Nightshades is the common name given to a group of plants in the Solanaceae
family of plants.
Plants in this family include aubergine (eggplant)
, goji berries
, cape gooseberry, potatoes
Nightshade allergies are relatively common, but there is a lot less information about them as they are not easily defined and categorised. Here we aim to provide more information on the different allergenic proteins which may be the cause of allergic reactions to nightshades.
Sichuan peppers are NOT in the nightshade family. Sichuan peppers
are actually in the Rutaceae
family of plants which makes them more closely related to citrus fruits.
There are six allergens associated with these foods, profilins, lipid transfer proteins, hevein, Bet v 1 like proteins, gibberellins and thaumatin.
If you are interested in which foods contain which allergenic proteins you can visit the Food Allergy Tool Page
Most of these foods contain profilin proteins, with the exception of goji berries, gooseberries and potatoes.
are found in a variety of fruits, vegetables, seeds and grains as well as plant and tree pollens.
How profilin proteins react will vary from person to person and the food they are found in, but they are generally broken down by digestion, cooking or processing, so are considered to be one of the minor panallergens. They are most likley to cause oral allergy type symptoms.
Profilin allergies can sometimes be linked to Latex Food Syndrome
as profilins are a minor panallergen found in the rubber plant which can sensitise latex allergy sufferers.
Lipid Transfer Proteins
Lipid Transfer Proteins are found in aubergine (eggplant), goji berries and tomatoes.
Lipid Transfer Proteins
(also called LTPs) are panallergens found in many groups of foods and can cause serious allergic reactions. It is often the allergen found to be linking what initially looks like lots of random food allergies together.
These proteins are heat stable, so can cause allergic reactions even after a food is cooked or processed, they are more likely to cause serious allergic reactions.
When a person is allergic to many foods containing LTPs, usually across many food groups they are said to have LTP Syndrome
is an allergenic protein found in potatoes and goji berries.
Hevein is the allergenic protein responsible for Latex Allergy, it has cross reactivity with similarly shaped proteins in the skin of the fruit or vegetables which can cause an allergic reaction; this is called Latex Food Syndrome
It is a very stable protein, so is not damaged by heat or processing and can cause severe allergic reactions.
Gibberellin regulated proteins are found in chillis, peppers and paprika.
are less common panallergens, they are plant hormones associated with growth and development. They are found in some tree pollens as well as fruit.
There have been a lot of recent studies on these proteins, so anticipate them being found in foods they are not currently linked to.
They are very heat stable and not broken down by digestion, so are an important food panallergen of note.
Thaumatin proteins are found in chillis, peppers and paprika.
proteins are made by plants to inhibit fungal growth and cause allergic reactions to certain foods. They are found in some tree pollens as well as fruit.
They are also referred to as thaumatin-like proteins (TLP) and have been shown to maintain their shape after thermal processing and are resistant to digestive enzymes. This makes them another important allergenic protein of note.
Bet v 1 Proteins
The only nightshade to contain Bet v 1 like allergens are tomatoes.
Bet v 1 allergies are commonly linked to Pollen Food Allergy Syndrome, which was previously called Oral Allergy Syndrome. These terms are still used interchangeably.
In this syndrome a person first becomes sensitised (allergic) to a tree or plant pollen. The most common in Pollen Food Allergy Syndrome is birch tree pollen. The allergenic protein in birch tree pollen is called Bet v 1
. A person can then find themselves allergic to other proteins in foods which are similar to Bet v 1 proteins, often called Bet v 1-like or Bet v 1 homologues. Bet v 1 proteins are found in a wide range of foods including fruits, vegetables, nuts, seeds and grains.
The symptoms of this syndrome are called oral allergy symptoms as they can cause sneezing, itchy mouth and lips as well as a scratchy throat and tongue. All in all, these foods can cause a general irritation of the mouth, nose and throat. It is very rarely serious enough for the throat to close as it does in anaphylaxis.
The Bet v 1 allergens are often referred to as ‘heat labile’, meaning that the proteins are damaged by heat and lose their ability to cause an allergic reaction. There are more proteins in the skin of the plant than in the flesh and seeds. If you can eat the food once heated or peeled with no or reduced allergic reactions then you should be able to determine if this is Pollen Food Allergy Syndrome or a true IgE allergy (an IgE allergy will have immediate symptoms which may include anaphylaxis, swelling and/or hives).
You can read more about Pollen Food Allergy Syndrome HERE
Table Showing which nightshades contain which allergenic proteins
Information in this table is from multiple resources – please visit the Food Allergy Index
for information on each individual allergen.
You can download a Nighshades Factsheet from the Allergy Resources Ko-fi Shop
for just $0.50 (£0.40 or €0.45).
Lots of fruits have been linked to lectins and/or salicylate intolerance. You can read more about food intolerances on the Food Intolerance
page, visit individual foods on the Food Allergy Index
or see the dedicated Lectins Page
to see which foods may be causing a problem.
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