Olives are fruit from trees in the Oleaceae family of plants, these are exclusively olive trees. This family of plants is important as those with an allergy to pollen from olive trees can be sensitised so they are allergic to other pollens which are similar in structure. You can read more about this on the Olive Pollen Page.

It is important to note that sensitisation to olive pollen does not mean you should avoid eating olives or using olive oil, there is very little evidence that there is cross reactivity through food.

Olive oils are very processed, so like other oils, unlikely to cause allergic reactions, but allergy to olives themselves has been recorded.

The allergen thought to cause food allergy reactions to olives is Thaumatin Like Proteins. These proteins give flavour and taste to a food. Thaumatins are not easily damaged to heating or processing, so can still cause allergic reactions when cooked.

Green olives are picked when the fruit is still not yet ripe and black olives are fully ripe fruit.

Olives can be high in histamine, especially those that are canned and preserved, so is not suitable for people following a low histamine diet.

They can also be high in sulphites, depending on how they are purchased and consumed - always check the label. 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.

Olives 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.

Green olives are high and black olives moderate 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.

An allergy to olives can be associated with allergic rhinitis (hayfever) for those who suffer with an allergy to olive pollen and in some rare cause olives or olive oil can cause contact allergic dermatitis.

Thaumatin like proteins are also found in apples, banana, cherry, garlic, grape, kiwi, orange and peach.

Note these food lists are not exhaustive, you can find the most up to date information on the Cross Reactivity Tool.

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