Vegetable intolerance and allergy

Vegetable allergy and intolerance

Many of us have been repeatedly told about the importance of eating our vegetables. You may even have flashbacks of being forced to finish your plate of vegetables as a child. They’re full of fibre and nutrients and are an essential part of a healthy diet. However, while these plants may generally be very good for you, the way you react to some of them may not be so good. Today we’re going to look at what vegetables might be wreaking havoc with your health and what you can do to test for a vegetable allergy and intolerance.


Vegetable allergy

It may surprise you to hear that you can be allergic to vegetables. As we’ve discussed in our previous articles, an allergic reaction can occur within minutes to a couple of hours after coming into contact with a food trigger. Once the immune system reacts to the food, the symptoms can range from mild to severe, depending on the type of reaction and how sensitive you are to the food.

When it comes to vegetable allergies, there are two main types of reactions:


Vegetable Allergy

  1. pollen food allergy syndrome (PFAS): a reaction experienced by people with an allergy to pollens; and
  2. a true allergy to vegetables: animmune
  3. reaction unrelated to pollen, which can lead to anaphylaxis.

These reactions have different triggers, as well as different symptoms. To understand them better, let’s explore both of these reactions in more detail.

Pollen food allergy syndrome (PFAS)

Some people who are allergic to pollen and have hay fever can also experience allergic symptoms after eating certain fruits and vegetables. This is because these plants can carry similar proteins to pollen. The immune system then recognises the vegetable proteins as pollen, and it reacts to the vegetables as well.

This reaction usually only happens when the vegetables are raw and cause more minor symptoms the more the vegetables are cooked. This is because cooking the vegetables changes (or breaks down) the proteins that the immune system is reacting to, so they no longer seem like pollen protein.

Pollen Food Allergy Syndrome

The symptoms of pollen food allergy syndrome can include:

  • tingling of the tongue or lips
  • redness, itching or swelling of the tongue, mouth or ears
  • sneezing
  • runny nose
  • itchy or watery eyes
  • mild swelling of the throat
  • stomach pain or nausea (rarely)

Pollen food allergy syndrome symptoms are usually mild and rarely lead to anaphylaxis (a severe allergic reaction).

Sometimes pollen food allergy syndrome is referred to as oral allergy syndrome (OAS). While some medical professionals may still refer to it in this way, oral allergy syndromeis technically meant to refer to mild allergic reactions that predominantly affect the mouth and throat and are not necessarily connected to pollen. However, pollen food allergy syndrome can lead to oral allergy syndrome if the symptoms are confined to the mouth, lips, and throat. Oral allergy syndrome is prevalent in people who react to raw vegetables.

Testing for vegetable allergy

If you have a latex allergy, you may also react to certain fruits and vegetables like avocado, banana, and melons. This is because the latex has proteins that are similar to the proteins in these fruits and vegetables. Just like the pollen and vegetables can cause an allergic reaction, the latex and vegetables share such similar proteins that your body reacts to both. These reactions are caused by “cross-reactivity”, – which is a reaction to different triggers (e.g. latex and vegetables) that appear the same to your immune system.

True vegetable allergy and anaphylaxis

A true allergy to vegetables is not related to pollen and hay fever. It is a reaction to the proteins in the vegetables. While any vegetable can cause an allergic reaction, those that have been most documented include potato, bell pepper (capsicum), carrot, cabbage, avocado, asparagus, turnip, zucchini, pumpkin, and lettuce.

The symptoms of vegetable allergy can range from mild to a severe reaction called anaphylaxis. These symptoms can include:

Vegetable intolerance

Leafy Green Allergy

  • swelling of the tongue or mouth
  • throat swelling that can cause restricted breathing
  • wheezing
  • coughing
  • difficulty breathing or gasping for breath
  • nasal congestion
  • skin rashes (e.g. hives)
  • stomach pain or cramps
  • nausea (or vomiting, rarely)
  • a drop in blood pressure that can lead to dizziness and fainting
  • loss of consciousness

Seek immediate medical attention if you experience these symptoms. If you are at risk of anaphylaxis, you may be prescribed self-injectable adrenaline (Jext or EpiPen) as well as anti-histamines.

Vegetable intolerance

A vegetable intolerance is different to having a vegetable allergy. An intolerance to vegetables is caused by either an issue with how your body digests vegetables or your body’s reaction to a chemical in the food. It is not an immune reaction but an issue with metabolism (the way your body breaks down, absorbs, and eliminates foods and food chemicals).

Some components in vegetables that you can react to include:

Cucumber Allergy

  • Alkaloids

Alkaloids are chemicals that plants produce to protect themselves from pests. This is one reason why people can react to nightshade plants like tomatoes, eggplants and chilli.

  • Salicylates

Like alkaloids, salicylates are made by plants to defend themselves from insects and disease. Salicylates can be a problem in people who have an impaired ability to digest and excrete them properly.

  • Amines

Amines (like histamine) are formed when certain foods ripen or age. They can cause allergy-like symptoms in sensitive individuals who cannot effectively metabolise them.

  • Oxalates

Oxalates are naturally found in plants and are made by your body. Having too many oxalates in the body can draw out minerals, like calcium, and lead to issues like painful urination and also kidney stones.

  • Insoluble fibre and FODMAP sugars

Some vegetables contain fibres and sugars (called FODMAPs) that are not easily broken down in the gut. This can lead to digestive symptoms like gas and bloating and also contribute to irritable bowel syndrome symptoms (IBS).

Allergy to Raw Fruits and Vegetables

Testing for vegetable allergy or intolerance

If you suspect that you have an allergy, it’s essential that you see your doctor as soon as possible. Your doctor may refer you to an allergy specialist (called an allergist or immunologist), who will conduct a skin prick test and blood test to determine if you have an allergy and also identify what you’re allergic to.

To check for food intolerance’s, it is beneficial to work with a nutritionist (like a dietitian or naturopath) who can help you pinpoint what you’re reacting to. You can also use a food intolerance test, like the one we offer online HERE. Our lab provides a fast analysis of over 350 foods so you can understand what’s triggering your symptoms.

Carrot Allergy

Pear Allergy


Today we took a deep dive into the different types of vegetable allergies and intolerance’s. We learnt that a vegetable allergy can occur when your immune system reacts to the protein in vegetables. This can lead to mild symptoms or a more severe reaction known as anaphylaxis. An allergy to vegetables can also happen because of cross-reactions with pollen, known as pollen food allergy syndrome (PFAS), and latex. We compared these different allergic reactions to a vegetable intolerance, which is not caused by an immune reaction. Instead, we learnt that vegetable intolerance is caused by poor digestion and metabolism of vegetables and the chemicals that they contain. We then looked at how you can test for vegetable allergy and intolerance to determine what you are reacting to.


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