Allergy

14 June 2010

Allergic to food additives?

What are food additives? Most people will answer, "Preservatives added to food, that cause allergies." There are two things wrong with this answer, writes DietDoc.

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Ask the majority of people what food additives are, and they'll reply: "Preservatives added to food, that cause allergies!" There are two things wrong with this answer.

Food additives include a whole range of compounds such as food colourants and flavourants, as well as preservatives. The second misconception is the belief that all food additives cause allergic reactions.

It is true that there are certain individuals who are allergic to one or more compounds that are added to foods and beverages during food processing. The incidence of this type of allergy is, however, not as common as many people think.

Why do we need food additives?
The addition of certain chemicals to foods and drinks is certainly not a recent development. People have been adding salt, vinegar and saltpetre to foods and meat in particular, for centuries to prevent spoilage. Sugar is another flavourant and preservative that has been in use since biblical times.

Food additives are added to food and beverages to enhance or improve their taste, aroma, colour, texture, or appearance, and to preserve the products.

The vast majority of food additives are perfectly harmless (e.g. vinegar, salt, sugar, citric acid, vitamin C, vitamin E etc.) and do not cause allergic reactions.

Food additives and the media
Food additives are, however, a popular subject in the media and make great headlines such as "MSG causes blindness" or "Tartrazine - the yellow peril!"

While some people do suffer from true allergic reactions or sensitivity to food additives, research indicates that the general incidence is only about 0,12% to 2% of the population.

Preservatives
a) Sulphites
Sulphites include sulphur dioxide, sodium sulphite and potassium metabisulphite. Sulphites are added to processed foods, fruit juice concentrates, wine and certain pharmaceutical products.

If a sulphite-allergic individual ingests a food or beverage treated with sulphite, he or she may develop acute bronchospasm (difficulty with breathing), chronic urticaria (skin rash) or even life-threatening anaphylactic reactions (such as swelling of the face and throat which may cause asphyxiation).

b) Benzoates and parabens
These preservatives include sodium benzoate, benzoic acid and methyl-paraben, which are used to prevent spoilage of foods caused by yeasts, fungi, bacteria and other microorganisms.

Symptoms of benzoate or paraben allergy include: angio-oedema (swelling of the face), urticaria (skin rash), asthma, rhinitis (runny nose, hay fever symptoms).

Some foods contain natural benzoates, namely cinnamon, tea and berries.

c) Nitrates
These preservatives are mainly used to cure and preserve meat products giving them an attractive red colour. Most processed meats such as ham, bacon, sausages, cold meat cuts, and Viennas may contain nitrates.

Symptoms of nitrate allergy: asthma, urticaria and rhinitis.

Flavourants
a) Monosodium glutamate (MSG)

MSG is not really a flavourant, but rather a so-called 'flavour enhancer' (i.e. it brings out the flavour of other flavourants). MSG has been accused of causing every type of allergic reaction and a vast array of other conditions, including multiple sclerosis, blindness, yuppie flu, and hyperactivity.

Research results indicate that MSG sensitivity or allergy is relatively uncommon, only occurring in about 0,2% of the general population.

In sensitive individuals MSG can trigger asthma attacks and some individuals may develop 'Chinese Restaurant Syndrome'. The latter syndrome includes a burning feeling in the chest, neck pain and flushing, headaches and rapid heartbeat.

The jury is still out about the actual role of MSG in Chinese Restaurant Syndrome because anyone eating at a Chinese restaurant could ingest a wide variety of potential allergens, such as fish, peanuts, soya and other beans, nuts etc. The present finding is that a sensitive individual who eats a large amount of glutamate in the form of MSG and soy sauce on an empty stomach may develop Chinese Restaurant Syndrome symptoms.

Glutamates also occur widely in common foods such as soya products, tomato, cheese, and even human breast milk. A person with a true (not imagined) glutamate sensitivity should take note of this fact and also avoid all glutamate-containing foods, namely:

  • cheeses, especially Parmesan, Emmenthal, Roquefort, Cheddar and Camembert
  • eggs, chicken, duck
  • beef, pork and cured ham, mackerel
  • peas, maize or corn, onions, spinach, tomatoes, cabbage, Chinese cabbage, broccoli, green asparagus, mushrooms and grape juice

Be careful of foods that are labelled 'Free of MSG' or 'No added MSG' if you are sensitive to MSG or glutamates, as such foods may still contain naturally-occurring glutamates and trigger your allergy.

Foods containing MSG list this additive on their labels so it should be relatively easy to avoid ingesting MSG, but then you still have all the foods that contain glutamate to look out for.

b) Tartrazine
This yellow colourant, which is used widely in foods, beverages and pharmaceutical products, may cause skin rashes (urticaria) and trigger hyperactivity in susceptible children. According to SA law, all foods that contain tartrazine must state 'Contains Tartrazine' on the label, so that individuals who are allergic or sensitive to this colourant can avoid these products.

If you have been diagnosed with an additive sensitivity or allergy, it is important for you to read food labels carefully and avoid processed food that contains the specific additive that you are allergic to. The only exceptions are MSG or glutamate allergy where patients must also avoid foods that contain natural glutamate as listed above, and benzoate allergy patients who need to cut out cinnamon, tea and berry fruits. – (Dr Ingrid van Heerden, DietDoc)

Any questions? Ask DietDoc

 

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Allergy expert

Dr Morris is the Principal Allergist at the Cape Town and Johannesburg Allergy Clinics with postgraduate diplomas in Allergology, Dermatology, Paediatrics and Family Medicine dealing with both adult and childhood allergies. obesity and diabetes societies and runs a trial centre for new drugs.

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