Could a histamine intolerance be silently affecting your health?

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Histamine intolerance is a hot topic at the moment within the holistic and functional medicine field. Research is still emerging, however with the current research at hand, we are starting to get a solid understanding of the exact mechanisms behind this interesting food intolerance, which is often misdiagnosed and underestimated due to its multifaceted symptom presentation.

Approximately 1% of the population has histamine intolerance and 80% of those patients are middle-aged. Most are also female due to a strong connection between estrogen levels and histamines.

Research is starting to show that a disrupted gut microbiome may be one of the main drivers behind histamine intolerance, which is no surprise due to what we already know about the role of the gut flora in food allergies and intolerances. This once again highlights the significant connection between the gut microbiome and our health.

What is histamine intolerance?

Histamines are naturally produced in the body by specialised cells called mast cells. They play important roles in immune function, brain function, sleep, skin health, libido, estrogen balance and digestive function. They also play important roles in mood and alertness, which is why anti-histamine medication causes drowsiness. Mast cells are located in high amounts within these various body systems, which makes them very widespread in the body.

Most people know about histamines due to their role in allergic reactions. The release of histamines in response to allergens such as pollen, is what causes symptoms like a runny nose, watering eyes, sneezing, throat and face swelling, itchy skin and hives. This is why antihistamines are prescribed for things like hay fever and other types of allergies. Histamine release in response to allergens that are harmless to the body such as pollen, is a result of an over reactive, hyper-sensitive immune system, which is usually due to genetics and a disrupted gut microbiome. 

80% of our immune system is located in our gut and if the microbiome is imbalanced, so will the immune system. Therefore, in people with hay fever, harmless antigens enter the body, but because the immune system is disrupted, it sees these antigens as harmful, therefore mounting an immune response, in which histamines are released. A disrupted gut microbiome is driven by and exacerbated by various diet, lifestyle and environmental factors. 

Mast cells on a daily basis produce histamines as part of normal physiological functions, and these functions are mentioned above. Also, histamines are naturally occurring molecules that are contained within our foods. Moreover, some foods are not necessarily high in histamines, but when they are consumed, they can cause the release of histamines from mast cells.

High concentrations of histamines can be found in the food products listed below. Some of these foods may not contain histamines, but once ingested, they increase the release of histamines from mast cells or in the case of processed foods, they can feed certain strains of bacteria in the gut that can produce and release histamines. 

Protein: Eggs, seafood (fresh shellfish, fresh finfish, smoked or canned seafood like smoked salmon or trout), Greek yoghurt, kefir yoghurt, bone broth, processed, cured and smoked meat (e.g. bacon, meatballs, patties, sausages, salami etc)

Vegetables: Tomato, spinach, eggplant and microbially fermented food like pickled vegetables, kimchi, natto, tempeh, kombucha and sauerkraut. 

Carbs: Citrus fruits like pineapple, orange, grapefruit, mandarin, lemon, lime, papaya, paw paw, kiwi, grapes, plums, passion fruit and berries (except blueberries/blackberries). Yeast products, gluten grains (i.e. barley, rye, oats, wheat, spelt), dried fruits, beans, legumes, lentils, peas, soy milk, tofu (i.e. soy products), pumpkin and processed carbs, such as deep fried food, pizza, pasta/noodles, breads, desserts, baked goods, chips, chocolate, confectionary and lollies.

Fats: Dairy products like milk cream, sour cream, cheese and butter. Vegetable oils as well (e.g. canola oil, safflower oil, sunflower oil, soybean oil and peanut oil), which are found in most takeout foods, restaurant food, cafe food, and processed/packaged food (i.e. foods/drinks/condiments/sauces/flavours in bottles, jars, containers, boxes, packets etc).

Herbs and spices and flavours: Chili powder, chilli, cloves, anise, nutmeg, curry powder, cayenne, soy sauce, yeast, ketchup, mustard, vinegars, salad dressings, relishes, tomato-based sauces, processed sauces (with sugar and vegetable oils), lemon/lime juice, stocks, jams, condiments, curry pastes, as well as artificial flavours, preservatives, additives and colours (i.e. processed food).

Drinks: Herbal teas, milk, alcohol (especially beer, cider, champagne and wine), drinks with added sugar and fermented drinks like kombucha and kefir milk. 

Note: As you can see, people on a vegan diet will struggle on a low histamine template because many high histamine foods are staple foods on a vegan diet. I often run into this road block in clinical practice. 

Note: It is well known that eating too much processed food and not enough home cooked nutrient dense wholefoods is detrimental to our health and can increase the proliferation of negative strains of bacteria that as you will see in this blog post, can drive not only histamine intolerance, but other food allergies/intolerances, digestive issues and chronic health issues. Processed food feed bad bacteria. A lack of healthy food starve the good bacteria of nutrients and prebiotics (i.e. fibre). 

All of the wholefoods listed above are very healthy for most people, however, as you read on, you will understand that in some people with a disrupted microbiome, the histamines, as well as some of the proteins and sugars in these foods can cause and exacerbate various health issues, through various mechanisms. This clearly demonstrates that when it comes to diet, there is no such thing as “one size fits all,” which is why it is silly to follow fad diets in the  media thinking it will solve your specific issues, because they don’t take into account individual differences between people, such as food allergies and intolerances.  

Most people can break down the histamines consumed via food, the ones released in response to food, as well as the ones produced naturally in the body. However, those with histamine intolerance can’t effectively break down histamines taken in via the diet and may have trouble breaking down histamines produced in the body and released in response to histamine triggering foods. This leads to the excessive accumulation of histamines in the blood, which as you will see soon, can then manifest in the symptoms of histamine intolerance. Too much of a necessary thing in the body can be bad.

As I alluded to above, these people also tend to have an overgrowth of certain bacteria in their gut, which are caused by diet, lifestyle and environmental factors that produce excessive amounts of histamines. This is one of the reasons why histamine intolerance is associated with gut issues/symptoms, as histamine producing bacteria are pro-inflammatory and can cause disruptions to normal digestion and absorption in the gut, leading to uncomfortable digestive symptoms. More on this to come. 

Essentially, histamine intolerance results from a disequilibrium of accumulated histamines in the blood due to increased intake of histamine high foods (and triggering foods), combined with the decreased ability for histamine degradation, as well as increased histamine production from a disrupted gut microbiome that contains an overgrowth of histamine producing species.

Because histamines are naturally produced in the body for physiological functions on a daily basis, when someone can’t effectively break down histamines ingested via their diet or histamines that are produced in the body and from the gut, it leads to excess histamines in the blood.

Exacerbating this is the fact that inflammation in the body (driven/exacerbated by poor diet and lifestyle habits) and excess estrogen can also cause the release of histamines from mast cells, which is why histamine intolerance is more common in females, especially those on the contraceptive pill and those with hormonal disruption issues that result from excess estrogens. Such as endometriosis, heavy periods, painful periods and fibroids. Interestingly, while estrogens increase histamine release, increased histamines can cause excess estrogen production from the ovaries, which can therefore be a driving factor behind estrogen dominant hormonal issues. More on this down below. 

Histamines are inflammatory in nature, therefore an excessive accumulation of them in the blood can cause widespread inflammation in body tissues where mast cells are densely located (i.e. skin, gut, urinary tract, uterus, ovaries, immune system, nervous system, endocrine system).

Increased histamines in the blood also activate histamine receptors on mast cells to release more histamines. As mentioned above, mast cells are densely located in the skin, gut, uterus, ovaries, urinary tract, immune system, nervous system and endocrine system. Therefore, once mast cells are activated to release more histamines in these tissues, it causes inflammation in them.  

Inflammation from high histamine levels in these tissues, as a result of over stimulation of histamine receptors, can manifest in a wide variety of symptoms relating to the aforementioned organ systems that have high amounts of mast cells, as well as exacerbating existing health issues relating to these body systems. These include:

  • Hay fever symptoms like itchy eyes, watery eyes, runny nose, sneezing, blocked sinuses etc. People with hay fever tend to also have histamine intolerance, which is why decreasing histamines via the diet seems to improve reactions to pollen due to the decreased amounts of histamines in the blood.
  • Hormonal imbalances in females like heavy periods, painful periods, irregular periods, and PMS (e.g. food cravings, mood disturbances – anxiety and depression, fluid retention, bloating, changes in bowel motions, breast tenderness, nausea, fatigue, acne, a flare in skin issues). These issues are driven by excess estrogen and low progesterone production. Histamines increase the production of estrogen and estrogen increases histamines, which is why histamine intolerance can manifest in hormonal issues. Excess estrogen and increased histamines also lowers progesterone production. This hormonal imbalance is often made worse by a disrupted microbiome and nutrient deficiencies that are needed for progesterone production and estrogen clearance, which are both common in people with histamine intolerance.
  • Fatigue, mood disturbances and mental health issues (e.g. anxiety and depression).
  • Digestive issues like reflux, nausea, gas, bloating, constipation and diarrhea.
  • Asthma.
  • Hives and exacerbation of existing skin issues like acne, dermatitis and eczema etc.
  • Acne.
  • Cognitive issues like brain fog.
  • Insomnia.
  • Chronic fatigue and fibromyalgia. 
  • Bladder symptoms like increased frequency and urgency.  
  • Decreased immune function and increased risk of infection. 
  • Flare up of symptoms relating to a specific health condition. Most chronic health conditions are driven by and exacerbated by inflammation. Excess histamines increase inflammation. 

Note: Interestingly, pharmaceutical drugs that increase histamine release from mast cells or block histamine breakdown in the body often have side effects similar to what is mentioned above.

As shown above, histamine intolerance can manifest in many ways and depending on a person’s genetics, it will determine how it manifests for them. The most common health issues that I see in clinical practice, which are driven by or exacerbated by histamine intolerance are hormonal disruption, gut issues and skin issues. 

Now just to make it clear once again, I am not saying that histamine intolerance single handedly causes the above health issues on its own. These health issues, just like many chronic health issues, usually are a result of a complex interplay between genes and negative diet, lifestyle and environmental factors. However, histamine intolerance, as well as diet and lifestyle factors, including other food allergies and intolerances (driven by microbiome disruptions), are all likely to be exacerbating factors. The issue is that when food is a trigger/exacerbating factor for the flare up of symptoms, it means that most of the day, a person could be exacerbating their symptoms because humans spend most of the day in a post prandial state. when hey eat high amount of particular foods that trigger their symptoms, this is when their conditions can worsen, along with other poor lifestyle habits. 

This is why as a naturopathic practitioner, I use diet and lifestyle interventions, as well as herbal and nutrition supplementation to treat the underlying causes and exacerbating factors for people’s most concerning health issues. And when it comes to dietary interventions, as you will see in this article, there is a lot we can do to help improve a person’s health issues. It is possible to remove certain foods (e.g. high histamine foods) or macronutrients that may be exacerbating a particular health issue, in order to achieve a specific therapeutic goal. This is what we call using food as medicine. We can then help change a person’s gut microbiome to tolerate these foods better so that they can be reintroduced back into the diet without causing issues or flaring up symptoms. 

Essentially, the right diet and lifestyle habits for a person’s health issues help decrease inflammation in the body, increase nutrient status and improve microbiome balance. This decreases people’s symptoms and prevents worsening of symptoms, as well as disease progression. 

Histamine intolerance is hard to diagnose

Histamine intolerance can be hard to diagnose because histamine intolerance is a dose dependent food intolerance, which means the more the amounts of histamine accumulate in the blood, the worse symptoms get. Or, a certain threshold needs to be reached that overwhelms the body’s ability to degrade histamines, therefore causing symptoms due to histamine excess. 

For one person, only a small amount needs to accumulate in their blood to trigger symptoms, which results from increased intake, increased production and decreased breakdown of histamines. For someone else, it may need the consistent intake of high amounts of histamine containing food/s.

Everyone has a different sized “cup” in regard to the amount of histamines they can tolerate in the body, as well as different abilities to effectively break down ingested histamines. Some people have a small cup and very ineffective mechanisms of breaking down histamines, therefore it only takes a small amount of histamine ingestion and histamine accumulation to make the cup overflow and cause symptoms. While others have a larger cup and more effective mechanisms to break down histamines. 

This is why a person with a large cup and somewhat effective histamine breakdown mechanisms, may consume a lot of histamine food/s in one day. Then at the end of the day, they eat a particular food high in histamines and it results in the exacerbation of symptoms relating to histamine intolerance, therefore causing them to pinpoint this particular food as an issue for them. This is often without them realizing that it was all the other histamine foods preceding this particular food that contributed to their cup filling up over the day and then eventually overflowing. 

Maybe if they consumed this particular food at the beginning of the day, it may not have triggered an allergic reaction because it wasn’t enough to overflow their cup. In saying that, some foods are very high in histamines and can cause an overflow of a person’s cup in one hit, even if they have a large cup, therefore leading to histamine intolerance symptoms.

People with smaller cups and less effective breakdown mechanisms are obviously more reactive to smaller amounts of ingested histamines, as these people will easily have a sharp increase in excess histamines after the ingestion of histamine foods. 

As mentioned above, because everyone has different sized cups, different efficacies of breakdown mechanisms, as well as different thresholds for histamine amounts in the blood – diagnosing histamine intolerance can be quite a challenge. 

All of these factors makes pinpointing a particular food culprit quite difficult and people often don’t recognise the commonalities behind all the foods they are reacting to. This is why this intolerance is often undiagnosed and can be mistaken for other allergies and intolerances such as foods high in FODMAPs and dairy, which can also be high in histamines as well. For example, dairy products have lactose, which is a FODMAP, but they also contain casein, which drives up histamines. 

Also, because clinical symptoms and their provocation by certain foods and beverages appear similar in other diseases, such as food allergies and intolerance to sulphites or other biogenic amines (e.g. tyramine), this further makes histamine intolerance hard to diagnose. 

High histamine foods are often very healthy foods for most people, which is why this intolerance can often be frustrating for the individual because they are eating foods that are supposed to be healthy for them, but they keep getting reactions that appear quite random and sporadic. 

A tell tale sign of histamine intolerance is someone who is eating a good, wholefood diet and their health issues are not improving as they still feel reactive to various foods, which appear to be quite random. One day a particular food/meal may set them off and other days it might not, which is due to the overall intake of histamines each day and whether or not this particular amount ‘overflows’ their cup. As you can see, this makes food culprit identification very hard and confusing, as a person will experience symptoms after a food one day and on another day they won’t.

In saying that, some foods consistently set a person off because of their high histamine content and especially if the person has a small cup. If their diet is good, they may be reacting to certain wholefoods high in histamines. 

Lastly, the diverse number of symptoms of histamine intolerance in various body systems makes histamine intolerance hard to diagnose as well.

What causes impaired breakdown of histamines leading to histamine accumulation? 

Diamine oxidase (DAO) is the main enzyme required for the metabolism and breakdown of ingested histamine. In healthy people, dietary histamine can be rapidly detoxified by DAO, whereas those with low DAO activity are at risk of excess histamine accumulation in the blood, which over time (not always immediately) may result in numerous histamine intolerance symptoms and the mimicking of an allergic reaction. These are the people who develop histamine intolerance.

Research has shown that reducing histamine-rich foods in the diet dramatically reduces symptoms. However, as a functional medicine practitioner, I am always concerned about treating the underlying cause(s) of health issues. While symptomatic treatment is necessary, it is imperative to address the causes in order to achieve long-term health. This is especially true for histamine intolerance because foods high in histamine foods tend to be nutrient dense foods such as fish, seafood, various fermented foods and some varieties of fruits and vegetables. Therefore, removing them from the diet permanently may not be ideal for long-term health. This means that as a practitioner, one potential question I need to ask is, why are DAO enzymes not being produced in sufficient amounts? Looking to the gut might give some answers. 

The gut microbiome and histamine intolerance

The fact that histamine intolerance is a food intolerance, it should come as no surprise that the gut microbiome has a large role to play in its pathogenesis. 

DAO enzymes are synthesised and stored within the cells lining the small intestine walls and colon. Upon histamine ingestion, these enzymes work to metabolise histamines and therefore reduces the amount of histamines absorbed into the bloodstream. Decreased DAO production leads to increased histamine absorption from foods, resulting in excess histamine accumulation. 

As mentioned above, this is exacerbated by increased histamine production/release from mast cells in the body due to normal day-to-day physiological functions, increased production from various histamine producing species in the gut, as well as increased estrogen levels and increased inflammation (inflammation and stress trigger histamine release). Inflammation in the body is usually driven by poor diet and lifestyle habits, chronic health issues and inflammatory gut bacteria releasing inflammatory molecules into the blood. 

Decreased DAO production is usually a result of inflammation within the lining of the gut walls and this is likely driven by an overgrowth of “bad” bacteria in the gut lining, which as mentioned, release inflammatory molecules that increase inflammation in the digestive tract, as well as the rest of the body. 

Within the gut there are billions of colonies of bacteria, both good bacteria and bad bacteria. The good keeps the bad in check. It is all about balance in the gut. 

Poor diet and lifestyle habits such as increased processed food intake, increased meals eaten out, erratic/disordered eating patterns, lack of good quality home cooked meals, excess alcohol intake, not enough exercise, smoking, excess alcohol consumption, too much sitting during the day, poor sleeping habits like technology exposure before bed, stress and decreased mental wellbeing. 

Also, being born via a C-section, decreased breastfeeding as a child, a family history of gut issues, a history of gastroenteritis (i.e. food poisoning), parasitic gut infections, surgeries on the gut, as well as the overuse of medications such as antibiotics, NSAIDs (e.g. ibuprofen), opioids, the oral contraceptive pill (estrogens in the pill increase histamine release and block DAO function) and ant-acids for reflux, are all significant risk factors that increase the likelihood of bad bacteria overgrowing in the gut and overrunning the good bacteria. To put it simply, all of these factors, through various mechanisms, ‘feed’ the bad bacteria, kill off good bacteria and also ‘starve’ the good bacteria populations of nutrients and prebiotics, leading to an imbalance of good to bad bacteria in the gut. 

Once this happens, the bad bacteria that has overgrown release excessive amounts of histamines, as well as inflammatory molecules that cause inflammation in the digestive system, thus affecting proper digestion and absorption of ALL food, not just high histamine or high FODMAP foods. When food is not properly digested and absorbed in the gut, it sits there longer than it should. This leads to bacteria in the gut excessively fermenting that food. The byproduct of fermentation is gas, which is why people experience symptoms like excessive flatulence, bloating and reflux, which is due to increased intra-abdominal pressure causing the lower esophageal sphincter to open up and allow stomach acid to move into the esophagus, causing heartburn. 

Note: Certain foods, including high histamine foods can also cause the malfunction of the lower esophageal sphincter, allowing acid to reflux into the esophagus. These foods combined with increased intra abdominal pressure is a recipe for heartburn.

Poor digestion and absorption also leads to key nutrient deficiencies due to malabsorption, such as iron, B12, zinc, magnesium, protein etc. Obviously these nutrient deficiencies will be more severe in people who already are eating a diet that lacks nutrient density. Nutrient deficiencies can cause and exacerbate existing health issues (e.g. skin issues, mental health issues, immune issues, hormone imbalances). 

Inflammatory molecules in the gut, released from bad bacteria also cause motility issues in the colon, which can either manifest in constipation, diarrhoea, a mix of both or even loose stools that are infrequent and hard to pass. Overgrown bacteria, in response to fermenting undigested food (e.g. vegetable fibers, protein fibers, glucose, fructose, lactose) can also release excessive amounts of hydrogen or methane, which are often tested for via clinical breath tests. Methane usually causes constipation and hydrogen usually causes diarrhoea.

As mentioned above, a disrupted microbiome can also affect the body’s immune system due to 80% of immune cells being located in the gut, which is why people with disrupted microbiomes can also have hay fever, suffer from chronic infections, autoimmune conditions and have allergies to certain proteins in food that are also found in high histamine foods (e.g. casein in dairy). More on this down below. 

Inflammatory molecules from the gut can also travel into the blood and cause the release of histamines internally, as well as inflammation elsewhere in the body, hence exacerbating other symptoms and health issues (e.g. skin issues, mental health issues, immune issues, hormone imbalances). It also leads to decreased DAO function as mentioned above, which can drive up histamine intolerance. 

Digestive disorders/diseases like Crohn’s disease, ulcerative colitis, celiac disease and irritable bowel syndrome (IBS) are characterised by inflammation in the digestive tract and are associated with overgrown bad bacteria in the gut, which is likely driving the inflammation associated with these conditions. This is why these people tend to commonly suffer from food intolerances like histamine intolerance and have been shown to have worsening of symptoms with histamine rich foods in some cases. The inflammation resulting from these conditions in the gut lining impairs DAO function. 

Another enzyme worth mentioning in regard to histamine intolerance is HMNT. This enzyme is produced in the liver and breaks down histamines that are absorbed into the blood once they make their way through the gut lining. People who have compromised liver function or liver diseases, which tend to coincide with gut issues (due to increased inflammatory molecules from the gut travelling to the liver), may have decreased function of this enzyme. Poor functioning of this enzyme will impair the breakdown of histamines absorbed via the gut from food and gut bacteria, as well as the ones released in the body from food triggers, inflammation and normal physiological functions. 

While there is a genetic predisposition to histamine intolerance and a genetic predisposition to the malfunctioning of DAO and HMNT, these genetic predispositions are more likely to manifest in the backdrop of the risk factors for poor gut health.

Based on all of this, it seems quite clear that excessive production and intake of histamines, combined with decreased degradation of histamines from impaired DAO activity, is the likely driver behind histamine intolerance. And more specifically, the inflammation on the gut lining and excess histamine production resulting from a disrupted gut microbiome may be an underlying driving factor behind histamine intolerance. Put simply, gut disruption is the underlying cause, while environmental, diet (e.g. high histamine and processed foods) and lifestyle factors are the exacerbating factors but also the factors that need to be changed to address the underlying cause. 

Lastly, as mentioned numerous times above, research clearly suggests that there are some species of bacteria in our gut that once overgrown (e.g. E.coli) can release histamines into the gut, further exacerbating the issue. Many of these species are also found in fermented foods and dairy, which is why these foods can exacerbate the symptoms of histamine intolerant individuals. These strains can be found in probiotic supplements too, therefore caution must be taken when prescribing probiotics in those who are histamine intolerant. It is necessary to prescribe probiotics with species that degrade histamines, rather than contribute to their production. 

Note: Due to environmental, diet and lifestyle factors, some people may have a pro-inflammatory and disrupted microbiome that may also increase histamine release and prevent breakdown, however it does not manifest in digestive issues. It may manifest in other body systems

Note: DAO enzyme function differs from person to person and depends on how much inflammation is in their gut from a disrupted microbiome. This makes the severity of symptoms different for different people, as well as their histamine intolerance threshold (e.g. how many high histamine foods they can tolerate before symptoms occur).  

Note: H.pylori infection can also lead poor DAO function due to the inflammation that is causes within the gut. New research suggests that H.pylori might be a normal resident of our gut microbiome, however, for all the reasons listed above, it can rear its ugly head and start causing. It can release inflammatory molecules in the gut that can cause significant inflammation (especially in the stomach) leading to some very uncomfortable symptoms (e.g. gastritis, nausea, pain).

It also decreases stomach acid production as a means to survive in the stomach’s acidic environment. This is a huge issue becuase stomach acid is vital for proper digestion and absorption of food and nutrients. Low stomach acid leads to food malabsorption and nutrient deficiencies. As mentioned above, when food stays longer in the gut then it should, bacteria excessively ferment it, leading to excess gas production and increased abdominal pressure. This leads to reflux, gas, bloating etc.

Stomach acid is also the gut’s first line of defence in our gut, so if there is a decreased amount, unhealthy bacteria can move freely into the stomach and small intestine, which can cause or exacerbate the overgrowth of “bad” bacteria in the gut.

Lastly, to make matters worse, the typical treatment for H.pylori is hardcore antibiotics, as well as ant-acids that further decrease stomach acid production, which is obviously not ideal. This is why many people after H.pylori treatment can develop further gut issues. H.pylori could potentially be managed by removing high histamine foods, as well as increasing good bacteria in the gut to overthrow H.pylori.  

What does this all mean?

In patients with histamine intolerance symptomatology that are potentially triggered by histamine foods, who have health issues relating to histamine intolerance and who have a negative diagnosis of allergy or other disorders, histamine intolerance should be considered as an underlying mechanism. Especially if the person is already eating a wholefood diet with lots of healthy foods that they think should be helping their health but seem to be hindering it instead. 

Furthermore, if a person has got histamine intolerance symptoms or health issues that could be helped by a low histamine diet (e.g. gut, skin, hormone and allergy symptoms), but they are eating a diet high in processed food, the first goal should be to increase the intake of nutrient rich wholefoods, regardless of histamines. By doing this, it is likely their symptoms will improve. To then take it a step further, a low histamine diet can be introduced to improve their symptoms.

A low histamine diet obviously helps to reduce symptoms of histamine intolerance, however as you will see, a low histamine diet has many benefits that go far beyond addressing histamine intolerance and the issues relating to this intolerance. 

The benefits of a low histamine diet 

  1. The first good thing about a low histamine diet is that it is anti-inflammatory in nature. It is high in anti-inflammatory and antioxidant nutrients, it decreases the intake of pro-inflammatory foods and it helps people increase the nutrient density of their diet due to increased wholefood intake. This is going to help most people with inflammatory health conditions, regardless of histamines or a histamine intolerance. Therefore, a low histamine diet can be used to decrease symptoms of chronic, inflammatory, health issues.

  1. A low histamine diet removes processed foods and increases wholefoods, which is very important. Removing processed food prevents feeding bad bacteria that are inflammatory to the gut and the body, immune disruptive, decrease DAO production and increase/trigger histamine release. 

In saying this, I commonly see people who tell me they follow a low histamine diet. This is often after spending time on google and seeing that their symptoms link up with histamine intolerance. 

However, when I speak to them, I find out that while they are avoiding most of the main histamine foods, they are still eating lots of processed food and takeout/restaurant food.  They remove things like gluten, dairy, soy etc. which are high in histamines, yet they consume processed food alternatives that don’t contain these ingredients.

This defeats the whole purpose of a low histamine diet and will unlikely lead to desired results. When removing high histamine foods, one must also make sure they are improving the nutrient density of their diet as well, in order to feed the good bacteria of their gut, decrease inflammation in the body and increase their overall health and wellbeing.

As you will see written down below, it is so important to increase healthy gut bacteria balance, which goes far beyond improving DAO function, starving bad bacteria that release histamines and decreasing histamine intolerance.  

  1. Many high histamine foods also contain other compounds that can exacerbate gut issues and other inflammatory health issues, which are unrelated to the histamine content. These are compounds like FODMAPs and immune reactive proteins. 

Take dairy, soy and wheat for example. All of these not only contain histamines (i.e. casein and gluten) and compounds that increase histamine release, they also contain FODMAPs and proteins that can cause immune reactivity.

FODMAPs is an acronym for fructo-oligo-monosaccharides and polyols. They are various carbohydrates/sugars found in plant based foods that in people with an imbalanced microbiome can have trouble digesting and absorbing. Poor digestion of these sugars means they linger in the gut longer than they should and undergo excessive bacterial fermentation, leading to excessive gas production. The result of this is very uncomfortable digestive symptoms such as bloating. To learn more about FODMAPs and how they relate to gut health, read here. 

Moreover, proteins like casein in dairy, gluten in wheat and phytoestrogens in soy, have particular structures that in people with a disrupted immune system, as a result of poor gut bacteria balance, can have inflammatory reactions to. 

Remember how I mentioned earlier that 80% of the immune system is located in the gut and gut bacteria play a vital role in regulating immune cells? Well, if the gut microbiome is imbalanced (which is usually the case in histamine intolerant people or people with gut issues), this leads to the immune system being overactive and seeing proteins like gluten and casein as “harmful,” therefore mounting an immune response to them once they are consumed.

The immune response creates inflammation in the body and can manifest in digestive symptoms, as well as the symptoms listed above that relate to histamine intolerance. 

As you can see, a person with a disrupted gut microbiome can react to foods like gluten, diary and soy in multiple ways, which could also be occurring all at once.

Because of this, as a practitioner, if I have diagnosed a person incorrectly and I believe a histamine intolerance is occurring but it is actually due to FODMAP intolerance or immune reactivity to food, it doesn’t really matter and is relevant. What matters is that we still end up removing the problematic foods with the goal of re-adding them back in once we treat the gut imbalance. Therefore, a low histamine diet doesn’t have to be called a low histamine diet. You could call it a low dog diet – whatever funny name you want. It doesn’t matter what the name of the diet is, what matters is that the foods we are removing are likely to improve people’s symptoms. 

  1. A low histamine diet makes it easier to identify what high FODMAP foods a person is reacting to. In clinical practice, I often have people coming to me with gut issues that have tried a low FODMAP diet in the past, based on the recommendations of google or a health practitioner.  Some of them struggled to follow the diet due to its restrictiveness and therefore never really saw results. 

Many others tried it for a while with some improvement in symptoms, however they were still having gut issues. This is because many of them removed all of the FODMAPs at once, which made it hard to identify which FODMAPs they were actually reacting to (raw or cooked) and in what amounts. As you will understand in this post, FODMAP reactions can also be dose dependent, meaning it is based on how much a person has consumed one particular FODMAP in a meal or a combination of them together. Also, whether they were cooked or not makes a difference because high FODMAP foods are often high in insoluble fiber, which can be tough for an inflamed gut to digest. 

It must be noted that most people do not react to all FODMAP foods, they usually only react to at most a handful. As stated above, the ones they react to are usually because too much has been consumed at once of the same FODMAP or different types of high FODMAP foods. 

More often than not, clients who come to me having tried a low FODMAP, usually gave up on it as they didn’t feel empowered. Because despite going low FODMAP, they were still getting symptoms.

The reason why they were likely to be getting symptoms is because people with IBS (irritable bowel syndrome) type symptoms, as a result of a disrupted microbiome or even small intestinal bacterial overgrowth (SIBO), usually react to low histamine foods and proteins in food, as well as some FODMAPs. This is because gut bacteria drive these issues and when the microbiome is not balanced, lots of different reactions to different food categories can occur.

However, these clients of mine are often unaware of this and feel helpless after trying a low FODMAP diet and not realising that some of the healthy, wholefoods they are consuming, may be harming them due to the histamine content and protein content. 

As a practitioner, through a detailed case history, it is my job to help people identify and see the connection/commonalities between the foods they are eating and their symptoms.

In some cases, people can find it quite easy to identify if they react to certain FODMAPs or not. This is because FODMAPs are digested high up in the digestive tract, therefore if there are symptoms, you are likely to feel it straight after your meal. However, histamines on the other hand are hard. This is because they require a build up in the body before they manifest in symptoms. It can sometimes take the whole day for a person’s “cup” to overflow and manifest in symptoms. Which is why a person may react to their evening meal that is high in histamines and not their breakfast for that day. But their breakfast meal was a contributing factor to filling up their cup for that day.

This is what makes histamine intolerance feel so sporadic. People often tell me they eat a certain food or meal one day and feel fine. But then a few days later they feel unwell afterwards and can’t understand the mechanisms of why this happens. 

This is because on the day they felt ok, they potentially didn’t consume other amounts of histamines to overflow their cup. 

As you can see, this makes it hard to pinpoint trigger foods. 

Now because a low FODMAP diet is more restrictive than a low histamine diet and most people usually only react to a few FODMAPs (at certain doses – both cooked and uncooked), I don’t find there is a need to remove all of them. The more FODMAPs we can keep in a person’s diet the better. This is because FODMAPs are high in prebiotics, which help to feed healthy bacteria. These healthy bacteria are essential to overrunning the bad bacteria that are imbalanced in the gut. Therefore, removing FODMAPs all together, in a person with or without gut issues, leads to starving good bacteria in the gut. This may worsen the issue we are trying to correct. You also don’t want to be causing one problem while trying to solve another. 

Based on this, I tend to put my patients on a low histamine diet, which is less restrictive than a low FODMAP diet. If a person is certain about which FODMAPs they react to and in what amounts,  we take these out of their diet. The rest of them, I like to keep on a person’s treatment plan. However, this is not without making my client aware of what foods on the treatment plan are in the high FODMAP category. 

Therefore, if they eat a meal and get symptoms, they know it wasn’t due to the histamines because they are following a low histamine diet, so, it must have been a FODMAP. They can look back on their meal, identify what foods were FODMAPs and then try these foods individually by themselves, at certain doses (and maybe certain combinations), to see what it was they were reacting to.

I tell my patients to try them both cooked and raw, because some people tolerate FODMAPs better when they are cooked, due to the breakdown of some of the sugars and insoluble fibers that can cause gastric upset.

Once they identify the FODMAPs they react to, I ask them to remove them for their diet, along with all the high histamine foods that they have already removed.

To make it easier for my patients, I tell them to eat low histamine fruit and vegetables willingly and if they consume FODMAPs in a meal, try not to add more than one or two per meal. Just so it is easier to identify the trigger foods if they end up having a reaction. 

Utilising a low histamine diet to help identify FODMAP intolerances is very practical. A low histamine diet is not nearly as restrictive as a low FODMAP diet and like I said, most people don’t react to the full spectrum of FODMAPs, therefore it is just a matter of using the low histamine base to identify which ones. 

A low histamine diet combined with a strict low FODMAP diet is very restrictive and impractical. In saying that, it is sometimes needed in very extreme cases. However, just like any elimination diet, this is only temporary. because once people start to feel better and their gut microbiome becomes more balanced, we can look at food reintroduction. More on this down below. 

Lastly, with some clients, I may even combine a low histamine diet with an autoimmune protocol (AIP), especially if the client has an autoimmune condition. AIP removes a lot of the same foods as a low histamine diet.

This is because, as discussed above, a lot of high histamine foods contain proteins in them that can trigger immune responses and inflammation in a person who has a disrupted gut microbiome, which in turn causes a dysregulated immune system. 

People with a dysregulated immune system may be prone to reacting to certain proteins in food because their body will mount an inflammatory immune response to these proteins that are completely harmless, but are perceived as harmful to their disrupted immunity. This exacerbates inflammatory conditions like autoimmunity. 

Due to the link between gut bacteria and immune function, it is no surprise that people with autoimmune conditions usually have some kind of imbalance in their gut microbiome and therefore have digestive issues. 

Where low histamine and AIP mainly differ, is that AIP does not allow for the consumption of gluten free grains, nuts and seeds. This is because the proteins in these foods may be immune reactive in people with autoimmunity. 

Even if a person does not have an autoimmune condition, the proteins in grains can exacerbate digestive issues and inflammatory issues in people with imbalanced gut bacteria, as well as a dysregulated immune system. Grains also contain fibers that can be hard to break down in those people with inflammation in their gut due to inflammatory gut bacteria affecting proper digestion. This can cause gastric upset. 

For these reasons, regardless of whether a person is using an AIP diet with a low histamine diet or not, I still get my patients to prioritise their carb intake from things like fruit and starchy vegetables (e.g. sweet potato). These foods are easier to digest, higher in prebiotics and more nutrient dense than grain based carbs.

As you can see, a low histamine diet is a great platform to integrate other types of elimination diets.

  1. A low histamine diet is great for weight loss. It makes people eat more healthy wholefoods that are low in calories but very satiating. This makes people feel full, without eating too many calories. 

  1. The last and most important benefit of a low histamine diet is that it removes histamine containing foods, which will improve symptoms in a person with histamine intolerance.  

Can you use a test for histamine intolerance?

Histamine levels can be measured in plasma or urine. Serum DAO levels can also be measured. Elevated histamine concentrations and reduced DAO levels are both classically found in histamine intolerance and can be used as diagnostic tools. 

However, the gold standard for diagnosing histamine intolerance is via a food elimination diet. If a person presents with potential symptoms linked to histamine intolerance and the removal of histamine-containing foods improves their symptoms, it is likely that histamine intolerance may be an underlying cause.

While on the topic of food allergy testing, I would like to clear up a few things around this topic.

Various types of food allergy and food intolerance testing is usually done via pin prick on the skin or measuring gas production through the breath after the ingestion of testing substrates (e.g. fructose breath test after ingesting a fructose solution). 

I don’t particularly like these tests. Firstly, they are very expensive. Secondly, I feel like they give no real world application of the results for patients. As mentioned above, food elimination and food reintroduction is still the gold standard for figuring out allergies and intolerances. The only exception being celiac disease, in which diagnosis involves internal gut scopes, biopsy and blood tests. 

The reason for this is because elimination and reintroduction allows us to see what foods and in what amounts do people react to in real life. People consume FOOD, they don’t consume solutions of lactose, glucose or fructose, such as the ones given for breath tests. And they certainly don’t eat food by rubbing it onto their skin. 

Therefore we need to figure out what real foods people feel unwell for and what flares their symptoms, as well as in what amounts. We need to see the real world application of their intolerances and allergies.

 This is so we can remove these foods to control symptoms while we improve the rest of their diet and lifestyle, so their good bacteria increase. After we have improved the gut microbiome, we can re-introduce foods to see if a person reacts. Hopefully, reactions will be at a minimum, due to the changes in the gut microbiome. 

Moreover, people react in completely different ways when they eat real food, compared to ingesting an isolated substrate from a particular food/food group that they may be reacting to. It is also dose dependent, some people have a limit of how much of a certain food they can eat before they react. Clinical tests can’t tell you a person’s limit of a particular food before they react. 

On a final note, what I also don’t like about these allergy and intolerance tests is that not only do they fail to show how people react to food in real life situations, they also mislead people with their results. What I mean by this is that when people get their results back and for example it may show they are fructose intolerant, people are often told to remove ALL fructose foods – without knowing exactly what foods they actually react to, because they never did an elimination diet. This is counterproductive because removing a whole group of foods can restrict a person’s diet so much that it becomes stressful and anxiety promoting, which in the long term, affects dietary adherence. 

Also, as mentioned above, if a person is reacting to a substrate in certain foods, it is more than likely they will only react to a few types of foods that contain this substrate. Therefore we need to find out what foods they are reacting to and in what amounts (via removal and reintroduction) so that we can keep as many foods in their diet for the purpose of variety and nutrient density. As well as sanity for the patient. We also don’t want to starve the gut microbiome of beneficial nutrients if it is not necessary. 

In any food removal it is never enough to remove the foods in question. There must always be an improvement in the person’s diet with all of the foods they can eat and don’t react to. This is to support their overall health and wellbeing, as well as their gut microbiome. 

People often forget the importance of keeping a healthy diet during food elimination diets for identifying food allergies and intolerance. They become so focussed on removing the foods that have a substrate in them in which they tested positive to, they forget to improve their diet elsewhere. Therefore, they end up eating a crappy diet, free of the substance they react to and don’t actually get better. 

Lastly, although certain foods can be grouped together based on the similarities of the substrates contained within them, the way these substrates  exist in each of these foods is very different. This is why it is possible for a person to react to certain foods that have a particular substrate they tested “positive” to via a food allergy or intolerance test while they may be fine with other foods that contain the exact same substrate. Their reaction to each food will be governed by their gut microbiome. 

Also, this can explain why two people who may have an allergy or intolerance to a particular food substrate, react to completely different foods. One may tolerate a certain food completely fine, while the other may react. The difference in reactions to food, between two different people, would also be due to their gut bacteria composition. 

This is why there is never a one size fits all approach when it comes to diet and nutrition. 

Treatment options for histamine intolerance?

Typical treatment for histamine intolerance obviously involves a low histamine diet and focussing on what can be eaten rather than what cannot. As mentioned above, if necessary, the low histamine diet can be used alongside an AIP or low FODMAP diet if necessary.

While it is important to remove high histamines and other foods in question (and food triggers), it is also important to address the underlying causes of histamine intolerance. Therefore, addressing imbalances of the gut flora is crucial. This can be done by adjusting diet and lifestyle (e.g. sleep, stress, exercise, alcohol, smoking etc.) risk factors that cause and exacerbate bacterial overgrowth in the gut, as well as using herbal and nutritional supplementation to help correct the bacterial imbalance. 

Furthermore, based on the information described above, improving estrogen balance, the inflammatory status of the body and liver function in order to increase HMNT activity, via diet, lifestyle and supplemental interventions, will also be useful to decrease histamine intolerance symptoms. This is because excess estrogen in the body drives up histamines, increased inflammation in the body increases histamine release from mast cells and HMNT is the enzyme that helps break down histamines absorbed via the gut. Estrogen balance and the inflammatory status of the body can be highly influenced by diet and lifestyle habits, as well as the gut microbiome.

Note: Improving gut bacteria composition will decrease inflammatory molecules from bacteria, travelling into the blood and towards the liver, which in turn causes inflammation in the liver. This will decrease HMNT production and if you remember, the HMNT enzymes help break down histamines absorbed into the blood from food and gut bacteria. Therefore, improved HMNT function will increase histamine breakdown and decrease histamines in the blood. Also, Improving gut bacteria composition will improve DAO function and therefore decrease the amount of histamines absorbed, hence less stress on the HMNT enzyme.

It is important to increase the nutrient density of the diet via wholefoods, as well as removing processed and refined foods. By removing food triggers, decreasing processed food and improving a person’s diet, this will help to starve the inflammatory bacteria that are driving a person’s symptoms. 

This is because overgrown “bad” bacteria affect DAO production, increase the release of histamines, affect normal digestion and absorption of foods/nutrients, cause immune disruption leading to food allergies, as well as increase the release of inflammatory molecules that are traveling into the blood and causing inflammation in other body tissues.

After doing this, a person will see a shift in their symptoms and after a while (i.e. 2-3 months), given enough time for their microbiome to shift, they can slowly and carefully try to reintroduce foods that they removed on their elimination diet. They are not to reintroduce processed foods, but rather, wholefoods. Upon reintroduction, it is unlikely they will react to these foods due to improved immune function, improved DAO function and improved digestive function – all as a result of less inflammatory bacteria in the gut that disrupt normal digestion, normal immune function and normal DAO function. Improved DAO function will improve histamine tolerance and  improved digestion will improve digestion of high FODMAP foods. Lastly, improved immune function as a result of a healthier microbiome, will lead to decreased immune reactivity to proteins in foods that are also high in histamines. This will decrease immune mediated, inflammatory reactions to foods. As mentioned above, this inflammation can manifest in the gut, as well as other body systems, causing and exacerbating a whole host of issues. 

Tolerance to once problematic foods/food combinations that the person was either aware of or not, should increase if the underlying causes of histamine excess are addressed and if they are eaten in the backdrop of a low histamine diet. This is due to a lowered threshold and less histamines in the person’s “cup.” A person should start with re-introducing foods they once craved, regularly enjoyed eating and foods that are good for their health.  

It becomes up to the individual in the re-introduction phase to find out how much histamine food/s (one or combined amounts) can be added (and how regularly they can be eaten) without causing symptoms. By going on a strict low histamine diet and with symptoms clearing, the re-introduction period can give a person a clear picture as to what foods, what combinations of food and in what amounts they still react to. Individual sensitivity varies tremendously.

Upon reintroduction, if a person still reacts to a certain food, it is advisable to remove it and try to reintroduce it in a few months time. This usually works as it gives time for the gut microbiome to shift some more. However, this obviously depends on a person adhering to a consistently healthy diet that feeds their good gut bugs. 

Interestingly, if a low histamine diet improved a person’s symptoms and prior to the diet they had no idea of what specific foods they were actually reacting to. If the re-introduction goes smoothly, they will still have no idea what foods that had previously had issues with. In saying that, some people, prior to the elimination diet knew of some foods that they were reacting to. Therefore, it is always interesting to see how much of those foods they can re-introduce, without reacting, if at all. 

Also, because a person’s gut becomes less inflamed due to the changes of their microbiome, what usually happens is that they can tolerate more processed foods and takeout foods. This means that foods eaten out or processed foods will end up affecting a person less. They will have a decreased symptom flare, if at all, which is very different to previously going on a healthy low histamine diet. Even if their symptoms do flare, it will usually be not as intense and will subside quicker. This however doesn’t mean a person should be eating more takeouts/restaurant/cafe meals or more processed food!

The goal of the treatment plan is not to help people consume more processed foods, take outs and alcohol without symptoms. The goal is to help you get rid of uncomfortable symptoms and be able to tolerate most wholefoods, that are nutrient dense. Instead of having reactions to these types of foods as well. If it so happens that a person becomes more tolerant of processed foods, processed drinks, alcohol and takeouts, then this is the cherry on top of treatment! 

A person will also soon realise that with most foods and drinks, will only cause issues if consumed in too high amounts. The flare of symptoms becomes dose dependent. 

Also, any processed foods or meals eaten out should always be consumed in the context of a healthy diet, as part of the 80/20 rule. 80% of the time, they eat healthy, 20% can be left for indulgences, which can be enjoyed with friends and family. In the backdrop of a good diet, it is unlikely to effect them. 

After following a low histamine template and having symptom reduction, it should be empowering for a person to know exactly what their triggers are when they stray from the diet template. It should also be empowering to know if they have a meal/food that flares their symptoms, they will understand how to get back on track and make those symptoms subside with good eating habits. This gives them much more control. 

It should also be empowering to know that there is a template where food can be used as medicine to decrease a person’s symptoms. 

Lastly, in the long term, if a person becomes complacent with their treatment plan and symptoms do happen to flare up again, they know that they can always revert back to a template that works and it allows them to reset themselves. 

Supplementation for histamine intolerance 

Supplementing with nutrients that help support DAO function, support histamine detox, as well as using natural antihistamine herbs/nutrients that stabilise mast cells is effective. Also, any drugs that decrease DAO activity should be avoided (e.g. NSAIDS and antibiotics).

Supplementing with probiotic strains that degrade histamines, help increase healthy microbiome balance, as well as healthy gut function may also be beneficial. These include bifidobacteria species (particularly Bifidobacterium infantis), L. plantarum, L. rhamnosus, L. salivarius and L. gasseri.

Lastly, it is important to supplement with any nutrients that a person may be deficient from poor gut absorption as a result of an inflamed gut. 

Not all supplements are equal, so make sure you see a practitioner to receive good quality practitioner only brands that are safe and effective. 

Wrap up

As you can see, we can manipulate a person’s diet via food-category removal, as well as adjusting macronutrient ratios to achieve specific therapeutic outcomes and health goals. This is where we use food as medicine. However, what you will see throughout the process of working with me, is that the basic principles of healthy eating don’t change. Despite you having to adjust what foods you can and can’t eat and the serving sizes around them.

After this process, you will come away with understanding the basic principles of healthy eating, which will be beneficial for your long term health, regardless of your treatment outcomes. What you will learn and implement, certainly will not adversely affect your health. 

If this post resonated with you, call Oak Health today or book an appointment online.