There seems to be a lot of interest in histamines in foods on the board, lately, (and for good reason, because I have a hunch that they affect virtually all of us to some extent, before we recover from severe MC flares). So I thought I would post my thoughts on the source of those histamines.
I could be wrong, but IMO, the primary source of histamines in food is mold, (for all I know, molds may be the sole source). Even though you usually can't see them, they're there, (especially on the foods that are highly susceptible to the growth of certain molds). Some molds grow rapidly, and others grow more slowly, but in many cases, they are not there on that food to begin with - their spores settle onto it, and then they develop and grow. That's why fresh foods are histamine-free, (or at least low-histamine), and aged, or dried foods, are usually loaded with histamines. On many dried fruits,for example, you can actually see the mold, but you don't have to be able to see if for it to be present at a very high level.
Sometimes nuts develop molds during the growing season, (especially in unusually wet conditions), and so some of the infected ones will be mixed in with the "clean" ones at harvest, and during processing. When eating nuts, most of us automatically throw out any that appear shriveled and diseased, so we can reduce the chances of ingesting histamines that way. That's probably why nut butters are more likely to be reactive, (in years when the nuts are infected before harvest), because infected nuts may be blended intro the mix.
Grains often develop molds in the fields, in seasons when the weather is unusually moist between the time when the grain matures, and the time at which it is dry enough to be harvested. Certain molds commonly infect such crops, including aspergillis species, and fusarium. Mold growth can also occur, or continue during storage, if moisture levels are too high, (above about 13% moisture). Here are some examples of the more common food molds, but there are others, of course.
Alternaria alternata is a common indoor mold, considered to be the main cause of allergy and asthma in young children.
Some species of Clarosporidium are often associated with the spoilage of refrigerated meats.
Aspergillus is the most common genus of molds on the planet, with over 160 different species, (16 of which are known to cause human disease). A couple of these species produce aflatoxin, for example.
Fusarium inffects most grains, and sometimes produces the toxin fumonisin, for example. At least one species can infect bananas, during the growing season. Believe it or not, there is a company that produces fusarium mold commercially, and sells it as a “meat alternative food” under the name of "Quorn".
Rhizopus fungi grow on mature fruits and vegetables, and they can be found in jellies, syrups, bread, peanuts, etc.
There are others, of course, that cause allergy problems, but aren't known to be major problems on food.
Anyway, I believe these molds are the source histamines in food, and I would assume that anyone who has mast cell issues related to MC, would also be likely to be susceptible to classic allergy symptoms in response to mold spores in the air. I know that pre-MC, molds never seemed to be a problem for me, (even though I was sensitive to ragweed and similar yellow pollens). Now, though, molds cause me to react with sneezing, watery eyes, runny nose, congestion, etc., if I breath the spores.
Tex

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