RISK FACTORS FOR FOOD ALLERGIES
1. Hereditary and genetic factors
It is associated with factors like family history of food allergy, gene polymorphism and mutations, age, sex and ethnicity. The Caucasian population is highly predisposed to food allergies as compared to populations of African origin. On the other end, infants and young children are more likely to develop IgE mediated food allergies than are older children or adults. Food allergies experienced during infancy or childhood years are likely to be outgrown within a few months to several years after the onset of the food allergy.
2. Changes in the diet trends
This theory is based on the introduction of genetically modified foods or the decrease in consumption of food rich in antioxidants over the years. This has allegedly contributed to the increase in allergic reactions among individuals. Maternal diets, inadequate breastfeeding practices and early introduction of new foods to infant diet are assumed to increase incidences of food allergic reactions in individuals perhaps to a larger extent in young children.
3. Hygiene hypothesis.
This hypothesis proposes that the lack of early childhood exposure to infectious agents, gut flora and parasites increases susceptibility to allergic diseases by modulating immune system development.
4. Exposure to allergens and other allergenic diseases.
Researchers argue that cross-reactivity between allergenic and non-allergenic foods and pre-existing allergic reactions not related to food predispose one to suffering from food allergenic responses. Time and route of contact with food allergens also plays a major role in exposure i.e. first and subsequent exposure at different age levels either via oral or body contact.
5. Biological factors in the gastrointestinal tract
The biological make up of the gut could predispose one to food allergies. For instance gastric acid in the stomach, gut immune systems and microorganisms in the gut affect the rate at which the body recognizes or digests foreign matter that could include food allergens.
Lack, G. (2012). Update on risk factors for food allergy. Journal of Allergy and Clinical Immunology, 129(5), 1187-1197.
Kaza, U., Knight, A. K., & Bahna, S. L. (2007). Risk factors for the development of food allergy. Current allergy and asthma reports, 7(3), 182-186.
University of Nebraska-Lincoln. (n.d.). Allergenic Foods and their Allergens, with links to Informall. Retrieved from https://farrp.unl.edu/resources/gi-fas/informall
ALLERGENIC FOODS AND THEIR ALLERGENS
THE ‘BIG 8’
This group comprises of eight foods that are known to cause almost 90% of all food allergies. They include milk, eggs, fish, shellfish, tree nuts, peanuts, wheat and soy beans.
It accounts for the largest cause of food allergies during infancy. Milk allergy is associated with an immune action against a specific protein or the inability to metabolize the milk sugar lactose. The most problematic allergens in milk are the most abundant and they are caseins and whey alpha-lactalbumin and beta-lactoglobulin proteins. An attempt to consume milk substitutes from animals by allergic consumers is often unsuccessful although plant-based milk substitutes and hypoallergenic milk preparation are recommended to such individuals. Allergy symptoms usually manifest in different body organs including gastrointestinal tract, skin, and the respiratory tract.
The major proteins associated with egg allergy are located in the egg white specifically ovalbumin, ovomucoid, ovotransferrin, lysozme. The egg white may not be the only criminal since egg yolks are also known to cause allergies although they are somewhat infrequent. These allergens retain their allergenicity even after heating. However, even though eggs are poultry sources, poultry meat is usually not problematic to egg allergic patients.
Allergies to this food is common in regions of high fish consumption. Most of the reactions are attributed to the fish muscle protein parvalbumin which retains its allergic properties even after heating. Exposure to fish parasite anisakis simplex may also trigger allergic reactions after consumption. Adverse reactions observed due to histamine poisoning (scombroid) in decayed fish may be mistaken food allergies therefore it is important for specialist to differentiate these allergic mechanisms.
4. CRUSTACEAN SHELLFISH
His group comprises a range of members e.g. shrimps, prawns, crabs and lobsters. Allergic incidences are high in regions of high consumption as well and occurs majorly in adults and older children. Reactions occurs due to the presence of shellfish allergen tropomtosin which also survive cooking and heating temperatures .Allergic reactions can be noted in other types of crustacean shellfish like molluscan shellfish, edible land snails which also contain this same allergen.
5. TREE NUTS
They comprise of Brazil nuts, chestnut, hazelnut, pine nut, walnut, almonds, pecan nuts, coconuts, cashew nuts and peanuts. They are known to be the most potent allergenic foods in terms of amounts required to elicit a response and severity of reactions. Multisystemic reactions, respiratory symptoms and fatal anaphylaptic reactions are occasionally observed in nut allergic individuals. The victim allergens include storage proteins (vicilins, legumins, albumins), plant defense related proteins and profilins. Cross-reactivity between nut allergens in nut allergic individuals is quite common. There however exist differences in occurrences of nut allergies between different geographical regions e.g. United States and Spain. Allergic reactions to nuts are not only triggered by oral contact but also through the skin or inhalation.
6. PEANUTS/ LEGUMES
Some potent allergens belong to the legume family e.g. peanuts, chick pea, lentils, lupins , peas. Allergens responsible for responses belong to the family of seed storage proteins aalbumins, globulins and prolamins. They retain their allergic properties even after heating. Reactions vary from mild and local to life threatening systemic reactions. Peanuts have been put on the spotlight to be the most potent allergenic food as it has a low eliciting dose and there are high frequencies of fatal reactions.
7. WHEAT / CEREALS AND GRAINS
Allergens in this group are associated with both IgE and non-IgE mediated allergies e.g. celiac disease, baker’s asthma, exercise induced anaphylaxis. The particular allergen in question is gluten that is supposedly present in most cereals and cereal products. Related crops include corn maize, wheat, rye, oats, rice, barley. Allergic reactions range from mild to life threatening anaphylactic reactions.
8. SOY BEAN/ LEGUMES
Also in the legume family, soy beans are another trigger to food allergy. Exposure to allergens may be found in soy bean and its products. Allergic reactions also vary depending on geographical regions e.g. North America and Europe. The seed storage proteins are the major allergens contained in soy beans which cause a range of symptoms that might be life threatening.
OTHER PRIORITY ALLERGENS
Other priority allergens associated with severe allergic reactions include
They are buckwheat, mustard, poppy, pumpkin, sesame and sunflower seeds. Major allergens associated with allergic reactions are the seed storage proteins vicilins, legumins, and albumins that are heat stable and highly abundant in whole seeds.
Allergies reactions caused by vegetables e.g. celery, pumpkin and avocado occur in parts where consumption is high. Allergenic reactions are associated with pollen allergy which cause mild to severe symptoms are largely heat and processing resistant.
Spices and herbs
Some herbs and spices allergens are related to pollen or seed storage protein allergens that are heat stable, easily degradable and resistant to food processing. Examples are anis, celery, coriander, cumin, fennel, ragweed, Echinacea, artichoke, dandelions and hibiscus.
They include gastropods (abalones, limpets, land and marine snails, whelks), bivalves (oysters, mussels, scallops) and cephalopods (squids and octopuses). The major allergen is tropomyosin which retains its allergenic properties even after heating. Cross reactivity between allergens of foods of the same species is likely to occur upon consumption by molllusc allergic individuals.
Beef, Chicken, Mushroom and Textured Mycoprotein (Fungus-derived foods), Honey and Frog
Allergic reactions to animally derived foods e.g. beef and chicken may be independent from those caused by milk and egg allergens. Fungus-derived foods like mushroom and textured mycoproteins may contain hidden allergens similar in structure to egg protein allergens. Allergic reactions to honey may be caused by the presence of either plan (pollen) or bee (venom) protein allergens. Frogs allergies are commonly associated with allergy to the fish allergen parvalbumin