Pagophagia and the Umami Hypothesis
    By Seth Roberts | February 16th 2009 02:46 PM | 3 comments | Print | E-mail | Track Comments
    Pagophagia is an eating disorder where you chew a lot of ice. A friend of mine had it. After she discovered she loved crunching ice cubes, she started going through several trays of ice cubes per day. A trip to Russia, where ice cubes were unavailable, was highly unpleasant.

    Eventually my friend learned that pagophagia is caused by iron deficiency. When she started eating more iron, her ice craving went away.

    Why do we work this way? The evolutionary reason, I think, is that in the ancient world where this tendency evolved, a desire to crunch something was usually satisfied by crunching bones. After you discovered how pleasant it was to crunch bones, you sought them out.

    Bone marrow is high in iron. Crunching those sought-out bones increased your iron intake.

    The umami hypothesis says that we like umami tastes, sour tastes and complex flavors so that we will consume more harmless-bacteria-laden food (which keeps our immune system on its toes). In the ancient environment where these tendencies evolved, in other words, a desire to eat food with these characteristics led us to eat bacteria-laden food. At the Fancy Food Show, I met a maker of sparkling tea who was unable to get enough complexity without using bacteria.

    Just as a person with pagophagia chews ice, most of us do one or more of these:

    • add monosodium glutamate (e.g., Accent) for umami taste

    • add vinegar for sourness (I put a few drops of vinegar in coffee-like drinks)

    • add many spices for complexity

    The result, I suspect, is that most of us have immune systems with plenty of room for improvement. I stopped getting easy-to-notice colds when I started sleeping better so the high frequency of reported colds (the average American adult gets about three per year) may be a sign that this is true.


    Seth, I am glad to see you connecting the dots between evolutionary science and the purpose of umami in our (and other mammals') physiology. I do believe that part of what you propose is correct, in that umami drives food selections that are biologically active and promote the development of a sophisticated immune response. In my research and correlation of information, I have come to the conclusion that umami's real purpose is much more basic and intrinsic to human and mammalian survival. I'll summarize here and will gladly discuss it further if you wish.

    In essence, umami is only formed through the natural (or more recently unnatural) dissolution of complex proteins by the destruction or reformation of peptide links. In nature the most common method of this process is through biologically active means -- bacteria, fungi, etc. The nexus between the process of decay and our physiology is that carrion and other rotting food is a survival food only. Humans would scavenge only in times of extreme starvation due to the risks of disease and parasites. Umami gave us the power to find this rotting protein not only inoffensive but extremely tasty. Furthermore, it radically stimulates appetite at the same time, and has a series of neurological affects promoting hyper-awareness and increased agitation. In a sense it turns us into a more animal state where we can gather the resources necessary to avoid starvation. There are other "starvation responses" that are well known, such as the conversion of muscle tissues to energy. The danger and problem with umami's effect is that it comes at a terrible price, just as when we destroy muscles to survive. It is highly neurodegenrative (you can think of it cannibalizing neurons the same way as muscles) which cannot be sustained over long periods of time without causing crippling neurological diseases. When flavor enhancers began permeating our food, the "starvation response" became more and more sustained -- resulting in a marked increase of all the related disorders. Now, the addition of these compounds plus the predilection for umami-laced foods has caused epidemics of neurodegenerative diseases such as Parkinsons and Alzheimers, obesity, diabetes and a host of other ailments. What was originally a very valuable tool in our survival has now become our undoing. And, as you know, umami is highly addictive.

    I know many Thai people are seriously addicted to umami. I also sometimes crave for nam plaa. Would there be a higher incidence of Alzheimer and Parkinson in Thai?
    You could easyly test on lab-mouses.

    Larry Arnold
    Is it not possible, merely to like crunching ice cubes.

    It is not something I do often, but when I enjoy a coke, with Ice I inevitably end up chewing the ice cubes. (seems such a waste otherwise) In between times I have no such craving