Food intolerance

What is food intolerance?

 

Food intolerance is basically an abnormal reaction of the body to certain types of foods, which can take many forms. This can be a result of different mechanisms, however, we will focus on intolerances which emerge as a result of an immune response (for example when IgG antibodies are produced) and which can be detected from blood samples.

There are many other mechanisms where an immune response does not play a part. These include:

Enzyme insufficiency/deficiency

– lactase deficiency that plays a part in lactose intolerance (which causes bloating, loose bowels and abdominal pain)

Irritability to chemicals/drugs

– MSG (monosodium-glutamate) in Chinese food (headaches, perspiration, dizziness)

– Sulphites in dried fruits and vegetables, wine and beer (asthma symptoms)

– Vasodilator amines, such as phenyl ethylamine in chocolate and red wine (migraine).

 

What’s the difference between food allergies and food intolerance?

 

A lot of people believe that food allergy and food intolerance are the same thing. In fact, there are many differences:

•  ● The reactions to an allergy usually occur right away after the food is consumed, while intolerances cause symptoms later on (sometimes even days after consumption).
•  ● Allergies are caused by IgE antibodies, while intolerances cause IgG antibodies to be produced.
•  ● Allergies are relatively rare, while intolerances are widespread.
•  ● Allergies are usually caused by infrequent exposure, while intolerances are a result of frequent consumption.
•  ● Allergic reactions are caused by the fast release of histamine from the mast cells, while intolerances are characterised by a slow build-up of antigen-antibody complexes, which – deposited into the cells – causes inflammation.
•  ● Allergies are accompanied by their characteristic symptoms: redness, sneezing, hay fever, difficulty in breathing, asthma, even anaphylaxic shock. Intolerances can cause problems in any part of the body, and the patients usually have several complaints.
•  ● An allergic reaction can be fatal, while intolerances do not threaten the patient’s life.
•  ● Allergies are a life-long condition, while intolerances can be reversed by eliminating the food that causes the high IgG production.
•  ● Allergies show a positive skin test (prick test) while intolerances cause negative results.
•  ● Allergies can be diagnosed by the patient himself/herself, as the food consumed can directly be connected to the reaction. However, it is much harder to determine the cause of food intolerances simply by the help of the symptoms. This is whyIgG tests are important.

 

The mechanism of food allergy

 

Classical food allergies cause the mast cells (which are bound by IgE antibodies) to release inflammatory mediators. The order of events is the following:

● The food antigen stimulates a particular class of lymphocites called the Th2 helper T cells.

● These Th2 cells exude cytokines which instruct the B lymphocites to prodcue antigen-specific IgE.

● The IgE antibodies are bound to mast cells. In case the body comes into contact with the allergen again, it attaches to the bound IgE on the surface of the mast cells, which causes the mast cell to release inflammatory mediators (hystamine among others).

● The inflammation is responsible for the classic symptoms of allergies: sneezing, tears, itching, redness, difficulty of breathing, etc.

 

The mechanism of food intolerance

 

Food intolerances cause antigen-antibody complexes to form, which are deposited to the cells, damaging them and causing inflammatory chemocins to be released. This can happen in every part of the body, for example in the intestines where it causes IBS-like symptoms, in the joints where it can cause arthritis, in the brain causing migraines etc.

The order of events is the following:

•  ● Partially digested food enters the blood stream through the intestinal cells.
•  ● The body identifies these proteins as ‘alien’, and starts to produce food-specific IgG.
•  ● The IgG, together with the partially digested food, causes antigen-antibody complexes to be produced. The symptoms of food intolerances appear later, as the production of complexes is a gradual process, they do not materialize right away.
•  ● The complexes are deposited in the tissue (this can occur anywhere in the body, e.g. the intestines, the brain, the skin etc.).
•  ● The complement system becomes active, which causes the neutrophile white blood cells to release proteolytic enzymes, mast cell mediators, vasoactive peptides, and also platelet aggregation.
•  ● The complement system and the macrophages stimulate an inflammation, while the complement system ensures that smaller complexes do not become larger.
•  ● C2 and C5 (part of the complement enzyme cascade) can also release hystamine.
•  ● The macrophage releases inflammatory mediators (such as interleucin-1, tumor necrosis factor, ROS and nitrous oxides).

(Note: the complement system is an enzime cascade which helps the body fight infections.)

 

Symptoms of food intolerance

 

A lot of symptoms can be connected to food intolerance, and because the reaction only occurs later, it is very hard to ascertain what food causes the problems. This is why IgG antibody tests are important.

Symptoms may include the following:

•  ● Arthritis, fibromyalgia, joint pain
•  ● Anxiety, depression
•  ● Asthma
•  ● Weariness
•  ● Headaches or migraines
•  ● Palpitations
•  ● Water retention
•  ● Autoimmune diseases
•  ● Attention deficit, hyperactivity (ADHD: attention deficit hyperactivity disorders)
•  ● Bedwetting and chronic urinary infections
•  ● Intestinal problems (colitis, IBD, IBS, constipation, diarrhoea, bloating, abdominal pain, flatulence)
•  ● Chronic respiratory problems (asphyxia/bronchitis)
•  ● Dark rings or bulges around the eyes
•  ● Insomnia, lethargy, ‘hazy’ feelings
•  ● Myalgic encefalomyelit/Chronic fatigueness syndrome
•  ● Constant coughing, catarrh
•  ● Inflammation of the accessory sinus
•  ● Skin conditions (eczem, erythema, acne)
•  ● Weight gain

Food products often connected to intolerance

 

The food products most often connected to intolerance are the following:

Cow milk, eggs, nuts, wheat, gluten, soy and yeast.

Connection between IgG antibodies and the symptoms

 

It is important to note that a healthy immune response also produces IgG antibodies, but these do not cause symptoms, proving that

1. A) the immune system is functioning effectively and/or

1. B) the transmissibility of the intestines is not heightened.

Symptoms usually appear when the immune system is not functioning effectively and/or the transmissibility of the intestines is heightened. We will describe these mechanisms below, and compare them with the normal reaction given by a healthy body to food products, e.g. those processes that occur when the bowel wall and the immune system is healthy.

 

1. Normal reaction to food products

A small amount of undigested food passes through the enterocytes into the bloodstream, and causes an immune reaction. This happens in every healthy body. The order of events is the following:

•  ● The gastrointestinal tract is healthy, and so is the immune system
•  ● Food products are digested to their basic units (glucose, amino acids and fatty acids), and absorbed from the intestines, thus reaching the bloodstream.
•  ● A small amount of only partially digested food also passes through the enterocytes, and reaches the bloodstream directly.
•  ● The body produces antibodies (IgG) to fight these partially digested food, and antigen-antibody complexes are formed.
•  ● When the immune system is healthy, the macrophages eliminate these complexes.
•  ● No complex remains that may be deposited to the tissue.
•  ● This means that the tissue is not damaged, and no infection is caused.
•  ● As a result, no symptoms appear (despite the immune response).

 

 

To sum up, the body produces antibodies as part of the response given to the foodstuff, but this causes no problems, as the immune system is functioning effectively.

 

1. Response to food products in case of an unhealthy immune system

 

When the immune system is not functioning properly, a similar chain of events occur, however, the macrophages are not fully efficient, and thus cannot eliminate the immune complexes. These are then deposited to the tissue, and provoke an inflammation, causing the following symptoms:

•  ● The gastrointestinal tract is healthy, but the immune system is affected.
•  ● Food products are digested to their basic units (glucose, amino acids and fatty acids), and absorbed from the intestines, thus reaching the bloodstream.
•  ● A small amount of only partially digested food also passes through the enterocytes and reaches the blood flow directly.
•  ● The body produces antibodies (IgG) to fight these partially digested food, and antigen-antibody complexes are formed.
•  ● The macrophages are inefficient, and thus cannot eliminate all the immune complexes.
•  ● This means that a large amount of immune complexes reach the bloodstream, where they are deposited to the tissues (anywhere in the body).
•  ● This causes inflammation and tissue damage.
•  ● As a result, the symptoms start appearing.

 

 

1. Response to food products when the transmissibility of the intestines is heightened

 

In this case, the immune system is functioning perfectly, but the transmissibility of the bowel wall is larger than normal (which means that a larger amount of undigested food passes to the bloodstream), and this causes the immune system to be overloaded. As a result, the defensive system cannot eliminate all the immune complexes, and the remaining complexes pass to the tissue, and cause symptoms:

•  ● Normal, healthy immune system with a larger transmissibility of the bowel wall.
•  ● A larger amount of partially digested food passes through the enterocytes, and into the bloodstream.
•  ● The body produces antibodies to fight this partially digested food, and antigen-antibody complexes are formed.
•  ● These overload the immune system.
•  ● Macrophages cannot eliminate all the immune complexes.
•  ● This means that a large amount of immune complexes is deposited to the tissues.
•  ● This causes inflammation and tissue damage.
•  ● As a result, the symptoms start appearing.

 

Factors that may aggravate the permeable intestines

 

The following factors may further damage the health of the patient, and lead to a heightened transmissibility of the bowel wall:

•  ● Low level of secretory IgA

– Secretory IgA is an immune marker and the first line of defence against bacteria, food residues, fungi, parasites and viruses in the intestines.

– Stress can deplete the secretory IgA of the body, and thus weaken the defence system of the body against foreign materials. Stress can also reduce the number of ‘good’ bacteria, and lets ‘bad’ bacteria and fungi (e.g. Candida) to gain prevalence.

•  ● Unbalanced intestinal flora
•  ● Damage to the mucous membrane as a result of infections or certain medications.

– Non Steroidal Anti-Inflammatory Drugs (NSAIDS) such as Aspirin can also damage the bowel wall and cause an inflammation entailing a heightened transmissibility.

•  ● Parasites.

• – Parasites can also cause an inflammation entailing a heightened transmissibility.

•  ● Lack of a sufficiently diverse diet (e.g. too much gluten)
•  ● Reduced production of gastric acid
•  ● Reduced secretion of pancreatic enzymes

• – When the transmissibility of the intestinal system is damaged, the intestinal villi also suffer, which means that the essential nutrients necessary for the production of the digestive enzymes are not absorbed in a sufficient way. As a result, the body cannot sufficiently digest foodstuff, which thus enters the bloodstream and provokes an antibody response.

•  ● Malnutrition

• – The damage suffered by the bowel wall inhibits the absorption of the food, which means that the intestines cannot regenerate fully, which causes further digestive and absorption-related disorders.