Following on from yesterday’s post on new research into the histamine content of non-fermented fruit, nuts & vegetables I thought I’d break down the information contained in the paper for us mere mortals to understand.
Histamine Intolerance (HIT) is thought to be caused by low levels of two enzymes: HNMT and DAO. DAO is an enzyme in the gut which breaks down and converts the histamine we eat in our food, and if levels are low this process isn’t effective and results in high levels of histamine in our bodies (at least, that’s the layman’s version!). In order to keep symptoms at bay, HIT patients need to stick to a low histamine diet, which makes perfect sense and has worked miracles for me personally.
However, there is very little information on the actual histamine content of foods and the researchers found that many foods excluded from low histamine diets actually have been shown to be low in histamine and therefore are safe to eat which is fabulous news!
What constitutes a high level of food histamine is currently guesswork – we don’t know what ‘high’ is, and safe levels of histamine in food probably differs from patient to patient depending on how well their DAO and HNMT are functioning. I’m making the assumption that ‘high’ is anything over 20mg/kg but this is a purely made-up number in the absence of any guidelines. Based on this, then, the only non-fermented plant foods tested in this research paper and found to be high in histamine are:
- Eggplant (aubergine)
- Avocado is borderline at just over 20mg
- Fresh tomato & tomato ketchup is borderline at just over 20mg & chopped tomato is fine!
So as you can see, there are less than a handful of non-fermented plant foods which are high in histamine (though of course fermented plant foods like sauerkraut aren’t included and are known to be high in histamine). I don’t know about you but this tiny list is a massive shock! To think I’ve been missing out on loads of foods for no good reason for the past five years is heartbreaking.
This isn’t the full picture however. The research paper suggests that it isn’t just histamine which may be causing a problem for HIT patients. Other biogenic amines, such as putrescine, compete for DAO and the reason that patients report issues with foods low in histamine may be that they’re high in other amines. We have no evidence this is true though – bare in mind it’s just a theory and might be totally wrong.
The biogenic amine putrescine is found in nearly all foods to some degree, so again we have no idea what a high level is, so I’m using 20mg/kg as my figure but it’s not based on anything. The following is a list of ‘high’ putrescine foods – if you react to any of these, none of which are high in histamine, it might be you have an issue with putrescine instead:
- Green pepper
- Tomato, fresh, concentrate & ketchup
- Peas (fresh & frozen)
- Soybeans, dried & sprouted (but not soya milk or tofu!)
- Grapefruit, fresh (juice is borderline)
- Passion fruit
- Pear is borderline
- Papaya is borderline
- Wheatgerm (but not bread or other wheat based products)
- Green beans
- Purple beans
- Broccoli was borderline in 1 study but fine in the others
- Courgette was borderline
- Cucumber was borderline in 1 study but fine in the others
I regularly eat several of the foods on this list, including bananas, passion fruit, pear, broccoli, courgette, green peppers, sweetcorn and peas and have no problems with them whatsoever. However, you may have a totally different experience.
Tyramine, another amine, was found in some of the foods tested, though in very low levels. So using pure guesswork and nothing else I’ve based my ‘high’ figure on foods which contain a level of tyramine of 5m/kg – it’s not based on anything though and could be way off the mark. Foods with a ‘high’ level of tyramine include:
- Fresh tomato
- Green beans are borderline
Bare in mind that tomatoes and avocado contain relatively high levels of histamine, so you may react to those due to their histamine content, but if you have a problem with plums or green beans it might be due to their tyramine content.
Cadaverine was found in some of the foods tested, though like Tyramine in very low levels. So using pure guesswork and nothing else I’ve based my ‘high’ figure on foods which contain a level of cadaverine of 5m/kg. These include:
- Soy milk was high in 1 study but fine in the other
- Green peppers were borderline
- Banana was high in 1 study but undetectable in the others
- Grape was borderline
- Almonds were borderline
- Sunflower seeds were high in 1 study but undetctable in the other
The biggest question people new to low histamine diets asks is, “now I know what I can’t eat, but no-one tells me what I can eat!” and this new paper helps with this. There is a long list of plant based foods which are low in all amines including:
- Red pepper
- Apple, fresh & juice
- Pineapple (fresh & juice)
- White bread
- Wholemeal bread
- Corn-based cereal
- Yellow beans
If you have symptoms after eating any of these foods it looks like it’s down to a problem not related to biogenic amines and therefore isn’t Histamine Intolerance.
There are some interesting foods on the ‘allowed’ list. Bread contains yeast and yeast is banned from most low histamine foods lists, however from the research trawl I did for my Histamine in foods: the Evidence page, and from this research paper, baker’s yeast (ie the yeast used in bread) tested low for histamine, it was the yeast extract (a by-product of brewer’s yeast) found in marmite which was the problem. Many low histamine food lists exclude nuts but most appear to be low in all amines so should be fine. Soya beans are also excluded on all low histamine lists, yet tofu and soya milk tested low in all amines and soy beans tested low in histamine yet high in putrescine. It’s the fruit which has shocked me the most though. Berries, cherries, pears, plums and pineapple are all excluded from low histamine food lists yet all are low in histamine and most are low in all amines so I will be eating strawberries again before the week is out (I already eat blueberries and drink pear juice daily so knew I had no problem with them).
Although dairy foods weren’t looked at in this particular research paper milk, fresh cheeses like mozzarella (but not hard or blue cheeses!), butter, cream and yoghurt have all been found to be low in histamine, though I’m unsure of their other biogenic amine content – I’ll look into that when I’m not suffering from a sickening migraine, which I currently am Most fresh meats have also tested low for histamine, but again I’m unsure of their other amine content. So, all in all low histamine diets don’t need to be anywhere near as restrictive as they are which really is great news 🙂
In light of recent evidence I’m going to totally re-vamp the low histamine food list on my blog when I have the time, energy and brain power. I haven’t been following the list faithfully for a long time and am managing my HIT symptoms really well, so for me the list here on my blog is way too restrictive. However, as I say all the time, my blog reflects my experience and yours may be totally different.
The new research paper talks about cooking methods and the fact that boiling vegetables reduced their histamine content, sometimes dramatically. So, if you’re having an issue eating raw veg you might want to try boiling it and eating it cooked instead.
The other thing to mention while I’m on about food reactions is that Mast Cell Activation Disorder (MCAD) and Histamine Intolerance (HIT) are two distinct and separate illnesses. Patients with HIT only have a problem with amine-related foods, while people with MCAD can react to just about anything so trying to control MCAD symptoms by a low histamine diet alone is fruitless. The two diseases can sometimes occur together as in my own case, but many people ‘just’ have HIT and most people with MCAD ‘just’ have MCAD, so when I talk about low histamine diets I’m exclusively talking about controlling HIT. If people with MCAD find eating low histamine helps some of their symptoms too that’s great but it’s much more complicated than just diet for mast cell diseases. If you’ve been religiously following a low histamine diet for more than 6 months and are still reacting to foods, or are reacting to foods low in biogenic amines, or are reacting to other things in the environment like heat or cold, your period makes your reactions worse, stress or strong emotions like excitement make your reactions worse and/or your hair is falling out, I would imagine you have more than HIT going on and it’s much more likely you have a mast cell issue.