Lupin is a legume which includes several hundreds species. Three species are used for human consumption. As a legume, lupin is related to peanuts, soybeans, peas, beans, lenses and chick peas. They all belong to the same botanical family, Leguminoseae/Fabaceae. Among those allergic to one legume it is not unusual to react to several legumes due to structural relations between proteins. Allergy to lupin is sometimes accompanied with allergy to peanuts, soy, peas, beans, lenses or chick peas.
Lupin seeds serve as raw material for the production of lupin flour. Lupin seeds are consumed as snacks in the southern part of Europe. Lupine flour is used in a variety of goods like bread, pastries and biscuits. Lupin flour is a common ingredient in gluten free products like pasta.
An allergic reaction to lupin in fortified pasta was first reported in 1994. Since then a number of reports of allergic reactions have been published including one case of anaphylaxis. Lupin flour sensitization may also occur via inhalation. Some of the patients had a known allergy to peanuts and/or soy.
Several proteins have been identified in lupin to which allergic individuals may react.
Labeling
The presence of lupin and products thereof in food products must always be declared, se further in LIVSFS 2004:27 Livsmedelsverkets föreskrifter om märkning och presentation av livsmedel [in Swedish]. (see link to the right).
Examples of methods of analysis
Sensitive commercial ELISA test kits are available for the analysis of lupin. The limit of quantification is 1 mg lupin /kg (ppm) but varies somewhat with the matrix being analyzed.
Lupin can be identified with DNA methods. A positive result in a DNA analysis indicates the presence of lupin in a sample.
Providers of test kit often have a validation protocol to be submitted with the test kit upon request. Laboratories using commercial assays must establish in house control of limit of detection and limit of quantification in actual matrices even if the test has been validated by the provider.
Allergic reactions / Doses
Few studies have been performed to determine the minimum tolerable dose in lupin sensitized individuals.
Challenge doses of lupin flour ranging from 265 to 1000 mg triggered allergic reactions in five children with peanut allergy in addition to allergy to lupin. However, the lowest dose triggering reactions has not been established.
Anaphylaxis was reported in a 38 year old female after ingestion of three lupin seeds.