My throat itches after I eat raw tomatoes, but not after I eat pasta sauce. Why?

Question: My throat itches after I eat raw tomatoes, but not after I eat pasta sauce. Why?

Answer: These symptoms are most likely due to something known as an oral allergy syndrome, caused by the relationship between proteins found in fresh tomatoes and grass pollen. The oral allergy syndrome (OAS) is a form of food allergy that is caused by a person having an allergy to particular pollen. The pollen, in this case grass pollen, has similar proteins (called profilins) found in a certain fruit, in this case tomato, which causes a person to be allergic to both.

When a fresh tomato is eaten, a person may experience itching, burning, or stinging sensations of the mouth, throat and tongue. The symptoms generally last only a few seconds or minutes, as the proteins that cause the symptoms are broken down quickly by saliva. Since cooking, baking or processing the food (as is the case with tomato sauces) breaks down these proteins as well, a person with OAS to a fresh tomato can eat tomato–based sauces without symptoms.

Want to find out more? Read the full-length article on the oral allergy syndrome.

_Sources:

Sicherer SH. Clinical Implications of Cross-Reactive Food Allergens. J Allergy Clin Immunol. 2001; 108:881-90.

Ortolani C, Ispano M, Pastorella EA, Ansaloni R, Magri GC. Comparison of Results of Skin Prick Tests and RAST in 100 Patients with Oral Allergy Syndrome. J Allergy Clin Immunol. 1989; 83:683-90.

Sampson HA. Adverse Reactions to Foods. In: Adkinson NF, Yunginger JW, Busse WW, et al, eds. Middleton’s Allergy Principles and Practice. 6th edition. Philadelphia: Mosby Publishing; 2003:1619-1643.

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