Most foods won’t make you sick if you eat them, but they may do you long-term harm if you don’t moderate how much of them you eat. The ultimate price of a bad diet could be obesity, diabetes, heart disease, iron deficiencies, or cancer.

There really aren’t any genuinely bad foods. The problem is how much of them you eat and how healthy your overall diet is.

Balance is the key, so when you eat foods like bread, pasta, rice and potatoes you should make sure you also take plenty of fruit and vegetables, meat, fish, and dairy products, and only small amounts of food and drink containing fat and/or sugar.

Children should eat the best, but research shows that most kids are eating a dangerously unbalanced diet, high in saturated fats, sugar and salt, and low in fruit and vegetables. More than one in five children are now overweight, and one in three children have tooth decay before they even begin primary school.

Additives are also a problem. According to government research, food colourings used in many popular children's foods can cause temper tantrums and disruptive behaviour in up to a quarter of toddlers.

Research scientists at the UK’s Asthma & Allergy Research Centre concluded that “significant changes in children’s hyperactive behaviour could be produced by the removal of colourings and additives from their diet”.

Following the study, the Food Commission (www.foodcomm.org.uk) found more than 100 children’s foods and drinks containing one or more of the additives called into question by the research.

The problem, particularly when dealing with children, is that product labelling can be extremely misleading. For example, Kellogg’s Real Fruit Winders were condemned by a parents’ panel because they claimed to contain more than 50% real fruit, but neglected to mention that each Fruit Winder is 47% pure sugar.

If you are a fan of Robinsons Fruit Shoot Juice Drink, the Food Commission points out that as the drink contains only 11% juice. You would need to buy 31 bottles of 300ml each, costing a total of £20.60, before you would get a litre of pure, undiluted fruit juice.

Ironically, as Coca Cola is one of the official sponsors of the Olympic Games, it is interesting to note that the athletes who compete are banned from taking caffeine – which is one of the ingredients of Coke.

Alcohol

We all know that a drink or four causes people to lose their inhibitions and act out of character. Alcohol depresses the nervous system, and it can also depress people despite its association with celebrations and having a good time. Too much closes off the part of the brain that controls judgement, while long-term alcohol abuse can lead to depression, anxiety and lethargy.

A glass of wine a day is said to protect against heart disease, strokes and possibly some form of gallstones. The official government guidelines for safe drinking are 14 units a week for women and 21 for men. A unit is equivalent to one small glass of wine, half a pint of regular-strength beer, or a single pub measure of spirits.

There are various illnesses caused by excess alcohol. Although red wine can protect the heart, too much is thought to cause heart disease and high blood pressure, which can lead to strokes.

Alcohol is very fattening. A single glass of white wine contains 85 calories and sweet wine 120. If you stick to recommended drinking levels, you can consume an extra 6,500 calories per month.

Alcohol also affects the liver. Prolonged heavy drinking upsets the delicate balance of enzymes in the liver, causing fatty globules to develop that can swell this vital organ.

Nuts

A nut allergy is a reaction to the proteins in nuts, with symptoms that can be fairly mild (nausea, streaming eyes), or more severe (swollen throat and mouth, drop in blood pressure and breathing difficulties). A sudden, severe reaction is known as anaphylactic shock and can be fatal. The British Nutrition Foundation (www.nutrition.org.uk) estimates that up to one per cent of the population may be allergic to nuts.

Nuts, particularly peanuts, are used in a surprisingly large number of products, including breads, desserts, yoghurts, chocolate and vegetarian products. If a production line is used for a food that contains nuts, there's a chance non-nut foods will be contaminated.

There's no specific British law on nut labelling, but there is a voluntary code of conduct outlined by the Institute of Grocery Distributors (www.igd.com). This says a manufacturer should try to ensure its products don't carry traces of nuts.

Dieters need also beware: just 100 grams of peanuts contains more than one quarter of the calories needed daily by a woman to remain fit and healthy.

Salt

Too much salt over time can cause health problems, including high blood pressure and heart disease. But many of our favourite foods are packed with salt. Crisps, digestive biscuits, tomato ketchup, cornflakes, and even bread, all contain large amounts of hidden sodium.

Quick, easy changes to your diet will have an instant effect. Stop adding salt at the table and halve the amount you use in cooking. Try to replace salt in your diet with natural flavours: chilli, ginger, garlic, cumin, and herbs such as basil, mint and coriander. Foods with plenty of natural flavour are onions, tomatoes and beef and need no salt.

Most people don’t realise that they are eating high levels of salt in everyday foods such as bread, breakfast cereals and pastry products, and up to 70% of their salt intake comes from processed food.

The government’s Scientific Advisory Committee on Nutrition (www.sacn.gov.uk) has reported that “High blood pressure is common in the UK. It is a major risk factor for cardiovascular disease and premature death. Reducing the average salt intake of the population is likely to decrease the burden of high blood pressure and improve public health”.

But many processed foods have high salt levels, and in many cases these have gone up in recent years, rather than down. For a list of these foods, go to: www.foodcomm.org.uk/salt_may_03.htm

The sodium contained in salt helps regulate the body's fluid balance and is also necessary for nerve and muscle activity. Recommended daily intake is 1,600mg (1.6g) of sodium a day - that's just 4g of salt. The average UK intake in adults is more than twice the recommended amount at 3,640mg (3.4g) of sodium.

Artificial Sweeteners

Artificial sweeteners exist in all sorts of foods from yoghurt to toothpaste. The soft drinks industry is the biggest user, but they are present in many forms, in addition to the tablets to sweeten tea and coffee. They contain virtually no calories (compared with 16 calories per teaspoon of sugar) and are widely used in diet foods and supplements. They are also much cheaper than sugar.

The use of artificial sweeteners in food is regulated in the UK and there are controls on how much can be included in a product. There is an 'acceptable daily intake', but there have been concerns expressed over their safety.

The EU has pushed for clearer warnings to be included on food labels and a directive stating that the words "with sweeteners" should be written next to the name of the food. The directive is now UK law, but MAFF (now DEFRA: www.defra.gov.uk) told companies