People with food allergy have an immune system which reacts to certain food proteins. Such compounds are targeted by their immune systems as if they were a dangerous pathogen, such as a bacterium or virus.
The National Institute of Allergy and Infectious Diseases reports that in America about 5 percent of children and 4 per cent of adults are allergic to food. This is a 20 percent increase in allergies to food from childhood over the last 20 years. Food allergies affect 250 million to 550 million people in developing and developed countries worldwide.
In this post, we’ll discuss the food allergy signs, causes, remedies, and triggers.
Fast facts on food allergies
- Allergies in children appear to be increasing.
- In some people, food allergies can be life-threatening.
- Symptoms can include nausea, diarrhea, and streaming eyes.
- Common triggers include eggs, nuts, soya, and milk.
- Diagnosing food allergies can be challenging.
Symptoms of food allergy
Symptoms can range from mild to extreme and have different impacts on each person. Not everyone will experience all of the things below and each reaction may be slightly different, but typical signs and symptoms include:
- tingling in the mouth
- burning sensation in the lips and mouth
- lips and face might swell
- skin rash
- skin may become itchy and/or blotchy
- runny nose
- streaming eyes
Symptoms of anaphylaxis
Anaphylaxis means a severe allergic reaction. It usually happens shortly after exposure to the actual allergen, but may take a couple of hours.
Signs and symptoms are typically rapid and worsen rapidly; they can include:
- a rapid fall in blood pressure
- fear, a feeling of apprehension
- itchy, tickly throat
- respiratory problems, which often become progressively worse
- skin is itchy, rash may spread rapidly and cover much of the body
- streaming nose and eyes
- tachycardia (accelerated heartbeat)
- throat, lips, face, and mouth swell rapidly
- loss of consciousness
Common food allergy triggers
The most common foods that cause allergic reactions in children are peanuts, wheat, soya, milk, and eggs, according to the National Health Service, UK.
These are varieties of fish, peanuts, some shellfish in adults, like lobster, crab, and prawns, tree nuts, like pistachios, Brazil nuts, almonds, walnuts, and peanuts.
The most popular allergic foods, responsible for nearly 90% of all food allergies, commonly referred to as the “big eight,” are:
- nuts from trees (including hazelnuts, walnuts, almonds, and Brazil nuts)
- peanuts (groundnuts)
- shellfish (including shrimps, mussels, and crab)
Other major allergens in European countries include sesame, celery, lupin (a legume), and mustard.
Diagnosing food allergies
The doctor will ask the patient about their reaction, including the symptoms, how long a reaction takes, what food triggers it, whether or not the food is cooked and where it was eaten.
Any other known conditions, such as hay fever or asthma, will be of concern to the doctor.
Also, the patient will have to tell the doctor about close relatives who may have allergies.
Skin prick test – Diluted foods are placed on the patient’s head, then the skin is pierced and the food is inserted into the system. If there is any reaction, such as scratching, swelling, or redness, some form of allergy is probable.
Skin prick testing will sometimes show false-negative or false-positive results. Doctors usually order to be certain about certain examinations.
Blood test – a patient’s blood is drawn to check for IgE antibodies that are specific to certain food proteins.
Elimination diet – suspected foods are not eaten for 4-6 weeks, typically, to see whether symptoms clear up. They are then reintroduced to see whether symptoms return.
A doctor or dietitian will supervise the elimination diets. It is necessary not to ceaselessly exclude major food groups. Elimination diets are often seen as the gold standard for detecting unhealthy foods, as many diagnostic tests can yield false results.
Food diary – patients write down everything they eat and describe symptoms if they occur.
Physician-supervised blinded oral food challenge – That’s even more precise. There are several different diets provided to the patient. Each of them contains tiny quantities of the suspected allergen. Each of the patients eats, and their reaction is closely observed.
Blinded means that the patient does not know which food has the potential allergen; this is important because some people react to certain foods psychologically (this would not be known as an allergy.
This type of test should only be done by a doctor at a suitable medical facility.
Allergy vs. intolerance
Experts also found that many people who believe they have a food allergy are simply intolerant of food, which is not the same. Food intolerances do not need IgE antibodies although it may include other parts of the immune system.
Symptoms can be acute or intermittent, and similar to food allergies. Unlike a protein-only allergy, food intolerance may occur because of proteins, chemicals, carbohydrates in foods, or because of a lack of enzymes or a compromised intestinal permeability.
Usually, the person may eat small amounts of that particular meal without being affected. The exception is someone suffering from Celiac disease.
The following conditions or examples are often confused for food allergies:
Enzymes – Individuals do not have an enzyme (or enough) to properly digest a meal. For instance, intolerance to lactose which causes diarrhea, gas, cramping, and bloating.
IBS (irritable bowel syndrome) – a long-term (chronic) condition in which the patient has diarrhea, constipation, and stomach pains. IBS sufferers are often intolerant to fermentable carbohydrates.
Food additive sensitivity – such as sulfites, which are used for preserving dried fruits or canned foods.
Psychological factors – Some people may just feel ill thinking about a particular meal. No one is entirely sure why this is happening.
Celiac disease – a long-term intestinal autoimmune disease that is caused by gluten intake. Although many cases are asymptomatic, the patient may have vomiting, stomach pain, and bloating; There’s involvement of the immune system but experts say it’s a food sensitivity, not an allergy.
Food allergy means that even a small amount of food will likely trigger the immune system, which will cause an allergic reaction. Food allergy can cause fainting, vertigo, dizziness, breathing problems, swelling of various parts of the body, such as the mouth, tongue, face and hives. The person may get tingling in the mouth as well.
What causes food allergies?
In food allergies, a particular protein in a food is viewed by the immune system as a harmful substance, pathogen, something that can cause disease. It reacts to that protein by producing antibodies.
The antibodies are ready when the same food is eaten next, and warn the immune system to react immediately. The immune system responds by releasing histamine into the bloodstream and other substances. Histamine and those other compounds cause food allergy symptoms.
Histamine dilates (expands) the blood vessels and inflames (swollen) the skin. It also affects the nerves and makes people feel itchy. The nose will produce more mucus, scratching, burning and a streaming nose.
Who is at risk?
Family history – Scientists believe that genes that people inherit from their parents may trigger some food allergies. For example, people with a parent or sibling with a peanut allergy are 7 times more likely to have that allergy themselves compared to those with no family history.
Other allergies – Those with asthma or atopic dermatitis have a substantially higher risk of developing food allergy compared with those without any other allergies.
Early years – Research has also shown that babies born in the cesarean section who received antibiotics at birth or in the first year of life and those who received food late, after seven months, all had a higher risk of allergy.
Gut bacteria – recent research shows that bacteria in the gut are changed in adults with nut and seasonal allergies. In particular, they have higher bacteroidal rates, and lower Clostridiales strains. Scientists are trying to determine whether influencing bacteria in the gut could help treat or prevent allergies
Why do certain people have allergic reactions?
Food allergies seem on the rise. For example, the CDC says “the prevalence of food allergies increased from 3.4% in 1997-1999 to 5.1% in 2009-2011.” No one is sure why numbers are increasing; however, several theories exist:
Diet – some scientists suggest changes in eating habits in Western nations may be the cause, while others say it could be due to lower animal fat consumption and higher vegetable fat intake.
Pesticides and genetically modified foods – some believe that high exposure to residues of pesticides and the ingestion of genetically modified foods influences the functioning of the immune system during production in utero and also as humans mature.
Antioxidants – many people eat less fresh fruit and vegetables than previous generations (foods rich in antioxidants that help protect against cell damage); a lower intake of antioxidants during childhood that undermine the proper development of the immune system.
Vitamin D – the prevalence of food allergies is higher in countries beyond the equator, where there is less sunshine, an essential source of vitamin D. The suggestion is that low intake of vitamin D may result in increased risk of food allergy.
Lack of early exposure – also named hygiene hypothesis. Children are brought up in super-sterile environments, with much less germ exposure than their parents had been. Developed countries with higher use of antibacterial soaps and goods with lower exposure in soil and atmosphere to healthy bacteria have significantly higher rates of food allergies.
Maybe the immune system wasn’t properly trained to distinguish between good and harmful substances. This theory is valid not only to food allergies but also to many other environmental allergies.
All of the above are just hypotheses, though, with no convincing evidence to back them up.
Elimination diet – many patients will need to see a dietitian after diagnosing an allergy to the food. If food needs to be omitted from one’s diet, it is important that it is done in a way that doesn’t harm the wellbeing of the person.
For example, if the allergy is only to peanuts, if the person never eats peanuts again there will be no health consequences. An aversion to milk therefore means finding other calcium and protein sources.
Elimination may not simply mean not consuming the particular food; it may also include never inhaling it, touching it or eating foods containing traces of it within. Cutlery, crockery, surfaces for cooking, and chopping boards must be allergy free.
Patients will need to read food and drink labels carefully. Even some soaps, pet foods, glues, and adhesives may have traces of a food allergen.
When eating out, being vigilant can be particularly difficult.
Medication for emergencies
Antihistamines – these come in gels, liquids, or tablets. In general, these are effective in patients with mild to moderate allergies. Histamines are compounds that cause the most signs of allergies, and antihistamines inhibit their effects.
Epinephrine (adrenaline) – this is used by people with food allergies which can contribute to anaphylaxis. Epinephrine regulates blood pressure by constricting the blood vessels and by relaxing the airways.
People who have had severe allergic reactions should bring an auto-injector of epinephrine with them, such as the EpiPen, EpiPen Jr., Twinject or Anapen.