Tomatoes are in the Solanaceae family of plants. Other plants in this family include aubergine (eggplant), peppers, chillis and goji berries. This group of plants are also commonly called 'nightshades'.

There are 7 allergens associated with tomato allergy - the main allergen in tomato is Sola l 4 which is similar in shape to the Bet v 1 allergens which can cause oral allergy type symptoms.

Three of the proteins found in tomato are Lipid Transfer Proteins, (LTPs). These proteins are panallergens with the potential to cause serious allergic reactions.

Sol l 1 is a profilin protein, these proteins are also panallergens and can cause problems across lots of groups of fruit and vegetables.

Tomatoes also contain a plant cyclophilin, which are multi functional proteins.

Tomato is a food high in histamine, so is not suitable for people following a low histamine diet.

Tomatoes which have been pickled or preserved, e.g. chutney is also high in sulphites. These can be eaten in small amounts by people who are sensitive to them, but high sulphite foods are best avoided.

Tomatoes are a low FODMAP food. FODMAP stands for Fermentable oligosaccharides, disaccharides, monosaccharides and polyols. Foods high in FODMAPs can cause symptoms of food intolerance, affecting the gastro intestinal system and this can be mistaken for a true IgE food allergy.

Fresh tomatoes are low in salicylates, but being processed or canned increases the amount of salicylates in the product. So tomatoes have the potential to cause gastrointestinal food intolerance symptoms in people who are sensitive to salicylates.

Tomatoes are one of the few vegetables to contain a moderate amount of lectins, another cause of food intolerance. Cooking foods with lectins makes them more digestible and can reduce the symptoms of food intolerance.

You may have Pollen-Food Allergy Syndrome if you suffer from tomato allergy with oral allergy symptoms to 3 or more of the foods mentioned in cross reactivity section.

Allergy to tomato is sometimes linked to Celery-Mugwort-Spice Syndrome as the sensitising allergen is a profilin protein called Art v 4, these proteins are also sometimes also called Bet v 2 proteins.

The lipid transfer proteins in tomato may cause problems if you suffer from LTP Syndrome.

To a lesser extent tomato allergy has been linked to Latex Food Syndrome, which is caused by the body confusing the proteins it encounters in food to that of the profilin proteins found in latex to which it is already sensitised.

If sensitised to birch tree pollen you may have Pollen Food Allergy Syndrome and may also react to apple, kiwi, pear, peach, plum, nectarine, apricots, cherries, potato, celery, carrot, parsnip, pepper, dill, cumin, peas, coriander, fennel, hazelnut, walnut, almonds, peanuts, lentils and beans.

If sensitised to grass pollen you may also react to melon, potato, oranges and peanuts.

Common foods involved in LTP allergy include kiwi, strawberries, sunflower seeds, walnut, apple, mulberry, banana, pea, apricot, cherry, plum, almond, peach pomegranate, raspberry, tomato, grape, celery, peanut, asparagus, cabbage, broccoli, chestnut, lemon, tangerine, orange, hazelnut, lettuce, lentils, lupin, green bean, pear, mustard, wheat and maize.

Other foods containing plant profilins are kiwi, pineapple, celery, peanut, chilli, watermelon, orange, hazelnut, melon, strawberry, soya, barley, walnut, lychee, lupin, apple, banana, date, cherry, almond, peach, pear, mustard, carrot, aubergine and wheat.

The only other foods to contain cyclophilins are peanuts, but the protein has been acknowledged as an airway allergen in mould, birch tree pollen, dust mites, olive tree pollen and magic mushrooms.

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