Allergy to Vegetable Products
Food allergies to vegetables products is well known. It is mostly provoked by vegetable allergens and can cause an immediate reaction.
What are the ill-effects of vegetable product allergy?
The most common allergic diseases reported because of vegetable products are irritant dermatitis, allergic dermatitis, asthma and rhinitis. Extrinsic allergic alveolitis, allergic photodermatitis and allergic urticaria (hives) can also be seen in some cases.
Dermatoses such as pachylosis, hyperkeratosis, nail injury chromatosis and dermatitis are also observed.
How can this type of allergy be diagnosed?
To screen and diagnose vegetable product allergy, a number of immune tests are available.
Some of these eg. prick test, intradermal test, measurement of allergen-specific IgE antibody and allergen challenge test are used for immediate allergies, whereas the patch test is used for delayed-type allergy. The allergen-specific lymphocyte proliferation test is helpful in diagnosing both types of allergy.
Vegetable parts such as thrichomes, spicules, coarse hairs and spines are responsible for irritant dermatitis.
What are the symptoms of allergy?
- Patients experience a range of symptoms including itching on the weals, irritation, erythema, rash, swelling and vesicles.
- The place of lesions are mainly the hands, arms, face and neck – ie the upper torso.
- A majority of symptoms are confined to the mouth area, and include itching, tingling, blisters and swelling – this is called oral allergy syndrome.
- People with allergy caused by vegetable products always show high levels of serum IgE antibody, eosinophil count and a positive prick test.
- Nasal symptoms are provoked in allergic dermatitis patients when handling vegetables such as carrots and lettuce.
- Mucocutaneous and respiratory symptoms appear in most people with this allergy.
- Trouble breathing, speaking or swallowing
- Cramps, diarrohea, vomiting
- A drop in blood pressure, rapid heart beat, loss of consciousness
What preventive measures can be undertaken?
Cooking fruits and vegetables make them less likely to cause an allergic reaction. Pasteurisation and other heat treatments also help in a lot of cases, but exceptions are there.
Fish oil, particularly omega-3 fatty acids, help reduce the severity of allergy related asthma attacks, possibly due to their anti-inflammatory properties.
Eat small and frequent meals.
Some special cases of vegetable product allergy:
Vegetable oil –
Vegetable oil is usually a combination of oils, such as soya, rapeseed, sunflower, groundnut oil. Since it is the proteins in the oils that can cause allergic reactions and refining process removes almost all of the proteins from the oils, allergic people don’t react much to refined oils.
Oils, if not refined, but consumed in virgin form can cause reactions in people who are sensitive to the nuts or seeds they are made from.
The symptoms of soya allergy include rashes, diarrhoea, vomiting, stomach cramps and breathing difficulties. Very rarely, soya can cause anaphylaxis.
Soya is used as an ingredient in many manufactured food products, including bakery biscuits, sweets, drinks, breakfast cereals, ice cream.
Refined soya oil is generally safe for people with soya allergy, because the proteins that cause allergic reactions are removed during the refining process.
Allergic reactions to spices are rare and usually mild, but extreme reactions can also happen occasionally. People react to mustard, coriander, fennel, chilli powder, onions, garlic and many more. Reactions to mustard can even cause anaphylaxis. The allergens in spices are similar to those in pollens and vegetables.
It has been estimated that on an average, about 5 percent of asthmatics are sensitive to sulphur-containing compounds (especially sulphites) that are readily found in foods. In the solid form, sulphites can cause urticaria when ingested.
Sulphur-containing compounds are added to a number of foods for the purpose of colour, bleaching and prevention of oxidation and bacterial infestation.
Sulphites destroy vitamin B1, and thus they must not be permitted in foods that are significant sources of this vitamin.
Possible foodstuffs that may contain sulphite include:
- Beverages: soft drinks, fruit juices
- Condiments: vinegar, pickles, salad dressings
- Fish: canned or fresh shrimps, shellfish
- Processed fruits and vegetables: dried fruit, fruit juice concentrates, purees
- Soups: dried or canned soups
- Syrups and jams
Allergy can also be triggered by the preservative sodium benzoate, colourants like tartrazine, flavour enhancers like MSG and salicylates.
How is allergy due to vegetable products treated?
The most effective approach to treating vegetable product allergy is to avoid the offending food(s) in the first place. However, identifying the offending food may not be easy or it may not be possible to completely avoid it. In this situation, medication to control allergy must be taken by the patient.
Read labels on foods very carefully and avoid all food that contains the preservative or additive that you are allergic to.
Allergic reactions to vegetable products occur commonly in the digestive system and the skin, and rarely in the lungs and nose. The most common and reliable way to diagnose allergy is by the elimination – challenge testing.
Can intra-uterine vegetable product allergy also take place? Is maternal diet of importance during pregnancy and lactation?
Intrauterine allergy is rare, therefore maternal diet during pregnancy is not of importance for the development of allergy.
However, sensitization to food antigens via the breast milk is possible in allergic babies, especially if some allergy runs in the family. Maternal avoidance of some particularly allergenic foods like cow’s milk, fish and nuts may be considered.