Hypersensitivity to foods – in short
Hypersensitivity can be due to allergy or to intolerance. And it gets even more confusing, as it is possible for the same food to cause both allergies and intolerance. Here is a short guide which explains some similarities and differences.
Allergies: An allergy is caused by the body for some, often unknown, reason producing antibodies against a protein or a carbohydrate in the food. Most often, the body makes IgE antibodies. Common symptoms are hives, eczema, nausea, vomiting, stomach pain, diarrhoea, asthma and rhinitis. But all IgE-mediated allergies can potentially, in the worst case scenario, result in a life-threatening anaphylactic reaction and deaths have been reported.
Nuts, seeds: Almond, hazelnut, walnut, cashew, pecan, brazil nut, pistachio and macadamia are all nuts to which you can develop an allergy. Sesame and mustard are the most common allergenic seeds.
Legumes (peanut and soy): The peanut is not actually a nut, but a legume, and is therefore included in the same group as soy, peas, beans, chickpeas, lentils and lupin. Allergies are often formed in childhood, and rarely go away with age. It is common to be allergic to several different legumes.
Cereals: Allergy to cereals is most often caused by antibodies to wheat protein, but there are also allergies to other types of cereal.
Milk/dairy products: Allergy to milk protein is most common in infants, and they often outgrow it. Up to one per cent of children and 0.2 per cent of the adult population suffer from this type of allergy. All forms of milk have to be avoided, even sheep and goat’s milk.
Eggs: Affects up to two per cent of small children, but in many, the allergy disappears with age. The most common allergy is to protein in the egg white, but there are also cases of allergy to the yolk. In those cases, the person is often also allergic to chicken meat.
Fish and shellfish: Fish allergy normally presents in early childhood and will rarely disappear with age, but it is uncommon. The IgE antibodies involved are only found in 0.5 per cent of children. Allergy to shellfish, on the other hand, most often occurs in adulthood and may also include mussels and octopus.
Intolerances: Gluten intolerance (celiac disease): Is an autoimmune disease where the body has formed IgA antibodies (not IgE antibodies) to the enzyme tissue transglutaminase (tTG). In practice, this entails an intolerance of the proteins found in wheat, rye and barley. In the long term, continued intake damages the intestines, which can lead to malnutrition.
Lactose intolerance: Is due to a lack of the enzyme lactase, which is necessary to break down lactose, or milk sugar, in the small intestine. Lacking lactase is not a disease, but normal in many areas. In Sweden, it only affects around 4–10 per cent of adults, 15–20 per cent in Finland, 30–60 per cent around the Mediterranean and essentially everyone in Asia, South America and Africa. The most serious symptoms include flatulence, stomach pain and diarrhoea. The solution is to avoid milk and dairy products.
Initiatives for increased dissemination of knowledge
The state of knowledge on food allergies and hypersensitivity is changing rapidly, which means that there is a great need for knowledge to be disseminated to patients, healthcare professionals and other stakeholders. For this reason, a regional centre for food allergy research is being established in Stockholm to raise the level of knowledge within the health service.
At the same time, the Centre for Allergy Research at Karolinska Institutet, together with Astma- och allergiförbundet (the Swedish Asthma and Allergy Association) and the Swedish Food Federation, has received funding from the Swedish Inheritance Fund to start an interdisciplinary centre of excellence on food hypersensitivity with the device “Good food for everyone”. The centre is to disseminate information to the public, work with political advocacy and provide a point of contact for collaborations on food hypersensitivity – across all sectors of society.
Source: Stockholm County Council and Karolinska Institutet
Text: Fredrik Hedlund, first published in Swedish in Medicinsk Vetenskap No 4/2018.