Oral Allergy Syndrome

Oral Allergy Syndrome

As we approach the warmer months of the year, many start looking forward to enjoying the sunshine and the seasonal perks to come. However, for others, health issues such as hay fever, can rear their heads during this time, plaguing the lives of sufferers who should be enjoying the warmer weather. For those with Oral Allergy Syndrome (OAS), it can be a time of concern. However, with some expert knowledge and advice, you can plan how to effectively manage this allergy condition.

What is Oral Allergy Syndrome (OAS)?

Also known as ‘pollen-food allergy syndrome’, many people confuse OAS with general food allergies i.e. the type that results in anaphylaxis. Whereas that type of reaction is related to the specific food being consumed, OAS is triggered in those suffering from long-standing pollen allergies (grass, mugwort, ragweed or birch tree) when they consume food antigens which have a similar structure to pollen after cross-reaction during growth. The syndrome presents itself via symptoms in the mouth and throat after coming into contact with a triggering food (usually fruit, vegetables, nuts, herbs or spices)1,2.

Foods to Avoid

Unfortunately, if you suffer from Oral Allergy Syndrome, managing the condition is not as simple as just avoiding a certain list of foods. The range of possible triggers is vast, and you wouldn’t want to avoid them all as they contain much of the nutrition we need in our diets. Triggering foods can also depend on where you live, the climate the food was grown in and the type of pollen you have allergies to. For example, a peach in one location may cross-react with a type of tree pollen, but in another area, the same peach may cross-react with grass pollen. The best advice is to avoid the foods that personally cause you symptoms of OAS1.

Foods associated with the various types of pollen1,3,4:

  • Grass pollen – carrots, celery, coriander, cumin, fennel, green peppers, melons, oranges, parsnips, peaches, pears, peas, parsley, plums, potatoes, prunes, rye, soya, tomatoes, walnuts, watermelon, various seeds (caraway, poppy, sesame, sunflower)
  • Mugwort pollen – apricots, asparagus, chestnuts, lentils
  • Ragweed pollen: bananas, cantaloupes, courgettes, cucumbers, honeydew, melons, squash, sunflower seeds, watermelons
  • Birch tree pollen: almonds, anise, apples, apricots, beans, carrots, celery, cherries, cilantro, dill, fennel, hazelnuts, lentils, kiwi fruit, nectarines, parsley, parsnips, peaches, pears, plums, potatoes, walnuts

What are the Symptoms of OAS?

Common OAS symptoms include1,3,4:

  • tingling, itching or irritation in the mouth
  • swelling of the tongue, lips, mouth or throat
  • scratchy throat
  • blisters on the lips and tongue
  • tightness in the throat
  • itchy ears (less common)

While most symptoms present in the mouth and throat, in more serious cases, it’s possible for sufferers to go on to have anaphylaxis or abdominal symptoms. However, these are unlikely, and most symptoms of OAS usually occur within 5 to 30 minutes of triggering foods coming into direct contact with the oral cavity or throat2. These should subside quickly3 once the trigger has been removed.

What Causes OAS?

When looking at the causes of OAS, it relates to the structure of the food and how it’s been affected by the pollen around it. In plant-derived foods such as fruit, nuts, herbs, spices and vegetables, cross-reactivity may occur if pollen comes into contact with these foods as they’re grown. There has to be a match of at least 70% in the amino acid sequence of the food and pollen proteins for a reaction to take place1. Immunoglobulin E (IgE) is a type of antibody made by cells in our blood plasma. It’s believed to be this antibody which mediates the OAS reaction in those allergic to pollen4,5. Our immune systems attack the proteins in the food as if they were proteins of pollen, creating an allergic reaction when eating triggering foods6.

Managing OAS: Making the Necessary Changes

Once diagnosed with OAS, sufferers can manage the condition through lifestyle and dietary changes, using their symptoms as a guide for which specific foods to avoid. Many of the triggering food can be eaten once they’re cooked as this process can distort the proteins in the food meaning their structure no longer resembles that of pollen. However, this is not guaranteed3,4.

Most sufferers of OAS manage their condition by avoiding the foods that trigger their symptoms, so if you’re not sure which ones these are, you may wish to conduct an elimination diet to narrow down your OAS-triggers1.

Unfortunately, the types of food OAS-sufferers have to cut out are often full of nutritional value. Therefore, it’s important to eat the types of non-triggering foods which may replace the vitamins and minerals you’re missing out on. You can also take supplements to ensure you don’t develop any deficiencies, especially if you’re cutting out a substantial number of nutritional food items. A few you may like to consider are vitamin C, vitamins B1, B2, B6, vitamin A and folic acid as they’re present in most fruit, vegetables and other OAS-triggering foods.

Vitamin C

Vitamin C is commonly found in plant-based foods including oranges, kiwi fruit, and carrots, so OAS-sufferers may wish to find another source for this. It’s a vital vitamin which contributes towards the health of our tissues, bones and blood vessels, helps maintain normal metabolism and is a natural energy-booster. It also helps with the absorption the iron in our diet and regenerate vitamin E, another antioxidant which aids cell integrity7.

Vitamin A

Often found in dark leafy vegetables, carrots and parsley, vitamin A can also be sourced in butter, cod liver oil, whole milk, oily fish and egg yolks. Its main health benefits include maintaining normal vision, strengthening the immune system and keeping mucous membranes healthy. Those who are pregnant or planning to be, should seek medical advice before consuming8.

Vitamins B1, B2, B6

This group of vitamins are important for the promotion of a normal metabolism which is vital for reducing fatigue. They also improve overall psychological function by helping to maintain our nervous system. Other benefits include maintaining the health of our skin, iron metabolism and mucous membranes, as well as actively helping towards healthier vision9.

Folic Acid (Vitamin B9)

Natural sources of folic acid include dark leafy vegetables, broccoli and beans (kidney and soya). It’s an essential supplement for pregnant women and those wishing to conceive, and along with vitamin B12, promotes the health of our nervous system and blood10.

With the warmer months ahead, everyone wants the confidence to enjoy themselves without health issues caused by the seasonal changes putting a dampener on life. As the pollen count rises, OAS-sufferers should manage their condition by cutting out the foods that affect them and seek advice if possible. Luckily, those having to cut out triggering foods have plenty of options when it comes to restoring the nutrition they’re missing out on.


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Joneja J. (2016) Oral Allergy Syndrome. Available at: http://www.foodsmatter.com/allergy_intolerance/oral_allergy_syndrome/articles/joneja-oral-all-syndrome-04-16.html

Webber C.M. and England, R.W. (2010) ‘Oral allergy syndrome: a clinical, diagnostic, and therapeutic challenge.’, Annals of Allergy, Asthma & Immunology, 104(2), pp. 101-108.

American College of Allergy, Asthma & Immunology (2015) Types of Food Allergy: Oral Allergy Syndrome. Available at: http://acaai.org/allergies/types/food-allergies/types-food-allergy/oral-allergy-syndrome

Ausukua, M., Dublin, I., Echebarria, M.A. and Aguirre, J.M. (2009) ‘Oral allergy syndrome (OAS). General and stomatological aspects’, Medicina Oral Patologia Oral Y Cirugia Bucal, 14(11), pp. 568-572.

Ivković-Jureković I. (2014) ‘Oral allergy syndrome’, Acta Medica Croatica, 68(3), pp. 283-287.

Kashyap R.R. and Kashyap, R.S. (2015) ‘Oral allergy syndrome: an update for stomatologists’, Journal of Allergy





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