By Allergen Bureau

What is Pollen Food Syndrome?

Pollen Food Syndrome, commonly referred to as oral allergy syndrome, is a hypersensitivity reaction to fruits, vegetables and nuts, usually causing mild irritant symptoms such as itching of the mouth, lips and throat when these plant foods are eaten in their raw form. People with the condition are often also sensitised to grass, tree or weed pollen.

Many plant-based foods, including fruit, vegetables, nuts and cereals, have a protein structure that is very similar to the proteins found in pollens in trees, grasses and weeds, causing allergic cross-reactivity. The most common symptoms of pollen food syndrome are the same as those associated with hay fever, although it can sometimes also cause contact urticaria, leading to swelling of the mouth and throat. Symptoms usually arise within five to 10 minutes of eating the allergic food and settle within an hour, often without any medical intervention.

When the trigger food is a tree nut (usually almond or hazelnut) or peanut, pollen food allergy may cause concern about the potential severity of any future reactions, indications for prescribing adrenaline, and the extent of the necessary dietary avoidance.

Recently, molecular allergology has shown that those who have pollen food syndrome are exclusively sensitised to the proteins PR10 and profilins, whereas people with more severe nut allergy generally exhibit sensitisation to seed storage proteins as well.

Managing pollen food syndrome involves avoiding the specific trigger foods and understanding the risk of more severe allergic reactions. Although avoidance is currently the primary strategy, future research aims to clarify the risk of anaphylaxis in those with pollen food syndrome and explore the role of food or pollen allergen immunotherapy in preventing or mitigating pollen food syndrome.

References: Giovannini et al. Diagnosis and Management of Pollen Food Allergy Syndrome to Nuts. J Allergy Clin Immunol Pract. 2024 Mar;12(3). DOI. 10.1016/j.jaip.2024.01.025.

Additional reporting: Pollen Food Syndrome – Allergy UK