Klinik Dr ShahAn Original Article by:Dr.Shahjahan Bin Kassim

Food Allergies

Introduction
Allergies to a single food item or food group is a frequent occurrence that we may know someone who suffers from it. While food allergies occur commonly in babies and the young; in reality, it can occur at any age. The Center For Disease Control (CDC) USA estimates it affects 4-6% of children and 6% of the adult population. Common foods that one can be allergic to vary in countries; perhaps due to different diets. Some food allergies are common however across the world (Tab. 1).

Symptoms
Allergies occur when our normal healthy immune system (that normally protects us from infections) overreacts to certain proteins in food. The overactive immune system releases many chemicals designed to disable food protein. These immune chemicals are related to eating certain foods. It's not clearly understood why an individual develops food allergy all of a sudden. When a sensitive individual eats an allergic food, he/she develops the allergic symptoms usually within a few minutes. This type of immune reaction is called an immediate reaction. The reaction may be mild such as itch and tingling sensation of lips or more severe such as swelling around eyes, lip swelling and in severe cases, throat swelling. Food allergy can cause very serious reaction including breathing difficulty and even death. This is called anaphylaxis. Sadly there have been a number of accidental deaths related to food allergy in the west.

Common allergy symptoms include :

• Vomiting and/or stomach cramps
• Hives - hot swelling on the skin
• Shortness of breath
• Wheezing while breathing (non-asthmatic) *
• Repetitive cough- unable to speak without coughing *
• Shock or circulatory collapse *
• Tight, hoarse throat; trouble swallowing *
• Swelling of the tongue, affecting the ability to talk or breathe *
• Weak pulse *
• Pale or blue colouring of skin *
• Dizziness or feeling faint *

* Seek immediate medical attention if you have these symptoms -Anaphylaxis

Triggers Of Allergies

Although any food can cause an allergic reaction, these top 8 food groups account for 90% of food allergies:

Table 1

1. Egg :       

                                          

• Albumin (also spelled albumen)
• Egg (dried, powdered, solids, white, yolk)
• Lysozyme
• Mayonnaise
• Meringue (meringue powder)
• Ovalbumin
• Surimi

    

        Eggs are sometimes found in the following processed food:

• Baked goods (although some people can tolerate these foods—consult with your allergist)- Pastries
• Egg substitutes
• Ice cream
• Lecithin
• Marzipan
• Marshmallows
• Pasta
• Noodles (Egg noodles)

2. Milk :

     Cows Milk Protein Allergy (CMPA) often cause allergy in newborns and infants. Children can 

develop an allergy to 2 main proteins in cows milk- Casein & Whey. CMPA allergy children cause chronic diarrhea & vomiting when fed formula milk. Formula milk manufacturers have now developed special milk for children with CMPA allergy, such as partially hydrolyzed or extensively hydrolyzed formula. These new formulas are free from milk Casein & Whey. However, such formulas are expensive. It must be noted there is >90% similarity between cows & Goats milk- thus CMPA children should never be fed with Goats milk as a substitute.

  3. Peanuts :

      While peanut allergies are common in the west and Australia, its numbers are increasing in the developing world. Peanut allergy can provoke a life-threatening allergic reaction (Anaphylaxis) in certain individuals. While in reality, peanut belongs to the legume family, it does share its allergy with other nut families such as Brazil & Almond nut. There are many proteins in a peanut that cause allergies; the most toxic allergenic protein belongs to ARA group (Arachis hypogaea). Ara h3 protein is of particular significance in that its heat stable. Heat stable Ara h3 allergic protein does not degrade when the peanut is roasted or fried-which means roasted & fried peanut may cause more allergies than an unroasted peanut. As roasted groundnuts(peanuts) are used in many processed packaged food, one must be careful when purchasing (think pastries, cookies, candy bars, cereals & granolas). Severe anaphylactic reactions ( throat swelling,difficulty of breathing, wheezing, etc)  may occur of these food items that were accidentally consumed by a peanut-allergic individual. In addition, in rare cases, a person with a peanut allergy may also have allergies to other nuts such as almond, brazil nuts (1) Therefore, individuals suspected of peanut allergy must seek an allergist for proper investigation and management.



 4. Tree Nuts:
            Tree nuts are a group of eight nuts: almonds, Brazil nuts, cashews, hazelnuts, macadamia nuts, pecans, pistachios, and walnuts. Some individuals may develop a single nut allergy while others may develop multiple allergies (cross reactivity) to all nuts. It's best to see your allergist to determine your allergy type.

                             Source of chart : Jcionline.org

Next : Food Allergy - Part 2- Tests for Food Allergies











Bibiliography
1.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3962743/

An Original Article By:

Klinik Dr Shah 

Dr.Shahjahan Bin Kassim Mbbs, Di Derm (Lon), Msc Alelrgy (Imperial)

How Can We Test For Allergies

       

       Yes, allergies are a common occurrence. It can manifest in many forms such as on skin(Eczema), respiratory(Rhinitis/Asthma) and even our digestive system(Gut-food allergy).

As almost anything can cause an allergic reaction, it can be frustrating form patients who often suffer silently for years.

        Consulting an allergist (allergy doctor) is a good first step to find out the allergies we have; how to avoid them & how to best manage it. Some allergies may disappear spontaneously after weeks or months while others may be persistent. In addition, allergy may be from an Exogenous-outside origin ( dust mite allergy) or it may an Endogenous (from within our body-immune system overdrive)

In addition, an allergic reaction may be caused by a single or multiple allergens. All of these factors make it a challenge for your doctor to arrive at a diagnosis from a single visit. Let's take a  look at what tests are available in Malaysia and its pros & cons(if any):

TEST	REMARKS
Allergy History	The most important step in narrowing the search for allergens
Physical Examination	Again- a vital step to identifying allergy location, severity and possible other underlying immune disorder
Allergy Test- Skin Prick Test	Accurate method to confirm or rule of if you have a specific allergy- can perform up to 20 allergens at a time. Pros: 1. It’s a painless procedure and may 2. Test within  20 minutes.       3.Results are read the same day
Blood Test(Specific IgE antibody)	Blood Test is done as a screening test of allergies when we can’t identify the suspect allergen.       Pro:  Many tests can be done(>100 test)     Con:-             -Not as accurate as the skin test -         Higher cost -         Results may take up to a week
Skin Patch Test	Test to identify chemical & metal allergies Allergens are applied on the skin directly and results are read after 48 hours Pro: Accurate                                   Con: can’t be done is patient has extensive eczema
Challenge Test	If skin & blood test is not conclusive - a challenge test is performed. Suspected food or allergen is either applied on the skin; inhaled or ingested in front of medical personal to record the allergic reaction. Done only in limited conditions. Best done in a hospital with an emergency facility.

          Skin prick test is relatively simple and easy to perform when the reagents are available (watch the video)

Hence, there are many tests available at Allergy clinics that help identify what our allergies are and how we can avoid them. Allergy avoidance will definitely improve the allergy symptoms such as asthma frequency and improvement of skin texture of an eczema patient.

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Urticaria - Hives & Angioedema

What are they?
Hives (urticaria) are sudden breakouts of intense red often blotchy skin swelling. They can occur almost anywhere on the skin surface (including scalp) but occur most commonly on limbs and trunk.
They vary in size from mico dots to large discoid shape. The hive surface may be hot and itch intensely, and in some cases may burn and sting. Scratching may worsen the itch. The reactions last for a few minutes to a few weeks. Rarely, they last more than 6 weeks (chronic hives). It's said that acute urticaria affects 20% of the world population at least once in their lifetime.
Patients suffering from hives suffer through the day and night, losing sleep and are often frustrated and even depressed.

What Causes Hives?
The swellings in an acute episode usually come on within a few minutes and last for a few hours, only to completely resolve (disappear) within hours. So what happens during an episode? Disregarding the trigger(s), there are a series of events that occur within our immune system. The primary event is the release of an inflammatory (swelling) chemical called Histamine by our immune system. When an allergen (Eg dust mite protein) comes into contact with the immune system, it triggers a chain reaction within the immune cells (namely the mast cells), which results in the release of Histamine (Simplified explanation).
Histamine, in turn, causes the tiny blood vessels (capillaries) just under the skin to dilate that causes local skin cells to retain fluid (swelling/heat). Histamine also stimulates the skin nerve endings that cause intense itchiness. Scratching causes more tissue swelling and thus more itchiness.
 Possible causes of hives:

1. Foods                                                Milk, Egg, Nuts, Seafood, Fruits, Spices
2. Drugs                                                Antibiotics, NSAID(painkillers), ACE inhibitors
3. Viral Infections                                 
4. Insect Stings
5. Allergens                                          House Dust Mites, Cat/Dog/Rabbit Furs,
6. Others                                               Stress, Temperature change, Autoimmunune disease
7. Idiopathic                                         Unknown cause

What is Angioedema?

Angioedema is swelling of deeper tissues of skin - namely the subcutaneous and mucose membranes. It's easily seen where there is thick layers of subcutaneous tissue such as around eye socket (orbit) and lips. When an allergic reaction is severe it may involve the tongue and throat which may lead to breathing difficulty.

 What test can I do?

First of all, seek out a doctor who treats allergic disease. Diagnosing urticaria involves a detailed medical history taking, blood tests of the immune system and the allergy tests where appropriate.
The doctor may ask the patient to keep a medical log on timing of urticaria in relation to food, allergy exposure and frequency of episodes.
In some cases, the allergy doctor may conduct a skin prick or a patch test of different allergens to determine sensitivity.

Is there treatment available?

Urticaria may spontaneously remit after a couple of weeks in some cases. Here, the doctor's main aim is to control symptoms such as itch and redness. He may recommend antihistamines and corticosteroids to keep histamine action to a minimum. In persistent urticaria, the doctor may run deeper blood analysis on the immune system to determine if the urticaria is part of a bigger autoimmune disease.
The use of biologic agents such as xolair (omalizumab) is gaining popularity in steroid-resistant urticaria. However, high drug cost remains a challenge for mainstream usage.

Other causes of itch?

Itching (Pruritus in medical terms) can be very frustrating when it’s continuous.

Itch certainly can disrupt life. Studies have shown intense itch at night causes sleep deprivation especially in children. This can cause poor concentration in class and consequently; poor examination results.

Types of Itch

                     To many, an itch is an itch; however, it’s important to note its mechanism as not all itch responds to antihistamines. Let’s look at the itch experienced in eczema:

The intense itch of eczema is mainly due to stimulation of the tiny nerve endings on the skin. In a dry and cracked skin, these nerve endings become exposed to air thereby causing a sensation if itch. Other than itch sensation, these same nerves also carry pain and temperature signals to the brain. Scratching of an itchy skin replaces the itch sensation with pain.

On the other hand itch due to the release histamines (insect bite or contact dermatitis) responds well to antihistamine tablets such as piriton and cetirizine. Histamine is released when our body comes into contact with the virus (virus/bacteria) or allergens (dust, insect toxins). Our immune cells such as Mast cells and Basophils release histamine which is a toxic chemical; to kill virus and bacteria.

                    So we can say allergic reactions are due to a confused immune system. Whatever the allergic trigger maybe, the end result of an allergen contact will release huge amounts of histamine; resulting in itchy skin, sneezing with a runny nose and watery eyes- similar to flu symptoms except without fever. Hence, an allergic reaction mimics a virus or bacterial attack. The confused immune system releases histamine thinking its fighting off an infection.

Causes if itch

While itch is common to allergy, one must be aware that there may be other non-allergic causes of itch. The following are some non-allergic causes of itch:

                   1.    Medication that may cause itch

•         ACE inhibitors- hypertension medication.
  
•          Allopurinol for gout.
  
•          Amiodarone for heart rhythm problems.
  
•          Diuretics that relieve bloating and heart conditions.
  
•          Oestrogen- a female reproductive hormone
  
•          Hydroxyethyl cellulose (used during surgery)
  
•          Opioids- Powerful pain control medications
  
•          Simvastatin for high cholesterol.

·                 

·                                2. Liver Disease

·         Liver is the largest solid organ in the body. It does many critical functions in the body. Injury or disease of the liver may disrupt the bile production and distribution. Excess of bile in blood will settle below the skin giving the yellow jaundiced colour. The deposition of a breakdown of bile products such as bilirubin causes an intense itch on the skin.

                   3.Kidney Disease

In the same way, kidney disease results in the accumulation of urea and uric acids. These are waste products of the body which is usually excreted in urine. Accumulation of these waste products in blood cause intense itch on the whole body

                

                4.Other Skin Conditions

Not all itchy skin conditions are due to eczema. Fungal infection of the skin (commonly called Tenia) may mimic eczema especially if it’s infected. Fungal infection may also coexist with eczema and other bacterial skin infections; thereby complicating diagnosis.

Psoriasis is another scaly skin condition that has intense redness and scaly skin that flakes off when scratched. It’s a genetic autoimmune condition that requires special care for the itch.

                 5. Infestations

         Infestation such as tapeworm, pinworms, scabies and head and body louse cause intense itch due to the reaction of our immune system against these parasites

                  6. Diabetes

                    

                     Diabetic patients with uncontrolled sugar are prone to cause nerve damage. This damage is collectively called polyneuropathy. High sugar levels damage to nerve endings. This in turn release inflammatory chemicals called cytokines. The high cytokine levels cause intense itchiness, especially on the hands and feet.

                7. Cancers

                  

                     It’s rare for cancers to cause itch per se, however, itch may occur if cancer involves the liver or bile duct. Chemotherapy often causes skin dryness eczema and itch as a side effect.