Not Too Long Ago, a Stud...
Highlights
- Not too long ago, a student I was working with asked me why patients with iron-deficiency anemia experience ice-craving AKA pagophagia. I had no idea. So I thought I’d look. Spoiler—we’re still not sure. But I did turn up some neat stuff.
A 🧵about 🧊 (1/14) (View Tweet)
- “Pagophagia” derives from the Greek “pagos” (ice) and “phagein” (to eat). It's a type of pica, the eating or chewing of non-food like clay, corn starch, and paper. Pica, delightfully, derives from the Latin word for magpie, for the bird’s indiscriminate eating habits. (2/14) (View Tweet)
- The first documented case of pagophagia was the Byzantine emperor Theophilus (829-842 AD), who ate snow to calm down stomach irritation (although it’s also possible that the stomach irritation came from dysentery from the snow, which he was eating for some other reason). (3/14) (View Tweet)
- Pica has long been known to be associated with blood disorders. Hippocrates wrote that “a craving to eat earth” was associated with “corruption of the blood.” de Cervantes even describes pica in Don Quixote. (4/14) (View Tweet)
- In more modern times, Dr. Charles Coltman described pagophagia as “an unusual perversion of the appetite” in JAMA in 1969, and notes resolution with iron administration. https://t.co/k8lf2swGfw (5/14) (View Tweet)
- Coltman “arbitrarily defined” pagophagia as “the purposeful ingestion of at least one ordinary tray of ice over a period in excess of two months.” Others have attempted to quantify, but the emphasis more recently has been on the compulsive nature rather than the amount. (6/14) (View Tweet)
- Pagophagia is the most common manifestation of pica overall. This may not have always been the case, as ice was not widely available for consumption until the 20th century. In any case, symptoms of pica are often intense, embarrassing, and disruptive to the patient. (7/14) (View Tweet)
- An appealing explanation for pica would be that the eating of non-foods may still be meeting some micro-nutrient need. But the craved substances rarely have any meaningful iron content, and ice (AKA very cold water) is not exactly notorious for its nutrient density. (8/14) (View Tweet)
- Some have hypothesized that addiction centers of the brain may be selectively affected by iron deficiency given the powerful cravings associated with pica, but there has not been evidence for this. Worth noting that iron is an enzymatic co-factor in dopamine synthesis. (9/14) (View Tweet)
- Why ice? Why not just warm tap water? Maybe it’s a tactile thing. Scheckel et al coined the term “hapticophagia” to describe specific tactile cravings, positing pica may lead to dopamine release that offsets dopamine deficiency from low iron. https://t.co/WFazD3Ct4Y (10/14) (View Tweet)
- Maybe it’s because ice is cold? Some have suggested that since glossitis is common with anemia, patients chew ice to treat their oral pain. Not terribly satisfying, since most patients with iron-deficiency anemia do not report oral pain. (11/14) (View Tweet)
- One paper suggests that chewing ice may increase alertness and processing speed in patients with anemia. Mechanistically, this resembles the diver reflex, with increased sympathetic activity and peripheral vasoconstriction that allows for increased cerebral perfusion. (12/14) (View Tweet)
- In this paper, patients with iron deficiency anemia had “a dramatic improvement in response time on a neuropsychological test.” This improvement was not seen in patients without anemia. https://t.co/eKBVtceEfY (13/14) (View Tweet)
- To recap:
-Pica is common in iron-deficiency anemia, and pagophagia is a common manifestation
Ice-chewing may soothe the tongue, boost dopamine, or mitigate the brain fog of anemia. (14/14) (View Tweet)
- This was a lot of fun to put together, but I feel like I've only scratched the surface. Would love to hear what others have come up with! (View Tweet)