Food intolerance
What is food intolerance?
Food intolerance is essentially an abnormal reaction to certain foods and can manifest itself in a number of ways.
This response can be the result of different mechanisms, but because of their frequency, we will focus on those food intolerances that are the result of an immune response (e.g. IgG antibodies are produced) and can be detected in blood samples.
What is the difference between a food allergy and a food intolerance?
Many people think that food allergy and food intolerance are the same, but in fact there are many differences:
- Allergies usually cause an immediate reaction after eating the food, while food intolerance causes symptoms later (even days after eating).
- Allergy is an IgE antibody-induced process, while food intolerance produces IgG antibodies.
- The prevalence of allergy is low, intolerance is high.
- Allergies are usually the result of infrequent exposure, while food intolerance is the result of frequent consumption.
- The allergic response is characterised by rapid histamine release from mast cells, while intolerance is characterised by slow antigen-antibody complex formation, which causes inflammation when deposited in tissues.
- Allergies usually present with the classic symptoms of allergy: redness, sneezing, hay fever, breathing difficulties, asthma and even anaphylactic shock; however, food intolerance can affect any part of the body and patients usually report multiple symptoms.
- Allergic reactions can be fatal, while food intolerance does not cause life-threatening conditions.
- Allergies can last a lifetime, but food intolerance can be reversed by eliminating foods that cause high IgG production.
- Allergy shows a positive skin test (prick test), while food intolerance gives a negative result.
- Allergies are often self-diagnosed by the patient, as the trigger food is the obvious cause of the symptoms of food intolerance.
However, it is much more difficult to determine what is causing the intolerance on the basis of symptoms.
This gives the IgG test its importance.
Mechanism of food allergy
In classical food allergy, inflammatory mediators are released from mast cells after IgE antibodies have bound to them.
The sequence of events is as follows:
- The food antigen stimulates a class of lymphocytes called Th2 helper T cells.
- These Th2 cells secrete cytokines that instruct B lymphocytes to produce antigen-specific IgE.
- IgE antibodies bind to mast cells.
When the body encounters the allergen again, it binds to IgE bound to the mast cell surface, which causes the mast cell to release inflammatory mediators, including histamine. - The inflammation caused is responsible for classic allergy symptoms such as sneezing, tearing, itching, redness, difficulty breathing, etc.
The mechanism of food intolerance
During the development of food intolerance, antigen-antibody complexes are formed, which are deposited in tissues and trigger the release of inflammatory chemokines that cause tissue damage and inflammation.
This can happen anywhere in the body e.g. in the intestines where it causes IBS symptoms, in the joints where it causes arthritis, in the brain where it provokes migraine symptoms etc.
The sequence of events is as follows:
- Partially digested food passes between the intestinal cells into the bloodstream.
- These proteins are identified by the body as “foreign” and food-specific IgG production begins.
- IgG forms an antigen-antibody complex with partially digested food.
The symptoms of food intolerance develop later, as the formation of complexes is a gradual process and not immediate. - Complexes are deposited in tissues (this can happen anywhere in the body, in the intestines, head, skin, etc.)
- The complement system is activated, resulting in the release of protein-degrading enzymes, mast cell mediators, vasoactive peptides from neutrophil white blood cells and platelet aggregation.
- The complement system and macrophages stimulate inflammation (although the complement system also protects against the conversion of smaller complexes into larger complexes).
- C2 and C5 (part of the complement enzyme cascade) can also release histamine.
- Macrophages release inflammatory mediators such as interleukin-1, tumour necrosis factor, reactive oxygen species and nitric oxide.
Note: the complement system is an enzyme cascade that provides protection against infection.
However, it is important to note that there are many other mechanisms that do not involve the immune system.
Typical examples include:
- Enzyme deficiency/insufficiency – role of lactase deficiency in lactose intolerance (associated with bloating, diarrhoea, abdominal pain)
- Chemical/medication sensitivity – MSG (monosodium glutamate, sodium glutamate) in Chinese food (headache, sweating, dizziness) – Sulphites in dried fruit and vegetables, wine, beer (asthma symptoms).
– Vasodilating amines (phenyl ethylamine) in chocolate and red wine (migraines).
Symptoms may include
- Arthritis, fibromyalgia, joint pain;
- anxiety, depression;
- asthma;
- exhaustion;
- headaches or migraines;
- palpitations;
- water retention;
- autoimmune diseases;
- attention deficit hyperactivity disorder (ADHD);
- bedwetting and chronic bladder infections;
- intestinal problems (colitis, IBD, IBS, constipation, diarrhoea, bloating, abdominal pain, flatulence);
- chronic respiratory symptoms (choking/ bronchitis);
- dark circles or swelling around the eyes;
- insomnia, lethargy, “fogginess”;
- Myalgic Encephalomyelitis / Chronic Fatigue Syndrome;
- constant cough, hurut;
- sinusitis;
- skin conditions (eczema, redness, acne);
- excess weight problems.
Foods commonly associated with food intolerance
Food intolerance can be caused by a number of foods, but in most cases the following are responsible for the unpleasant symptoms:
- cow’s milk;
- Eggs;
- oil seeds;
- Wheat;
- gluten;
- soya;
- yeast.
The source of the article can be found on the FOODTEST.hu website.
