Legumes are a family of plants used for food. They include peanuts, soya, lupin, green beans, green peas and fenugreek.
Dried seeds known as pulses are also part of the legume family. These include chickpeas, lentils, kidney beans and other dried beans.
If you know or believe you are allergic to any legume, this article will provide you with the basic facts to help you better understand your allergy.
What is a food allergy?
Food allergy occurs when a person’s immune system reacts inappropriately to a food. The first stage of the process is called sensitisation – when the immune system’s “memory” registers the food as a threat. Antibodies to that food are produced, and at a subsequent encounter, these antibodies connect with the food’s proteins and trigger the release of certain substances in the body, such as histamine. This results in an allergic reaction.
Symptoms of food allergy
The symptoms of a food allergy can come on rapidly. These may include nettle rash (otherwise known as hives or urticaria) anywhere on the body, or a tingling or itchy feeling in the mouth. Many people’s allergy symptoms are mild but on rare occasions serious symptoms occur.
More serious symptoms of a food allergy may include:
- Swelling in the face, throat and/or mouth
- Difficulty breathing
- Severe asthma
- Abdominal pain, nausea and vomiting
The term for this more serious form of allergy is anaphylaxis. In extreme cases there could be a dramatic fall in blood pressure (anaphylactic shock). The person may become weak and floppy and may have a sense of something terrible happening. This may lead to collapse and unconsciousness. On rare occasions, death from a food allergy can occur.
See the links at the end of this article for more details about anaphylaxis and its treatment.
Types of legumes
Peanuts: Peanuts are a common cause of allergic reactions, especially among children, and reactions can be severe. In our experience, the number of people with peanut allergy who react to other legumes is relatively small and this is supported by research from the USA. Care is needed, but most people with peanut allergy find they can tolerate these other legumes without problems. Raise this with your allergy specialist for specific advice. Read more about peanut allergy.
Soya: Allergy to soya is uncommon in the UK compared with milk, egg, peanut and fish allergy. Read more about soya allergy.
Lupin: The seeds from some varieties of lupin are cultivated as food. These can either be eaten whole or else crushed to make lupin flour, which can be used in baked goods such as pastries, pies, pancakes and in pasta. Read more about lupin allergy.
Others legumes including their dried seeds (pulses): Any food containing protein has the capability of causing an allergic reaction. The following list includes just some of the legumes that may trigger allergic reactions for some people. Many people with a legume allergy will only be sensitive to one or two foods on this list.
- Green peas
- Black-eyed peas
- Kidney beans
- Haricot beans (navy beans)
- Adzuki beans
- Butter beans (lima beans)
- Broad beans (fava beans)
- Cannellini beans
- Flageolet beans
- Pinto beans
- Borlotti beans
Diagnosis and treatment
If you suspect you have an allergy to a food – in this case any member of the legume family – it is important to see your GP as soon as possible. Some GPs have a clear understanding of allergy, but allergy is a specialist subject and your doctor may need to refer you to an allergy clinic. Anyone who has suffered anaphylaxis should certainly be referred.
Your GP can locate an allergy clinic in your area by visiting the website of the British Society for Allergy and Clinical Immunology.
Once you get a referral, the consultant will discuss your symptoms with you in detail as well as your medical history. Skin prick tests and blood tests may help form an accurate picture. If your reactions are likely to be severe you will be prescribed an adrenaline auto-injector for self-use in an emergency.
The presence of asthma – especially when poorly-controlled – is known to be a major risk factor for the occurrence of more severe allergic reactions.
Read ingredient lists carefully every time you shop. When buying catered food, such as that sold in restaurants and takeaways, it is important to question staff directly. Staff may not be aware that legumes can cause allergic reactions. Make sure you name the specific legume or pulse that causes the problem.
Foods to watch out for:
- Dahl, or dal, in Asian cooking is made up of lentils, peas or other legumes
- Houmous, or hummus, is a thick paste made using chickpeas
- Most commercial canned baked beans are made from haricot beans
- Falafel is a deep-fried ball made from ground chickpeas, fava beans, or other legumes
- The seed of the fenugreek plant is used in Indian-style spiced foods such as curries. See our separate article on fenugreek
- Tamarind can be an ingredient of Worcestershire sauce and BBQ sauce
There appears to be a trend in the food industry for using pea protein in a variety of goods. These foods include some meat and fish products, processed foods, soups, sauces, pancake mixes, baked goods, cereals, snacks and some gluten-free products. The key message is read ingredient lists carefully.
It is also worth noting that researchers based in Canada reported on five children who had various allergy symptoms upon eating cooked peas, but were able to eat raw peas. Although this may not be a common occurrence, we believe doctors should consider allergy to cooked legumes even in patients who can tolerate them when eaten raw.
Our helpline has been asked whether guar gum is a problem for people allergic to legumes. Guar gum is a chemical extracted from guar beans and used as a thickening and stabilizing agent in food. It is also used in some medicines. Medical experts have made us aware of an extremely small number of allergic reactions to guar gum contained in foods. However, it is probable that the risk to people who are allergic to other legumes (such as peanut or soya) is minimal. As far as we know, allergy to guar gum is extremely rare.
What else might you react to?
If you react to one member of the legume family, it is possible you could react to another member of this group. This process is known as “cross-reactivity” – where the proteins in one food share certain characteristics with those in another food. Cross-reactivity among different legumes is not common, but this is something that should be discussed with your doctor.
The above information sheet has been peer reviewed by Dr Patrick Yong, Consultant Immunologist in the Department of Clinical Immunology and Allergy, Frimley Park Hospital, Surrey. He has no conflicts of interest in relation to his review of this information sheet.
All the information we produce is evidence based or follows expert opinion and is checked by our Clinical and research reviewers. If you wish to know the sources we used in producing any of our information products, please let us know, and we will gladly supply details.
Published: March 2019
Review date: March 2022