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Author: Hon A/Prof Marius Rademaker, Dermatologist, Hamilton, New Zealand, 2003.
There is a wide held belief that food additives are the cause of many skin problems. The evidence, however, that food additives cause skin problems is weak. Even foods themselves seldom cause problems. Studies suggest atopic dermatitis may be aggravated by a dietary factor a small percentage (10–15%). Certain foods and additives may aggravate hives (urticaria).
Food additives are natural or artificial substances that may be added to food in small quantities to perform specific functions. These include:
The main reason for using food additives is to keep food fresh and consistent in quality. Without food additives, food would quickly spoil as the shelf life would be much shorter and it might even pose a health hazard. Some additives are essential for the creation of the product, for example, carbon dioxide to give the fizz in fizzy drinks, or raising agents in cakes.
1. To prevent food spoilage and maintain freshness
Antioxidants: these prevent or delay the rancidity of fats by retarding the process of oxidation due to oxygen in the air. Many crude fats and oils contain antioxidants naturally. Antioxidants also prevent enzyme browning which causes the discolouration of fruit, vegetable and fruit juices.
Preservatives: these kill micro-organisms (bacteria, fungi, mould and yeasts) that would otherwise cause food decay and possibly create health hazards. They extend the shelf life and some also protect the colour and flavour of certain foods. In the past sugar and salt were the main preserving agents used.
2. To assist the processing or preparation of food
Acids: these impart a tart flavour desirable in some foods. They also assist in the release of carbon dioxide when present in raising agents. They have a preservative effect.
Acid regulators/buffers: these change or maintain the acidity or alkalinity levels for desired effects. These include preservation, added or altered flavour or tartness, texture development, colour retention and assistance in the action of raising agents.
Anti-caking agents: these prevent the lumping or caking of finely powdered or crystalline substances such as salt, dried milk and sugar.
Bleaching agents: these bleach or whiten flour and bread.
Bulking agents: these add bulk to food without providing energy (i.e. kilocalories) so are frequently used in slimming foods. They are not usually digested and may, therefore, act as a source of dietary fibre.
Diluents: these dilute or dissolve other additives such as colours.
Emulsifiers: these aid the formation of an emulsion between two substances that would not normally mix, such as between oil and water. Examples include mayonnaise and salad dressing, which are oil in water emulsions or butter and margarine, which are water in oil emulsions. They also reduce the amount of fat needed to produce the desired effect in food so are often added to ice cream and cakes.
Firming agents: these prevent fruits and vegetables from softening and falling apart when canned or frozen. They help maintain the firm or crisp nature of the food.
Flour improvers: these can extend the elastic properties and aid the development of dough in bread making. They can also accelerate the effects of bleaching agents.
Freezants: these extract heat from food.
Glazing agents: these produce sheen on the surface of confectionery. They also provide a protective coating.
Humectants: these retain moisture in foods to help prevent them from drying out.
Propellants: these are gasses or volatile liquids used to expel foods from aerosol containers.
Raising agents: these promote aeration, thus making the product lighter texture and increasing volume (e.g. baked products).
Release agents: these prevent foods from sticking to surfaces.
Stabilisers: these stabilise emulsions, preventing the two substances from separating.
Thickening/gelling agents: these agents form gels that modify texture and provide stability. Often starch or gum is used.
3. To enhance the flavour or appearance of food
Artificial sweeteners: these are sweetening agents other than sugar. They are widely used in low-calorie products to aid slimming and, at the same time, provide a sweet taste.
Colours: these can improve the products' appearance, giving colour to otherwise bland looking food, restoring the original colour lost in processing and to overcome variations in colour between batches.
Flavours/flavour enhancers: these improve food acceptability when used in minor quantities. They may restore flavours lost in processing, supplement bland food, magnify existing flavours or enhance the natural flavour. Concentrated natural flavours are provided as extracts or essential oils, whereas flavour enhancers or modifiers intensify existing flavours without imparting a distinct flavour of their own.
4. To improve or maintain nutritional value
Nutrients: these enrich food, by replacing the necessary vitamins and minerals lost during processing or by fortifying foods with nutrients possibly lacking in the average diet. Examples include iodised salt, folic acid in bread, etc.
The ingredients in manufactured foods should include food additives, depending on local regulations.
DermNet has included a list of the most common standard codes (E numbers) of the European Union (EU)
The following web sites include detailed information about food additives, including the names of approved additives and their code numbers.
Australia and New Zealand
The European Union (EU)
Books about skin diseases
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