Allergic to our diet? It's a complaint that's hard to swallow

NEVER before have we paid so much attention to what we eat. Never have we read labels so diligently, fretted over so many food scares, gone on so many miracle diets. Once upon a time, food was simply fuel. Now, it's our obsession.

Ten years ago, food allergies were rarely mentioned outside medical circles. Now they are believed to be widespread. This week, in Food Allergy and Intolerance Week, the charity Allergy UK estimates that as many as 40 to 45 per cent of the population suffers from a form of food intolerance. Hidden Food Allergies: Is What You Eat Making You Ill? the new book by nutritionist Patrick Holford published last week, claims the figure could be as high as 50 per cent.

The well-publicised food philosophies of some celebrities have helped catapult the issue into the public eye. There seems no end to beautiful people who claim their lives have been transformed by eliminating a component of their diet: gluten in the case of mathematician-turned-diet-guru Carol Vorderman, lactose for Rachel Hunter, wheat for Geri Halliwell.

As our concern over food intolerance has grown, so an industry has grown around it. Practitioners of complementary medicine claim to offer diagnostic tests, while all major supermarkets have launched "free from" ranges. For perhaps the first time in history, we are paying premium prices for products because of what they do not contain.

Meanwhile, doctors question whether the rise of all this food intolerance is just another food fad. A survey of 250 GPs by Norwich Union Healthcase revealed that 73 per cent of doctors believed that patients who claimed to be suffering from a food intolerance were suffering psychological not physical symptoms.

They expressed concern at the fact that as many as one in five people were self-diagnosing food intolerance after reading about celebrities in gossip magazines, and warned that cutting out an entire food group without taking medical advice can do more harm than good.

Dr Mairi Scott, chairwoman of the Royal College of General Practitioners in Scotland, says she would be "surprised" if as many as 20 per cent of people suffered from a genuine food intolerance: "People don't tend to come to the doctor and say they've got a food intolerance. They decide on their own to withdraw something from their diet because they've read about it. When you probe into that you find that the reason they've made that decision is often questionable.

"Celebrity stories have a real influence on what people do. When a famous name goes on to produce diets, exercises, healthy eating plans, people buy them, and get further caught up in it. Some of it is very useful stuff, some of it is nonsense, but individuals have no way of knowing that."

She says many people do not know the difference between a food intolerance and a life-threatening allergy. "We are getting increased reports of significant food allergies, like peanut allergy. These are very important and serious allergies and we need to be more aware of them, but people confuse them with food intolerance. It makes them even more anxious about what they eat."

A food allergy happens when the body's immune system attacks a normally harmless dietary protein. Symptoms include coughing, rashes, nausea, shortness of breath, a runny or blocked nose, sore and itchy eyes. The reaction can be immediate or delayed.

The most dangerous reaction is anaphylactic shock, which happens immediately, causing swelling of the mouth and throat, difficulty in breathing, abdominal cramps, nausea and vomiting, a drop in blood pressure, and, in the worst cases, collapse and unconsciousness.

Slower reactions, known as "delayed-type hypersensitivity", include coeliac disease, a condition of the gastrointestinal tract associated with gluten, which affects more than 250,000 people in the UK, and hypersensitivity to cow's milk. Allergies can be tested for quickly and easily by a medical practitioner using a skin-prick test or blood test.

Food intolerance is a broader term, less well understood and less easy to pinpoint. Symptoms include bloating, indigestion, lethargy, abdominal pain, diarrhoea or constipation and sudden weight gain. Many believe food intolerance can exacerbate conditions such asthma, eczema, migraine and irritable bowel syndrome. In some cases, it is caused by the failure of the digestive tract to produce adequate amounts of particular digestive enzymes, such as lactase, which is needed to digest lactose. In other cases, the reaction is pharmacological, for example, in the case of caffeine. About five per cent of children experience allergic or intolerant reactions to food at some time, but the majority grow out of them.

According to a task-force report by the British Nutrition Foundation (BNF) three years ago, the figure for those medically diagnosed with a food intolerance is fewer than 2 per cent of the population, and for those with a truly allergic response fewer still. However, many people who suspect they have a food intolerance never seek medical advice. Dr Joanne Lunn, nutrition scientist with the BNF, urges anyone who believes they have a food intolerance to visit their GP. "If you do have a true intolerance, you will need proper advice on how to make changes. By cutting out a whole food group, you immediately reduce the level of micronutrients you get. If you don't get them from somewhere else, you could end up with more problems. If you cut out lactose, you could end up deficient in calcium." Lunn says food intolerance is easy to misdiagnose. "If you suddenly cut out all dairy food, that will have a massive effect on the foods you eat. You will almost certainly eat more fresh fruit and vegetables in your diet, and that might be what's making you feel better. People are not eating as many fruits and vegetables or as much fibre as they should, so it might be a general diet problem rather than specific intolerance."

Muriel Simmons, chief executive of Allergy UK, says the increase in allergies and intolerance could be due to the changes in our eating habits: "At one time we all ate according to the seasons. Now, with refrigerated lorries and planes, we can eat strawberries at Christmas time. If you like something you will eat it all through the year and after a while the body says 'I've had enough'."

She advises anyone with an allergy to seek medical advice straight away. Those experiencing milder symptoms might find it helpful to keep a food diary. "Keep a food diary for three weeks, write down absolutely everything you eat or drink and record how you're feeling each day.

"With food intolerance it can take 24 to 48 hours until the symptoms show. Often it is surprising what it shows, either to the person, or to a GP or dietician."

Food intolerance testing is not available on the NHS. The only self-test kit which is clinically proven is the York Test, available online (www.yorktest.com) or in major pharmacies. Simmons advises anyone concerned about a food intolerance to take a clinically proven test, and not to cut out any major food group without taking professional advice.

Scott says she encourages patients to exercise commonsense: "If a patient thinks chocolate causes their migraine and as a result they rarely eat it, I would have no problem with that. But if you're thinking about making a life-long commitment to altering your diet, you need to get professional advice. It's very important to eat a healthy, balanced diet."

Hypersensitive or oversensitive? Recognise the symptoms

BLOATED stomach? Muscle cramps? Diarrhoea? General fatigue? If you experience these complaints on a regular basis you might be suffering from a food intolerance.

Dairy, wheat and alcohol intolerance are three of the most common in the UK, but medical experts warn that you should never self-diagnose: cutting a major food group out of your diet could leave you deficient in vital nutrients, leading to health problems.

The symptoms of allergies could also be indicators of unrelated underlying illnesses, so if you suspect you have an allergy, visit your GP who will be able to refer you to a specialist for advice if necessary.

Dairy

AN intolerance to cow's milk occurs when the body can't process lactose, the sugar which naturally occurs in milk. In most people lactose is broken down by the enzyme lactase, which is produced by the body in the small intestine. However, if the body is not producing enough lactase, the lactose cannot be broken down and absorbed into the bloodstream. As a result, large quantities of dietary lactose pass undigested into the large intestine and this can sometimes give rise to flatulence, bloating, abdominal pain and diarrhoea. Some sufferers can eat yoghurt (which have lower levels of lactose than milk) and hard cheese (which has almost none) and are encouraged to do as these are sources of calcium, which is essential for healthy bones and teeth.

Wheat

WHEAT intolerance is a difficulty digesting wheat, or more precisely its gluten - a protein found in wheat and some other cereals including rye, barley and oats (there is still some debate among nutrition experts whether the list of irritants should include oats).

Most people who have this intolerance suffer from Coeliac disease, a bowel disease in which the microvilli in the small intestine cannot absorb gluten, which can then damage the microvilli's capacity to absorb other nutrients.

As a result, sufferers who continue to eat gluten-laden foods can suffer from diarrhoea, abdominal pain and bloating, and malnutrition. To avoid this, a strict adherence to a gluten-free diet may be required.

Alcohol

A COMMON intolerance among those of Asian origin who can suffer from facial flushing, abdominal pain and headaches soon after ingesting alcohol. This is because many people of Asian origin are relatively deficient in alcohol dehydrogenase, the liver enzyme which is needed to break down alcohol. Even small amounts of alcohol can make affected people feel unwell, so sufferers are encouraged to abstain from drinking alcohol altogether.