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Most of us don't have year-round access to farm-fresh foods. Instead, we fill our grocery carts with processed foods to help save time in the kitchen. Our reliance on factory-made foods means that natural and synthetic chemical additives have become a significant part of our diet. It's estimated that food additives comprise about 10 per cent of the food consumed by the average adult.

Without additives, food products would spoil quickly. Additives prolong shelf life, prevent potentially life-threatening food poisoning and boost the nutrient content of foods. While most additives have excellent safety records, others are controversial because questions about their safety have been difficult for scientists to answer.

In some people, certain additives can trigger hives, headache, diarrhea, asthma, even anaphylactic shock. (Anaphylaxis is a severe allergic reaction that occurs rapidly and causes a life-threatening response involving the whole body). Research in animals has linked other food additives to cancer.

Here's what you need to know about questionable food additives and how to avoid them.

Artificial dyes

Artificial colours are used to enhance a food's natural colour or add colour that's not naturally present. Because their purpose is to make foods look better, some argue that food dyes are frivolous. Others say that food dyes are harmful.

In the 1970s, researchers suggested that synthetic food colours were linked to hyperactivity in children. In 1982, the U.S. National Institutes of Health concluded that there was no scientific evidence to support the claim that colour additives caused such behavioural problems. However, studies did show that for some children with attention deficit hyperactivity disorder and food allergy, eliminating artificial food dyes led to improvement in behaviour.

A study published in 2004 suggests synthetic dyes do influence behaviour in children and their effect does not depend on prior hyperactivity or the presence of a food allergy.

Researchers from the University of Southampton in England evaluated the effects of artificial food colours and benzoate preservatives on 277 preschool children. (Benzoate additives inhibit bacteria growth and are often added to acidic foods such as jams, fruit juices, pickles and tomato products.) Regardless of whether a child was considered hyperactive or had a food allergy, the researchers found significant improvements in hyperactive behaviour when additives were eliminated from their diets and greater increases in hyperactive behaviour when they were consumed.

Certain food dyes cause adverse reactions, while others may be carcinogenic. Yellow dye No. 5 (tartrazine) used to colour beverages, desserts, candy and processed vegetables may cause itching, hives and nasal congestion in a small number of people. The U.S. government requires that all food products containing tartrazine have the colour listed on their labels so sensitive people can avoid it. That is not so in Canada, where manufacturers need only to state the word "colour" on the label.

Red dye No. 3 (erythrosine), added to ice cream, jams, pickles, liqueurs, ketchup and smoked fish, is a cancer-causing agent in animals. Based on the animal studies linking it to cancer, erythrosine was banned in the United States in 1990. It is still permitted for use in Canada.


Used to maintain colour, prolong shelf life, and prevent the growth of bacteria, sulphites are added to a wide range of products, including beer, wine, baked goods, dried fruits, dried herbs and spices, grapes, lettuce, jams, snack foods and soy products.

Sulphites are among the top nine food allergens because of their potential to cause severe reactions in sensitive people.

Sulphites do not cause a true allergic reaction (one that involves the body's immune system), but sensitive people may react to them with allergy-like symptoms ranging from nausea, stomach pain, diarrhea, seizures, asthma and anaphylactic shock. Some people with asthma are extremely sensitive to sulphites.

If you have a sulphite sensitivity, read food labels carefully. Avoid products that contain potassium bisulphite, sodium bisulphite, sulphur dioxide and sulphiting agents.

Food packages are required to declare a list of ingredients and their components (ingredients of ingredients). However, if a food includes components that are exempted from labelling, it's possible that sulphites won't be mentioned on label. (Roughly 47 food ingredients are exempt from having their components declared on the label, including flour, butter, margarine, starches, soy flour and hydrolyzed plant protein.) Health Canada is working to amend regulations so that labels declare key food allergens, including sulphites. In the meantime, contact the manufacturer or your local allergy association if you're unsure about a food.


glutamate (MSG)

This additive is used to intensify the flavour of meats, poultry, seafood, snacks, soups and restaurant foods. It's also a component of other food ingredients, including hydrolyzed vegetable protein and yeast extract.

Studies have shown that some people are sensitive to MSG and report reactions such as headaches, dizziness, chest pains and flushing. Studies have not determined how little MSG it takes to trigger a reaction in sensitive people.

If you're sensitive to MSG, scan ingredient lists for monosodium glutamate, hydrolyzed vegetable protein, yeast and natural flavouring.


Approved for use in 1981, aspartame is used to sweeten more than 5,000 low-calorie foods. A small number of individuals report aspartame causes headache, skin reactions, dizziness and mood changes. Despite numerous claims that aspartame causes a wide range of diseases including epilepsy, Parkinson's and multiple sclerosis, there's no scientific evidence to suggest that aspartame is to blame.

However, a new study released in July questions the safety of aspartame.

Italian researchers reported they found that it increased the risk of cancer (lymphoma and leukemia) in female rats at doses close to acceptable daily intakes for humans. Health Canada is currently reviewing the data and working with European scientists to determine whether the evidence warrants making recommendations about aspartame use.

In the meantime, read ingredient lists. Aspartame must always be declared on a food label; there are no exemptions.

To reduce your intake of food additives, eat fewer highly processed junk foods. Many questionable additives, such as aspartame and synthetic dyes, are used primarily in foods of low nutritional value.

To avoid a certain additive, read ingredient lists. However, if an additive is a component of an ingredient, it might not be mentioned. And ingredient lists that state "colouring" or "colour" won't help you determine whether a food product contains an artificial dye.

If you're leery about synthetic additives, consider going organic. Organic foods are grown and processed without the use of synthetic or artificial chemicals. But keep in mind that intolerance or sensitivity to an additive does not depend on whether it's natural or artificial. The human body can't tell the difference between a natural additive and the same one that's produced synthetically. Beta-carotene, used to colour margarine and butter, can be derived naturally from algae or beet root, or it can be made synthetically.

This was the second of two articles on food additives. The first appeared last Wednesday.

Leslie Beck, a Toronto-based dietitian at the Medcan Clinic,

is on CTV's Canada AM every Wednesday. Visit her website