Histamine intolerance is a condition where histamine accumulates in the body as a result of defective histamine metabolism(3). This occurs as a result of reduced DAO activity, something that is made worse by a magnesium deficiency as referenced in the above study. In addition, HDC activity increases which increases the conversion of histidine to histamine in the gut and circulation. Histidine can be found in most high protein foods and is an essential amino acid. As histamine accumulates in the body, numerous symptoms related to allergic reactions can occur including rash, GI symptoms, headache, hypotension, heart arrythmia, and a host of other symptoms. Below is a flow chart of symptoms taken from reference #(3).
It becomes important for a person experiencing these symptoms to do a good job of managing histamine levels. To do this, one should avoid foods that contain histamine, foods that liberate histamine from mast cells, and foods that block DAO activity. Foods that contain histamine include alcohol, any food that has undergone microbial fermentation including cheeses, meats, pickled foods/sauerkraut, beans, pulses, nuts, chocolate, wheat based products, shellfish, canned foods, and smoked meats(4). Leftovers should be strictly avoided as bacteria act on the histidine in foods quickly, converting it in to histamine even in the refrigerator. Foods that are known to liberate histamine from mast cells include citrus fruits, chocolate, nuts, papaya, beans/pulses, tomatoes, strawberries, pork, spinach,wheat germ, undercooked egg whites, and food additives(3,4). Finally, foods that are known to block DAO activity include alcohol, green/black/mate teas, and energy drinks(4).
In addition to minimizing foods that can increase histamine levels in the body, it is a good idea to increase magnesium levels to help support DAO levels and reduce HDC levels. Another nutrient that appears to be important in supporting DAO levels is Vitamin B6(5,6). There is also evidence that vitamin B6 may help transport magnesium in to cells, possibly by forming a complex between the two(7). As far as foods to support DAO activity, one interesting finding is that fat is the only macronutrient that increases DAO levels in the lymphatic system, protein appears to only increase DAO levels in the intestinal lumen while carbohydrate seems to have no effect on DAO levels(8). Therefore, DAO only enters the circulation in the presence of fat. If you are experiencing systemic symptoms of histamine intolerance, increasing fat intake may be something you want to look at. Just make sure you take any oral magnesium supplement away from high fat meals as there is evidence that fat negatively impacts magnesium absorption(9). However, if the reduction of magnesium absorption is due to utilizing more magnesium for DAO production, this may be a positive effect.
Most of you who have been "enjoying" the paleo autoimmune protocol are probably jumping for joy that you get to eliminate a bunch of other foods. Ironically enough, some of the foods that are known to negatively impact histamine levels are also FODMAPS. The point here is that if you are experiencing autoimmune symptoms you should be keeping a strict food journal to identify foods that are triggering responses so that you can compare those foods to foods that are known to cause negative reactions in the body to establish mechanism. If these foods seem to match up to foods known to negatively impact histamine levels, try that route. If it's FODMAPS that tend to be causing the problems, remove those foods. If there doesn't seem to be any rhyme or reason to the reactions and you eat a lot of leftovers, something people who eat a paleo diet do often, try eating only fresh food. If you want to find out if histamine is a problem, try antihistamines for a couple of days to find out if that ameliorates some of the symptoms. I wouldn't use that as your solution since it's not a solution, it's a band-aid, but improvement from antihistamines infers that histamine may be a problem.
If you do identify histamine as being the culprit, it is probably a dose/response issue. What I mean by that is you should find your tolerable dose of histamine and attempt to limit exposure to foods that increase histamine to below that dose. The absolute fastest way to remedy the situation would be to eliminate those foods altogether, but that doesn't really leave much left if you are already on a paleo diet. In any case, you may also want to increase magnesium and Vitamin B6 intake to both increase DAO production and reduce HDC production. It seems fairly apparent that one of the underlying issues in the whole situation is a magnesium deficiency. My best guess is that correcting the magnesium deficiency corrects the histamine intolerance. In this situation I would recommend both oral and topical magnesium supplementation to make sure both the gut and your cells are getting their fair share of magnesium.
