Salad Allergy: Can Healthy Vegetables Cause an Allergy?

Introduction

Salad is becoming popular as a main meal rather than a side dish due to increased awareness of health, wellness, and longevity. The salad-eating trend with highly-packed flavor, protein, antioxidants,  fiber, and plant-based ingredients is paving its way as a source of nutrients for many consumers. 

Yet discomfort or an allergy following consumption of salad is not unheard of. This can be associated with allergy testing, including oral allergy syndrome or pollen-food allergy, which we are going to explain further in this article.

Symptoms of salad allergy

Symptoms of allergy from salad can be mild, localized to the mouth area, though one can experience allergic symptoms affecting other parts of the body. In most cases, salad allergy symptoms are mild and go away following stopping consumption of the culprit food allergen. 

In some cases, the allergy may progress to a full-blown anaphylaxis, which is life-threatening if unaddressed medically in time. Hence, it is imperative to understand and be aware of the potential allergic symptoms.

Affected Body Areas	Allergy Symptoms
Oral Region	Itching, tinkling sensation over the lip, tongue, throat Swelling of the lip, tongue Scratchy throat Rash over the lips Hoarseness of voice
Respiratory System	Difficulty breathing Cough Wheezing
Gastrointestinal System	Bloated Nausea Vomiting Diarrhea
Dermatological	Hives Eczema Contact dermatitis rash
Systemic(Anaphylaxis)	Airway closing Difficulty breathing Dizzy/ fainting spell Impending doom Eyes and Mouth swelling Generalized body rash

Oral Allergy Syndrome

Oral Allergy Syndrome is a type of food allergy that happens after consumption of certain fruits and vegetables. A person with Oral Allergy Syndrome is first exposed and sensitized to certain grass pollen in the environment through direct contact on the skin or inhalation. 

Over time, the immune system builds memory cells in the blood and lymphatic circulation. 

When a person consumes certain fruits or vegetables, the body's immune system inadvertently recognizes the fruit-vegetable allergen as grass-pollen allergens, resulting in a cascade of inflammatory and allergic responses. This eventually manifests itself as a clinical picture of localized swelling, redness, itch, and discomfort.  As the protein structure between the fruits-vegetables are similar to grass-pollen structures, this explains the cross-reactivity of allergic reactions between the two. Hence, Oral Allergy Syndrome is also known as Pollen-Food Allergy Syndrome. Expectedly, Oral Allergy Syndrome can be more severe during pollen season. 

Vegetables in salad that have the potential to cause allergy

Although salad is a dish that can be added to with animal proteins, it generally comprises of vegetables, fruits, nuts, and legumes. The base of the salad is generally made up of a variety of 'healthy' greens. Below summarizes the common fruits and vegetables seen in salad that can cause allergic symptoms by cross-reactivity to certain grass pollen. 

Understanding the correlation between fruits-vegetable and grass-pollen is useful in evaluating a person's predisposition to concurrent airborne and food allergies, thereafter making prudent consumer choices in avoiding certain food or pollen exposure (if possible).

Salad Greens	Cross-reactive Grass/Pollen
Carrots Celery Kiwi Banana Apple Peach Apricot Cherry Potato Parsley Coriander	Birch
Garlic Onion Bell pepper Broccoli  Cabbage Cauliflower Celery Parsley Coriander	Mugwort
Cucumber Banana Melons	Ragweed
Tomato Peach Orange Kiwi Melon	Grass

Lettuce is another common salad and sandwich vegetable that can be associated with allergy. Allergy to lettuce is due to the presence of lipid transfer protein (LTP), which is a type of protein that plays a role in transporting cholesterol (lipids) between cell membranes of the plants and regulates the transportation of cholesterol in humans. In susceptible individuals to LTP, one can develop allergy symptoms. As LTP can be found in various plants, vegetables, and fruits, there is cross-reactivity of lettuce with various foods, fruits, and vegetables.

Lettuce is associated with food allergy, which can range from mild to even severe reactions in the case of anaphylaxis. Allergy symptoms such as hives, gastrointestinal upset, facial swelling (angioedema), and eczema have been reported. Hand allergic contact dermatitis due to lettuce has been documented in food handlers and chefs dealing with lettuce. 

Can it possibly not be related to the vegetable in the salad that triggers the allergy?

Yes, this is possible. While vegetables and greens are the key components found in salad, the dish is frequently garnished with meat such as beef/ chicken/ pork/ shellfish, nuts and various salad dressings. Besides, allergies can be completely unrelated to the salad, secondary to concurrent surrounding allergens such as dust mite, pet dander allergens and etc.

For these reasons, it is always prudent to discuss your symptoms with your healthcare providers so that they can tease out your potential allergies further. Learn more about DB Clinic and the allergy care available at the clinic.

Does it make a difference in salad allergies if I cook my vegetables?

Cooking or boiling the fruits and vegetables found in the salad can alleviate the allergy symptoms. The allergenic proteins found in fruits and vegetables are able to be denatured under high temperature; hence, the immune system is able to tolerate them better following consumption. 

Alternatively, one can consider peeling off the outer layer of the vegetable (if possible) or the skin of the fruits.

How can I test for potential salad allergies?

It is worth discussing with your healthcare providers your symptoms and potential exposure to salad. Do let your doctor know the components that are found on the salad. Your doctor may also enquire about your medical history on any history of grass or pollen or seasonal-related allergies, as these can be relevant to salad allergies.

Allergy tests can be useful to evaluate the potential vegetable-fruits that may cause you allergic symptoms. Your doctor may also advise considering grass-pollen allergy testing to evaluate potential concurrent allergies.

Allergy tests can come in the form of

• Skin prick tests
• Blood RAST test
• Food challenge tests

Allergy test options are usually determined based on

• Severity of allergy symptoms
• Safety of the allergy tests on patients
• Commercial availability of the tests
• Patient's concerns and preference

Need an allergy test? If you are unsure which type of allergy testing may be appropriate for your symptoms, speak with our medical team.

What should I do if I have salad allergies?

• Key management of salad allergies is to avoid identifiable food triggers. Being mindful of the potential cross-reactivity with pollen and reducing exposure to pollen-grass or fruits and vegetables, especially during peak pollen seasons
• Avoid eating raw fruits or vegetables; consider boiling or cooking the vegetables. Peel the skin of the fruits or the external layer of the vegetable.
• Your doctor may prescribe you antihistamine and steroid medication to manage the allergy symptoms.
• In those with a history of anaphylaxis or severe allergic reactions, carrying an EpiPen is advisable to reverse any potential catastrophic allergic event. 

Afterwords...

Although allergy to salad vegetables and fruits is uncommon, it is not unheard of that one experiences discomfort following a salad meal. This can potentially be due to oral-pollen allergy. Understanding the triggering raw fruits and vegetables and the links with grass and pollen allows one to take appropriate steps in mediating the triggers and symptoms, ensuring patients with oral pollen syndrome can still enjoy a variety of hearty meals.

If you are looking for an allergy testing clinic in Singapore or would like to discuss your symptoms with a healthcare professional, you can contact DB Clinic for further advice.

References: 

1. Kato Y, Morikawa T, Fujieda S. Comprehensive review of pollen-food allergy syndrome: Pathogenesis, epidemiology, and treatment approaches. Allergol Int. 2025 Jan;74(1):42-50.
2. Muluk NB, Cingi C. Oral allergy syndrome. Am J Rhinol Allergy. 2018 Jan 1;32(1):27-30.
3. Muñoz-García E, Luengo-Sánchez O, Moreno-Pérez N, Cuesta-Herranz J, Pastor-Vargas C, Cardona V. Lettuce Allergy Is a Lipid Transfer Syndrome-Related Food Allergy With a High Risk of Severe Reactions. J Investig Allergol Clin Immunol. 2017;27(2):98-103.
4. Paulsen E, Andersen KE. Lettuce contact allergy. Contact Dermatitis. 2016 Feb;74(2):67-75.
5. Fernández-Rivas M. Fruit and vegetable allergy. Chem Immunol Allergy. 2015;101:162-70.