Celiac, Coeliac and Food Allergies explained

June 23, 2009

What’s the difference between an intolerance and an allergy?

A food intolerance is quite different from a food allergy. Intolerance is a diverse reaction to a food that does not involve the immune system. Lactose intolerance is a good example, where sufferers lack the enzyme needed to digest the lactose in milk and some milk products.

Symptoms of intolerance may be vague and can include headache, fatigue and irritability, gastrointestinal problems such as bloating and wind, diarrhoea, nausea and indigestion, aggravation of eczema or asthma, and joint pain. Sometimes the symptoms of an intolerance can resemble those of an allergy. It’s important to note that food intolerances can also mimic the symptoms of other medical conditions, so be sure to consult a doctor to eliminate other problems.

The only way to really tell whether you have intolerance or an allergy is to go through the diagnosis process. Once an allergy and other medical condition diets prove successful, an intolerance is a likely answer.

What are the symptoms of a food allergy?

They range from hives ( the most common reaction) to swelling around the mouth, itchy eyes, diarrhoea, vomiting and eczema. The most serious allergic reaction is anaphylaxis, when histamine floods the body causing serious heart and lung problems, and sometimes death.

Eczema is often the first sign of a food allergy and can appear in the first few months of life. Although not all eczemas are caused by a food allergy, up to 40 per cent of infants with eczema have an allergy as a significant trigger. An allergy to cows’ milk is the most common cause, closely followed by eggs.

Asthma and runny noses are not usual symptoms of a food allergy. In a small number of very young children, respiratory problems can be triggered by food but in most cases there are other symptoms. In more unusual cases, food allergies can manisfest by aggravating gastro-oesophageal reflux (acid reflux or heartburn).

Foods that most commonly cause anaphylaxis, the most serious reaction, are peanuts, tree nuts, fish and shellfish, but any food can cause an allergic person to react in this way.

Death from allergy in children is rare, but can happen. The most common food causes are peanuts, followed by tree nuts, fish and shellfish.

Who is most likely to have a food allergy?

Allergies are genetically predetermined. Dr Crump says if both parents are allergic, their children have a 60 per cent chance of inheriting an allergy. But specific allergies, like a wheat allergy, are not passed on, just the tendency to be allergic.

Will children “grow out of it”?

Food allergy may start during infancy, with the first symptom often being a rash or hives accompanied by vomiting and diarrhoea. How severe it is and how long it lasts depends on the age when it first appears, the type of food involved and the severity of the first reaction. In general, the later the onset of the food allergy, the less likely it is that the child will “grow out of it”. Most children allergic to cows’ milk can drink it again by the age of three, and most of those with an egg allergy are able to eat egg by the age of five.

A test called a RAST (radioallergosorbent test) can confirm if IgE antibodies are dropping to normal “safe” levels in allergic children and, if this is the case, a trial of the food  can be  undertaken in the doctor’s surgery. Asthma and hay fever may develop as the food allergy subsides.

But Dr Crump says 20 per cent of children with allergies will not outgrow them, with reactions to peanuts and fish usually becoming more severe and persistent.

How are allergies and intolerance diagnosed?

Some of the same tests are used for the diagnosis of allergies and intolerances.

Short-term “elimination diets” are required for indentifying food intolerances. Particular foods there are high in natural or artificial food chemicals are eliminated from diet for two-to-three weeks. If symptoms abate, there is a good chance one of the foods chosen is the one causing the problem. This can be tested by re-introducing one food at a time.

Food Challenges should not be undertaken by people with history of anaphylaxis, and should always be performed in a specialist setting under medical advice.

The most definitive test of whether a person has a food allergy is by looking for raised IgE antibodies (the antibodies created by a true allergy) in their blood. This is achieved using “skin prick” tests or a RAST blood test.

In a skin prick test, a drop of the potential allergen is placed on the skin. The skin is then lightly scratched to allow a small amount of the extract to enter. If the person produces IgE antibodies in response to that allergen a skin irritation will be evident.

This test is very good for diagnosing an allergy to milk, eggs, wheat, peanuts, tree nuts, seafood and soy.

One positive test on its own is not proof of an allergy, but fortunately a negative one pretty much rules out an allergy.

Dr Crump says other tests for allergies have not been proven.

Can allergies be treated?

There is no specific treatment for a food allergy apart from avoidance, so it’s very important to have an accurate diagnosis. Advice from a dietician who specialises in food allergies is also recommended to ensure that the diet contains the correct foods so that it remains nutritionally adequate, while particular foods are avoided.

Should pregnant mothers avoid certain foods?

Current evidence suggests that foetal sensitisation to food allergies during pregnancy appears to be minimal. Allergens from the mother’s diet are passed into breast milk, however, and can occasionally cause eczema and other allergic reactions in young babies.

Dr Crump cites the frightening case of a six-month-old child who displayed a very rare and severe allergy to macadamia nuts – the child’s mother had craved these nuts and eaten many during her pregnancy.

“If you consume any allergic food, you may occasionally put your child at risk during breastfeeding”, warns Dr Crump.

So for most women, the golden rule is moderation. Despite this, some doctors advise high-risk pregnancy and lactating women (those with allergies themselves) should avoid peanuts, other nuts and seafood. The jury is still out on the amount of milk and eggs they should eat. However, just as eating a lot of one type of food is not advisable, avoiding eggs and milk altogether is also not recommended. In fact, the ASCIA advises against any moderation of maternal diet during pregnancy or lactation to prevent the development of allergic disease in the infant.

The delayed introduction of solid foods may reduce food allergy risk; high-risk children should not begin solids before six months of age, introducing wheat at one year , dairy, eggs and fish between one and two years, and sesame, nuts and shellfish after two years of age.

Common Allergies:

Foods which most commonly cause allergies reactions

Offenders:
Tree nuts; almond, brazil nuts, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios and walnuts.
Peanuts; including peanut oil
Eggs
Shellfish; Prawns, oysters, crab, mussels, scallops and lobster
Fish; salmon, tuna, anchovies and fish oil
Milk; and products containing milk
Sesame seeds
Soybeans; used in soy sauce, soy milk and tofu

Wheat; used in bread, pasta, cereal and beer

The future

Dr Crump says some promising studies in Australia and New Zealand have shown that giving “probiotics” (food containing bacteria beneficial to the gut) to breastfeeding mothers is improving infant’s eczema and decreasing their prevalence of allergies.

There is also research being undertaken using genetically engineered antibodies to block IgE antibodies. The first study saw the majority of people allergic to peanuts without reacting.

Professor Ameratunga says another approach involves the development of genetically modified foods to alter their ability to cause an allergy. Genetically modified allergens may come into use as a desensitisation strategy.

He says it is likely that effective forms of treatment will become available within the next 10 years.

What is lactose intolerance?

Lactose intolerance is the inability to digest lactose, a sugar found in dairy products. If digestion doesn’t occur, lactose accumulates in surrounding tissue, which leads to bloating, cramping and diarrhoea.

The likelihood of someone having lactose intolerance is very much dependent on their genetic makeup. Allergy expert Dr Vicent Crump says 80 per cent of people of Asian descent have “primary” lactose intolerance, where they lack the gene responsible for producing the lactase enzyme necessary to digest the milk sugar.

However, anyone can suffer a bout of “secondary” lactose intolerance. This is not because of an absent gene but when something (like a tummy bug) damages the lining of the person’s small intestine where the enzyme is produced. This can last for several weeks after the infection and sufferers cannot tolerate any type of dairy product.

Lactose intolerance starts to show when a child is about four or five years old. These kids have diarrhoea and may not gain weight when milk is part of their diet. In some people, severe diarrhoea may prevent proper absorption of nutrients. However, symptoms are usually mild.

Dr Crump says people with lactose intolerance can handle small amounts of dairy products, such as that found in biscuits, yoghurt or bread, if they are not totally deficient of the enzyme.

“But they could not drink a glass of milk or put milk in their tea or coffee”, he says. Breastfeeding mums should also be aware that their milk contains lactose, he says.

If a person’s symptoms are eliminated after a three-to-four week trial period of a diet free of dairy products, the diagnosis can be confirmed. The intolerance can be controlled through diet by eliminating all food containing lactose, primarily dairy products.

There are lactose enzymes in liquid or tablet form that can be purchased over the counter and added to milk. For people who do not consume dairy products, it is recommended they obtain their calcium from other sources, such as soy milk or rice milk.

What’s the difference between coeliac disease and wheat allergy?

Coeliac disease and wheat allergy are two distinct conditions.

Coeliac disease is a permanent adverse reaction to gluten. Those with coeliac disease will not lose their sensitivity to this substance. This disease requires a lifelong restriction of gluten. The major grains that contain gluten are wheat, rye, oats and barley. These grains and their by-products must be strictly avoided by people with coeliac disease.

Wheat-allergic people have an IgE-mediated response to wheat protein. These individuals must only avoid wheat. Fortunately, most wheat-allergic children outgrow this allergy.

How to get the nutrients you need if you have a food allergy:

Vital Nutrient Main Sources

(common food allergens)

Other sources for allergic people
Vitamin A Dairy foods, eggs, fish Dark green and yellow/orange fruits and vegetables
Thiamin (B1) Bread, pasta, cereal Brown rice, legumes, vegemite
Riboflavin (B2) Dairy foods vegemite
Folic acid Cereals Orange juice, leafy green vegetables
Vitamin B12 Fish, eggs, milk Lean meat, chicken
Calcium Dairy foods, seafood (salmon, tuna, sardines), almonds Enriched rice milk, enriched soy milk, tofu, leafy green vegetables, dried fruit (such as figs)
Iron Wholegrain cereals, fish Meat, chicken, legumes, dried fruit

Regards

Paul Smith

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