Health
| Food culprits |
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| Written by Dr Sarah Brewer, 2008 | |
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Can you eat some foods and yet find that others disagree with you? Dr Sarah Brewer looks into the complex area of food intolerance and suggests ways you can cope. If you have a food intolerance, you have a reproducible, adverse reaction to a specific food or ingredient, which occurs even when you eat that food in a disguised form. Unfortunately, symptoms of food intolerance are typically delayed and come on several hours, or even days, after the food was eaten. This can make the culprit, or culprits, difficult to identify. However, the best-known examples of food intolerance are to lactose and gluten. Food allergiesFood intolerances are very different from food allergies in which an abnormal immune response triggers a potentially serious chain of immune reactions.Food allergies involve the 'a type' of antibody called IgE, which triggers the release of histamine and other immune chemicals. Reactions develop very quickly and may include a red, itchy rash, swelling (e.g. of the tongue), difficulty breathing and collapse. These reactions can be life-threatening. Official figures suggest that 2 per cent of adults and up to 8 per cent of children have a classic IgE mediated food allergy. Lactose intoleranceThis occurs when you make insufficient amounts of lactase, the enzyme that you need to digest the milk sugar, lactose. Lactase enzyme is normally released from the lining of the small intestine.If you produce too little, lactose sugar remains unabsorbed and passes down to the large intestines where it is fermented by bacteria to produce the typical symptoms of lactose intolerance: bloating and wind, audible bowel sounds (borborygmi), abdominal pain and diarrhoea. Lactose intolerance is a fact of life for much of the world's population. Although people of European ancestry are likely to produce lactase into adulthood, those from Asia, South America and Africa tend to stop producing lactase after childhood. It is estimated that 15 per cent of British adults are affected - many of whom are wrongly diagnosed as having irritable bowel syndrome (IBS). Lactose intolerance can be diagnosed by tests such as the Hydrogen breath test. People who are affected can control their symptoms by avoiding foods containing lactose and by taking a lactase enzyme supplement (see "Digestive enzymes"). A lactose-free cows' milk was recently launched in the UK. Lactofree is a dairy drink with the taste of milk but less than 0.05 per cent lactose. Available in most good supermarkets, it is semi-skimmed cow's milk with the lactose filtered out and then a small amount of lactase enzyme added in. The result is nutritious milk that's at least 99.95 per cent lactose free. Gluten intoleranceGlutens are a type of protein found in grains such as wheat, rye and barley. In some people, eating glutens triggers the production of certain IgA antibodies (antigliadin antibody, endomysial antibody, transglutaminase antibodies) that are associated with abnormal changes in the lining of the lower part of the small intestine (jejunum).Why this suddenly happens remains unknown, but one theory is that it may develop in susceptible people by exposure to a particular virus. Gluten sensitivity - known as coeliac disease or gluten sensitive enteropathy - is an auto-immune condition that can develop at any age. Symptoms vary in severity and can include: tiredness, generalised feelings of being unwell, breathlessness, abdominal pain, bloating and wind, diarrhoea, vomiting, passing pale, bulky, offensive, fatty stools that float (steatorrhoea) and weight loss. Some sufferers are prone to mouth ulcers and sores at the corners of their mouth while with other people there may be skin changes including pigmentation, scaliness, easy bruising and a rash known as dermatitis herpetiformis. Coeliac disease is thought to affect as many as one person in 100 across Europe, but many remain undiagnosed. Treatment involves following a gluten-free diet, which produces a rapid improvement within a few weeks and must be followed for life. So, severe food allergies are linked with production of IgE antibodies, and coeliac disease is linked with IgA antibodies. Some researchers increasingly feel that some food intolerances are due to other components of the immune system, such as IgG, and activated white blood cells that react against certain foods. These ill-understood intolerances may be involved in a number of long-term health problems such as IBS, arthritis, eczema, psoriasis, migraine, asthma, Crohn's and ulcerative colitis. This is controversial, but many people with these conditions find that eliminating certain foods from their diet improves their symptoms. Eliminating suspect foodsThe traditional approach to identifying foods that trigger reactions is an Elimination and Challenge diet. The simplest type involves removing suspect foods from your diet, then sequentially reintroducing them to see which, if any, provoke your symptoms. The foods to test are identified by keeping a food and symptom diary for at least one week.A more advanced approach involves following a bland, hypoallergenic diet that initially allows you to eat only a few limited items, typically:
After symptoms have disappeared, you start to reintroduce eliminated foods one by one, usually at three-day intervals, while keeping a careful food and symptom diary to help identify problem foods. If an adverse reaction occurs, you continue to avoid the test food and wait 48 hours after all symptoms have improved before testing another food. The Elimination and Challenge diet is time-consuming and difficult to stick to. A number of alternative tests have therefore been developed to help identify foods to which you are intolerant. Although not available on the NHS, some private companies offer blood tests that detect raised levels of anti-food IgG antibodies in a pin-prick sample of blood (York Test FoodSCAN - tel: 0800-458 2052, www.yorktest.com), or that analyse live white blood cells to see how they react to different foods (Immogenics Novo Test - tel: 0845-612 0612, www.novotest.com). Eliminating the foods identified by these tests has undoubtedly improved the health of thousands of people, although many doctors remain sceptical. Pharmacological reactionsSome foods produce intolerances due to the presence of chemicals that have a drug-like effect in the body. Tyramine (found in cheese, wine, yeast extract and vinegar) triggers migraine in some people, for example, while benzoates and sulphites added as preservatives can trigger asthma.Salicylates - aspirin-like substances naturally found in many foods and plants - may also trigger asthma in aspirin-sensitive individuals. Tartrazine (a yellow food colouring) and other artificial additives have been linked with behavioural problems in children, while monosodium glutamate (a flavour enhancer) can cause flushing, headache, nausea and other symptoms known as Chinese Restaurant Syndrome. Perhaps the most unpleasant pharmacological reaction to food is caused by pre-formed histamine, varying amounts of which are found in fermented foods, cheese, tomatoes, spinach, aubergine, berries and citrus fruits. Histamine is the main chemical involved in the body's own IgE allergy reactions, and the histamine present in food can trigger symptoms that resemble a true allergy such as rashes, vomiting and diarrhoea. The amount of pre-formed histamine needed to cause a reaction varies from person to person. Some people are susceptible to the small amounts found, for example, in a strawberry, while the large amounts present in Scromboid fish (tuna and mackerel) contaminated with certain intestinal bacteria (Vibrio species) causes symptoms in everyone. Incorrect storage allows a bacterial enzyme to convert an amino acid (histidine) in the fish flesh to toxic levels of histamine. Affected fish have a hot or peppery taste when eaten. Symptoms start within an hour and can include a swollen throat, flushing, palpitations, anxiety, skin rash, headache and diarrhoea. Occasionally, severe toxicity leads to difficulty breathing or collapse. Treatment is with antihistamines and symptoms usually resolve quickly. Although common, this form of food intolerance is usually misdiagnosed as common food poisoning and treated with fluids and bed-rest - without the histamine that would have given fast relief. Digestive enzymesSupplements containing digestive enzymes can help to overcome intolerances to particular food groups (fats, proteins and carbohydrates) or particular foods (e.g. fruit, milk, yeast and gluten-containing cereals) if symptoms are due to enzyme deficiencies.When eating carbohydrates causes bloating, select carbohydrate-digesting enzymes such as amylase and cellulase. If milk causes symptoms, try taking milk-digesting enzymes such as bromelain (from pineapples), papain (from papaya), lipase and lactase. Should you be gluten-intolerant, a product supplying gluten protease, cellulase and amylase may help. When you want to improve general digestion, or are not sure which food group is upsetting you, select a mixed digestive enzyme supplement containing lipase (digests fats), amylase (digests carbohydrates), protease (digests protein), lactase (digests milk sugar) and cellulase (digests cellulose). Dr Sarah Brewer has written a new series of Natural Health Guru books on High Blood Pressure, Diabetes, Arthritis and Asthma, to be published in the spring Further information
Try these recipes - you'll feel better!Glenis Lucas, a Worcestershire WI member, has compiled a recipe book especially for food intolerance sufferersThese days it is possible to find 'special diets' or 'free from...' shelves in most supermarkets. But seven years ago, when Glenis Lucas, a yoga teacher and member of Kinver WI, Worcestershire, challenged herself to recreate varied, interesting, home-cooked meals using only gluten-free flours and grains, dairy-free ingredients and other permitted ingredients, no one, least of all publishers and supermarkets, seemed interested. Today, with a rising number of people in Great Britain with allergies and with food intolerances to gluten and lactose making life miserable for so many of us, her book, filled with over 200 delicious and nutritious recipes, is a winner. "Compiling The Complete Guide to Gluten-free and Dairy-free Cooking was a steep learning curve," says Glenis. "It took me several years to put the collection of recipes together. I finally succeeded in finding a publisher and the book came out in 2006, with a foreword and introduction by Michael Matthews, the Chairman of Allergy UK. "My aim was to share the recipes I had created for myself and my family with other people who experienced the same symptoms as me." Glenis says her home-cooked meals for her family never sacrificed flavour in order to cater to her own intolerance to gluten. "I never bought processed food and the dishes I make are so good they wouldn't have known they were gluten-free!" The book also contains a chapter of essential information on the differences between classical allergy and intolerance, the diagnosis and treatment of allergies and particular deficiencies and sensitivities, plus a list of which foods and drinks to avoid. Here are three of Glenis's recipes for you to try: Cream of Mushroom and Fennel Soup Fruit Crumble Carrot and Ginger Cake |
