Trading Standards Institute Advice

Food borne illness and food poisoning

This leaflet is for all food businesses including those involved in catering, food production, food preparation, retail premises, restaurants, pubs, cafes, and fast food shops, as well as for individuals.

How serious is the problem?
Food borne illness is a problem, especially for high-risk groups such as very young people, elderly people and those who are already ill or who are recovering from illness. Unborn children may also be at risk from some food borne illnesses. However caused, and whatever the resulting symptoms, the general name given to these illnesses is food poisoning.

The Food Standards Agency estimates that there are around one million cases of food borne illness each year in the UK. Most food poisoning is not diagnosed or reported as many people don't visit their doctor.

A person may start having symptoms 30 minutes after they've eaten contaminated food but others may not develop food poisoning symptoms for several days or even weeks. This onset time will depend on the type of bacteria in the food.

Most bacteria are harmless to people. We carry millions of bacteria on and inside us all the time, and many bacteria promote life by breaking down unwanted waste and producing oxygen. Our immune system is very good at coping with a wide range of bacteria that can cause illness.

Some bacteria cause food to go off (food spoilage), while other bacteria are used to help produce food. 

However, a small percentage of bacteria can cause problems. When food contaminated by certain micro-organisms is eaten it can cause illness. These organisms, called pathogens, can be found in a wide range of foods such as meat, eggs, rice, vegetables, puddings, sauces, milk, and seafood. All contaminated food has the possibility of causing sickness and disease. 

Depending on the type of micro-organism, food poisoning can be caused by the body's reaction to being infected by a disease carried in food and water or be caused by the body's reaction to the toxins (poisons) that some bacteria produce. These poisons can be resistant to heat so may still be there even after contaminated food has been cooked. 

Many organisms produce similar symptoms, including being sick, diarrhoea, nausea, and fever. Because of this, it's difficult to identify the actual microbe responsible and laboratory tests may be needed to confirm this. 

What are the main causes of food borne illness?
The Food Standards Agency say that Campylobacter, Salmonella, E. coli O157, Listeria monocytogenes and Clostridium perfringens are the five major bacteria that may account for most cases of food borne illness in the UK. 

Viruses often spread directly from one person to another but also cause food poisoning. They can be killed by cooking food thoroughly. Shellfish such as oysters that are caught in infected waters are still contaminated when served uncooked. 

The World Health Organisation defines food borne illness as 'diseases, usually either infectious or toxic in nature, caused by agents that enter the body through the ingestion of food'.

To cover all examples of people being badly affected by the food they eat, this definition should cover other sources which can cause a bad reaction rather than disease. 

Other sources of illness
Although mould is usually harmless, it can produce poison on foods such as nuts.

Some types of fish, dried red kidney beans, rhubarb leaves and some mushrooms are naturally poisonous. They may be mistaken for food that is safe to eat.

Lead, mercury and other metals and compounds can contaminate food or be taken into food if you use unsuitable metal storage containers.

Some people can react badly to certain foods that others can eat with no problems. 

Many foods such as nuts and seeds have been linked with allergies, but any food made up from other ingredients could be linked to allergy.

Food allergies can cause a wide range of symptoms, some similar to food-poisoning symptoms, but can also cause rashes, tingling or a numb mouth. 

For some people, eating certain foods can cause their mouth and throat to swell, which can make it hard for them to breathe, or may even make them collapse or fall unconscious. There could be a very fast reaction to just small amounts of these allergens (substances that cause allergies) and they can be life-threatening. 

Food intolerance can be caused by someone being unable to digest or absorb certain types of food or nutrients, while some people may react badly to chemicals produced naturally in foods. There are many different symptoms of food intolerance, including feeling unwell, being tired, getting headaches, feeling bloated and suffering from diarrhoea, eczema and breathlessness. 

Chemical food-poisoning symptoms vary and can range from a tingling sensation in the mouth to being sick, stomach cramps and headaches. 

Some chemicals, such as antibiotics and pesticides, are controlled under regulations and are unlikely to get into the food chain. There are also regulations in place to stop the use of some additives previously used for flavouring, colouring or preserving food that have been found to be potentially harmful. 

If you use non-food-grade oil in food mixers and other equipment for oiling or greasing them, this could contaminate food and cause your customers to become ill. 

A more common way in which you could cause chemical contamination is by not using cleaning material such as disinfectants and detergents correctly. These can contaminate foods directly or from the equipment used for food production. This can happen if you don't train your staff properly or keep to a cleaning routine.

Sometimes chemical contamination will give food a strange taste or smell (taint). Having a good food safety management system will help you to avoid chemical poisoning through buying food from reliable suppliers, keeping your cleaning materials stored safely and making sure your staff are trained properly to use the cleaning products.

By keeping your business clean, you will protect your customers keep to the law and have more chance of being successful. A customer won't think a business is well run if it isn't clean and hygienic.

If your business is found to be the cause, or even linked to, food poisoning, it can obviously suffer and lose trade. In recent years, consumers have become more aware of poor food safety and are more demanding than ever.

In running a successful food business, you must make sure that you run it safely and that you can show and prove you are doing so.

Food safety and providing food that is safe to eat depends on the issues surrounding producing, handling, storing, cooking and serving food. 

By law, you must have a food-safety management system in place to make sure you produce the food you supply for people as safely as possible. You have to be able to show that the system identifies and deals with possible hazards. Your system must be based on the Hazard Analysis of Critical Control Points (HAACP) principles.

The processes in HACCP identify the possible hazards in an individual food-production process, helping you to put the right controls in place to limit the risk to your customers and consumers.

More information
You will find further guidance in our other leaflets on this website. Information can also be found on the Food Standards Agency website.

Alternatively, contact your local environmental health service for advice.

Please note
This leaflet is not an authoritative interpretation of the law and is intended only for guidance.

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