Food Intolerances vs. Food Allergy - The Overview

What will you learn in this guide?

1. What's behind it?
2. Symptoms of food intolerance vs. allergy
3. Measures for recognition
4. The most known food intolerances
5. The most common food allergies
6. Pseudoallergy or real allergy?
7. Food supplement against intolerances and allergies

1. What's behind it?

Almost 20% of all Germans suffer from at least one allergy [1]. In short, an allergy, whether it is directed against food or pollen, is based on a malfunction of the immune system. The body perceives certain proteins, for example from peanuts, as a threat and initiates an immune reaction. Foods that are actually harmless can thus quickly become a danger!

A survey shows that 23% of people in Germany are affected [2]. 

In most cases, food intolerance is due to the absence or deficiency of certain enzymes responsible for digestion. Often, there is also an insufficient absorption capacity (limited absorption capacity) of certain food components. 

Therefore, in case of intolerance, there is a "dose-response threshold"! This means that the body can usually still  tolerate small amounts of the food, but as more is ingested, the symptoms become worse. In the case of an allergy, even small traces of food can cause severe reactions [3].

2. Symptoms of food intolerance vs. allergy

The symptoms of a food intolerance can partly overlap with those of an allergy. In the case of an intolerance, however, redness and swelling do not occur directly after eating the food. 

As a rule, it is mainly various digestive complaints that become noticeable. Among other things, a bloated belly, abdominal pain, diarrhea, sluggishness, concentration problems, headaches and palpitations occur after eating. Even small amounts of the food can trigger the symptoms.

In the case of an allergy, the first effects usually occur even with small amounts of the allergen. Swelling and redness to severe rashes immediately after eating the food are not uncommon. 

Because our esophagus and trachea are so close together, respiratory distress can occur so quickly. Headaches and fatigue are less common, but also possible. In the worst case, anaphylactic shock (life-threatening condition) can occur [4].

3. Measures for recognition

If you suspect the presence of an intolerance or allergy, keeping a food diary is sensible. This enables you to trace back the foods that are the cause of the symptoms. To be really sure, consume the respective food alone and do not mix it with other food if there is a concrete suspicion.

Start with a little bit of food and slowly increase to see if it causes any problems. If you have a general idea from the food diary, see a doctor to find out the specific reasons. For example, problems that occur when drinking milk may be due to a lactose intolerance or a milk allergy. To initiate the right treatment, it must be clarified in advance what the diagnosis is.

If an allergy is suspected, a doctor should also be consulted. The doctor can carry out various tests to determine which food you are allergic to. For example, various allergy solutions are rubbed, pricked (prick test) or injected to the skin. In addition, so-called provocation tests can be carried out, in which the allergen is administered under medical observation.

4. The most known food intolerances

4.1 - Lactose intolerance

About 15% of all Germans [5] and 75% of the world population [6] are affected by lactose intolerance. This means they have a low or absent production of the enzyme lactase. 

This enzyme breaks down the milk sugar lactose into glucose and galactose. These sugars are then absorbed in the small intestine for further energy production. If no or too little lactase is produced by the body, this is called lactose intolerance.

In case of an intolerance, lactose enters the small intestine and has an osmotic effect. It binds water to itself and causes diarrhea.

Alternatively, bacteria in the intestine ferment it, forming gases that cause flatulence and abdominal pain. If you still want to consume dairy products, you can either use lactose-free milk, long-matured cheese or the enzyme lactase. In case of a milk allergy, renunciation is unfortunately the only way!

The solution: milk alternatives

If the milk intolerance is due to lactose intolerance, it is possible to use lactose-free milk or the enzyme lactase. If there reason for milk intolerance is not lactose intolerance, there are many vegetable alternatives. Oat milk, almond milk, rice milk and soy milk are the most common alternatives. You can prepare them yourself or buy them ready-made.

4.2 - Fructose intolerance

Fructose, commonly known as fruit sugar, appears in two forms: as fructose itself or as sucrose (household sugar). Sucrose consists of one molecule of fructose and one molecule of glucose and is broken down into both molecules in the small intestine.

In the case of intolerance, the problem is that the fructose cannot be absorbed by the small intestine, or only to a limited extent. The fructose enters the small intestine and can cause various symtoms in the gastrointestonal tract. These include flatulence, abdominal pain, diarrhea and stomach cramps. This food intolerance has different gradations and often goes unnoticed for a long time!

4.3 - Sucrose intolerance 

Sucrose requires the enzyme saccharase to be broken down and then absorbed by the small intestine. If this enzyme is missing, the sucrose also reaches the small intestine. There it can cause symptoms similar to lactose intolerance.

4.4 - Sorbitol intolerance

The sugar alcohol sorbitol occurs naturally in fruits and is used as a sugar substitute. The absorption of sorbitol into the small intestine may also be impaired. The symptoms are similar to those of lactose, fructose and sucrose intolerance [7].

The solution: sugar alternatives
Nowadays, there are many options for people who cannot tolerate fructose or table sugar but still want to sweeten their food.

  • Xylitol

Xylitol is also known as birch sugar. It is a sugar alcohol and is found in plants, such as birch, and in various fruits and even naturally in the human body. Its sweetening power is the same as sugar, but its calorie content is about 40% less

In addition, xylitol affects blood sugar and insulin levels less than table sugar. In addition, it cannot be metabolized by the bacteria that cause tooth decay [8].

  • Erythritol
Like xylitol, erythritol belongs to the sugar alcohols and occurs naturally in fruit. Its sweetening power is about 50-70% of the sweetening power of household sugar. Unlike sugar, it has no direct influence on blood sugar levels. 
Erythritol is usually obtained by fermentation for use as a sweetener [9].
Moreover, erythritol has almost no calories (20 kcal/100g), as it cannot be used for energy production. Instead, it is excreted through the kidneys. Like xylitol, erythritol cannot cause tooth decay.
  • Rice syrup
Originally from Japan, rice syrup is a sweetener made from rice flour with the addition of water and natural enzymes and boiled down to a syrup. Its advantage is that it naturally contains no fructose, but glucose (simple sugar), maltose (double sugar) and oligosaccharides (multiple sugars). In addition, it also contains minerals. 
In terms of taste, rice syrup is less sweet than sugar and often has a slight caramel note. Meanwhile, it is also available as a powder. It can be a good substitute for all those who avoid fructose [10].
  • Stevia

This unusual plant from South America has been approved as a sweetener in the EU since 2011. It contains stevioglycosides responsible for the sweetness, which are 200-300 times sweeter than sugar. Since stevia is not metabolized, it has 0 calories and does not affect blood sugar levels. As a result, caries bacteria cannot do anything with it. 

Stevia is available in leaf form, as an extract or as pure stevioglycosides. Since it is heat-stable up to a temperature of 200 °C, stevia is suitable for baking. However, this sweetening alternative has its own flavour, which can become bitter in large quantities[11].

4.5 - Gluten intolerance (celiac disease)

People who suffer from gluten intolerance can experience severe symptoms even from small amounts of the gluten protein or its component gliadin. Gluten is contained in wheat, spelt, rye, barley, but also in original varieties such as kamut, emmer and einkorn.

Celiac disease is an inflammatory bowel disease. Even minimal amounts of gluten can lead to an immunological reaction in the small intestine and damage the intestinal mucosa. In addition to digestive complaints, the most common symptoms include general fatigue, headaches and fatigue

If the intestine is exposed to gluten too often, the intestinal mucosa can be severely damaged by chronic inflammatory processes that food components can no longer be properly absorbed through the intestinal mucosa into the blood. This damage can cause severe deficiency symptoms despite a nutrient-rich diet. In this case, the only way is to completely avoid foods containing gluten. 

There are now many products labeled gluten-free. These products (e.g. made from corn or rice) are processed exclusively in production facilities where no gluten-containing grain enters [12].

In some cases, there is also an intolerance to wheat. In these cases, more original cereals such as spelt, kamut, emmer and einkorn can usually be tolerated well. About 1% of all people are affected by celiac disease, although the typical symptoms are noticeable in only 10 to 20% [13]. Celiac disease can also be present without abdominal pain and nausea after eating.

The solution: wheat alternatives and gluten-free flours
Who does not tolerate wheat has nowadays many alternatives to not have to give up bread, pasta, cookies and cakes. The following flours are are gluten-free: Oats, buckwheat, rice, corn, teff (millet), quinoa, amaranth. Nut flours such as almond flour or flours from legumes such as chickpea flour can also be used. To compensate for the lack of gluten properties of wheat flour, there are many alternatives such as chia seeds, flaxseed meal or psyllium husks.

Not only flours, but also many other products are avaiable gluten-free. For example, there are gluten-free noddles made from rice, corn, buckwheat, lentil or pea noodles. Even ready-made cakes and cookies, as well as baking mixes, are now available as gluten-free products.

4.6 - Histamine intolerance

Histamine acts as a hormone and neurotransmitter in the human organism. It is produced when food ripens. However, it can also be found in some fresh foods. 

If the body cannot produce enough enzymes to break down the histamine from food, histamine intolerance is present. After a meal, there is often redness of the skin, rashes, wheals, itching, a runny or stuffy nose, nausea, gastrointestinal problems, diarrhea, dizziness, headaches (including migraines), circulatory problems, and palpitations [14]. As the histamine content in foods increases with storage time, it is recommended that affected individuals always consume fresh foods whenever possible. Nevertheless, a special diet must be followed and some foods must be completely avoided.

Foods rich in histamine include cheese, tomatoes, nuts, citrus fruits, pork meat and many more [14]. Alcoholic beverages also contain histamine. However, the amount is usually so small that people with histamine intolerance often do not experience any problems. The alcoholic beverage with the highest histamine content is red wine [15].

5. The most common food allergies

Almost 20% of all Germans suffer from at least one allergy [16]. These can basically be triggered by certain foods or substances.

With regard to food, there are 14 foods that are the most common allergens. These are eggs, peanuts, fish, gluten, nuts, soy, lupins, sesame seeds, mustard, cow's milk, sulfur dioxide, and sulfites [17].

Jewelry (nickel), textiles, disinfectants, animals, latex products, mediactions, and many other substances can also cause allergic reactions [18].

Nut allergy

One of the most common food allergies is nut allergy. People who react to this allergen do not necessarily experience symptoms for all types of nuts.

The name nut does not always mean that it is a nut from a botanical point of view. Often, nuts, stone fruits and legumes also trigger the same reactions because they are very similar to nuts. Therefore, we do not go into botanical terms further in the article, but will refer to nuts colloquially.

According to current studies, about 1.4% of the European population is affected by nut allergy [19]. The most common allergies are peanut allergies. Hazelnuts, walnuts, almonds, cashews, pecans, macadamia nuts, Brazil nuts and pistachios are also frequently responsible for allergic reactions.

Depending on the severity of the allergy, it must be decided whether it is sufficient to avoid the nuts or all products that may contain traces of nuts. It should also be considered that the oils of the respective nuts can also cause allergic reactions [20].

The solution: nut alternatives
In case of nut allergy, there are also alternatives for consuming healthy fats and proteins. Seeds and kernels like flaxseeds, chia seeds, sesame seeds, poppy seeds, sunflower seeds or pumpkin seeds have a similar composition. 

From a botanical point of view, hemp seeds are also nuts. But they possess a a lower allergen potential and also contain abundant healthy fats, proteins and minerals. 

Although both coconut and tiger nut have the word "nut" in their names, botanically they are not. Most nut allergy sufferers tolerate them well [21]. If the alternatives are not suitable, olives and avocados can also serve as excellent sources of healthy fats.

Spice allergy

During Christmas time, spices such as cinnamon, vanilla, cardamom, anise, etc. are used to add flavour. However, it's not just the nuts in the pastries that can cause issues for people with allergies.

People who are allergic to certain pollens often also have a so-called cross-allergy. For example, birch pollen contains a protein that protects the pollen from bacteria. This protein is also present in foods such as apples, carrots and nuts [22]. 

A lot of people with pollen allergies also show allergic reactions to this protein. 70% of  those with birch pollen allergies experience cross-allergies.

Certain spices can cause a cross-reaction depending on the type of pollen allergy as well. The classic gingerbread spice as well as curry powder contain a variety of allergens overlapping with those from pollen. Therefore, we advise caution for pollen allergy sufferers! 

If you have a pollen allergy, try only a small amount of gingerbread first. See if it causes nausea or other reactions [23].

6. Pseudoallergy or real allergy?

When allergy symptoms occur, it can also be a so-called pseudoallergy. In this case, the immune system reacts differently than in a real allergy and also does not form antibodies. Therefore, no correct diagnosis can be made via the conventional route (antibody blood test). 

Only by adding and omitting certain substances can the pseudoallergy be determined. In addition to many drugs, food additives are among the main triggers. Therefore, the best way to avoid such reactions is a natural diet with as few additives as possible [24].

7. Food supplement against intolerances and allergies

Dietary supplements support many areas of life. The question now arises whether they also help with food intolerances and allergies. The answer is simple: yes.

Histamine plays a central role in the occurrence of allergic reactions. Fortunately, there are some nutrients that have been shown in various studies to lower histamine levels!

Quercetin - For allergy sufferers

Quercetin is a naturally occurring secondary plant compound from the flavonoid group. This promising nutrient with antioxidant activity is gaining increasing attention for the treatment of allergies. Many doctors see quercetin as a promising candidate for the natural relief of allergy symptoms.

Study proves the effectiveness

In a Japanese study, Quercetin significantly inhibited antigen-stimulated histamine release. The effect of quercetin was almost twice as strong as that of sodium cromoglicate at the same concentration.  Sodium cromoglicate is a conventional anti-hay fever medication. 

This suggests that people suffering from swollen mucous membranes may benefit from quercetin [25]. 

According to various studies, quercetin has a positive effect on the stabilization of the defense cells. These in turn are responsible for the release if histamine. The release of substances responsible for allergic reactions is reduced. This reduces both the symptoms and the allergic reaction itself. 

To achieve the best effect, preventive quercetin supplementation is recommended two weeks before exposure to allergens [26,27].

Vitamin C - The all-rounder

An adequate supply of Vitamin C is necessary for a normally functioning immune system [28]. 
It is therefore recommended not to let an undersupply occur in the first place. In some cases, more vitamin C than usual can be consumed. This can be the case with physical and psychological stress, smoking or increased strain on the immune system. In addition, it has been shown that an extra portion can also make a valuable contribution to allergy sufferers.
Researchers found that the concentration of histamine in the blood increases exponentially when blood plasma vitamin C-levels are low. A balanced vitamin C supply is usually 0.5 to 1.5 mg per 100 ml [29]. If the ascorbic acid level is below 0.7 mg per 100 ml, the blood histamine level rises. This in turn promotes allergies [30].

A study at the University of Erlangen showed that vitamin C supply influences the serum histamine concentration. Patients suffering from allergies or infectious diseases were administered a high dose of vitamin C intravenously. Subsequently, a significant decrease in histamine concentration was subsequently observed. The decrease in patients with allergic diseases was even higher than in patients with infectious diseases [31].

Vitamin D - The sunshine vitamin

An adequate supply of Vitamin D3 in the body is essential for the immune system to function properly. 

Vitamin D serves as a messenger for controlling our immune system. Our human immune cells such as B cells, T cells and antigen-presenting cells all have vitamin D3 receptors. It is not for nothing that vitamin D can influence the innate adaptation of our immune response. 

The vitamin protects the body from self-attacks, as it cannot distinguish between its own and foreign cells. It is therefore also known as an immunomodulator [32,33,34]. Deficiency of vitamin D is associated with increased autoimmunity and susceptibility to infection [35,36]. 

It is certain that UVB radiation in winter is too low to produce sufficient vitamin D amounts [37]. In Germany, about 60% of the population is deficient in vitamin D according to international criteria [38]. Many physicians even advocate that at least values between 40- 50 ng/ml should be achieved in the blood serum [39].

The trace element zinc

The immune system is influenced by the essential trace element Zinc. The relationship between zinc and the immune system is complex, as it influences it in various ways. It acts as an important cofactor in more than 300 enzymes.

The enzyme DAO (diamine oxidase) is an enzyme that is involved in the breakdown of histamine in the body [40,41]. 

It is therefore no wonder that many doctors recommend that allergy sufferers have their zinc status checked. A zinc deficiency can severely impair the resistance of the immune system. Even a minor deficiency can have an impact on the immune system. Increased zinc intake is therefore recommended in cases of acute deficiency [42,43,44,45].

32% of men and 21% of women do not reach the recommended D-A-CH reference values for daily zinc intake. In the 65 to 80 age group, as many as 44% of men and 27% of women are affected [46]. Brittle nails with white spots and grooves, for example, are a strong indication of a deficiency [47]. 

Anyone who suspects that their allergy symptoms are related to a zinc deficiency should have their zinc levels checked. This can prevent a deficiency of the essential trace element.

Read more now!

1) Langen U et al, Häufigkeit allergischer Erkrankungen in Deutschland, Robert Koch-Institut, Mai 2013
10) Masood, S., Ashraf, M., & Ahmad, I. (2022). Replacement of table sugar with clarified rice syrup in beverages.
11) Saß, M. (2010). Anwendung von Stevia in Getränken–Herausforderungen und Lösungen. Journal für Verbraucherschutz und Lebensmittelsicherheit, 5, 231-235.
14) Maintz, L., Bieber, T., & Novak, N. (2006). Die verschiedenen Gesichter der Histaminintoleranz. Dtsch Arztebl, 103(51-52), 3477-83.
16) Langen U et al, Häufigkeit allergischer Erkrankungen in Deutschland, Robert Koch-Institut, Mai 2013
32) Femke Baeke, Tatiana Takiishi, Hannelie Korf, Conny Gysemans, Chantal Mathieu, Vitamin D: modulator of the immune system, Current Opinion in Pharmacology, Volume 10, Issue 4, August 2010, Pages 482-496, ISSN 1471-489
33) Kamen, Diane L.; TANGPRICHA, Vin. Vitamin D and molecular actions on the immune system: modulation of innate and autoimmunity. Journal of molecular medicine, 2010, 88. Jg., Nr. 5, S. 441-450.
34) Maria C. Borges, Lígia A. Martini, Marcelo M. Rogero, Current perspectives on vitamin D, immune system, and chronic diseases, Nutrition, Volume 27, Issue 4, April 2011, Pages 399-404, ISSN 0899-9007
39) Power, M. L., & Dittus, W. P. (2017). Vitamin D status in wild toque macaques (Macaca sinica) in Sri Lanka. American Journal of Primatology, 79(6). doi:10.1002/ajp.22655
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