Food chemical sensitivity is VERY complex. We don’t have all the facts – at least not yet. As you read this, scientists continue to work hard to understand the complexities of food chemical sensitivities. Perhaps we’ll have all the answers some day! In the meantime, we can use what we DO know to help you understand the possible mechanisms of specific food sensitivities.
One of the food chemicals we get asked about often is histamine. You may have heard of histamine in the context of allergies – like taking an antihistamine to manage your hay fever. So, what is histamine exactly? And what does it have to do with food? Let’s dive in!
Nutrition for Histamine Intolerance
Traditional (IgE) Allergies and Histamine
Histamine is a biogenic amine that aids many important functions in the human body. One of its biggest roles is to mobilize your immune system when there is a perceived invader. Unfortunately, if the immune system overreacts, a person can develop IgE allergies – or inappropriate immune responses to ‘antigens’ (which could be food proteins, pollen, bees, etc!) When the body experiences an allergic reaction, it releases excess amounts of histamine, which triggers the immediate symptoms of allergy (like hives, swelling, difficulty breathing, digestive issues or anaphylaxis to name a few).
Histamine Intolerance and Histamine
Releasing histamine is a normal part of immune function, and one that most of our bodies are able to handle. So how does a person become histamine intolerant? When the body releases histamine, healthy individuals are able to break down the excess histamine with a specific enzyme called diamine oxidase (DAO), maintaining a state of equilibrium in the body. However, there appears to be some people who struggle to fully degrade excess histamine, resulting in excess histamine in the body. These people appear to have a deficiency of the DAO enzyme, preventing the efficient breakdown of histamine. This can lead to symptoms similar to those of an allergic reaction, although many cases of histamine intolerance aren’t connected to a specific allergy and food allergy tests come back negative. Histamine builds up in our bodies over time, like filling a bucket. If we have no way of emptying this bucket, symptoms can occur.
In rare cases, histamine intolerance appears to be caused by an excess of mast cells in the body or by over-reaction of these mast cells. Mast cells are the storage cells for histamine, and ‘degranulate,’ or release histamine upon exposure to antigens, or simply as part of the body’s normal function. When we have too many of these mast cells, or our mast cells are over-active, research shows that a person can have excess levels of circulating histamine in the body triggering allergic-type symptoms.
Interestingly, there has been an association between an increase of mast cells in the gut and IBS. In some studies, patients with IBS appear to have a higher amount of mast cells in the gut, and it has been theorized that mast cells and/or their degranulation may play a role in IBS-like symptoms.
Symptoms of Histamine Intolerance
As mentioned above, the symptoms of histamine intolerance are similar to those of traditional allergies and include the following:
- Hives and itching
- Tissue swelling, particularly around the face and mouth
- Rapid heartbeat and increased pulse
- Chest pain
- Closing or tightening of the throat
- Watery nose and eyes
- Fatigue, anxiety, and irritability
- Indigestion symptoms including heartburn, reflux, and increased stomach acid
- Changes in bowel function – most commonly diarrhea
Each person with histamine intolerance can have a unique set of symptoms, meaning not everyone will experience all of the above symptoms. However, if you have only a couple of the above symptoms, it is less likely that what you are experiencing is histamine intolerance.
‘High Histamine Foods’ – What’s the Connection?
Although histamine intolerance is not necessarily connected to true food allergies, there are certain foods that can worsen someone’s histamine response if they have an intolerance. Many foods are naturally quite high in histamine or release histamine in the body and therefore contribute to the histamine “bucket”, meaning it may be beneficial to limit intake of said foods – more on this later!
Additionally, people who have other ‘histamine risk factors’ like environmental allergies, sulphite sensitivity, or other food chemical sensitivities may have a lower tolerance to histamine-containing foods, as their buckets are already pretty full to begin with!
Keep in mind, with all that we know about histamine in our food, there is still a lot we don’t yet know. At this point, a low histamine diet for the management of histamine intolerance is more of an ‘educated guess’ and each person likely has a very unique set of dietary triggers (if any).
Diagnosing Histamine Intolerance
Like many food intolerances and sensitivities, we don’t have a validated diagnostic test for histamine intolerance. Mast cell activation disorder on the other hand, can be diagnosed by interpreting a variety of different tests that can be ordered by an allergist or immunologist. This can include serum tryptase and a 24-hour urine collection to measure for compounds released by mast cell degradation. There have been studies that measure levels of histamine and DAO in the blood, but these are not evidence-based and therefore their use as a diagnostic test aren’t validated.
Histamine intolerance may also be informally assessed by looking at a person’s symptoms and empirically treating those symptoms with medication and/or low-histamine diet. If they achieve symptomatic relief, it could be an indicator that excess histamine is contributing to their symptoms. However, if someone does NOT feel better on a low histamine diet alone, this doesn’t necessarily rule out histamine intolerance. There are many times when this condition needs to be managed with medication and diet changes don’t provide the desired symptom relief on their own. It is best to work with your health care team to understand your management options if you are histamine intolerant.
Food chemical sensitivities can often be misdiagnosed, or other food chemicals may be implicated in your symptoms that aren’t related to histamine at all, so keep that in mind and see a dietitian to help you sort out if your symptoms are actually due to a histamine intolerance. For example, doctors initially thought that our owner, Andrea had a histamine issue! However, upon careful investigation, it turned out it was a sulphite sensitivity! Read her story here.
How is Histamine Intolerance Managed?
Histamine intolerance is dose-related. This means there is a threshold of histamine or histamine-releasing foods that most histamine-sensitive people can tolerate before experiencing symptoms. In addition, medications can be effective in managing histamine release or the reactions to histamine in your body. Ensuring proper diagnosis, medication management, and trialing dietary interventions are the most evidence-based ways to manage histamine intolerance at this time.
Low Histamine Diet
As dietitians, one of our top priorities is to ensure our patients’ diets are the least restrictive possible. Histamine intolerance is no different – our goal is to reduce the intake of high histamine foods without being too restrictive while helping our patients achieve symptomatic relief. Then we work with our patients to gradually and strategically add things back to identify how much histamine they can tolerate in a day or even in one particular meal. It is highly recommended to work with a dietitian experienced with histamine intolerance to work through this very specific diet!
While I won’t be including the full list of high histamine foods here, there are some key points to know about histamine in our food:
- Histamine is made by bacteria – foods that are higher in bacteria are higher in histamine as well, as histamine is a by-product of bacterial metabolism. So which foods are high in bacteria? To put it simply – old, spoiled, or fermented foods are at the top of that list. For example, leftovers that have sat in the fridge for days, fermented fish sauce, blue cheese, or kimchi are great examples of foods that have more bacterial growth, therefore higher levels of histamine.
- Meat and poultry are especially risky, as it develops bacteria rather quickly – both raw & cooked. Additionally, the heat from cooking meat and poultry will denature an amino acid in protein-rich foods called histidine, converting it into more histamine as a result. Simply put, meat and poultry are high-risk for increasing histamine, as they have two pathways of histamine production – microbial-developed histamine AND histamine produced from the denaturation of protein during cooking. Therefore, it is important to prepare and store meats in a way that will prevent bacterial build-up.
- Fish and shellfish – Consuming spoiled fish can lead to something called scombroid poisoning, where the high levels of bacteria in the old fish release high levels of histamine. If someone consumes spoiled fish, leading to excess histamine in the body, they can experience symptoms similar to an allergic reaction. Additionally, shellfish that still have their digestive tracts intact also have high levels of histamine, as they consume algae (a type of cyanobacteria) – they eat bacteria, and then we eat them, meaning we are ingesting more histamine as a result!
- Histamine present in food is not always related to bacterial growth. There are some foods that appear to naturally have higher levels of histamine. There are also some foods that are considered histamine liberators, meaning they have the ability to release existing histamine from mast cells. These foods include citrus fruit, tomatoes, avocado, spinach, eggplant, and some other fruits & vegetables.
- Alcohol is one of the most common histamine triggers – Many people start by removing or significantly reducing their intake of alcohol before moving into a more restrictive low histamine diet.
The takeaway: fresh is best for someone with histamine intolerance. Sure, leftovers are still totally appropriate, but storage protocols may need to be different. For example, you may need to freeze your chicken stir fry for lunch tomorrow instead of keeping it in the fridge – the lower temperature will ensure less bacterial growth and protein denaturation!
Medications and Supplements
Since one of the primary theories around histamine intolerance is low levels of the enzyme diamine oxidase (DAO), supplementation of DAO has been suggested as one of the leading management options. However, we still have a lot to learn about DAO activity.
What we do know is that DAO supplements will increase the amount of DAO circulating in the digestive system, but they won’t actually increase the amount of DAO in the bloodstream. What does this mean for histamine intolerant people? It means that DAO supplements won’t likely help to break down histamine from environmental allergens like pollen, grass, or pet dander. However, these supplements do still appear to help break down histamine from foods we consume, meaning we will absorb less, and our buckets will be emptier as a result.
What about antihistamines – like the types of medications you might take for your seasonal allergies? Antihistamine medications such as loratidine, desloratidine and certirizine are often used in conjunction with a low histamine diet in those that have histamine intolerance or mast cell activation disorder. They act by blocking histamine that already exists from binding to histamine receptors & releasing more histamine. Antihistamines can be helpful, but is often used in conjunction with other medications.
Mast Cell Stabilizers
Mast cell stabilizer drugs are a class of medications that work by preventing the release of endogenous histamine and other similar mediators from mast cells. They do so by ‘strengthening’ the cell membrane of mast cells, preventing the release of histamine by degranulation. The main drugs used to stabilize mast cells are called Cromyln and Ketofein.
There are also some food chemicals that have promising mast cell stabilization effects including vitamin C and quercetin, a polyphenol from plants. However, the research for these products in the prevention of histamine toxicity isn’t very strong and is mostly based on theory at this point. Recommended doses also haven’t been established. It is best to discuss these options with your healthcare team before purchasing them over the counter for the management of histamine intolerance.
Bottom Line about Histamine Intolerance
Histamine intolerance is complex, and it can take a lot of investigation to understand your unique histamine tolerance threshold. It is HIGHLY recommended to work with a dietitian experienced in food intolerance to learn about histamine contents of foods and to ensure you are well-nourished.
If the symptoms of histamine intolerance match symptoms you experience, talk to your health care team before restricting your diet, especially since the symptoms of histamine intolerance are non-specific and could actually be related to something else. We want to be sure it ACTUALLY makes sense to eat in such a restricted way prior to eliminating foods.