what you need to know about the role of your skin

Food allergies are increasing worldwide, ranging from a minor inconvenience to a possibility of sudden death, and leading to warnings of an "allergy epidemic". The most severe form of allergic reaction – anaphylaxis – can occur repeatedly or without warning. The reasons for the increase in allergies are complex, but it is now recognized that the skin plays an important role as a controller of the immune system.

Human skin is a protective barrier that provides dynamic coverage, ensuring that essential fluids (including water, protein, and minerals) stay inside, while harmful substances remain in the body. 39; outside. The skin barrier is structural – like a brick wall – but it is also alive and active, constantly detecting and reacting to the outside environment. This barrier is composed of several layers of interconnected human cells, as well as a multitude of microbes, tiny organisms that live on the surface of a healthy skin.

The skin forms a continuous lining on the outer surface of the body that seamlessly joins the lining of the mouth and intestines. Human cells are normally introduced into food through the mouth, but the body can also be exposed to food on the surface of the skin.

The immune system – cells and tissues that work together to defend the body against viruses, bacteria and potentially harmful foreign substances – can react in a very different way when food is first discovered through the skin rather than by the mouth. Indeed, "flowing" skin can disrupt the ability of the immune system to recognize a harmless substance.

Mice and humans

It has been shown that mice exposed to egg whites or peanuts through the skin develop allergic reactions or anaphylaxis to these foods when they are subsequently consumed. The human food allergy can develop in the same way.

When we eat foods, we normally develop a tolerance, which means that no immune response occurs. However, when the skin leaks due to defective genes or is damaged by a condition such as eczema, food allergens can enter it. This stimulates the immune cells of the skin, which release chemical attack signals. Then, the next time specific foods are encountered, the cells are prepared to produce an allergic reaction.

More: More people than ever suffer from severe food allergies

The "flowing skin" of a baby's skin shortly after birth (measured by the amount of water that evaporates from the surface) helps predict the risk of food allergy at the age of two years. And recent research has shown that people with food allergies have molecular evidence that their skin is leaking and ready to respond, even if the skin looks normal.

Treatment and prevention

In an emergency situation, a food allergy is treated with drugs that neutralize the most dangerous features of an anaphylactic response: low blood pressure and airway obstruction. Adrenaline (administered outside hospitals by means of a "pen" auto-injector) causes a tightening of blood vessels – in order to maintain blood pressure – while bronchodilators cause the opening of respiratory tracts. Steroid treatment can mitigate the adverse effects of an overactive immune response. Corticosteroids are therefore also used to limit the production of inflammatory signals in the blood and throughout the body.

Parents and guardians often ask what they can do to prevent the development of food allergy, especially if there is a history of allergies in the family. The study Enquiring About Tolerance, or "EAT", has shown that introducing peanuts and eggs into the diet of babies from three months of age could reduce the risk of developing an allergy to these foods. The protective effect was less evident with other common foods such as milk, fish, wheat and sesame. This may be due to the fact that smaller amounts of these foods have been consumed.

Another ongoing study is to determine if the use of moisturizers (called emollients) in babies can improve the skin barrier and help prevent eczema and food allergies. The results are eagerly awaited, but further research will still be needed to clarify if and how food allergy can be prevented.

In the meantime, UK government guidelines continue to say that babies should be exclusively badfed up to the age of six months. Although it is not known whether badfeeding protects against food allergy, it is clear that bad milk can offer many benefits for the health of the baby and the mother.

Some people develop food allergies, but for others, it is their responsibility all the life to carefully avoid the foods involved. Attempts to prevent accidental exposure can fail and have disastrous consequences, as in the case of teenager Natasha Ednan-Laperouse, who is allergic to sesame and died of cardiac arrest after eating a wand that she did not know how to contain. sesame seeds.

Although accidental exposure to food can be very dangerous, immunotherapy – the voluntary application of food substances to the surface of a healthy skin – is currently being tested in clinical trials to the treatment of allergy to peanut and milk.

A better understanding of the causes of allergy will offer the opportunity to develop new treatments – and our own skin can be a means of prevention as well as treatment of life-threatening reactions.