Nov
14
2020

Why We See More Food Allergies

A recent review in a BBC article explained why we see more food allergies. It is important to note that one of the more important food allergies are peanut allergies. Certainly, they have risen from 1 in 250 children in 1997 to 1 in 70 children in 2008.

By all means, allergies come in various degrees of severity; an anaphylactic reaction is the most severe form. Notably, in England there was a rise of hospital admissions for anaphylaxis from 1,015 in 2013 to 1746 in 2019. This is a 72% increase in 6 years!

Theories why there may be more food allergies now

There are a number of theories why food allergies have been on the rise. There is a consensus now that the right composition of the gut bacteria is important for normal immune reactions to take place.

Hygiene theory

David Strachan proposed the hygiene theory of allergies in 1989. Briefly, his observation was that children of larger families were less likely to develop allergies. He interpreted this to mean that infections among siblings stabilized the immune system. In the meantime, it has become obvious that the gut plays an important role for the immune system.

Graham Rook’s “old friends” theory

Graham Rook’s “old friends” theory came out in 2003. This theory states that friendly microbes in the environment are mixing with the gut flora. This trains the immune system to balance.

Gut bacteria theory

There is good evidence that the more a child is given antibiotics as a child, the more likely it is that the person develops a food allergy later. The mechanism seems to go via the gut flora. In a way this is the other coin of Graham Rook’s “old friends” theory. If you kill the “good friends” bacteria in the gut by antibiotics, the immune system strikes back with allergic reactions.

Dual-allergen exposure

By exposing the child at 4 to 11 months to peanuts or peanut butter, the immune system develops tolerance to the peanut protein (LEAP=learning early about peanut). A study showed that by doing this 80% of 5-year and older children and adults do not have a peanut allergy.

Prenatal vitamin D and food allergies

A German study found that prenatal exposure to higher amounts of vitamin D resulted in a higher risk of developing food allergies before the age of two.

Use antibiotics only when necessary

Gut biome studies showed that the use of antibiotics can have long lasting effects on the composition of the gut flora. A patient in sepsis may require antibiotics. But when the patient has recovered it is important that the bowel flora is restored with probiotics. This balances the immune system and avoids allergic reactions.

Immunotherapy for food allergies

Allergists have long used desensitisation techniques to deal with inhalant allergies. Allergy shots every two or three weeks can be very helpful to suppress immune reactions to inhalants. The same technique works also for many food allergies. The allergist tests the patient’s skin on the forearm to see what positive reactions occur. Based on these findings an allergy serum is composed. A small amount is injected in intervals. The smallest amount is given first and the concentration is gradually increased until the maintenance dose is reached. This causes the immune system to produce competing antibodies that reduce the antibody-mediated reaction to the food allergies.

Why We See More Food Allergies

Why We See More Food Allergies

Conclusion

Food allergies are increasing in frequency and severity. There are several theories why food allergies develop. The most likely one is that friendly bacteria in the environment become part of the gut environment in the newborn. If we have the right composition of gut bacteria our immune system reacts normally. Administering antibiotics frequently and overcleaning our kitchens with too many cleaning agents affects our bowel flora negatively. This disbalance can cause allergic reactions. On the other hand, exposing a newborn between the age of 4 and 11 months to a variety of adult foods including peanut products will desensitize the child to peanut protein and prevent future allergies. Those who are severely affected by food allergies can see an allergist for allergy testing and consider desensitisation through allergy injections.

Aug
31
2013

Peanut Allergies Are Deadly

In the US 1.5 million suffer from peanut allergies (Ref.1). People who have peanut allergies have to avoid peanuts and foods that contain even traces of peanuts lifelong. Here is a recent example of a 13-year old girl who died at a camp when she tried food contaminated with peanuts. Before we discuss peanut allergies in detail, we need to review first how the immune system is functioning.

How the immune system is primed to develop an allergy

Our immune system knows the difference between our own body components and substances that come from the outside. Scientists call this tolerance to our own surface proteins; and scientists call it an immune reaction that is mounting as a reaction to anything different from the surface antigens. There are different cells that make up the immune system. One of the main working cells of the immune system are the lymphocytes, with B cells originating from the bone marrow producing antibodies when an immune reaction occurs. Antibodies fit like a lock and key to the surface of an antigen, in this case the peanut protein. T helper cells are T lymphocytes (thymus derived lymphocytes) that help the B cells to recognize the difference between the own protein components and the outside components. There are also T killer cells, which get activated when parasites or viruses enter the body. With regard to peanut allergies it is the B cells and T helper cells that interact and the B cells produce a powerful, very specific IgE antibody directed against peanut protein. There are memory B cells, which continue to produce these specific anti-peanut protein antibodies and cause severe allergic reactions when future exposure to peanuts (even traces) occurs. So, the more often a person who is allergic to peanuts encounters even traces of peanuts, the immune system will get boosted and produce even more antibodies of the IgE type through reactivated B memory cells (Ref. 2). 98% of the population does not react to peanut exposure with allergies, but the other 2% who may have genetic susceptibility factors that predispose them to this often develop life-threatening reactions (an anaphylactic reaction).

What is an anaphylactic reaction to peanuts?

The most extreme form of allergies involving IgE antibodies can cause anaphylaxis. In the beginning stages of a peanut allergy there may only mild symptoms such as hives on the skin, itching and tingling around the mouth, a runny nose, a scratchy throat, wheezing, stomach cramps, vomiting or diarrhea. However, with a more severe allergy an asthma attack can develop, blood pressure drops leading to fainting or shock and severe airway obstruction in the throat or lungs can cause suffocation.

I vividly remember an 11-year-old boy who was brought in by ambulance to the emergency room of the hospital where I was working as the on-call physician. He had a hard time talking as his throat was swelling up as part of his anaphylactic reaction, within minutes he passed out completely (shock). Fortunately an anesthetist was in the department and could intubate him very quickly. However, despite adrenaline treatment, oxygen  by artificial ventilation and high doses of corticosteroid drugs he did not wake up until 10 hours later. In retrospect it turned out that he had eaten some crackers of a familiar brand that he knew as being free of peanut flour. However, he had seen an ad that the same brand of crackers was available as cheese crackers and he tried one of these, which prompted his admission to the hospital. The parents read the ingredients later: the label on the cheese crackers noted in small print that the flour of the cheese crackers contained peanut flour! Always read labels, even if it is a familiar brand! Fortunately for this boy he did not have brain damage from the time of his unconsciousness. He has been extremely careful since and is reading labels and avoiding unknown food items.

Peanut Allergies Are Deadly

Peanut Allergies Are Deadly

Cross-reactions between peanuts and other allergens

Allergies can be made worse when a person has inhalant allergies from pollens of trees or grasses that can share protein components from protein found in foods. The latest findings are that there are cross allergies between Fenugreek and lupine, which are both legumes, as are peanuts, so there are common antigens present in their proteins. A mouse-testing model has shed more light on this. Fenugreek has been shown to control mild diabetes by improving insulin resistance, but it cannot be consumed by persons who are highly allergic to peanuts because of the cross allergy mentioned.

There are other possible cross allergies to legumes like lentils, soy and chickpeas.

Other factors that can cause allergies to get worse

In the past the RAST test was often used.  This is a blood test for common food allergies that can cause severe allergic reactions like egg, milk, peanut, tree nuts, wheat, crustacean shellfish and soy. However, since about 2010 this has been replaced by the more sensitive ImmunoCAP Specific IgE test. Children who have food allergies to egg, milk, wheat, nuts, peanuts and soy often outgrow these allergies when they age, in other words their immune system can develop tolerance to many of these foods. Not so with peanut allergies ! They tend to be very persistent.

The immune responses to food allergies are complicated as there are immediate type immune reactions and delayed type immune reactions. The immediate immune responses are investigated with the above mentioned ImmunoCAP Specific IgE test. The delayed immune responses can be measured using the ELISA test. Positive IgE antibody tests for peanut protein are a marker that the person affected likely has more other allergies and they should be investigated by a knowledgeable allergist in that regard (Ref. 2).

What complicates the allergy sufferers’ lives even more is the fact that new wheat varieties since the 1970’s, called Clearfield wheat have a much higher gliadin (gluten) and lectin content than the old wheat varieties. As a result of exposure to this new type of wheat gluten intolerance and leaky gut syndrome have increased substantially in the world population (Ref.3). In addition, genetically modified foods like soy, corn, sugar beets, canola and others have challenged the immune system of sensitive humans even more. We do know that some people can develop autoimmune diseases from GMO foods and modern wheat, and this may be the reason that a host of diseases that belong into this disease category (MS, rheumatoid arthritis, Hashimoto’s thyroiditis, ankylosing spondylitis etc.) are much more common now than in the past. The geneticists who developed GMO foods seemed to be unaware how sensitive the immune system is, which will detect a few different amino acid sequences in a protein mounting a strong immune response to it.

Treatment for peanut allergies

The key for sufferers from peanut allergies is to avoid exposure to it. Read labels and use common sense. If something is not labeled, do not be tempted to eat it. Peanut flour is often mixed into the dough of crackers, not being labeled properly or only in fine print. With peanuts the antibodies usually circulate in the blood life long as the B memory cells do not diminish and get reactivated very quickly on repeat exposure producing antibodies again. As exposure to peanuts can cause severe asthma or anaphylactic shock, it is important to carry an EpiPen with you and to know how to use it.

In Europe attempts have been made to develop an oral desensitization method for food allergies including peanut allergies, but it has not produced concrete results yet. Recently, however, research from Texas, USA showed that it is possible to desensitize patients with peanut allergy by oral desensitization. In Australia where food allergies are more prevalent than in the US, tolerance to peanut, nut and shellfish allergies is being pursued by oral immunotherapy. Another group in Australia has developed a vaccination method using peptides, which are a sequence of amino acids, but shorter than the full peanut protein. It appears that this is the future direction of  treatment for peanut and other IgE mediated allergies: a kind of vaccination treatment to induce competing antibodies, which will neutralize the allergic IgE antibodies.

Conclusion

Peanut allergies have become more troublesome as the food industry has mixed peanut flour into Thai sauces, drinks, cookies, crackers and such. The person allergic to peanuts must read food labels and eat as much single-ingredient natural food as possible. This goes against the tendency of food processors who produce foods with a long rat tale of ingredients. If you see a label “may contain nuts or peanuts”, stay away from this product, as it is safer. Always carry an EpiPen or Twinject with you, just in case you develop an anaphylactic reaction (you only have a few minutes to stop the allergic reaction with adrenaline). In the future vaccination with a peanut protein specific peptide vaccine as mentioned regarding the Australian research, will probably become the treatment of choice.

More information on status asthmaticus (an acute asthma attack): http://nethealthbook.com/lung-disease/asthma-introduction/asthma-treatment/

References

1. Adkinson: Middleton’s Allergy: Principles and Practice, 7th ed. Chapter: Food Allergy. © 2008 Mosby.

2. Mandell: Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases, 7th ed.© 2009 Churchill Livingstone.

3. William Davis, MD: “Wheat Belly Cookbook. 150 Recipes to Help You Lose the Wheat, Lose the Weight, and Find Your Path Back to Health”. HarperCollins Publishers LTD., Toronto, Canada, 2012.

Last edited Nov. 7, 2014