Food intolerances vs allergies: Debunking the myths

With many of the symptoms of food allergies and sensitivities overlapping, it can be difficult to determine what your body is trying to tell you. So, let’s explore the top five myths about food intolerances and allergies and shed some light on how you can find your way back to food freedom.

A food allergy is the same as an “intolerance” or “sensitivity”


A food allergy is a potentially life-threatening event in which the immune system attacks a food it believes to be a pathogen. Most of the time, a food allergy is related to a protein component of food and will occur within 1-10 seconds of being exposed, requiring serious medical intervention to undo. 

Food sensitivity or intolerance are describing the same experience. Intolerance or sensitivity is when there is a link between consuming food and having an unwanted negative experience such as gas, bloating, diarrhoea, rashes, headaches, insomnia, hyperactivity or brain fog. You may hear someone express that they avoid a certain food because it generates a symptom. 

Histamine intolerance is all about histamine


Histamine intolerance is frequently related to a problem with digesting protein, which is necessary for producing the enzyme responsible for controlling histamine levels in the digestive tract.

Histamine intolerance is an umbrella term that describes the state of a person who is producing and consuming histamine while experiencing a reduction in the ability to metabolise that histamine at the same time. This leads to the experience of allergy-type symptoms such as rashes, wheezing and hives that occur after consuming histamine containing or triggering food, drink or ingredients. The symptoms of histamine intolerance could be driven by different underlying factors. Like IBS, it is more a collection of digestive irregularities that increase histamine production in the body, rather than an intolerance in and of itself. 

The role of histamine

The role of histamine is to produce inflammation as part of the body’s natural immune response. Every time we sneeze, cough or swell, we are experiencing histamine’s effects. With an allergy, histamine is triggered by an allergen such as dust or pollen, which is why we use antihistamines to reduce our reactivity.  

Histamine levels rise and fall in many ways, but for the purpose of untangling histamine intolerance, there are three main concepts at work. The first is that some foods contain histamine. High histamine foods tend to be foods that have been processed to have a longer life – preserved foods such as jams, fermented food, cheese, red wine, cured meats, tinned foods and dried beans. Secondly, the digestive tract and kidneys produce an enzyme called Diamine Oxidase (DAO), and this enzyme breaks down the histamine produced. 

Thirdly, 80% of histamine intolerance sufferers are middle-aged, a time of life when the body’s natural digestive processes are slowing down, particularly the production of stomach acid and DAO. DAO production in the digestive tract relies on the effective digestion of protein, which is digested by stomach acid and protease enzymes. Protease enzymes are released when stomach acid is of a sufficient amount and strength. Therefore, addressing protein digestion can be beneficial for those suffering from histamine intolerance, as it will support DAO production. A broad-spectrum digestive enzyme blend, with a high amount of protease enzymes (for example, Digest GoldTM from Enzymedica), is a good first step toward reducing a build-up of histamine in the digestive tract.

Intolerance reactions to food increase histamine production due to their inflammatory effect on the gut lining, which is why a digestive enzyme such as DPP-IV address allergenic and intolerance molecules (e.g. gluten or xylanase for phenols) can reduce the severity of histamine intolerance reactions. In addition to supporting natural DAO production, stomach acid and protease enzymes can also break down allergenic proteins such as gluten and casein, as well as other digestive enzymes that are responsible for protecting the gut from intolerance generating molecules such as milk, corn and soy.

Enzymes also require nutrients to function, while protein digestion supports the absorption of calcium, iron and vitamins B6 and B12, which are all important for DAO to work well and degrade histamine properly. Also helpful in reducing histamine production are zinc, copper and vitamin C, which should all be available through a healthy diet. Reduced absorption due to reduced digestive capacity could affect how much of the nutrients we’re eating make it into our body. 

DAO is produced by the intestinal mucosa, an important immune barrier that lines the digestive tract. Any irritation of this mucosa, such as irritation from food intolerances, IBS or IBD will affect DAO production. This, in turn, increases the level of circulating histamine in the body, leading to the classic intolerance symptoms of rashes, migraines, hives and fatigue. For this reason, any actions that assist with a healthy gut, particularly the health of the mucosal barrier, will have the side effect of reducing histamine production and increasing DAO production. 

A healthy gut barrier also needs healthy anti-inflammatory lipids, or ‘good fats’ as they are more commonly referred to in order to heal. Omega-3 fatty acids, such as those found in oily fish, flaxseeds, olives and avocados will reduce inflammation overall. Any negative experiences that relate to consuming dietary fat such as gas, flatulence, bloating, indigestion or heartburn should be supported by a lipase containing enzyme to support fat digestion. Poorly digested dietary fat can contribute to the production of a molecule called lipopolysaccharides (LPS), which generate inflammation. Lipase is an enzyme that will facilitate fat digestion when taken with food and will digest lipopolysaccharides when taken on an empty stomach.

This intestinal mucosa is an important feature of histamine regulation through its relationship with healthy and diverse gut bacteria populations. A gut with unbalanced bacteria will produce histamine. Butyrate is a fatty acid produced by healthy gut bacteria, and butyrate-producing gut bacteria need a healthy mucosal barrier in which to thrive. Considering a gut healing programme is another good step to take to reduce histamine build-up and the intolerance symptoms that may follow.

In conclusion, we can see that histamine intolerance is the product of multiple digestive dysfunctions which when corrected, can dramatically reduce histamine production and its associated symptoms. 

Salicylates can be difficult to digest


Salicylates are molecules that belong to a category of plant chemicals called phenols. Phenols are a group of molecules that have a unique structure when viewed under a microscope. Due to this structure, phenols can be difficult for some people to digest, leading to an intolerance reaction. Phenols are also used in food manufacturing as additives and colourants. 

Salicylates are a phenol that can be responsible for a group of sensitivity reactions, particularly those relating to mind and mood. Famous for being the precursor to aspirin, salicylate sensitivity is due to a genetic absence of the digestive enzyme that is responsible for degrading phenols in foods. Foods that contain naturally occurring salicylates tend to be healthy foods such as nutrient-dense fruits and vegetables.

Salicylate sensitivity can go unidentified for many years, and sufferers are more likely to suspect the more typical intolerance foods such as gluten or dairy as being the source of their intolerance reactions. A person suffering a salicylate sensitivity may naturally avoid the foods that trigger headaches, migraines and rashes, for example, peaches, or apples. But sometimes, the symptom of phenol intolerance can also appear as a more pleasant reaction. Giggling and hyperactivity can be a sensitivity reaction, as well as behaviours such as stimming, repetitive behaviour, gastrointestinal upset, and difficulties concentrating.

For those with a salicylate intolerance, total avoidance of foods that contain them is often recommended. However, this isn’t without the risk of nutrient deficiency due to the nutrient density of phenolic foods. A different way of approaching salicylate sensitivity is to avoid foods that contain colourants and additives, eliminate salicylate-containing foods for 48 hours, and then re-introduce foods with the lowest salicylate content along with a digestive enzyme that helps with the breakdown of phenols until a tolerance limit is found.  

The primary enzyme responsible for breaking down phenols in the body is called phenol sulfotransferase and is genetically missing for some individuals. To assist with the breakdown of phenols, choose an enzyme that contains xylanase (such as Digest Spectrum™, a specific enzyme for phenol digestion). Combining this with enzymes that address plant material overall such as amylases, hemicellulases, and cellulase will also be beneficial. 

It is possible to eliminate food intolerances


Food intolerance reactions are usually due to one or more missing digestive enzymes. Children with food intolerances tend to grow out of them as their digestive system matures and develops the enzymes they need. Adults over the age of 20 may find that they acquire intolerances due to their natural production of digestive enzymes being disrupted by food, drink, medication or their lifestyle. In both child and adult cases, the root cause of most food intolerances is insufficiency or lack of specific digestive enzymes. 

To understand the enzyme-food-intolerance link, it is important to see food in the way that the body does. It’s normal to think of food as being a whole entity. Let us take dairy milk as an example. To the body, milk is not a complete whole food, but a liquid structure made up of multiple molecules including fats, proteins, sugars, casein, lactose, nutrients and minerals. Each of the molecules in milk must be broken down differently, via digestion, in order for the body to be able to utilise all the nutrients it contains. This digestive work is completed by various digestive enzymes. Digestive enzymes match the specific molecules that they digest, much like a lock and a key. When an enzyme for a specific molecule is missing, a food intolerance reaction takes place. 

For example, lactose intolerance is due to the absence of an enzyme called lactase which breaks down the lactose molecules in milk. Just as milk is created from many component parts, so is the rest of the food we eat. Each molecule in each food item requires different digestive enzymes to successfully break it down to prevent a food intolerance reaction. 

Lactose intolerance and milk allergies are the same


Allergies and intolerances are quite different. A milk allergy is when the immune system mistakes casein, the molecules of milk protein, as pathogens and attacks them. That attack can generate life-threatening systemic inflammation throughout the body at a fast pace.

Food intolerances can feel extremely uncomfortable but are not life-threatening, as food allergies can be. Lactose intolerance is not an immune reaction, but a digestive reaction. 

Lactose is a disaccharide (two-sugars) that consists of galactose and glucose molecules bonded together by a glycosidic link. Lactose makes up around 2-8% of the solids in dairy milk. Lactose intolerance occurs when a person lacks the digestive enzyme called lactase, which is required to break down the lactose molecules (the disaccharides) in the milk. When lactase is missing from the digestive system, lactose reaches the bowel in its full disaccharide form, rather than the individual sugar molecules it should be in if digested effectively. In its full form, the lactose immediately begins to attract water and gas, quickly triggering a fast, loose bowel movement. 

We’re all individuals, and while there are common intolerances and sensitivities, we often require tailored advice and support to truly understand what our bodies need, and how to treat any discomfort or food sensitivity-related symptoms. 

On Nutritionist Resource, we have over 500 qualified professionals located across the UK, who are ready to help you live your best life. If you’re looking for support, simply browse profiles until you find a nutritionist you resonate with, and send them an email.

If you found this useful, you may be interested in reading, ‘What you need to know about digestive enzymes and nutrition’, also by Leyla Moudden, or ‘Why do I react to histamine, sulphites and salicylate?’ by nutritionist Margaret Moss.

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Written by Leyla Moudden
Leyla Moudden is a Naturopath and Educator for Enzymedica UK.
Written by Leyla Moudden
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