It has been estimated that about 1.1% of the population of the United States, over three million Americans, have peanut or tree nut allergies. The peanut is actually not a nut at all but is a legume, more closely related to beans and peas. While not the most common form of allergy, peanuts are the number one cause of fatal anaphylactic reactions triggered by food allergies in the United States. The proportion of children who have nut allergy also appears to be on the increase and, while some people are only allergic to one type of nut, others have multiple nut allergies. It is not an allergy that people usually outgrow. These factors combine to give nut allergy a higher profile than some other types of allergic conditions.Nut allergies are more common in adults than children, despite the fact that food allergies are generally more prevalent in children. When children develop a food allergy it is usually during the first two years of life. Once they have reached three years of age it is accepted that they are less likely to become allergic to food. Nut sensitivity, on the other hand, tends to persist and can occur later in life.Nut allergy tends to be an enduring life-long problem, especially if the individual is an adult when they develop the allergy. There is a higher percentage of adults with nut allergies today precisely because, unlike many other food allergies, people tend not to grow out of nut allergies. Children are less likely to outgrow their allergy to nuts than they are to outgrow allergies to milk or eggs.It has been estimated that about half of the people with nut allergy developed symptoms before the age of two and that most affected by the condition will observe the symptoms before the age of seven years. Even at this young age, peanuts were the most common form nut allergy. It has been suggested that children should not be introduced to nuts until they are at least two years old in order to reduce the risk of nut allergy. This, however, will not solve the problem if they became sensitised to nuts before they were born.It is possible that some babies become sensitised to peanuts while still in the womb. If the mother eats peanut products while pregnant an allergy can apparently develop in the unborn child. Peanut proteins have been found in breast milk so it may be passed on during breastfeeding. Some countries have recommended that mothers who are pregnant or are breastfeeding and have a family history of atopy should avoid eating products containing peanuts during this period. This includes those who have close family members with allergic reactions, hayfever, eczema, or asthma.Ironically, the increase in the number of people with nut allergy may be due to the better standards of hygiene in the modern world. Foetuses no longer have to respond to the parasites that used to be present in maternal blood so now they react to other things in the blood, like antigens.During an allergic reaction, the body mistakes a harmless allergen for a threatening foreign body. A reaction can take anywhere from a few minutes to hours after someone has ingested food that they are allergic to. In the case of nut allergy, the immune system has become sensitised to nuts, producing antibodies ready to fight the nut allergen. Immunogloblin E (IgE) antibodies attach themselves to mast cells. When the allergen is encountered, the mast cells release chemicals, including histamine, in an attempt to destroy the intruder. In the case of food allergy the reaction is often local, with swelling or itchiness of the throat, tongue, and lips, or nausea, vomiting, diarrhoea and stomach pains being experienced once the food is swallowed. Once the food is absorbed into the bloodstream then more general reactions can include skin rashes, palpitations, headaches, and allergic rhinitis.Nut Allergy SymptomsThere are a number of different symptoms that can be triggered by nut allergy. A tingling sensation and pallor may develop in the lips or mouth. The surface of the skin can become itchy as urticaria (hives) and angioedema (swelling) develop, especially in the eyelids, lips, and face. If swelling occurs in the throat, it may become difficult to swallow or breathe. People with asthma may be more at risk because a reaction can exacerbate asthma symptoms. Vomiting, tachycardia (rapid heartbeat), stomach cramps, and diarrhoea are all possible symptoms of a reaction. A sufferer may experience a feeling of faintness or a sense of unease. Having a nut allergy can complicate different aspects of everyday life. If someone comes into contact with the inner "meat" of a tree nut that they are allergic to, rather than the outer shell, they may experience contact dermatitis or "hives". Even kissing can be problematic if the other person has recently consumed nuts or is wearing a lipstick that contains nuts. Some people have had a reaction after kissing someone who has eaten nuts even though this was up to six hours after the nuts were originally ingested. Other allergy sufferers are so sensitive to peanuts that they react to the minute traces of peanut contained in cooking fumes. Certain airlines no longer serve peanuts on their flights because of the risk to allergy sufferers represented by dust from the peanuts being re-circulated through the air of the passenger cabin.The most extreme reaction caused by nut allergy is one of anaphylaxis, or anaphylactic shock, which is potentially fatal because it can obstruct breathing or cause a dramatic drop in blood pressure. Younger children seem to have comparatively less chance of dying from anaphylaxis than teenagers or adults. Teenagers may be more at risk as a group because, as they become more independent, they may not be as vigilant about what they eat as their parents were or they may not always carry their adrenaline injection with them. The unpredictable nature of nut allergy means that it should be treated seriously, even if the previous reactions experienced have only been mild ones.Nut CategoriesPeanuts are also known as groundnuts, monkey nuts, or referred to by the Latin name Arachis hypogea. Some products obviously contain peanuts, such as peanut butter, peanut flour or satay sauce. For other products, however, the presence of peanuts may be less clear-cut, as with hydrolysed plant or vegetable protein.As has already been pointed out, the peanut is not a nut but is in fact a legume. It remains a mystery as to why peanuts can cause severe reactions and yet similar severe allergies to legumes such as peas or soybeans are far more rare. This does not prevent some people from having multiple allergies that include sensitivities to both peanuts and tree nuts.Other types of nuts are collectively referred to as "tree nuts". Tree nuts include almonds, Brazil buts, cashews, chestnuts, hazelnuts (filberts), macadamia nuts, hickory nuts, pecans, pine nuts, pistachios, and walnuts. Below is a table showing some of these nuts and what family they are part of.Nut Family NutRosaceae Almond Lecythis Brazil Anacardiaceae Cashews, Pistachio Fagaceae Chestnut, Beechnut Betulaceae Hazelnut Juglandaceae Hickory, Pecan, Walnut Proteaceae Macadamia Of all the different types of tree nuts, almonds seem to cause the least problems to allergy sufferers.Peanut allergy does not automatically entail an allergy to tree nuts. It is not known why people are more likely to be allergic to tree nuts if they are also allergic to peanuts but the reverse is also true. If you are allergic to tree nuts then you are more likely to become allergic to peanuts. The safest approach to take is usually to avoid all nuts.Brazil nuts are the second most common trigger for "nut-related" allergies in the United Kingdom, second only to peanuts. Brazil nuts contain a protein called 2S protein. As little as one to two milligrams of this protein is enough to trigger an allergic reaction in individuals sensitised to it.Edible chestnuts, also called "Spanish chestnuts" or marrons, despite featuring the word "nut", typically do not seem to trigger reactions in people with nut allergies. Nutmeg is another example of this. Although nutmeg allergy does exist, it appears to be rather rare and it not usually linked to nut allergy.Pine nuts, also referred to as pinyon, are the edible kernels of several varieties of pine. They are not strictly a "nut" in the botanical sense of the word. A few people, especially those with multiple nut allergies, are allergic to pine nuts but this is a relatively rare allergy. Like coconut and nutmeg, pine nuts do not need to be avoided unless you are specifically allergic to them. Contact with pine cones or acorns is usually safe for people with nut allergies and should not cause an allergic reaction.Although fewer people are allergic to coconut, sesame seeds, poppy seeds or sunflower seeds than peanuts or tree nuts, they still need to be treated with a little caution by those with nut allergy. Sesame seeds are actually more closely related to tree nuts than peanuts. Sesame seeds are the main ingredient in tahini, also known as tehina or tchina, which is used in humus. Generally speaking, however, seeds like sesame, sunflower, canola, poppy, mustard, and safflower do not need to be avoided unless you are specifically allergic to them.A large proportion of people who are allergic to peanuts will not have a reaction to refined peanut oil. The possibility, however, of unrefined peanut being present in the oil, sometimes to improve the flavour, makes this a more dangerous proposition. There is also the chance that, even though these refined oils did not provoke a reaction, they may contain traces of peanut protein that increase the sensitivity of someone with a pre-existing peanut allergy. People with peanut allergy should not consume unrefined or so-called "cold-pressed" (expressed or unprocessed) peanut oil, or "gourmet oil" with peanut material added for flavour because they will usually not be tolerated. They are often contaminated with nut protein and may contain enough to cause an allergic reaction. Vegetable oil will only present a problem if it is processed in machinery that has also been used to manufacture peanut oil. Coconut oil and other pure nut oils, as well as palm oil and tropical oils, do not need to be avoided unless you are specifically allergic to them.Identifying Nut AllergensThere is a multitude of food that contains nuts, although it is not always obvious that this is the case. Crushed nuts are used in many sauces, like some chilli and Italian pesto. Peanut butter is sometimes used in gravy or sauce recipes as shortening or oil. Nuts can occasionally be found in Worcester sauce and bouillon. Noisette is meat dish made or flavoured with hazelnuts.Chinese, Vietnamese, Indonesian, African, and Thai foods often feature nuts and should be avoided by nut allergy sufferers unless they can be confirmed whether peanut or nut protein is present. In these types restaurants, even if a dish is free from nuts, the risk of cross contamination is extremely high. If you have eaten at a restaurant safely in the past, you should still check on ingredients used every time you visit since recipes can often change and this may not be immediately apparent to you.Mixed nuts, trail nuts, and some types of energy bars clearly contain nuts. Breakfast cereals like muesli often contain nuts, as does granola. Salads, salad dressings, and other vegetarian dishes can contain nuts. Nuts can be found in grain bread and some types of muffin, including walnut muffins. Some brands of margarine will also contain nut oil. Nuts are found in cashew butter and almond butter, as well as in nut pastes like almond paste and some speciality cheese spreads.Confectionary such as praline, made from caramelised sugar and nut kernels, nougat, and marzipan, which is a paste consisting of ground almonds and sugar, are nut products. Gianduja is a creamy mixture of chocolate and chopped toasted nuts sometimes used in premium or imported chocolate. The ingredients of pastries, cakes, biscuits need to be thoroughly checked, especially if they have a chocolate coating.Flavourings, both natural and artificial, and other nut extracts may contain nuts. You should usually avoid natural extracts, such as pure almond extract. Certain kinds of what are called "artificial nuts" are actually peanuts that have had their flavour removed and replaced with that of another nut, like pecan, walnut, or almond. Some ice creams, especially chocolate flavour, and frozen desserts present a problem to those with nut allergies.Some beverages will contain nut flavouring. Amaretto is an Italian almond flavoured liqueur while frangelico is a liqueur flavoured by toasted hazelnuts and sometimes used on desserts. Those with nut allergies should also treat certain speciality coffees with caution.Nuts are not only found in food. Sunblock, shaving creams, shampoos, bath oils, foundation creams, ointments, lotions, moisturizers, and lipsticks commonly contain nuts, usually in the form of peanut or almond oil. Peanutamide is a semisynthetic compound derived from peanut oil that is found, along with loramine wax, in cosmetics and toiletries. Prometrium, a pure progesterone medication taken by women during menopause, is another product that contains peanut oil.It is virtually impossible to guarantee that someone will be able to avoid all contact with nuts, no matter how vigilant they are. It is important to carefully read the ingredients listed on products but, even then, it may not be easy to ascertain whether a particular product contains nuts, especially if words like "arachis" are used instead of "peanut". Because they will probably come in contact with nuts in one form or another, those people with significant nut allergy should always carry some readily injectable adrenaline in the form of an EpiPen auto-syringe.Nut Cross ContaminationOne problem for someone with a nut allergy is that it can be difficult to know whether there was any cross contact with other nuts during processing or handling, or if one type of nut has been substituted for a different sort in a recipe. There is also the risk, unlikely as it may be, of potential cross-reactivity between different types of nuts.Cross-contamination can be a problem for individuals with allergies that react to trace quantities of nuts. While the products themselves my not actually contain nuts, it is possible that they may became contaminated with nuts during the manufacturing process. Chocolates, for example, are often made using shared machinery. The compounded chocolate used in Easter eggs, imported European chocolates, and health food bars may present more of a risk. This is because some European chocolates are allowed to use leftover chocolate that may contain traces of nuts.Cross-contamination can occur if the pans, dishes or utensils used for cooking were also used to prepare a food containing nuts. If shop assistants have previously handled food containing peanuts then there may be a risk of them contaminating subsequent food, even if they are wearing gloves. Make sure that the food that you purchase has not been left in close proximity to other food containing peanuts that may contaminate it. Sometimes peanuts will have been sitting with other nuts as part of a production line and contamination may occur as a result. Care must be taken when feeding pets because some types of animal feed, like that used for hamsters, and bird feed often contain nuts and carry an associated risk of cross contamination through handling them.Many products now have a warning printed on the packaging to let consumers know that there may be a risk of the product being contaminated by nuts during the manufacturing process. In fact, some manufacturers have been criticised for labelling so many items that it is difficult to ascertain whether they are just doing this for legal reasons. Detailed listings of the ingredients are more useful to allergy sufferers because it provides the information necessary for them to make up their own mind about the risks associated with each product. If you are still in any doubt about the ingredients of a product, you can contact the manufacturer directly.Just because you have had a product labelled "may contain nuts" without any problem in the past does not mean that the same product will not trigger an allergy the next time you eat it. A company that produces different foods, some with nuts and some without, using the same machinery may have difficulty in ensuring that no trace of nut remains. A particular batch of the product may be more likely to contain traces of nut if was produced after a batch that contained nuts. Because of the uncertainty that this can create, you are best to avoid eating all products that contain these warnings if it could trigger a life-threatening allergic reaction.Diagnosis of Nut AllergyA substantial number of people who have had a reaction to nuts have never thought of being tested for allergies. Doctors and allergists can help diagnose these allergies and teach you how to manage them. Providing a detailed medical history of the affected person and their family is an important part of any allergy diagnosis. Skin prick tests, Radioallergosorbent test (RAST) and ImmunoCAP Specific IgE blood tests may possibly be used. Skin tests and blood tests often reveal that people actually have more nut related allergies than they thought they had before they took the tests. If there is prevalent history of peanut allergy in a particular family then a skin test will probably not be performed because of the inherent danger this presents. A strong positive result during skin prick test often suggests that the allergy is likely to be life-long, especially if it is associated with other food allergies.The ImmunoCAP test is reliable, specific, and highly sensitive. If the skin tests are negative then a blood test is often administered to confirm this result. Once a nut allergy has been confirmed, an action plan may be devised to help you deal with possible emergency situations. A doctor or allergist will often be able to provide you with detailed advice on how to avoid nuts and can instruct you on how to use emergency medication such as the EpiPen adrenaline auto-injection. If both the skin and blood tests are negative for allergies then a double-blind placebo-controlled food challenge (DBPCFC) can be used as a test method that eliminates both patient and administrator bias. This challenge involves gradually feeding increasing doses of food suspected of causing a reaction at predetermined time intervals to see whether it is tolerated or whether it results in allergy symptoms, all under controlled conditions.Sometimes people do not have an allergy to a particular food but have intolerance, or hypersensitivity, to it instead. The difficulty with diagnosing these conditions is that an individual may exhibit symptoms similar to an allergy in certain situations. One test for food intolerance is an elimination diet. A supervised elimination diet requires the participant to remove any suspicious foods from their diet for a short-term period of a couple of weeks. These foods are reintroduced one at a time and any symptoms are recorded in a food diary. If an allergy is suspected, or a family has a history of allergies, then this type of system is less likely to be used because of the possible danger if reintroducing a food allergen.