Archive for the ‘Food Allergy’ Category

Outgrowing egg allergy

Monday, July 26th, 2010

Hen egg allergy is very common in infants with eczema and usually outgrown by age 6 with a few children retaining their egg allergy into adulthood.  The egg white or albumin is more allergenic than the yolk and heat or cooking damages the allergen making it less allergenic. Some children will therefore tolerate cooked but not raw egg, whereas other more severely allergic children will react to all traces of egg. Early onset of egg allergy is associated with asthma at age 18 months. Fortunately the Measles (MMR) vaccine no longer contains any egg so is not contraindicated in egg allergic children.  However the Influenza and Yellow Fever vaccines are grown on chick egg embryo’s and therefore may be a problem for egg allergic children.

A new ImmunoCAP f233 blood test can now determine whether hen’s egg allergy is likely to be severe and persists into adulthood. Once the IgE skin prick test or blood RAST testing show a positive allergy result for eggs, a further test for raised antibodies to the heat-stable  egg protein Ovomucoid (Gal d 1) is very useful for determining if egg allergy will persist.

Ref: Ando H, Moverare R, Kondo Y et al  Utility of ovomucoid-specific IgE concentrations in predicting symptomatic egg allergy. J Allergy and Clin Immunology 2008:122;583-8.

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Peanut allergy manifests in different ways

Friday, July 16th, 2010

Not all peanut allergy sufferes react in the same manner. Some will only have mild oral itching after eating a handful of peanuts, while others will have catastrophic anaphylaxis after minor exposure to airborne peanut allergen. Some peanut allergy sufferers will also have reactions to other seeds such as Sesame or tree nuts such as Brazil nut, Hazelnut and Walnut.  While others may only react to legumes such as beans, peas and lentils. Yet others may have allergic cross-reactions to soybean and lupin flour.

This has all been rather unpredictable and guess work until recently when a new blood tests was developed which can show with accuracy which part of the peanut an allergy suffer has or will react to in the future. For example there is a particular peanut protein called Ara h 2 which is likely to cause anaphylactic reactions. This type of component allergy test is useful in predicting whether a cross-reaction to nuts, beans, seeds or fruit is likely to occur.

Peanut component allergy testing and likely cross-reactivity:

Ara h 2 High risk anaphylaxis to peanut and nuts

Ara h 1 – cross-reactions with legume (pea, bean, lentil) and nuts

Ara h 3 – cross-reactions with soybean and lupin flour

Ara h 8 – localised oral reactions to peanut and stone-fruit only.

Reference: Astler C et al. Journal Allergy and Clinical immunology 2007: 118; 250

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Lactose Intolerance only causes diarrhoea

Thursday, February 18th, 2010

Lactose Intolerance is a deficiency of the digestive enzyme B-galactosidase (Lactase) in the human intestine and a meal containing the cow‘s milk disaccharide sugar lactose (galactose bound to glucose) will induce frothy diarrhoea, flatulence and abdominal cramps.  This is caused by undigested lactose passing into the colon where it is hydrolysed by bowel bacteria producing organic acids and gas including CO2, H2 and H2O.  Symptoms do not include vomiting, rashes or nasal congestion as there is no immune response, it is purely undigested lactose that results in runny poop!

So if you do indeed have Lactose Intolerance, a proper cow’s milk challenge must theoretically give you rapid onset diarrhoea. No diarrhoea equates to no Lactose Intolerance. If your nose blocks up or they get a rash on your tummy then you probably have some additional problem other than purely lactose intolerance.

Almost all people are born with sufficient lactase but with increasing age, levels drop. Most lactose intolerant individuals tolerate small amounts of lactose in the diet and usually a full glass of fresh milk is necessary to trigger symptoms. Temporary lactose intolerance may follow a bout of viral gastroenteritis due to inflammation and hence it is best to avoid cow’s milk during the recovery period.

Lactose Intolerance may be an inherited trait affecting 10% of Caucasians and up to 80% of ethnic Africans, Asians and people of Mediterranean origin. Treatment is basically lactose avoidance or supplementation with an oral Lactase enzyme preparation such as Colief. Yoghurt is often tolerated as it contains live B-galactosidase producing bacteria.

Useful tests for diagnosing Lactose Intolerance include the popular Hydrogen Breath Test (although less reliable due to false positive results from other dietary sugar intake), as well as measuring serial blood glucose levels after a lactose containing meal, or measuring Faecal Reducing Substances (Sugars) in the watery frothy diarrhoeal stool  produced as a consequence of a lactose containing meal.

References:

Joneja JMV. Food Allergy & Intolerances. Mechanisms and Management. J.A.Hall publications 2003.

Metcalfe D, Sampson H, Simon R. Food Allergy: adverse reactions to food and food additives 4th Ed. Blackwell Science 2008

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Irritable bowel syndrome (IBS)

Thursday, January 14th, 2010

Irritable bowel syndrome otherwise called IBS is a common medical condition affecting the lower bowel in 1 in 5 young adults. Females are especially prone to IBS which presents with one or more of 3 cardinal symptoms:

A. Abdominal pain and spasm which eases when emptying the bowels.

B. Bloating, fullness on eating and abdominal distension with wind.

C. Change in bowel habit with passage of frequent loose mucus-laden stools (an enhanced gastro colic reflex), often alternating with episodes of constipation.

Other more serious bowel conditions such as food allergies, inflammatory colitis, stomach ulcers, intestinal infection and coeliac disease may cause similar but more intense symptoms, and will need to be excluded by testing. A few simple blood tests undertaken by your GP (such as ESR, CRP, FBC) will exclude colitis or gut infection, while specific IgE allergy testing will identify food allergy and coeliac screening measuring Tissue Transglutaminase antibodies will exclude gluten intolerance. Certain non-specific food intolerances may be triggers for IBS and these include excess fruit intake, wheat, dairy produce, onions, excess tea, coffee, alcohol and highly insoluble dietary fibre such as bran, all of which may exacerbate IBS symptoms. The artificial sweetener Sorbitol and processed starch in ready meals may also promote IBS. While emotional stress, masked depression and missed or erratic meals may also be triggers, whereas taking a regular Probiotic supplement (Acidophilus GG) and drinking plenty of filtered water every day may calm the symptoms.

Discuss any concerns you might have regarding food allergies, intolerance or colitis with your GP, Practice Nurse or a qualified Dietician.

http://www.nice.org.uk/guidance/index.jsp?action=byID&o=11927

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Christmas allergies

Tuesday, December 22nd, 2009

Although some people have a general aversion to all things Christmas, this is not truly an allergy.  But for those genuinely allergic people, the festive season can be a frankly dangerous period. Unprecedented numbers of children have developed nut, fruit and general food allergies in recent years as the allergy pandemic takes hold of our lives on a scale that outstrips global warming and climate change.  Christmas time is a highly risky period for these people.  Consider the contents of Christmas foods such as cakes, mince pies, puddings, nuts and all those special treats abundantly available during the Festive Season.  No wonder it’s a worrying time for parents and allergy sufferers. Even the traditional Christmas tree may be a hotbed of allergens, distributing pollen, moulds and resin inside the home.  Whilst a synthetic tree may be as problematic for it may contain allergenic chemicals such as formaldehyde and isocyanates.  These chemicals can trigger off asthma, rhinitis, skin allergies and allergic conjunctivitis.

On a more positive note, the traditional Christmas turkey is a particularly low allergy-risk protein and if served together with low allergy-risk vegetables such as rice, sweet potato, cooked carrot, parsnip, beetroot and peas, this can make a particularly suitable Christmas meal for allergy-prone children and their parents. Finish off the festivities with a hypo-allergenic dessert of cooked pears or apricots. The process of cooking foodstuffs tends to reduce the allergy provoking effects on the immune system by slightly changing the molecular structure of the food.  If in doubt about allergy-risk friends and visitors always keep a good supply of antihistamine medication on hand just in case……………. 

www.allergy-clinic.co.uk/food-allegy/food-allergy-guide

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18% increase in food allergies amongst US children

Wednesday, November 18th, 2009

A scientific study due to be published in the American medical journal Pediatics (December 2009) has found a massive 18% increase in reported food allergies amongst US children (under 18 yrs of age).  This increased reporting of food allergies took place over the last decade between 1997 and 2007.  While between 1993 and 2006 ambulatory visits to the doctor for food allergies have tripled.  In 2007 alone, 3.9% of US children reported food allergic conditions.  The most severely affected were ethnic minorities such as Hispanics. In 2005 to 2006, an estimated 9% of US children had detectable peanut IgE in their blood on allergy testing while over the same period hospitalisations with a diagnosis of food allergy also tripled. It is uncertain whether this trend is due to a true increase in food allergic diseases or represents increasing allergy testing and physician and parental food allergy awareness.

http://pediatrics.aappublications.org/cgi/content/abstract/peds.2009-1210v1

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IgG antibody tests don’t indicate food intolerances.

Thursday, October 29th, 2009

In the UK, blood tests for immunoglobulin G4 (IgG4) against foods are actively promoted for the diagnosis of food intolerance and hypersensitivity. Mounting clinical research indicates that food-specific IgG4 allergy testing does not indicate (imminent) food allergy or intolerance, but is rather a normal physiological response by the immune system after food exposure. In fact IgG4 is more likely to indicate food tolerance and that the person can safely eat that food with no adverse effect. This should not be confused with IgE which is the main allergy antibody used in allergy testing and this has an established “track record” in conventional allergy diagnosis.

Not really convinced? Have a look at these research papers:

No recommendation for IgG and IgG4 testing against foods  
J. Kleine-Tebbe, I. Reese, B. K. Ballmer-Weber, K. Beyer, S. Erdmann, Th. Fuchs, M. Henzgen, A. Heratizadeh, I. Hutt egger, L. Jäger, U. Jappe, U. Lepp, B. Niggemann, et al Allergo J 2009;4: 267

Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report*  
 Stapel SO, Asero R, Ballmer-Weber BK, Knol EF, Strobel S, Vieths S, Kleine-Tebbe J.
 Allergy 2008 July;63(7):793-796.

Unproven techniques in allergy diagnosis.  
 Wuthrich B.
 J Investig Allergol Clin Immunol 2005;15(2):2-90

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Swine flu vaccination controversy in egg allergy

Saturday, October 17th, 2009

There has recently been a lot of debate in the media about safety of vaccines, particularly relating to the MMR (Measles, Mumps & Rubella) vaccination with unsubstantiated links to Autism and Ashbergers Disease.  In addition, the measles vaccine was historically grown on chick embryos, thus running the risk of egg allergen contamination, and consequently recipients could potentially develop anaphylaxis if highly egg allergic. Today the MMR vaccine no longer contains any egg allergen and is absolutely safe to administer to highly egg allergic children.

The influenza and yellow fever vaccines are still cultured on chick egg embryo’s and thus potentially contain egg protein. But the World Health Organisation (WHO) suggests that this is unlikely to be problematic if mildly egg allergic and in those who tolerate egg without anaphylaxis.  In severe egg allergy with anaphylaxis, administration of the conventional influenza and yellow fever vaccinations are contraindicated.

Does the same go for the current Swine Flu (H1N1) influenza vaccine?  I’m informed that Pandemrix currently being promoted to prevent the second wave of the Swine Flu pandemic is also cultured on chick egg embryos. Fortunately there is an alternative Swine Flu vaccine called Celvapan which is not cultured on egg and therefore safe to give to egg allergic individuals. But the Celvapan vaccine does not contain the immunity enhancing adjuvant Squalene and therefore requires 2 doses 3 weeks apart.  Celvapan is also the WHO preferred adjuvant-free Swine flu vaccine to be given during pregnancy.

Annual Flu vaccines are routinely recommended for asthma sufferers as they are generally more prone to viral illnesses, influenza and chest complications.  But Asthma sufferers are also a greater risk group for anaphylaxis if concomitantly egg allergic and inadvertently given the egg cultured flu vaccine. If in doubt, 1/10th of the vaccine should be administered under medical supervision as a test dose followed by the 9/10th balance if no reaction occurs within 30 minutes.  For detailed advice on egg allergy and Swine Flu vaccinations visit the British Society for Allergy and Clinical Immunology via this link:

http://www.bsaci.org/index.php?option=com_docman&task=doc_download&gid=80

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Peanuts allergy cure is here!

Saturday, October 17th, 2009

In a recent peanut allergy study at Addenbrookes Hospital in Cambridge, traces of peanut flour were used to desensitise 18 highly peanut allergic children. At the end of the study conducted in a controlled hospital environment, they were able to consume 12 peanuts each without any allergic reaction. The study involved eating minute trace amounts of peanut flour mixed with food or drinks on a daily basis to slowly induce peanut tolerance.  Then at regular 2 weekly intervals the peanut flour dose was doubled so that by the 10th hospital visit, they each ate 5-6 peanuts each without reacting on allergy testing. But to maintain thispeanut tolerance they will have to continue eating peanuts regularly on a daily basis, otherwise they may lose this tolerance and their peanut allergy recur.

WARNING: This was a highly controlled study in hospital and peanut allergic children should not be given peanut flour unsupervised!

http://news.bbc.co.uk/2/hi/health/7899383.stm

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