Dr. Adrian Morris of Surrey Allergy Clinic Tests and Treats allergies » Food Allergy

Hygiene Hypothesis revisited

Dr. Adrian Morris — Sun, 22 Jan 2012 18:54:43 +0000

The recent epidemic of allergic disease seen in developed countries has been difficult to explain. We have seen four-fold increases in allergic diseases such as asthma, rhinitis, eczema and food allergies. Changes in lifestyle and eating habits seem to be implicated and clean, sterile and infection-free “westernised” homes seem to be the probable trigger. One’s first year of life plays a pivotal role in allergic sensitisation and if an infant’s immature immune system is not correctly stimulated, it can transform into allergy-prone mode, particularly in children with a genetic predisposition to develop allergies (this is called atopy).

Factors that seem to reduce the likelihood of developing allergies include:

A home with 2 or more older siblings living in close proximity.
Pet ownership (especially dogs & early exposure to animal farms)
Exposure to parasite or hookworm infections (IgE was designed to combat worms).
Exclusive breastfeeding for 4 months (confers immune protection).
Early introduction of probiotic bacteria (acidophilus GG promotes gut immunity)
Micro-bacteria in spoilt food and drinking water
Dietary anti-oxidants, folate, fish oils and vitamins (such as Beta carotene)

Factors that seem to promote allergic sensitisation include:

Lack of older siblings (who carry germs that switch off allergies)
Advancing parental age (aging genes predispose to allergy)
Birth by Caesarian section (lacks exposure to protective vagina bacteria).
Sterile Westernised homes (no germs to stimulate the immune system)
Predominantly sterile indoor environment (no exposure to dirt )
No household pets (faecal endotoxins & germs)
Early use of paracetamol and antibiotics (alter immune responses)
Lack sun exposure (lack of Vitamin D effects genes)
Obesity and sedentary lifestyle (smaller lungs cause asthma).
Parental indoor smoking (maternal during pregnancy and infancy).
Withholding of potentially allergenic foods such as peanut and egg exposure in early infancy (4 months is better than 12 months).
Diesel exhaust particles (make aero-allergens more potent)

Reference: Tan T, Ellis JA, Saffery R, Allen KJ. The role of genetics and environment in the rise of childhood food allergy. Clinical and Experimental Allergy 2012 (42) 20-29

Iodine in shellfish does not cause allergies.

Dr. Adrian Morris — Tue, 01 Nov 2011 14:34:16 +0000

There is a well established myth that fish and shellfish allergy is linked to the iodine content of fish and that iodine allergy and shellfish allergy are interrelated. This is untrue.

Shellfish such as shrimp, prawn, crab and lobster are crustaceans (crawl around) and have a protein in their flesh that can cause allergies, they contain too little iodine to cause any problems. Mussels, clams and squid are members of the mollusc (snail) family and a protein in their flesh can also cause food allergies, but they do not contain enough iodine to be a problem. Shellfish can ingest a nasty flagellate organism which causes food poison and a toxic reaction with vomiting, diarrhoea and flushing (this is not an allergy).

Iodine allergy is unrealated to shellfish but iodine can cause a local skin reaction when exposed (contact dermatitis) or a more severe anaphylactic reaction when radiocontrast dye is injected into a vein during invasive radiological examinations such as an isotope scan or angiogram used for investigation of kidney, heart, bone and brain conditions. Many doctors dont realise this seafood myth and will still ask if you are allergic to shellfish before giving radiocontrast.

The common joint supplement Glucosamine taken to help arthritis symptoms, although processed from shellfish extract (crab, shrimp and lobster shells), can safely be taken by people with shellfish allergies according to the Mayo Clinic in the USA.

Reference: http://www.mayoclinic.com/health/shellfish-allergy/DS00987/DSECTION=prevention

Tick bites trigger anaphylaxis to red meat

Dr. Adrian Morris — Sat, 02 Jul 2011 17:36:29 +0000

Allergy to red mammalian meat is relatively common in Africa and so are tick bites. I was recently shown a study by Platts Mills et al from USA in 2011 in which they suggested there may be a link between tick bites by the Amblyomma species of North American tick and the development of IgE antibodies to a galactoside common to mammalian meat (beef, pork and lamb) and ticks. This IgE antibody then leads to anaphylactic sensitisation to mammalian red meat with angioedema and urticaria or hives. 80% of the people studied who had developed sensitisation and allergies to red meat reported previously being bitten by a tick. To confuse the issue, the allergic reactions are often delayed occuring 3 to 6 hours after eating red meat, Similar reactions have been reported following tick bites in Australia. This “alpha Gal” IgE antibody production is switched on by tick bites and could explain the relatively high incidence of red meat allergy seen in indiginous Africans as ticks and tick bites are very common in Subsaharan African.

Study by Platts Mills et al (2008)

Latest research on tick bites and meat allergy

Spring and April tree pollen hay fever

Dr. Adrian Morris — Fri, 01 Apr 2011 08:49:21 +0000

Spring has suddenly broken through the icy winter and the trees are covered in blossom this April. But this is a time of discomfort and suffering for those tree pollen allergic hay fever sufferers who will experience itching, sneezing, watering nose and irritatingly painful eyes. Silver birch pollen will be pouring from dangling catkins suspended from dormant trees coming back to life again after the long cold winter. Silver Birch pollen contains a particulary potent allergy provoking substance called Bet V 1 otherwise known as Profilin, which is curiously also contained in fresh apples, pears and stone fruit such as peaches, nectarines, cherries and plums. In addition, Profilin is found in hazelnuts and walnuts as well as vegetables such as celery, carrot, potato and tomato. Fortunately most afflicted will only experience itching of the mouth, palate and throat if they eat these foods in the raw form. Cooking these foods damages the Profilins and makes them less allergy provoking. These pollen-food cross reactions are usually irritating but rarely ever lead to more serious allergic reaction such as anaphylaxis and will respond promptly to antihistamine medication such as cetiriizine, loratadine and fexofenadine.

Visit our webpage on hay fever and oral allergies for more information

www.allergy-clinic.co.uk/airway-allergy/hayfever

http://www.allergy-clinic.co.uk/airway-allergy/oral-allergy-syndrome

Cow’s milk allergy may be misdiagnosed in babies

Dr. Adrian Morris — Mon, 06 Dec 2010 08:15:37 +0000

Cow’s milk allergy is relatively common in babies (1:50) but rarely develops after one year of age. Symptom improvement on a cow’s milk-free diet and recurrence of symptoms with reintroduction of cow’s milk formula is the most accurate diagnostic procedure. Cows milk allergy may be underdiagnosed as it is common (but misguided) practice amongst UK GP’s and Paediatricians only to perform food allergy testing in children once they are 4 years or older.

Skin prick tests using fresh cow’s milk and RAST blood tests for cow’s milk protein IgE antibodies are the only reliable tests and have 60-90% accuracy. The whey (liquid) fraction of milk tends to cause most allergies, but the casein (curd) fraction triggers more severe and persistent allergies.The higher the milk-specific IgE level, the more likely there will be a clinically relevant milk allergy. High levels of Casein specific IgE antibodies indicate a higher risk for severe cows milk allergy and also for persistent cows milk allergy, On the other hand, IgG antibody testing for cow’s milk proteins (casein and b-lactoglobulin) is of no allergy diagnostic value and merely indicates exposure.

The clinical history and observation of the infant feeding are very helpful, and a family history of atopy increases the likelihood of a food allergy. Cow’s milk allergy can manifest with immediate urticaria and facial angioedema and respiratory, oral and laryngeal symptoms, as well as deteriorating eczema in addition to typical intestinal symptoms such as vomiting, diarrhoea, persistent reflux, food refusal and even anaphylaxis in severe cases.

Mildly milk-allergic infants often tolerate small amounts of processed dairy produce such as yoghurt and cheese as well as Goat’s milk. Infants with severe cow’s milk allergy will react to any traces of milk protein in partially hydrolysed milk formula, cooked foods and even breast milk, as well as any skin contact with milk proteins.