed over 24 hours. The non-absorbed iron is excreted via the stool.
  
  Section::::Pharmacology.:Effectiveness, safety.
  
  The effectiveness and safety have been investigated and documented in numerous clinical studies and in various patient populations. This has included children, young people, adults, and the elderly, in addition to pregnant women and breastfeeding mothers.
  
  Section::::Pharmacology.:Effectiveness, safety.:Important clinical studies.
  
  Section::::Pharmacology.:Effectiveness, safety.:Important clinical studies.:Study in pregnant women.
   Section::::Dieting.
   The book suggests that diet is a key difference and contrasts key dietary components and "biomarkers" (such as body weight and temperature, blood insulin and glucose, cholesterol, etc.) between Mindspan Elite and Mindspan Risk. The book concludes that a key difference between Mindspan Elite and Mindspan Risk is dietary iron, and the amount of iron in the bodies and brains of Mindspan Elite (low iron) and Mindspan Risk (high iron). A key finding of the book that is at odds with current dietary recommendations regards certain refined carbohydrate (carbs) foods. The book presents evidence that the base of the dietary pyramids of the Mindspan Elite is refined carbs in the form of white rice (mindspan leader Japan), and refined wheat pasta and bread (Mediterranean). Dr. Estep says that these foods in Mindspan Elite countries and regions are not enriched with iron, while equivalent foods in Mindspan Risk countries and regions are enriched with iron.
   Mackie M, Hendy J, Lowe A, Sperduti A, Holst M, Collins MJ, Speller C (2017) Preservation of the metaproteome: Variability of protein preservation in ancient dental calculus, STAR: Science & Technology of Archaeological Research 3(1), 74–86. doi: 10.1080/20548923.2017.1361629
  
  Green EJ, Speller CF (2017) Novel substrates as sources of ancient DNA: prospects and hurdles, Genes, 8(7), 180; doi:10.3390/genes8070180
   Section::::History.:Modern times.
  
  In 1865, Armand Trousseau (a French internist) was one of the first to describe many of the symptoms of a diabetic patient with cirrhosis of the liver and bronzed skin color. 
  
  The term hemochromatosis was first used by German pathologist Friedrich Daniel von Recklinghausen in 1890 when he described an accumulation of iron in body tissues. In 1935 J.H. Sheldon, a British physician, described the pathophysiology mechanism linked to iron metabolism for the first time.
   The evidence provided during the show followed David Catz's description of an experiment by Dr. Babu George, Sacred Heart University, in which iron is extracted from cereals. The description dates from 1984. As a result of this experiment being published and inquiries being made to the manufacturers, some companies have replaced the metallic iron in their products with an iron compound such as iron (III) phosphate, ferric phosphate.
  
  Section::::Controversies.:United Kingdom.
  