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ADULT FOOD ALLERGY: POLLEN FOOD SYNDROME Kate Roberts RD Clinical Dietetic Advisor, Allergy UK
In primary care, it is common to see adults developing reactions to food. These foods can seem obscure and the symptoms can be vague. Dietitians are well placed to investigate these symptoms further, help identify trigger foods and educate on how people can manage their allergies. This article delves into Pollen Food Syndrome (PFS) which is increasing in the UK. Specialist adult allergy centres are not common and PFS sufferers are mainly seen in primary care or in general dietetic clinics. On average, 2% of the adult population across the UK suffer with PFS, but this ranges from 0.8% in Aberdeen to 4.1% in Croydon.1 It most commonly affects adults who have Allergic Rhinitis (hay fever); the reactions are caused due to the proteins in the food that are similar to those in pollen. The body mistakes them for allergens and this causes an allergic reaction. This is most common in birch pollen, as the main allergen Bet v 1 is highly cross-reactive to many plant foods.2 It is estimated that 50-90% of people who are sensitised to birch pollen also have PFS.1 The prevalence of Allergic Rhinitis has trebled within the last 30 years3 and, therefore, it is very likely that this is a condition that will be seen more in primary care and general dietetic practice. SYMPTOMS
The symptoms of PFS usually occur quickly (usually within five to 10 minutes) after eating and commonly involve itching, tingling or a burning sensation within the mouth, ears or throat. Swelling is less common but can occur in the lips, tongue and throat.2 More uncommon reactions include rashes, nausea, vomiting, sneezing and a blocked nose. More serious reactions 12
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could occur if large amounts of trigger foods are consumed and in very rare cases PFS can cause anaphylaxis. PFS is often referred to as Oral Allergy Syndrome (OAS), a term used to describe Mugwort any crossreactive plant food allergies. These include latex and non-specific lipid transfer proteins (LTPs); these allergies are not as common in the UK as PFS and result in more severe allergic reactions.1 Sensitisation to LTP allergens is more common in Mediterranean countries. If you have a patient of Mediterranean origin with severe reactions to fruit such as peaches, it is important to refer immediately to a specialist allergy team. FOODS ASSOCIATED WITH PFS
The foods that people react to depend on the pollen that they are sensitised to. Reactions only occur when the foods are raw or lightly cooked which can cause confusion in those having the reactions. Table 1 shows the main foods associated with allergic reactions and as pollens vary in different countries, the common UK pollens have been highlighted.
Table 1: Pollen and associated food4 Pollen
Fruit
Vegetables
Nuts
Grains
Kiwi, peach, apple, nectarine, apricot, banana, pear, plum, avocado, cherry, fig, strawberry, dried plum
Potato, carrot, celery, chicory, cilantro, fennel, pepper (green), parsley, parsnip, dill, cumin, tomato, bean sprouts, coriander, mangetout, tomato
Hazelnut, almond, walnut, brazil nut
Soybeans, wheat, lentils, peas, beans, peanuts
Apple, melon, watermelon
Carrot, celery, parsley, coriander, pepper, cilantro, fennel, aniseed, celery salt, mustard, spices
Sunflower seeds
Fig, melon, orange, kiwi, watermelon
Tomato, potato, Swiss chard
Peanut, wheat
Banana, melon, honey dew, watermelon
Pepper, squash, cucumber, artichoke, hibiscus, chamomile tea
Sunflower seeds
Weeds
Melon, watermelon, orange, kiwi
Tomato
Apple, cherry, peach, pear, strawberry, raspberry
Celery, parsley
Alder Parietaria
Cherry, melon
Birch*
Mugwort/ Wormwood*
Grass*
Ragweed
Hazelnut, almond, walnut
*common in the UK
Dietitians are well placed to take a detailed diet history in order to identify pollens involved. The use of a food and symptom diary can also be a useful tool, especially if people are able to complete it before the consultation.
• Allergic Rhinitis (hay fever) • Eczema • Asthma • Food allergy (could be resolved) • Family history of allergies
DIAGNOSIS
Questions to ask: • What are the symptoms of the reactions? • Are there specific foods which they react to? • Do they have reactions to the foods every time (are the reactions reproducible)? • Are the reactions the same?
In a perfect world, people would be referred to a specialist adult allergy centre for a diagnosis of PFS. Diagnosis will be based on an allergyfocused clinical history and often involves skin prick testing. The gold standard of diagnosis is an oral food challenge.1 However, often people are referred straight from GPs to a general dietetic clinic. If you are seeing someone with suspected PFS it is important to get a good clinical history and in-depth and allergy focused diet history as symptoms can be vague. Do they have any of the following?
The algorithm in Figure 1 overleaf is a useful tool for diagnosis. MANAGEMENT
People with PFS will need to avoid raw foods which trigger reactions. As mentioned previously, cooking the foods will make them www.NHDmag.com May 2018 - Issue 134
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CONDITIONS & DISORDERS Figure 1: Diagnosis algorithm to establish a reported reaction to food (RRF) and/or PFS1
less allergenic. Canned or pasteurised versions may also be tolerated. It is also possible that different varieties of foods may not have the same effect; for example, different varieties of apples or pears may not cause a reaction. Guides such as Table 1 are useful; however, there is no need to avoid food unless it causes symptoms. Eliminating multiple foods can result in a restricted diet, so it is important to ensure that estimated nutritional requirements are being met and that alternative sources of nutrition are suggested. When someone has a reaction, it is important that they stop eating the allergenic food. The symptoms should reduce naturally within 30
minutes; sipping water may help. Antihistamines can be prescribed to treat symptoms and, in rare cases, an adrenaline auto-injector (AAI) may be prescribed. People with asthma are more at risk of severe reactions and it is highly important that the asthma is well controlled. CONCLUSION
PFS is a common allergy in adults and is likely to increase in prevalence. Dietitians are well placed to help with diagnosis and management. Further information and support for healthcare professionals and patients can be found on the Allergy UK website www.allergyuk.org/.
References 1 Skypala IJ et al (2013). The prevalence of PFS and prevalence and characteristics of reported food allergy; a survey of UK adults aged 18-75 incorporating a validated PFS diagnostic questionnaire. Clinical & Experimental Allergy, 43, 928-940. doi: 10.1111/cea.12104 2 Allergy UK. Oral Allergy Syndrome Factsheet www.allergyuk.org/information-and-advice/conditions-and-symptoms/36-types-of-food-allergy 3 Gupta R et al (2007). Time trends in allergic disorders in the UK. Thorax. 2007 Jan; 62(1): 91-96. doi: 10.1136/thx.2004.038844 4 Kelava N et al (2014). Oral Allergy Syndrome - the need of a multidisciplinary approach. Acta Clin Croat 2014; 53: 210-219
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