Food intolerances vs. food allergies – the overview

What will you learn in this guide?

1. Allergy and intolerance - what's behind it?
2. Symptoms of food intolerance vs. allergy
3. Measures to detect intolerances and allergies
4. The most common food intolerances
5. The most common food allergies
6. Pseudo allergy or real allergy?
7. Dietary supplements against intolerances and allergies

1. Allergy and intolerance - what's behind it?

Almost 20% of all Germans suffer from at least one allergy [1]. 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. Actually harmless foods can quickly become dangerous!

According to a survey commissioned by SPIEGEL ONLINE, 23% of people in Germany suffer from food intolerances [2]. But what is the difference between allergies and intolerances?

While allergies are immune reactions, food intolerances are caused by a lack of certain enzymes that are responsible for digestion. Often there is also a low absorption capacity (limited ability to absorb) of certain food components. Therefore, there is a "dose-effect threshold" in the case of an intolerance!

Small amounts of the food are usually tolerated. However, the higher the amount consumed, the worse the symptoms. In the case of an allergy, however, even small traces of the food can cause severe reactions [3].

2. Symptoms of food intolerance vs. allergy

The symptoms of a food intolerance can partially overlap with those of an allergy. However, with an intolerance, redness and swelling do not occur immediately after eating the food.

In general, intolerance is primarily caused by various digestive problems . After eating, symptoms that can occur include bloating, stomach pain, diarrhea, lethargy, difficulty concentrating, headaches and heart palpitations .

In the case of an allergy, the first effects usually occur with small amounts of the allergen. Swelling and redness , as well as severe rashes, are not uncommon immediately after eating the food. Since our esophagus and windpipe are close together, shortness of breath can quickly develop. Allergic asthma can also occur.

Headaches and fatigue are less common, but also possible. In the worst case, anaphylactic shock can occur [4]. This allergic shock can even be life-threatening.

3. Measures to detect intolerances and allergies

If you suspect that you have an intolerance, it is a good idea to keep a food diary . This will enable you to trace back which foods are causing your symptoms. If you have a specific suspicion, you should eat the food alone and not mix it with other foods. This will help you identify which food is responsible for the reaction.

It is important to start with small amounts. Then you can should be increased gradually to determine which amount leads to intolerance.

If you have already gained an overview through your food diary, you should definitely see a doctor to find out the exact causes. Problems that occur when consuming milk could be due to lactose intolerance, for example. In order to initiate the right treatment , the diagnosis must be clarified in advance.

If you suspect an allergy , you should also see a doctor . He or she can carry out various tests to determine which food you are allergic to. For example, various allergy solutions are rubbed, pricked or injected into the skin. So-called provocation tests can also be carried out, in which the allergen is administered under medical supervision.

4. The most common 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 is caused by insufficient or non-existent production of the enzyme lactase . This enzyme breaks down the milk sugar lactose (double sugar) into glucose and galactose (both simple sugars) to be absorbed in the small intestine for further energy production.

In the case of intolerance, the lactose enters the small intestine and has an osmotic effect. There it binds water and causes diarrhea. It can also be fermented by bacteria in the intestine, producing gases. This causes flatulence and abdominal pain.

The solution: milk alternatives

If you are lactose intolerant and still want to consume dairy products, you can either use lactose-free milk, long-matured cheese or the enzyme lactase.

If you have a milk allergy, the only solution is to avoid dairy products. The good news is that there are many plant-based alternatives.

Oat milk, almond milk, rice milk and soy milk are the most common alternatives. You can make these yourself or buy them ready-made. Vegan yogurt and cheese alternatives are also becoming increasingly popular.

4.2 - Fructose intolerance

Fructose , commonly known as fruit sugar, appears in two forms: as fructose itself or as sucrose (table 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 small intestine cannot absorb the fructose or only absorbs it in insufficient quantities. The fructose enters the small intestine and can cause various complaints in the gastrointestinal tract. These include flatulence, abdominal pain, diarrhea and stomach cramps . This intolerance has different degrees and often goes unnoticed for a long time!

4.3 - Sucrose intolerance (sugar intolerance)

Sucrose (a disaccharide) requires the enzyme sucrase to break down and then be absorbed by the small intestine. If this enzyme is missing, the sucrose also ends up in the small intestine. There it can cause symptoms similar to lactose intolerance.

4.4 - Sorbitol intolerance

The sugar alcohol sorbitol occurs naturally in fruit and is used as a sugar substitute. Sorbitol can also be absorbed into the small intestine in a way that is impaired. The symptoms are similar to those of lactose, fructose and sucrose intolerance [7].

The solution: sugar alternatives
There are now 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 trees and in various fruits. Its sweetening power is the same as that of sugar, but its calorie content is about 40% lower . In addition, xylitol has less of an effect on insulin levels than table sugar. In addition, unlike conventional sugar, xylitol does not cause tooth decay [8].

• Erythritol

• Rice syrup

Rice syrup is a sweetener that originally comes from Japan. It is made from rice flour with the addition of water and natural enzymes and boiled down to a syrup.

Its advantage is that it does not naturally contain fructose. Instead, it does contain glucose (simple sugar), maltose (double sugar) and oligosaccharides (multiple sugars). It also contains minerals. Rice syrup tastes less sweet than sugar and often has a slight caramel note . It is now also available as a powder. It can be used as a substitute for people who avoid fructose [10].

• Stevia

This plant from South America has been approved as a sweetener in the EU since 2011. It contains steviol glycosides, which are responsible for the sweetness and are 200-300 times sweeter than sugar . Since stevia is not metabolized, it has no calories and does not affect blood sugar levels. Stevia also offers no substrate for caries bacteria, which means that this sweetening alternative does not cause caries. Stevia is available in leaf form, as an extract or as pure steviol glycosides. Since it is heat-stable up to a temperature of 200 °C, stevia is very suitable for baking. However, this sweetening alternative has its own taste, which can turn bitter if consumed in large quantities [11].

4.5 - Gluten intolerance (celiac disease)

There are many alternatives nowadays so that you don't have to do without bread, pasta, biscuits and cakes. The following flours are gluten-free: oats, buckwheat, rice, corn, teff (millet), quinoa and amaranth . Nut flours such as almond flour or flours made from pulses - such as chickpea flour -  can be used. To compensate for the lack of adhesive properties of wheat flour, there are many alternatives such as chia seeds, linseed flour or psyllium husks.

Not only flour, but also many other products are now available gluten-free. For example, there are gluten-free pastas such as rice, corn, buckwheat, lentil or pea pasta . Ready-made cakes, biscuits and baking mixes are now also available as gluten-free alternatives.

4.6 - Histamine intolerance

Histamine acts as a hormone and neurotransmitter in the human organism. The substance is mainly 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 , skin redness, rashes, itching, a runny or stuffy nose, nausea, vomiting, diarrhea, problems with the cardiovascular system, headaches (including migraines), circulatory problems and heart palpitations often occur [14]. Since the histamine content in food increases with storage time, it is recommended to eat the freshest food possible. Nevertheless, a special diet must be followed and some foods must be avoided.

Foods rich in histamine include chocolate, tomatoes, nuts, citrus fruits and pork [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]. This can be triggered by certain foods or substances.

There are 14 foods that are the most common allergens. These are eggs, peanuts, fish, crustaceans, cereals containing gluten, nuts, mollusks, soy, lupins, sesame seeds, mustard, celery, milk and lactose, as well as sulfur dioxide and sulfites [17].

Jewelry (nickel), textiles, disinfectants, animals, latex products, medications and many other substances can also trigger allergies [18].

Nut allergy

One of the most common food allergies is nut allergy. However, people who react to this allergen do not necessarily have to be allergic to all types of nuts.

The colloquial term "nut" does not always mean that it is also a nut from a botanical point of view. Nuts, stone fruits and legumes can also trigger these reactions because they are very similar to nuts. Therefore, we will not go into botanical terms any further below, but will speak colloquially of nuts.

According to current studies, around 1.4% of the European population is affected by a nut allergy [19]. The most common allergy is to the legume peanut. 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 themselves. It may also be necessary to avoid products that may contain traces of nuts . It should also be considered that the oils of the nuts in question can cause allergic reactions [20].

The solution: nut alternatives
However, in the case of a nut allergy, there are alternatives for consuming healthy fats and proteins. Seeds such as linseed, chia seeds, poppy seeds, sunflower seeds or pumpkin seeds are very similar in their composition.

Botanically speaking, hemp seeds are also nuts. However, they have a lower allergenic potential and are rich in good fats, proteins and minerals.

Coconuts and tiger nuts have the word “nut” in their name, but are not botanically classified as such. They are well tolerated by most allergy sufferers [21].

Olives and avocados are also good sources of fat. These can serve as alternatives to nuts to ensure you get enough fat and maintain a healthy diet.

Spice allergy

Especially at Christmas time, spices such as cinnamon, vanilla, cardamom, anise and the like are used to enhance food, but these can be a problem for some allergy sufferers .

People who are allergic to certain pollen can often 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]. If the body reacts allergically to it, as is the case with 70% of birch pollen allergy sufferers, this is referred to as a cross allergy.

Unfortunately, this can also apply to certain spices, which can cause a cross-reaction depending on the type of pollen allergy. The classic gingerbread spice (or curry, for example) can cause allergic symptoms .

People who are allergic to pollen and are unsure whether they can tolerate gingerbread spices should start with small amounts. This can help avoid nausea and severe reactions [23].

6. Pseudo allergy or real allergy?

7. Dietary supplements against intolerances and allergies

Dietary supplements can help in many areas of life. Now the question arises whether they can also help with 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, according to current research, can lower histamine levels !

Quercetin – For allergy sufferers

Quercetin is a naturally occurring phytochemical from the group of flavonoids. This promising nutrient with antioxidant effects is gaining increasing attention for the treatment of allergies. Many doctors see quercetin as a promising candidate for natural relief of allergy symptoms.

Study proves 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 drug.

Therefore, it is reasonable to assume that people suffering from swollen mucous membranes can benefit from quercetin [25].

One thing is certain: according to various studies, quercetin has a positive effect on the stabilization of the immune cells . These, in turn, are responsible for the release of histamine. The release of substances responsible for allergic reactions is reduced. This means that both the symptoms and the allergic reaction itself are weaker.

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

Vitamin C – The all-rounder

A study by the University of Erlangen showed that vitamin C influences serum histamine concentration . Patients suffering from allergies or infectious diseases were given a high dose of vitamin C intravenously. A significant reduction in histamine concentration was subsequently observed. The reduction in patients with allergic diseases was even greater than in patients with infectious diseases [31].

Vitamin D – The sunshine vitamin

In order for the immune system to function fully, a sufficient supply of vitamin D3 in the body is also essential.

Vitamin D serves as a messenger substance 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 without reason that vitamin D can influence the innate adaptation of our immune response.

Vitamin D protects the body from self-attacks because it cannot distinguish between its own cells and foreign cells. Therefore, vitamin D is also called an immunomodulator [32,33,34]. A deficiency in vitamin D is associated with increased autoimmunity and increased susceptibility to infections [35,36].

It is clear that UVB radiation is too low in winter to produce sufficient vitamin D [37]. In Germany, approximately 60% of the population has too little vitamin D according to international criteria. This is the case when the value in the blood serum is below 50 ng/ml [38].

At least values ​​between 40-50 ng/ml in the blood serum should be achieved [39].

The trace element zinc

Furthermore, 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 for more than 300 enzymes .

The enzyme DAO (diamine oxidase) is an enzyme that depends on zinc. It 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 slight deficiency can already have an impact on the immune system. Therefore, in the case of an acute deficiency, an increased zinc intake is recommended [42,43,44,45].

32% of men and 21% of women do not reach the recommended reference values ​​for daily zinc intake. In the age group of 65 to 80 years, even 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].

If you suspect that your allergy symptoms are related to a zinc deficiency, you should have your zinc levels checked. This can help prevent a deficiency of the essential trace element.

1) Bergmann, KC, Heinrich, J., & Niemann, H. (2016). Current status of the prevalence of allergies in Germany: Position paper of the Commission for Environmental Medicine at the Robert Koch Institute. Allergo Journal, 25, 22-26.