Symptoms can vary from mild, like sneezing, to life-threatening, known as anaphylaxis. Allergic diseases include hay fever, asthma, and food allergies, and it’s estimated that around 44% of adults and 50% of children have an allergy.

Other related allergies include coeliac disease, which is an adverse reaction to gluten, and eosinophilic esophagitis where a build-up of immune cells in the oesophagus causes inflammation, leading to difficulty swallowing.

Common allergies include tree and grass pollen; dust; foods including celery, cereals containing gluten (such as wheat, barley, and oats), crustaceans (such as prawns, crabs, and lobsters), eggs, fish, lupin (a type of legume), milk, molluscs (such as mussels and oysters), mustard, nuts, sesame, soy beans, and sulphur dioxide; animals, such as cats and dogs; insect stings, such as those from bees and wasps, and certain medications such as penicillin, antibiotics, and aspirin.


There are a few thoughts behind possible causes of an allergy:

• Genetics. Children who have a parent or grandparent with an allergy are at an increased risk of developing an allergy themselves. If one parent has an allergy, the risk is doubled, but if both parents have allergies, then this risk increases to between 60-80%.

• The hygiene hypothesis. As children, being exposed to germs is thought to help strengthen and develop the immune system. This can then help to protect against the development of allergies or asthma. However, in today’s modern world, we have become overly clean. The use of chemical cleaning products, antibacterial solutions, and antibiotics mean that we, and especially children, are being exposed to fewer germs than our ancestors, which is having a detrimental effect on the immune system.

• Changes in our diet. Western diets have become more reliant on processed and ultra-processed foods, which means we are not getting as many essential nutrients to support the immune system. There is also evidence that fewer food choices in the first year of life are associated with an increased risk of allergies and asthma in infancy, compared to those who have a greater variety of food, which reduces the risk and may offer protection against allergies, asthma, and food sensitisation.

• Pollution and environmental factors. As the world becomes more crowded, there is more urbanization and industrialisation. This, in turn, has meant greater air pollution and exposure to toxins in the environment, which is impacting our immune systems but also those of children. Air pollution alone has been found to have an adverse effect on respiratory health, which can make pollen more allergenic and increase the total pollen count.

• Vitamin D deficiency. Vitamin D is an essential nutrient that helps keep our immune system healthy and is important for lung development. However, vitamin D deficiency is now common as more of us work indoors, use sunblock, or actively avoid spending time in the sun. Therefore, low vitamin levels lead to a lower immune status, which can increase the risk of allergic disorders.

For more information please contact Grupo HPA Saude on (+351) 282 420 400.