Lupin Allergy; Coming Soon to a Town Near You

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Lupin beans have been popular on the European continent for many years and now lupin flour is increasingly being used as an ingredient in processed foods and health foods in other countries. So far, only IgE-mediated reactions to lupin have been reported, but they can be quite severe, especially for people who are also allergic to peanuts. Not only do more and more processed foods contain lupin flour, lupin can also be found in cosmetics and its fibres used to make clothing and linen products.

And now for the details, which include:

What is an allergy to lupin?

Lupin beans are the seeds of the lupin plant (genus Lupinus), a tall plant with colourful flower spikes. There are about 450 known species of lupin, but only four—known as ‘the sweet lupin group’—are used in food production:

• Lupinus albus (white lupin, Mediterranean countries)
• Lupinus luteus (yellow lupin, Central Europe)
• Lupinus angustifolius (blue lupin or narrow-leafed lupin, Australia)
• Lupinus mutabilis (pearl or Andean lupin, Andean Highlands)

Lupin is a legume, like broad bean, soybean, chickpea and peanut. It originated in the Mediterranean region, North Africa and the Middle East and has been cultivated for at least 2,000 years, possibly starting with the Egyptians. They, the Romans and the Greeks used the plant as a fertiliser, because of its ability to grow in poor soils and adverse weather conditions. They also ate its seeds (lupini beans). As did the Incas, who were harvesting pearl lupin on the other side of the world. We get its name from the Romans, who named the plant after the wolves—lupi—that roamed the Mediterranean hills where it grew.

These days, the sweet variety of white lupin is mainly cultivated in Portugal, Spain and Southern France, the sweet variety of yellow lupin in Northern Europe, Belarus and Ukraine, and sweet blue lupin in Germany, Poland and the Netherlands. However, Western Australia is by far the world’s greatest producer and exporter of lupins, accounting for over 80% of world lupin production over the past couple of decades.

The ‘old’ varieties of lupin produce bitter, high-alkaloid seeds which require a lot of soaking to make them safe to eat. A food shortage in Germany during the First World War focussed some people’s attention on lupin as a good alternative source of protein. Research and tinkering followed and, in the 1920s, scientists at the Kaiser Wilhelm Research Institute successfully created new varieties of ‘sweet’ lupin, with seeds that have a vastly reduced alkaloid content and are safe to eat without any processing.

Originally introduced to the interior of Europe by the Romans, lupin beans have been roasted and consumed as snacks, or boiled and enjoyed in salads or as antipasto in several European countries for many years, but they are still rarely found in bean form in countries like the UK and the Australia. A couple of decades ago, however, food producers woke up to the benefits of using lupin in their products, such as its ability to improve the texture of bread and make it seem more filling.

Lupin flour was introduced as an ingredient in the UK in 1996, in France in 1997 and in Australia in 2001 and can now be found in a wide range of flour-based goods like pastries, pies, pancakes and pasta. It’s a particular popular ingredient in bread because, when used in combination with wheat, it improves the bread’s structural quality. It also increases the protein and dietary fibre content of wheat-based products, and thus their nutritional value.

Lupin can be used as a substitute for fat, making lupin milk a good alternative to milk or soy-based drinks, and it’s used as a vegetable protein extender in a range of meat products, such as frankfurters, sausages and cold cuts.

Lupin protein isolates and concentrates have outstanding ‘techno-functional properties’ and are used to increase the water holding, emulsifying or gelation capacity of all sorts of food products. Yellow lupin, because of its colour and its emulsifying properties, is often used as an egg or butter substitute.

Consumption of lupin beans is also on the increase as more people are becoming aware of lupin’s nutritional value—it is very high in protein (30–45% of the total bean content, depending on the species) and fibre (30%) and low in fats (4–7%) and starch—and its health benefits, including its ability to lower cholesterol and blood pressure, reduce appetite and control blood sugar levels.

Lupin does not contain gluten and is therefore often used in gluten-free foods, and it’s also become a popular alternative to soya protein in vegan and plant-based products.

Unfortunately, lupin can cause allergic reactions in a small percentage people. This happens because their body’s immune system mistakes one or more harmless lupin proteins for toxic invaders and creates IgE antibodies against them. The next time they eat lupin, the antibodies recognise the proteins and prompt a response from immune system cells. These, in turn, release a variety of chemicals into the bloodstream, including histamine, the chemical that is primarily responsible for the symptoms of allergy.

As lupin becomes a more popular food item, reports of allergic reactions to this legume are on the rise.

Identified allergens

The proteins (and occasionally carbohydrates) in a food that are capable of provoking allergic reactions are called allergens. Allergens are named using the first three letters of the genus—Lupinus—the first letter (or two letters, to avoid confusion) of the species—angustifolius or albus—and a number reflecting the order in which they were identified.

As of March 2026, 3 lupin allergens from two types of lupin (the white lupin, Lupinus albus, and the narrow-leaved blue lupin, Lupinus angustifolius) have been added to the WHO/IUIS allergen database (the official peer-reviewed database of allergens maintained by the World Health Organisation and International Union of Immunological Societies).

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How common is lupin allergy?

A definitive diagnosis of allergy can currently only be established with a food challenge, but challenges are costly in terms of both time and resources, as well as potentially risky. So many prevalence studies measure sensitisation—using skin or blood test data—but sensitisation is not allergy. Being sensitised to something simply means that your immune system recognises it, but you may not actually react to it; in fact, many people don’t react to whatever it is they are sensitised to. Studies that use sensitisation data therefore tend to produce allergy prevalence numbers that are larger than they should be.

In a similar vein, studies that estimate allergy prevalence using questionnaires usually produce somewhat inflated numbers as people can self-report allergies that they do not actually have, although robust studies will use certain criteria to evaluate respondents’ answers and determine whether their symptoms suggest an allergy or not.

IgE-mediated allergy

Allergy to lupin had already been recognised in mainland Europe for some time but, from the end of the 1990s, as an increasing number of people were exposed to a wider range of lupin-containing processed food products, reports of adverse reactions grew, leading researchers to call for ‘allergy vigilance’.

That said, very few studies have looked into the prevalence of lupin allergy in the general population.

In 2014, German researchers invited people to their lab for allergy testing to lupin and other legumes. They ended up testing 163 people and found that, amongst those who had no known allergies, 2% were sensitised to lupin. The researchers also tested the study participants for allergies to other legumes and found that, of the non-allergic participants, 2% were sensitised peanut, 2% to pea and 3% to soybean. This made the prevalence of lupin sensitisation in the general population either comparable to or lower than that ofother legumes and, considering the fact that most of those people would not go onto develop actual symptoms, the researchers concluded that allergy to lupin in the general population was ‘relatively uncommon.’

Most of the studies that have been carried out have only tested people who have a known allergy.

A Finnish study reported lupin sensitisation in 25 of 1,522 (1.6%) suspected food allergy patients aged between 8 months and 59 years.

In the Netherlands, researchers tested 372 consecutive patients attending a clinic with a suspected food allergy and found that 22 (13.6%) of them were sensitised to lupin flour, whereas 135 (36%) were sensitised to peanut, and 58 (16%) of them were sensitised to soybean. After asking some of the lupin-sensitised patients to eat lupin flour and finding that most did not react, the researchers put the estimated prevalence of actual lupin allergy between 0.27 to 0.81%. They did however point out that ‘In selected cases, eliciting doses are low, making significant reactions possible.’

A study involving 1160 people consulting allergists in Lisbon, Portugal, found that 48 of them (4%) were sensitised to lupin.

However, the above studies looked at such different types of people—people with general allergies, people with food allergies, people without allergies—that it’s impossible to come up with any general conclusions regarding the prevalence of lupin allergy in the general European population, let alone anywhere else.

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Risk factors for lupin allergy

Reactions to lupin have often been reported in people who are allergic to peanuts. For example, in America, a 5-year-old girl with a known sensitivity to peanuts experienced hives and swelling after eating pasta that had been fortified with lupin flour and, in Canada, a 10-year-old boy with a known allergy to peanuts and tree nut experienced anaphylaxis after eating a pancake made from a mix containing lupin flour. In France, someone with a history of severe reactions to peanuts experienced acute asthma after eating baked goods made with lupin flour and, in Norway, someone with a known allergy to peanuts experienced a severe allergic reaction after eating a hot dog bun made with lupin flour.

The risk of having a lupin allergy if you are allergic to peanuts is quite high. A large study (of 5,366 patients) carried out by French and Belgian allergists showed that 17.1% of children and 14.6% of adults with peanut allergy were also sensitised to lupin.

Although not all peanut-allergic people who are sensitised to lupin will actually react to it, quite a few do. Dutch researchers tested 39 people who were sensitised to peanuts and found that 82% of them were also sensitised to lupin. Just over 1 in 3 (35%) of them showed symptoms when given an oral challenge with lupin flour.

French researchers tested 24 peanut-allergic patients and found that 11 (44%) of them were also sensitised to lupin. 7 out of the 8 people who were given a food challenge reacted to the same amounts of lupin and peanut.

Chilean researchers recently examined 43 patients who had visited immunology and allergy clinics in Santiago. 23 had peanut allergy but no history of lupin allergy, 2 had lupin allergy but no history of peanut allergy, and 18 were used as controls (they were not known to be allergic to any foods). 27 patients were found to be sensitised to lupin: 19 of the 23 (83%) patients with peanut allergy, 2 of the 2 (100%) patients with lupin allergy, and 6 of 18 (33%) control patients without any known food allergies.

9 of the peanut-allergic patients who were sensitised to lupin agreed to undergo a food challenge; of those, 4 (44%) reacted to the lupin (2 of whom needed to be treated with adrenaline), demonstrating quite a high rate of cross-reactivity between lupin and peanut allergy and a general severity of lupin-provoked reactions. (Of the 4 lupin-sensitised controls who consented to a food challenge, none reacted.)

A study carried out on 134 Australians who were either allergic to lupin or peanut found that 19 to 25% of the peanut allergic individuals were sensitised to lupin and estimated that between 5.8 and 7.5% of them would actually react to it. (By contrast, none of the people allergic to lupin actually reacted to peanut.)

Although researchers have declared that it’s rare for people who are not allergic to peanut to be sensitised to lupin, several studies have shown that lupin can be a primary allergy, and not just a cross-reaction to peanut allergens.

A study carried out on 95 allergy patients in the UK revealed that 34% of peanut-allergic children and teenagers were also sensitised to lupin, and 4% of those who weren’t allergic to peanuts were sensitised to lupin. Food challenges found that 4% of peanut-allergic people actually reacted to lupin (with respiratory symptoms, hives and itchy mouth), but none of those without peanut allergy did.

However, that is certainly not always the case. People without any known food allergies at all have had adverse reactions after eating lupin-containing gingerbread, bread rolls, croissant and quiche.

Primary allergy to lupin can also produce very serious reactions. The first reported case of an anaphylactic reaction caused by eating lupin was that of an 8-year-old boy without a peanut allergy. He developed a runny nose and watery eyes followed by facial swelling and difficulty breathing half an hour after eating a waffle that contained lupin flour.

When it comes to cases of anaphylaxis caused by eating lupin, the ratio of patients with a known legume (generally peanut) allergy to patients who are just allergic to lupin is about 1:1.

Another risk factor for lupin allergy is atopy. An atopic person is someone who is prone to developing an allergic reaction in response to a trigger. Studies have shown that the presence of other allergies is a risk factor for allergic reactions to food. This is no different when it comes to lupin allergy.

For example, a large investigation of French and Belgian patients visiting allergy clinics in 2009 revealed a sensitisation to lupin in 2 of 797 (0.002%) of non-atopic children versus 35 of 1395 (0.03%) atopic children, and 6 of 990 (0.6%) non-atopic adults versus 53 of 1422 (4%) atopic adults.

In the German study mentioned in the previous section, the people who were tested were split into 2 groups: atopic and non-atopic. They found that, whereas 2% of the non-atopic people were sensitised to lupin, 6% of the atopic ones were. Although they had estimated the prevalence of lupin allergy in the general population to be very low, they concluded that people who were predisposed to getting a food allergy (the atopic bunch) ran a ‘clear risk’ of reacting to lupin.

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Cross reactions to lupin

Technically-speaking, a person can be allergic to lupinand another food (or foods, or aeroallergen(s)) either by cross-reactivity—the immune system mistakes the proteinin one allergen for aprotein with a similar structure inthe other—or by an independent sensitisation to each food and/or aeroallergen(a co-sensitisation or co-allergy), in which case the immune system has developed specific IgE antibodies against each allergen. It can be difficult to determine whether reactions are caused by cross-reactions or co-allergies,but the end result is the same; problems, problems.

The most likely suspects for cross-reactions with lupin are other legumes.

A high level of cross-reactivity among the 3 commonly-grown species of lupin (L albus, L angustifolius and L luteus) due to gamma γ-conglutin has recently been demonstrated in lupin-sensitised patients by Chilean researchers.

A number of studies have shown a strong link between lupin allergy and peanut allergy (see Risk factors). This is probably because several of the allergens in peanut and in lupin structurally resemble each other.

When cross-reactions are involved, you do not have to have eaten lupin before to become sensitised to it, as demonstrated by this study in which 5 peanut-allergic patients developed symptoms after being tested with lupin flour, even though they had never eaten lupin before.

A review of the very different studies carried out so far finds that around 1 in 5 (15 to 20%) people with a peanut allergy will also be sensitised to lupin. A team of Italian researchers found that higher levels of specific IgE to peanut may indicate that someone has a greater risk of cross-reactive reactions. That said, according to another Italian study, most peanut-allergic people still seem to be able to tolerate food with lupin in it, although those who can’t are at risk of developing potentially dangerous reactions.

Although the risk of cross-reactivity between lupin and peanut is considered to be much higher than it is with other legumes, a high rate of co-sensitisation to soy and pea has been reported in a Finnish study (52% to pea and 72% to soy) and a German study (50% to pea and 83% to soy).

Despite the fact that research has shown that testing positive to one or more legumes does not necessarily mean that you are actually allergic to them and should eliminate them from your diet, a recent Dutch study has found that the lupin-allergic may need to be more cautious.

In this study, lupin-allergic subjects were found to be sensitised to at least 6 of the 10 other legumes tested—peanut, soybean, green pea, chickpea, blue lupin, white lupin, black lentil, green lentil, broad (faba) bean and white bean. And these sensitisations were often ‘clinically relevant’—i.e. produced symptoms. In fact, in people who were allergic to lupin, ‘co-allergy with peanut was almost inevitable’ and co-allergy with other legumes was frequent; of the 30 lupin-allergic patients in the study, 22 (73.3%) were allergic to peanut, 18 (60%) to soybean, 12 (40%) to green pea, 11 (37.6%) to lentil and 5 (16.7%) to bean.

A case of dangerous cross-reactivity between lupin and vetchling—a member of the pea family, which can also be used to make flour—has also been reported. According to the authors of the study, this is an uncommon cross-reaction and the risks of reactions are quite low since vetchling flour is not a common food in many countries.

Research carried out using mice also suggests a potential for cross-reactions between lupin and fenugreek. In this study, lupin-sensitised mice were challenged with other legumes—peanut, soy and fenugreek—and 37.5%, 31.5% and 12.5% of them developed serious anaphylaxis, respectively. Additionally, although 25% of the fenugreek challenged mice did not react at all, all of the mice challenged with peanut or soy showed at least a weak reaction.

It’s also worth nothing that legume sensitisation can (very occasionally) be a dynamic process. One case study describes a patient who initially reacted only chickpeas and who, over the years, developed sensitisation to lentils, white beans, lupin, soybeans and peas. But not peanuts.

In the end, you need to be aware of what you’re eating and how your body is reacting to it. If you notice any allergic symptoms, make a note of what you’ve eaten that day so that you can see if it gives you problems again the next time you eat it.

Finally, a study carried out in Portugal also found potential cross-reactivity between lupin and pollen and latex. In their study of 1,160 people with potential allergies, they found that 75% of those with a positive skin test to lupin were also co-sensitised to other legumes, 82% were co-sensitised to pollen, and 28.5% were co-sensitised to latex.

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Symptoms of lupin allergy

Immediate reactions to lupin

Immediate allergic reactions are caused by IgE antibodies. These antibodies bind to certain immune system cells—mast cells and basophils—and trigger the release of histamine and other inflammatory chemicals that cause the characteristic symptoms of allergy.

Immediate reactions are the only type of allergic reaction that have been reported to lupin (so far).

Reactions are different for different people, and they can also be different for the same person, varying in severity from episode to episode. They can be classified according to the organs they affect and include:

• Skin symptoms: eczema (atopic dermatitis), hives (urticaria), swelling of the face (angio-oedema) and/or tongue and/or throat and/or hands, redness (erythema), itchy skin (pruritus), oral allergy syndrome (OAS, commonly manifesting as ‘itchy’ or ‘burning’ symptoms often limited to the mouth, sometimes also swollen lips and cheeks)
• Breathing symptoms: blocked nose (nasal congestion), runny nose (allergic rhinitis), wheezing, difficulty breathing/shortness of breath (dyspnoea), persistent cough, hoarse voice
• Digestive (GI) symptoms: nausea, diarrhoea, vomiting, stomach pain
• Cardiovascular symptoms: low blood pressure (hypotension), rapid heart rate (tachycardia), loss of consciousness (syncope)
• Neurological symptoms: headaches, dizziness, blurred vision, anxiety, confusion, seizures, fatigue and malaise (aka ‘a feeling of impending doom’, which can occur during anaphylactic reactions)

Lupin produces an array of IgE-mediated symptoms, ranging from mild ones to anaphylaxis. It often manifests as hay fever-type symptoms, asthma or oral allergy syndrome.

In rare cases, contact rashes have been reported, like this example of a 25-year-old Spaniard who developed weals and severe itching around/in his mouth after kissing his girlfriend who had just been eating lupin beans. He apparently tested negative for dried and fresh lupin, but positive for wet lupin.

Unfortunately for those with lupin allergy, severe reactions seem to be relatively common. Some researchers have stated that lupin allergy ‘might equal peanut allergy in its severity’.

In 2002, lupin was the fourth most frequent trigger of food-associated anaphylaxis reported to the French Allergy Vigilance Network. Two of the children who suffered anaphylactic attacks had been given a chocolate drink for breakfast that contained lupin flour.

A 2013 German study investigating the cause of anaphylaxis in 93 adults with suspected food allergy listed lupin as the fourth most common trigger.

A 2022 Chilean study looking into the molecular basis of lupin allergy found that it manifested itself most often as anaphylaxis, sometimes after eating just 1 gram of lupin flour.

Some researchers have stated that lupin allergy ‘might equal peanut allergy in its severity’.

Don’t panic: To be clear, the official definition of anaphylaxis is probably not what you think it is.

This means that many of the cases of anaphylaxis reported in medical studies are not actually life-threatening—when dealing with an emergency, however, since it’s impossible to predict which reactions will become life-threatening, every case of anaphylaxis should be treated as if it is potentially deadly.

One problem with lupin is that it’s often hidden in places where you would least expect it. In 2005, for example, a case was reported in the Lancet medical journal involving a British woman who had been taken to hospital because of severe anaphylaxis after eating a meal at a restaurant. The meal consisted of chicken, French fries and onion rings. The culprit was found to be the onion rings, which had been made in the UK using a batter mix made in Holland and containing unlabelled lupin flour.

Additionally, as a team of German researchers observed about the patients included in their study:

‘Most of them were oblivious to their lupine allergy and did not even know that lupine is a food, although it must be declared on ingredient lists. Therefore, we believe that there is a huge number of unrecorded allergic and even anaphylactic cases based on lupine.’

It also doesn’t take that long or (that much) for people to develop an allergy to lupin. Finnish researchers investigating the prevalence of lupin sensitisation in their country were surprised by how many people were already sensitised to the offending legume, stating:

‘The occurrence of lupin allergy in a country where lupin has not been traditionally used is surprisingly common, suggesting that short-term use of modest amounts of lupin can cause serious allergic reactions.’

Because symptoms can be severe, if you do suspect that you’re allergic to lupin, it’s important that you see your GP/family doctor and get a referral to an allergy clinic for further testing.

Threshold for reactions

VITAL®, the Australian initiative for voluntary incidental trace allergen labelling, put out recalculated threshold doses for the ‘Big 14’ allergenic foods in 2020. Using a database containing datasets from studies carried out worldwide that used double-blind, placebo-controlled food challenges (DBPCFC), they calculated that the lowest threshold dose of protein that was needed to produce a reaction in 1% of the population allergic to lupin is 2.9 mg. (Note: in this case, the ‘population allergic to lupin’ is 25 people who were given a DBPCFC)

32.5 mg was the dose needed to produce a response in 10% of the test subjects, and 287 mg was the dose needed to provoke a reaction in half of the test subjects.

Note: we’re talking about milligrams of lupin protein. Lupin flour, the most common form of lupin in processed products, can contain up to 40% protein. In one study of 6 lupin-allergic patients, the dose of lupin flour needed to provoke subjective symptoms (that is, oral allergy symptoms, nausea and abdominal pain) was between 1 to 3 mg, whereas between 300 mg and 1000 mg was needed to provoke objective symptoms (that is, hay fever-type symptoms, hoarseness and shortness of breath).

In case you’re wondering what that means in terms of actual food, according to another study which provoked symptoms of asthma with 965 mg of lupin flour, that’s about the amount you’d get in 100 grams of bread, which is about 3 or 4 slices. Which is about 333 times more than what would be needed to provoke the most sensitive 1% of people with lupin allergy.

Subjective symptoms have been reported to amounts as small as 0.5 mg of lupin flour.

Ultimately, the threshold dose needed to provoke symptoms varies widely between people. It also varies per person, depending on the circumstances around the meal.

Your threshold can be lowered and your allergic reactions worsened by things called ‘cofactors’. Cofactors include things like how much you eat and whether those ingredients have been cooked or processed, as well as exercise, anti-inflammatory drugs, alcohol, infection and stress.

Cofactors are thought to play a role in about 14% to 30% of all anaphylactic reactions.

Please note: the amount of lupin needed to provoke a reaction says nothing about how severe the reaction will be. And, even if your reactions have been mild in the past, that does not mean that they will continue to be mild.

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Diagnosing lupin allergy

A diagnosis of lupin allergy will primarily be based on your clinical history—a record of consistent symptoms following the consumption of lupin or lupin-containing foods. This will require you to provide your allergist with answers to questions about your general medical background (including any other allergies you may have and relevant illnesses in your family) and your dietary history (what you ate to provoke your symptoms, what those symptoms were, how long they lasted, whether you had exercised or taken painkillers and many other details).

Your medical history determines what comes next; on the basis of your answers, the allergist will try to determine what type of allergy you have—a primary, immediate-type allergy, a cross-reactive allergy or a delayed-type allergy—or whether it could be something else, and this will determine the tests they ask for to come up with a diagnosis.

Diagnosing immediate reactions to lupin

Skin tests

An IgE-mediated sensitisation to lupin is typically confirmed by a skin prick test, which involves someone placing a small sample of lupin extract onto your skin (generally the forearm of an adult/older child or the upper back of a young child) and pushing it through the top layer of skin by pricking it with a lancet. It takes about 15 minutes to see a reaction (or not).

This test is often carried out first because it is quick and simple to perform and gives rapid results, but it is generally used to rule out an allergy rather than to confirm one, because it has excellent negative predictive value—if the skin weal is under a certain size, you are highly unlikely to have an allergy—but poor positive predictive value—the skin weal has to be very large before an allergist can say with any kind of confidence that you probably have an allergy.

The accuracy of the skin prick test can be limited by the fact that the processing of commercially-made allergen extracts can destroy the heat-sensitive allergens, often those which people with a suspected pollen-associated food allergy react to. In such cases, someone could get a false negative result and be wrongly told that they are not allergic to lupin.

One solution to this problem is the prick to prick test. This test is very similar to the skin prick test, except first the lancet is used to puncture fresh food and then it is used to prick your skin. When the food is in liquid form, the technique is actually the same as the one used for the skin prick test and, when the food is solid, it’s often ground down and put in saline solution.

The prick to prick test often produces superior results to commercial extracts because the fresh food used should contain all of the allergens that a person can react to. The lab used by the clinic can also prepare the extract in specific ways which may add to its efficacy.

Blood tests

Sometimes, the doctor may decide to order a blood test, aka an immunoassay. Perhaps the skin prick test was inconclusive, or the suspected allergen is not available for skin prick testing, or you’re unable to undergo the test for some reason.

A blood test involves having a small sample of blood drawn so that it can be sent to a lab where technicians will use allergen extracts to check whether there are IgE antibodies in your blood that react to them. It can take 1 or 2 weeks to get the results.

Blood tests can be less sensitive or specific than skin tests, but they have other advantages: they are perfect for people who cannot stop taking certain medications or have extensive skin disease or tattoos, and they can safely be used on infants, squirming toddlers and people who are at risk of suffering an anaphylactic reaction.

Blood test panels also typically include a whole range of potential allergen extracts including other foods or aeroallergens that the allergist may want to check your reaction to.

For more specific information, a component blood test—aka Component Resolved Diagnosis (CRD)—can be carried out. Instead of using extracts of whole foods containing only (heat-stable, plentiful) allergens, the CRD tests the reaction of IgE antibodies in your blood to isolated, individual proteins. This improves the diagnostic sensitivity of the test as allergens that would otherwise be missing from the whole lupin extract or exist only in tiny amounts are present in concentrated form in the CRD test.

This type of test enables the doctor to see exactly which allergen(s) you react to, which allows them to determine whether you are sensitised to cross-reactive allergens that are unlikely to produce symptoms, and whether you are sensitised to certain allergens that could affect your management plan. For example, if you’re sensitised to Lup a 5, you may also be sensitised to birch pollen and/or peanuts.

Component blood tests are also made up of very large panels of allergens which include many other foods and aerollergens that the allergist may want to check your reaction to and can help to determine whether or not a sensitisation to a cross-reactive allergen will be symptomatic or not.

Unfortunately, although CRD could potentially reduce the need for oral food challenges and contribute to tailored management plans, it’s not yet considered a routine diagnostic method and it’s not comprehensive; the most widely used tests neither contain all of the identified allergens (which are also not all of the possible allergens), nor are they universally available. Testing for certain specific lupin allergens would require special preparation and is therefore only likely to be done for research purposes.

Additionally, as it is with skin and standard blood tests, CRD is better at confirming an allergy than at eliminating the possibility of one. And, because sensitisation patterns differ according to geography and populations, with different allergens being more important in different regions and in people of different ages, allergists need to understand their patient populations so that they interpret the results of the tests correctly.

For example, in a Finnish study, only 7 of the 25 lupin-sensitised patients who were given an oral challenge had an allergic reaction, and when British researchers challenged peanut-allergic children sensitised to lupin, only 2 of 9 reacted.

Dutch researchers found even fewer cases of allergy in their study, reporting that only 1 of of their 9 lupin-sensitised patients experienced significant symptoms when challenged with lupin flour.

And when Norwegian researchers found that only 1 in 10 children with a positive skin prick test to lupin actually showed symptoms during their oral challenge test, they wrote:

‘Children with sensitization to lupin are not likely to have a clinical lupin allergy. Avoidance of lupin on the basis of lupin sensitization or peanut allergy would lead to unnecessarily strict diets.’

A positive test result simply means that your immune system is specifically aware of an allergen or allergens in that food. Why some people later develop an allergy to that food, and some do not, is not yet known.

Neither can the results of your blood or skin test predict how severe your reaction to eating some lupin might be; a large skin weal or high level of IgE in your blood do not mean that you will have a serious reaction if you accidentally eat some bread containing lupin flour.

Food challenge

The only way to get a definitive diagnosis of lupin allergy, and to have some idea of how severe your reactions may be and how much lupin is needed to provoke them,is to undergo an oral food challenge. This generally involves eating a very small amount of lupin, waiting for a reaction, and then doing it again, gradually increasing the dose until an objective—visible—reaction occurs or a maximum dosage is reached. It can take around 4 hours, depending on the type of challenge undertaken and the length of observation time needed.

You can read more about oral food challenges here.

Oral food challenges are generally undertaken either when someone’s history and their test results disagree (i.e. they have negative tests results but their history strongly suggests an allergy, or vice versa) or to check whether someone has outgrown their allergy to ensure that they don’t unnecessarily restrict their diet or worry about hidden allergens in processed foods.

Because of the risk of severe reactions, oral food challenges should only be done by an experienced consultant in a medical setting.

Practically speaking, most people do not undergo this kind of test since it requires a lot of time and resources. And oral challenges are rarely, if ever, offered to people whose history includes severe reactions to a suspected food. Whenever possible, allergy diagnoses are based on a combination of medical history and lab tests.

Although food challenges help to diagnose food allergies and identify a suspect food, there are other reasons to undergo food challenges, namely:

• to identify culprit foods in cases of allergies to multiple unknown foods
• to determine a patient’s threshold—how much lupin they can eat without reacting—so that dietary advice based on the outcome of the challenge can be given
• to confirm the development of tolerance to lupin

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Good to know

Lupin allergens can cause allergic reactions when inhaled.

A 2005 study described a case in which 8-year-old asthmatic child with a known allergy to peanuts was playing with his brother when he suffered an asthma attack. He was taken to a clinic with a suspected allergy to his asthma medication, which seemed to be mysteriously worsening his reaction. Instead, it turned out that his brother had just been eating lupin seeds as a snack and that he had reacted to inhaling some of the allergen. This was confirmed after he was encouraged to touch some seeds which provoked an asthma attack within 5 minutes.

In another case, an Italian woman developed symptoms including rashes, swelling, coughing and oral allergy syndrome on several occasions after eating lupin seeds, waffles, pasta, chocolate cake and tomato sauce. Twice, the attacks developed into anaphylactic episodes. The ready-made products were later found to contain lupin flour.

http://www.esmonformacion.com/jiaci/issues/vol20issue1/11.pdf

The real question for her doctors was, how had she developed the allergy in the first place? Some digging into her past revealed that 15 years previously, over a period of 3 years, she had suffered the same kind of symptoms when visiting her parents’ home. At the time, her mother, who had diabetes, had developed the habit of grinding lupin seeds to use as a sweetener. An inhalation exposure test, performed by tipping ground lupin seeds from one tray into another, confirmed the allergists’ theory—after 5 minutes of breathing in the ground lupin dust, the woman developed symptoms again.

And on a related note.. working with lupin can be hazardous for your health. Lupin proteins in the air have been shown to sensitise workers in food processing plants, and agricultural research centers and to cause respiratory symptoms like asthma, rhinoconjunctivitis (runny, itchy nose, sneezing, and red, itchy eyes).

Lupin seeds can cause problems even for people who are not allergic to them.

Lupin can cause symptoms that resemble food allergy. Lupin is a high FODMAP—fermentable oligosaccharides, disaccharides, monosaccharides and polyols—food. Foods that are high in FODMAPs are poorly absorbed in the gut. They draw water out of the intestines and produce gas as they ferment. This often results in gastrointestinal symptoms like abdominal pain, bloating, and gas, which can be mistaken for a true IgE food allergy. Just cut out the beans, and/or some other stuff, and you’ll be fine.

Eating too many beans at once can cause large masses of plant matter to get stuck in your digestive system. In 1994, a 7-year-old boy who had eaten a very large amount of lupin seeds developed terrible stomach pain and had to be operated on because a phytobezoar was blocking his intestines.

A phytobezoar is a trapped mass in the gastrointestinal system which is made up of indigestible plant material. Bezoars are thought to be responsible for up to 4% of mechanical intestinal blockages. Interestingly, gastric phytobezoars—those that form in the stomach—can often be dissolved by drinking Coca-Cola, thus avoiding the need for further medical intervention. So there you have it; Coca-Cola may not, in fact, dissolve your teeth, but it does get rid of unwanted digestive blockages.

When buying dried lupin seeds, follow the preparation instructions! The seeds of ‘bitter’ Lupin species contain toxic quinolizidine alkaloids, whose function is to protect the plants against grazing herbivores and disease-producing microbes. Their bitter taste is a clear giveaway of their toxicity. They should not be eaten without undergoing a de-bittering process of soaking in water, a process that can take up to 4 days. Some instructions state that soaking overnight, discarding the soaking water, and then changing the water once during cooking is needed to leech the toxic alkaloids out. The point is, if you buy some lupin seeds, follow the cooking instructions on the packet. They are there stop you from poisoning yourself.

One Italian woman who did not follow the instructions on the packet and only soaked her beans for 36 hours before having a few handfuls developed blurry vision, dry mouth, facial flushing and confusion—also known as anticholinergic syndrome—3 to 4 hours after eating them.

In a similar case, a 72-year-old woman in the US gave herself anticholinergic poisoning after drinking the cooking water of her lupin beans. She was under the impression that it would lower her blood sugar levels. Instead, she developed ‘classic anticholinergic signs’; dry mouth, flushed skin, blurred vision, rapid heartbeat and delirium.

Long-term exposure to lupin alkaloids has also proven to be bad for your health. A 28-year old French woman who ate 3 g of lupin seeds (with particularly high levels of alkaloids) each month for 8 years eventually developed motor neurone disease (MND). She started recovering about 2 months after she stopped eating the seeds although, 20 months later, her MND had not completely resolved.

People who are allergic to lupin seeds should avoid touching the garden flowers.

If you’re allergic to lupin as a food, you might get a skin rash if you handle the seeds of garden lupin.

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