Lettuce is in the Asteraceae
family of plants, other plants in this family include sunflower seeds, tarragon, artichoke and camomile.
Lettuce contains one allergenic protein called Lac s 1, it is a Lipid Transfer Protein
(LTP), these proteins are resistant to heat and are found in many types of plants. People suffering from a more severe allergy to cooked fruit may be sensitised to this group of proteins.
Lettuce also contains a contact allergen called lactucarium which can cause skin irritation. This is the white milky fluid found in the base of the stems when the plant is picked.
Lettuce is a low FODMAP food. FODMAP
stands for F
olyols. 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.
Lettuce is one of the few fresh foods that contains a moderate amount of sulphites
. Sulphites are inorganic salts used in preservations and have the potential to cause symptoms of food intolerance to those sensitive to sulphites, this food intolerance is more common in asthmatics. An improvement in symptoms can be made with a change to a low sulphite diet.
Most lettuce varieties have a moderate amount of salicylates (iceburg lettuce are low in salicylates). salicylates
have the potential to cause worsening of asthma, swelling, itching and hives as well as food intolerance symptoms in people who are sensitive to salicylates.
You can read more about Food Intolerances
on the dedicated Food Intolerance Page.
You may be suffering from LTP Syndrome
if you have reactions to various fruits, vegetables and nuts and your reactions continue to be severe after you have discarded the peel and have cooked the food.
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 plants which may cause a cross reaction on contact are chicory and endives.
Allergen Encyclopedia - Lettuce
Lipid Transfer Proteins (LTP Syndrome)
Dermnet NZ - Lettuce Contact Allergens
Anaphylaxis Campaign - Vegetable Allergies
Allergy information for: Lettuce (Lactuca sativa (Garden lettuce))
Healthline - FODMAP Foods
ATP Science - Salicylate Food List
Articles and Journals
Improving In Vitro Detection of Sensitization to Lipid Transfer Proteins: A New Molecular Multiplex IgE Assay, 2023
A case of eosinophilic pneumonia induced by lettuce, 2023
Lipid transfer protein allergy: A review of current controversies, 2022
The diagnosis and management of allergic reactions in patients sensitized to non-specific lipid transfer proteins, 2021
Asteraceae species as potential environmental factors of allergy, 2018
Lettuce Allergy and Hand Eczema, 2020
Occupational respiratory allergy to lettuce in lettuce farmers, 2020
Lipid Transfer Protein allergy in the United Kingdom: Characterization and comparison with a matched Italian cohort, 2019
Lettuce Allergy Is a Lipid Transfer Syndrome-Related Food Allergy With a High Risk of Severe Reactions, 2017
Lettuce contact allergy, 2016
Anaphylaxis to plant-foods and pollen allergens in patients with lipid transfer protein syndrome, 2013
Lettuce anaphylaxis: identification of a lipid transfer protein as the major allergen, 2003
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