Food allergies and intolerances: what they are, what foods cause them and how to prevent and treat them.

Why does our body generate an adverse reaction after eating certain foods, causing unwanted or harmful effects?

According to the European Academy of Allergology, adverse reactions to food can be Toxic (due to poisoning) or Non-Toxic. Non-toxic reactions refer to those that, when consumed, will not cause an adverse reaction in most people, while in others it will, depending on the susceptibility of each person. Thus, a non-toxic adverse reaction has to do with the tolerance or intolerance of the individual person to a certain food that, in any other person, would be harmless.

Non-toxic reactions include:

• Allergic reactions that consist of an abnormal response of the body, involving the immune system, to foods that would be harmless in another person.
• Intolerance reactions , which occur when the body cannot properly digest a food or one of its components, but there is no reaction from the immune system.

Although allergic reactions and intolerance reactions have aspects in common, such as the fact that a certain food causes discomfort and symptoms to those who have consumed it, inhaled it or come into contact with it, the mechanism by which they are triggered will be different.

The difference between allergies and intolerances has to do with the way the immune system reacts once the body has come into contact with the food causing the intolerance or allergy. In the case of allergies, the immune system would react and cause the symptoms of an allergic reaction that could be very serious. In the case of intolerance, the immune system, on the other hand, would not intervene in the reactions that could occur.

In addition, the frequency of these reactions also differs: for every case of a food allergy that is triggered, 5-10 cases of intolerance occur. Therefore, intolerance reactions are much more frequent than allergic reactions.

Types of food intolerances

1. Food intolerance due to enzymatic or metabolic causes

This is the most common type of intolerance and occurs due to a deficiency in the enzymes needed to metabolize a certain food. This category includes intolerances to lactose, fructose, galactose, saccharose, sorbitol and trehalose (mushroom sugar).

2. Food intolerance due to pharmacological or chemical causes.

Triggered by substances present in foods, such as amines or methylxanthine found in tea and coffee.

 

3. Metabolic food intolerance due to additives.

It is caused by additives added to foods, not by the foods themselves. They may include colorants, preservatives and flavor enhancers such as monosodium glutamate, for example.

Why are there more and more allergies and intolerances in the general population?

According to a report by the Spanish Society of Allergology and Clinical Immunology (SEAIC ), in so-called Western countries the proportion of people affected by this type of disorder has tripled in two decades: from 3.6% in 1992 to 11.4% in 2015 (results concerning the Spanish population).

It is difficult to determine the incidence of food intolerance and allergies in Latin America because there are no population studies that allow us to have a quantitative idea of ​​the population that could be affected by these ailments. Most of the studies carried out in Europe and North America indicate that the increase in the number of patients with food intolerance may be due to several factors such as contamination, pollution, the stress we deal with and consumerism that influence our lifestyle and health, favoring the appearance or intensification of allergies and intolerances.

The causes that favor the increase in allergies and intolerances today:

1. Inadequate development of intestinal flora or microbiota .

Intestinal flora refers to the set of microbes (mainly bacteria) that inhabit the human digestive tract, whose presence contributes to the proper physiological development and functioning of the digestive system of the person who hosts them.

Nutrition, i.e. the food consumed and drunk, the conditions in which food and drink are found, their quality and origin, therefore directly influence the microbiota from birth itself. Inadequate development of the intestinal microbiota can originate from early childhood due to birth by Caesarean section, as well as too short a period of breastfeeding.

In adulthood, the alteration of the microbiota known as dysbiosis can be caused by the abuse of antibiotics, an inadequate diet or the aging process itself.

2. Added to the above is the theory of hygiene. In today's society, according to which, the improvement of hygienic conditions makes the world cleaner than before, it has also altered the human immune system and in some cases, causes it to react by taking some substances that are not harmful as harmful elements. We have a wide variety of extreme cleaning products to the point that it distances us from any harmful organism and does not allow the immune system to activate naturally and defend us. In fact, what it does is fight against elements that are not harmful, but which it recognizes as such. This would be the case of a person's body that reacts to proteins in milk, eggs or any other food that for the rest of the people is harmless and it happens because their immune system is telling them that these are enemy substances and potentially harmful if absorbed by the body.

3. Pollution. Several studies have confirmed the harmful effects on the body caused by crowds, pollution and contamination. It is in cities where more allergic diseases occur, as well as asthma attacks, infections and respiratory diseases. This even affects people who are allergic to various types of pollen, since pollutants affect the life of plants in cities. Plants in cities also become stressed and produce a series of defense proteins that these same plants lack in natural and clean environments. It is therefore believed that pollen from plants in cities is more sensitizing, that is, it affects people with allergies to a greater extent.

4. Modern life even affects our diet, in the sense that we overeat fast food , consume too much ready meals and processed foods. There is no time to cook, much less to plant and harvest. Meanwhile, the food industry accelerates the pace of harvests, meat production, and the ripening of fruits and vegetables; while others offer prepared, processed and even ultra-processed foods.

Hundreds of food processing and preservation substances can cause adverse reactions in the body, from sulfites present in alcoholic beverages to monosodium glutamate present in processed meat, spinach and canned mushrooms.

What does intestinal permeability have to do with (the increase in) food intolerances?

A person is said to have increased intestinal permeability when their digestive tract, from the start, has a poor relationship with what they eat.

Imagine your intestine as an ancient alley paved with a very thin layer of cells. This layer lines the inside of the intestinal walls and is covered by a mucosa with two distinct parts: one of its layers contains the intestinal flora and the other contains cells called immunoglobulins of the IgA type, whose function is strictly defensive.

Intestinal permeability increases when the thin layer that forms the intestinal barrier thickens, which means that the space between the slabs that make up the paving stone becomes larger and allows food and nutrients that are consumed to be digested in an abnormal way. As the intestinal barrier is increased, the digestive tract allows certain proteins to pass through (something that does not occur with normal permeability of the intestinal mucosa), which causes the immune system to immediately recognise the proteins as foreign and harmful, going out to fight them. It can therefore be said that greater intestinal permeability is an indirect cause of the increase in food intolerances.

How the process that triggers food intolerance works in the body

Allergy to a particular food or one of its components occurs after ingestion due to the formation of antibodies of the immunoglobulin E or IgE type.

These antibodies are what trigger the allergic process. However, in the case of food intolerances, on the one hand, the immune system would not intervene and, on the other hand, in the body of the intolerant person, IgA type antibodies would not be formed, but rather IgE type antibodies, in a first stage, and then, after multiple stimuli, IgG type antibodies. Thus, food intolerance occurs after the ingestion of a certain food because the body reacts to one of its proteins by producing IgG antibodies. Generally, these antibodies cause symptoms in the body that may consist of diarrhea or other digestive disorders.

To determine whether the reaction is due to intolerance or allergy, although the symptoms may be common in both cases, the way and time in which the symptoms occur is the differentiating factor. If it is an allergy, the symptoms are acute and immediate, while if it is an intolerance, the symptoms will be more subtle and, in many cases, not so immediate.

How a food intolerance can be diagnosed

The diagnosis that determines whether or not a person suffers from a food intolerance, to what type of food and to what degree must be carried out by a doctor specialising in nutrition or allergology.

After an interview and a review of the medical history and background, the health professional must examine the person because many intolerances are reflected through the skin in itching, itching, spots, and more.

Often your doctor can order tests and schedule temporary elimination of certain foods from your diet or other measures.

The four most common types of food intolerances

Fructose:

Fructose is a monosaccharide that together with glucose forms what we know as sucrose or common sugar. That is,

1 molecule of sucrose = 1 fructose + 1 glucose

Both fructose and sorbitol, which is a sugar alcohol, are used as sweeteners and both require an intestinal transporter called GLUT ₅ that carries the substance from the small intestine to the cell.

What happens with people who have fructose malabsorption due to Glut ₅ deficiency is that When fructose reaches the colon, intestinal bacteria will subject it to a fermentation process that, in turn, will lead to the release of gases, such as carbon dioxide, methane and hydrogen; as well as short-chain fatty acids and water. These gases and acids are what cause the symptoms associated with fructose intolerance and the same occurs with sorbitol. Even more, things get complicated because sorbitol can also compete with fructose to use Glut _{5 .}

Common symptoms : gas, abdominal pain and distension, bloating, borborygmi (noises produced by the mixture of intestinal fluids with gases) or explosive diarrhea (diarrhea with abundant gas).

Other digestive symptoms may include nausea, vomiting, and headaches.

Extraintestinal symptoms : lack of energy, chronic fatigue; internal restlessness; nervousness, lack of concentration, depressed mood.

Some tips for coping with intolerance:

Although your doctor will perform tests to confirm your intolerance, he or she will prescribe a diet to eliminate foods containing fructose and, after a certain period of time, will allow you to gradually reintroduce foods containing fructose.

Apart from that, there are some practical tips that can help you cope with the discomfort of fructose intolerance:

• Chew your food well and take your time eating.
• Increase the number of small meals per day instead of eating 3 large meals.
• Eat sweet foods accompanied by fat, since the latter allows you to better tolerate fructose and contributes to delaying gastric emptying, so the fructose reaches the small intestine more slowly and has the opportunity to be better absorbed.
• Avoid consumption of dried fruits and fruit juices.
• Consume foods that are difficult to digest, such as cruciferous vegetables, with caution.

Lactose:

It is a disaccharide sugar made up of two simple sugars, glucose and galactose.

1 lactose molecule = 1 glucose + 1 galactose

Lactose is found naturally in all mammalian milk, including human milk, which contains the highest amount.

Lactose intolerance occurs when a person has a deficiency or complete absence of the enzyme lactase in their body, which prevents them from properly absorbing lactose. When lactose is not absorbed, it goes directly to the colon where intestinal bacteria ferment it and produce, as a result, various symptoms.

Intestinal symptoms of lactose intolerance: abdominal pain and distension, intestinal noises and flatulence, nausea and vomiting. Occasionally, diarrhea, but also, to a lesser extent, constipation.

Systemic symptoms : headache, loss of concentration, exhaustion, muscle pain, joint pain or stiffness, increased frequency of urination.

Treatment : Once the diagnostic tests confirming the intolerance have been carried out, the health professional will prescribe a diet to eliminate products containing lactose, which will consist of 3 phases:

Phase 1. The person must give up any type of dairy in their diet for a period that can range from 4 to 12 weeks.

Phase 2. This begins when all symptoms of intolerance have disappeared. At this point, the patient will only be allowed to consume products with a low lactose content, such as some aged cheeses.

Phase 3. At this stage, the person already knows how much lactose he or she can tolerate on a daily basis. Your doctor will prescribe lactase tablets for those occasions when you eat out and find it difficult to calculate the amount of lactose in the food you eat.

Gluten:

Gluten is a protein found in wheat in all cereal species of the Triticum group, which also includes durum wheat, spelt and kamut.

Gluten intolerance falls into two categories:

• Celiac disease : although there is an immunological component, the reaction caused by gluten when it comes into contact with the person's body triggers a reaction that does not depend on IgE antibodies, so it is not considered an allergy. In addition, celiac disease involves a genetic predisposition and may be hereditary or shared with several family members.

Gastrointestinal symptoms : heartburn that is not relieved by antacids but by removing gluten, dyspepsia (feeling of indigestion), flatulence and frequent changes in intestinal rhythm.

Extraintestinal symptoms : diarrhea, weight loss, anemia, fatigue, abdominal distension and pain, strange appearance of stools, nausea, joint pain.

• Non-celiac gluten intolerance:

Very common intestinal symptoms : bloating and abdominal pain.

Very common extraintestinal symptoms : malaise and fatigue.

Common intestinal symptoms : diarrhea, stomach pain, nausea, belching, gastroesophageal reflux and heartburn, and alternating bowel habits or constipation.

Common extraintestinal symptoms : headache, anxiety, muscle or joint pain, skin rash, dermatitis, and mental slowness or cloudy mind.

Treatment : First, the health professional will prescribe the relevant tests to determine whether it is celiac disease or non-celiac gluten intolerance.

The next step is to suggest that the person follow a gluten-free diet for 6 weeks. At the beginning of each week, the person undergoing treatment must report the symptoms they have and the type of discomfort they may be experiencing.

After this period, the doctor will review the patient's health and, based on the improvement of the main symptoms, will determine whether gluten can be reintroduced into the diet and check that the symptoms do not reappear.

Histamine:

Histamine is a biogenic amine or compound derived from the essential amino acid Histidine.

All living beings produce amines that are stored in mast cells (immune system cells) and basophils (a type of white blood cell) that are located mainly in the skin and various types of mucous membranes within the body. Among their physiological functions is that of intervening, within the immune system, in allergic reactions.

In order to be metabolized, biogenic amines require two types of enzymes: diamyoxidase (DAO) and histamine-N-methyltransferase (HMT) .

The accumulation of histamine or Histaminosis occurs due to the ingestion of foods rich in histamine that our body is unable to metabolize and this is when intolerance occurs.

Food intolerance to histamine occurs due to a deficiency of the enzyme DAO and can be caused by genetic, pharmacological or pathological factors. In any case, the health professional will prescribe the corresponding tests to diagnose whether the concentrations of histamine in the blood are normal (50-70 mg/l). If the limits are higher, symptoms of intolerance will begin to appear.

Most common symptoms of histamine intolerance:

• In the central nervous system: migraine, headache, dizziness.
• In the digestive system: irritable bowel syndrome, constipation, flatulence, satiety or bloating.
• On the skin: hives, dryness, atopic skin (eczema) or psoriasis.
• In the muscular system: fibromyalgia and chronic pain or fatigue.
• In the respiratory system: nasal congestion or asthma.
• In the circulatory system: high or low blood pressure, or arrhythmias.

Treatment : Once diagnostic tests confirm that it is a histamine intolerance, the health professional will prescribe a histamine-restrictive diet and possibly supplementation with the enzyme DAO to eliminate the little histamine that can be ingested, since it is very difficult to eliminate it completely. In addition, supplementation with Omega-3 fatty acids is recommended.

There are other less common intolerances, but the message for you is that if you suspect or have some of the symptoms mentioned after consuming certain foods, listen to your body, pay attention to the way it reacts and if you feel it is necessary, consult a health professional who can prescribe the appropriate diagnostic tests in order to detect any possible irregularities in your body and proceed to formulate the corresponding treatment.