14 June 2010

Common questions about peanut allergy

Peanut allergy is a serious and usually life-long allergy affecting both children and adults. We answer common questions about this allergy.


Peanut allergy is a serious and usually life-long allergy affecting both children and adults. It is essential that individuals with peanut allergy avoid even the slightest exposure to peanuts to prevent life threatening reactions. The commonest manifestation of peanut allergy is with acute hives (or urticaria) following exposure.

However, some patients may rapidly develop severe angioedema, swelling of the face, bronchospasm and anaphylaxis following exposure. They are an uncommon cause of exercise induced anaphylaxis. Some individuals are so sensitive that they will develop symptoms if they kiss someone who has eaten peanuts, or eat out of a food utensil which has been in contact with peanuts.

How dangerous is peanut allergy?
Peanut allergy can be life threatening, and surprisingly minute quantities of peanut can cause a reaction. One study done at Johns Hopkins hospital in the United States showed that highly allergic people could suffer an attack if they touched a counter that had been wiped clean of all visible traces of peanut butter. Even such indirect contact as being in the room where a jar of peanut butter was opened, or being on an aeroplane with packets of nuts being opened around them can cause a life-threatening reaction in people with severe allergy.

Allergies vs intolerance: what’s the difference?
There is some confusion among the public and even some medical practitioners regarding the differences between true food allergies and food intolerances. Professor Paul Potter of the Allergy Diagnostic and Clinical Research Unit of the University of Cape Town Lung Institute says the majority of peanut reactions are true allergies and not food intolerances. He explains the differences:


  • Is caused by an immune-system reaction called anaphylaxis;
  • Can be tested reliably through a CAP RAST blood test, which tests for levels of IgEs against different allergens;
  • Person will react to even minute quantities of the allergen;Can be life-threatening.


Food intolerance:

  • Is a non-immune reaction;
  • Will not appear on a CAP RAST blood test, as IgE is not involved in the reaction;
  • Symptoms may appear up to eight hours after exposure, and are often confined to the gastro-intestinal system;
  • May not appear after exposure to small amounts of the allergen, and may be worse for larger amounts;Rarely life-threatening.


How is peanut allergy diagnosed?
A history of an allergic reaction occurring within half an hour of exposure to peanuts suggests peanut allergy. This should be confirmed by the CAP RAST test performed at a laboratory on a small blood sample.

A CAP RAST test for peanut allergy will show negative results for a patient who hasn't ever been exposed to peanuts.

A CAP RAST test for peanut allergy will only show a true result three weeks or more after a patient's first exposure to peanuts.

A CAP RAST test can be carried out on a patient immediately after a reaction - as long as that specific reaction is not the patient's first.

The CAP RAST test is reliable, being both highly sensitive and specific. However, if the result is negative, then it is advisable to repeat the test about three weeks later. If a strong history of peanut sensitivity is given, skin testing is potentially dangerous and should not be performed. If the result is negative, it is recommended that blood CAP RAST tests for possible sensitivity to soya and various tree nuts should also be done, as a patient sensitized to peanut is quite likely to also be sensitized to soya and various tree nuts.

How is peanut allergy treated?

  • Avoid any possible direct exposure to peanuts;
  • Compile a list of possibly contaminated foods which should also be avoided;
  • It is important to carefully study labels of all packaged, processed foods, cereals and health foods;
  • Take particular care when eating out, particularly at oriental restaurants or at children’s parties;
  • Caregivers in crèches, school teachers, family members, friends and their mothers should be informed about the allergy and what to do in an emergency;
  • Wear a Medic Alert badge;
  • Always carry an adrenaline syringe and be familiar with its use;
  • Never take a chance with unknown foods.


How common is peanut allergy?
Food allergies in general are more common among more affluent people than among rural people eating a more simple traditional diet. It is more likely to occur in children whose parents suffer some sort of allergy, although peanut allergy itself does not seem to run in families.

What is anaphylaxis?
Anaphylaxis is an excessive reaction of the immune system to the presence of a foreign body it wrongly perceives as a threat. In its most severe form, it may be life-threatening.

What are the symptoms of anaphylaxis?
A person with a severe allergy will experience a combination of these symptoms. They will usually appear within minutes of being exposed to the peanut protein, but may take up to half an hour.

  • Itching in the mouth or throat;
  • Strange metallic taste in the mouth;
  • Difficulty in breathing;
  • Difficulty in swallowing;
  • A rash of hives (urticaria);
  • Flushed skin;
  • Stomach cramps and nausea;
  • Increased heart rate;
  • Sudden feeling of weakness;
  • Collapse or fainting;


Will my child grow out of peanut allergy?
Until recently, surveys done some years after diagnosis were not encouraging. Although a few children did seem to grow out of nut allergy, the general consensus was that it seemed to be a life-long condition. Recently, several groups of doctors have discovered that the picture does not seem to be quite so bleak, especially for young children. There do seem to be quite a lot of children who do grow out of nut allergy after all. This question is therefore getting a lot of interest from researchers.

Is the nutritive value of peanut important?
Peanuts provide niacin, magnesium, Vitamin C, manganese and chromium in significant amounts and smaller amounts of potassium, Vitamin B6, folic acid, phosphorus, copper and biotin. A peanut restricted diet will not negatively affect a growing child’s diet, since many other foods provide these same nutrients.

What is the most dangerous time of life for peanut allergy?
Small children are amazingly good about avoiding nuts if they are allergic to them. Parents make few mistakes. The main danger to children seems to come from mistakes made by adults other than their parents. That said, some foods contain nuts in a way that is not obvious, and anyone will make a mistake occasionally. Before the teenage years children also seem to have a much smaller risk of dying than teenagers and adults even if they do have anaphylaxis. For example this is true of young children who have anaphylaxis from bee or wasp stings, when they are stung with the same amount of venom as an older person.

The biggest risk period seems to be in the teens and young adulthood, perhaps because young people of this age become more independent, are no longer protected by parents so much of the time, and may not be so strict about keeping their treatment with them all the time.

Beyond the teens and twenties the impression is that the risk of accidentally eating nuts becomes smaller again as we adopt a less risky and variable lifestyle. But older people who do get anaphylaxis are more likely to die of it. One reason for this is probably that heart disease and hardening of the arteries make us more vulnerable as we get older.

Age is not the only thing which has a big effect on the risk. For example if you have asthma your risk is greater, because if you get anaphylaxis the asthma is prone to become very bad as part of this. People with asthma who get anaphylaxis need to be particularly careful to use preventive drugs for their asthma to cut this risk.

If you've only had mild reactions, does this mean future reactions will be mild as well? Although this seems to be true for most people, there are exceptions. The vast majority of reactions to peanuts don't kill in any case. But the stories of people who died from nut allergy show that this can happen even to someone who has only had mild reactions before. So to be on the safe side, doctors often regard peanut allergy as dangerous even if none of the previous reactions have been dangerous.

Are there any cures for peanut allergy?
Desensitising injections have been tested but are not generally recommended; they are still regarded as experimental. Scientists have come up with a number of other ideas which may make people with nut allergy safe. At least one of these is being tested now, but it is not available for prescription.


Should peanuts be banned from schools?
Many schools in the UK are doing this. Since there is probably no school without nut allergic children, this seems sensible.


Airline flights and nut snacks: how can we protect ourselves?
Some airlines have banned nuts from snacks, and others have done so on request for a particular flight when informed that a passenger was hypersensitive. Other airlines have been less helpful. Recently there has been a death from this cause.

The US Government Department of Transportation has told all large American airlines that they must set aside a "peanut-free zone" when requested to do so by passengers with medically documented peanut allergies. If they do not stop serving peanuts on the flight, the minimum for the peanut-free zone is the row of seating with the passenger plus the rows in front and behind. This is in conformity with a law passed in 1986 that guarantees access to planes for the disabled.

When should I use adrenaline (epinephrine)?
Some specialists advise that adrenaline should be used for any reaction. You should certainly not wait until you (or your peanut-allergic child) is beginning to be incapacitated. It is believed the earlier you give the treatment, the better it works. Rapid progression of symptoms is a danger sign.

If your child gets just a few itchy swollen spots near the lips and the reaction is not getting worse, by all means have the injection at the ready and make sure you can get help quickly if things deteriorate, but if they are not deteriorating, why inject?

On the other hand, if your child is unconscious, with obvious difficulty in breathing, it could already be too late. So there is a right time to give adrenaline (epinephrine) and your judgement as a nonmedical person needs to be be good enough to get this right.


What are the side effects of adrenaline (epinephrine)?
In the recommended doses, trembling, palpitations (feeling your heart beating fast), and a feeling of tension or anxiousness are quite likely to happen, though many people don’t notice any of these things. These are normal effects of the adrenaline and soon wear off. Higher doses cause an extremely unpleasant feeling and may be dangerous to the heart.


If you have some other medical conditions such as high blood pressure, or an abnormal heart rhythm, or narrowing of the coronary arteries, or if you are treated with some other medicines such as medicines for depression, special caution is needed with adrenaline, and a specialist should advise you.

If my child is allergic to peanuts, are other kinds of nut dangerous too?
Bearing in mind that the peanut is actually a legume, quite often they are not, but unfortunately many children and adults who are allergic to one kind of nut also become allergic to other kinds. This includes not only peanuts, almonds, brazil nuts, cashew nuts, hazel nuts, pistacio nuts, walnuts and pecan nuts, but also in rather fewer people coconut, sesame seed, poppy seed, sunflower seed, and pine kernels.

Sesame seed is particularly difficult to avoid with certainty as the seeds are so small and may fall off bakery products. It is the main ingredient of tahini (tehina, tchina), which is in turn an ingredient of other foods, for example houmous (various other spellings are used, such as hummus.)

One of my children has peanut allergy. Should I have my other children tested for peanut allergy?
This is a difficult problem right now, but it is not generally recommended. The reason is that tests would undoubtedly be positive in many children who can safely eat nuts, a so-called 'false positive' test result. A positive result shows sensitization against that particular allergen, but this does not necessarily lead to clinical symptoms. However, sensitization, as shown by a positive result, may well precede clinical symptoms.

Many children would end up carrying emergency treatment unnecessarily, and in the nature of things some will end up getting the treatment inappropriately. This is not just a problem with allergy, but with many medical tests; a test which is quite good for diagnosing a condition in someone with symptoms suggesting that condition, becomes a very poor test when applied to large numbers of people who have never had the symptoms.

But, allergy runs in families, and nut allergy affects people with allergies in the family
Nut allergy is now quite common as medical conditions go. In some cases, brothers and sisters do show positive test results. Perhaps this is important. We will only really know when we have found out more about whether such brothers or sisters really have reactions in practice often enough for this to demand action. At the moment it is generally felt it is wrong to prescribe adrenaline kits for children who have never had a reaction to peanuts.

Can peanut oil in nipple cream for breastfeeding mums cause peanut allergy?
In the past, certain brands of breast cream contained peanut oil, although maize and other plant oils are now predominantly used. The previous versions have been blamed by some people for the increasing numbers of peanut-allergic children seen by doctors.

This is an interesting idea, but does not seem to fit all the facts. Other allergies such as hayfever have also increased, but pollen concentrations have not, for example. There are clearly other reasons why allergies have increased. Nevertheless, it seems sensible to avoid any creams if they contain peanut oil.

What are the more commonly used language translations for peanut?
In English we have several quite different names: peanut, groundnut, monkey nut and names derived from the Latin name, Arachis hypogea. There are also items like peanut butter and saté sauce to consider; we haven't done so in what follows. Remember that the presence of peanuts may be taken for granted in some foods with a quite different name.

Remember that restaurant staff may be temporary workers with little knowledge of the foods they serve. A patient asked in a restaurant whether saté sauce contained peanut, and was told by the waiter that it did not. Of course it practically consists of peanuts.

The French and Dutch, for example, also have several quite different names. Harrap's dictionary gives:

  • pistache de terre;
  • arachide;
  • cacahouette;
  • cacaouette;
  • pinda (peanut butter is pindakaas);
  • aardnoot, aardnoten;
  • apenoot;
  • olienoot (given in dictionary but not used in everyday life).


Other languages:
It is obvious that other languages are likely to have similar complications. Get your information from a native speaker and a large dictionary (go to a public or university library), don't assume that they have remembered to tell you all the names, and don't assume you can correctly pronounce or understand the spoken versions unless you are a good speaker of the language.

How can I eat safely in restaurants?
Most allergic reactions to nuts happen when people are eating away from home, especially in restaurants. Restaurants are danger areas for people with peanut allergy.

Even if you explain yourself properly to the staff and don't end up eating something which has peanut put in intentionally, all it takes is for someone to move a utensil from one pot to another to transfer traces (perhaps more than traces) of nut to the food you eat. In a hotel breakfast room another customer could transfer nuts from muesli to something you eat. In some oriental restaurants a garnish of crushed nuts might be added to a nut-free dish by the harassed chef, who may not have been told why you ordered a nut-free dish.

A hot curry can mask the tingling you may get in your mouth if you eat nuts you are allergic to.

If you eat in Chinese restaurants or other oriental restaurants, you are liable to eat nut sooner or later, despite your best intentions and those of the staff. In fact non-oriental restaurants and hotels are not that safe unless they have very special arrangements in place. For example some fast food restaurants do not sell any products with nuts. Without such a precaution, there is always the possibility of cross-contamination of foods, even if you and the waiter understand each other's language properly.

Even if you tell restaurant staff the problem, they are often extremely busy. Remember, they have their own problems and may not have your rather unusual needs at the forefront of their minds every moment whilst they are handling your food.

Restaurant staff are increasingly aware of the problem and are in many cases now doing their best, but in most cases we feel that restaurants are inherently unsafe if you have nut allergy.



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Dr Morris is the Principal Allergist at the Cape Town and Johannesburg Allergy Clinics with postgraduate diplomas in Allergology, Dermatology, Paediatrics and Family Medicine dealing with both adult and childhood allergies. obesity and diabetes societies and runs a trial centre for new drugs.

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