The Greek physician, Hippocrates (around 460-370 BCE), was one of the first Western physicians to comment on the power of food. He is quoted as saying, ‘Each one of the substances of a man’s diet acts upon his body and changes it in some way, and upon these changes his whole life depends’. Scientists, naturopaths and doctors are now increasingly aware that, although food can cause or contribute to a wide range of health problems, it can also be used to help combat illness and promote good health.
Hippocrates’ theory about diet is clearly demonstrated in the case of food sensitivity. A food allergy can produce a whole variety of unpleasant symptoms until the culprit food is tracked down and eliminated from the diet. And vitamins and minerals are so important that a chronic shortage of just one can cause a deficiency disease. Although diseases such as rickets are now rare in developed countries, many people eat diets lacking in the vital minerals that could help to prevent conditions such as osteoporosis.
Social pressures to have a slim body drive some people to risk their health in the pursuit of an unrealistic body image. Eating disorders, such as bulimia nervosa and anorexia nervosa, are extreme expressions of a range of weight and food problems experienced by both men and women. Similarly, obesity is a problem for many people – some experts consider it to be the most common nutritional disorder in the Western world.
However, although destructive eating habits are responsible for lots of health problems, diet can be used therapeutically in many situations. Naturopaths, for example, believe that fasting can be a valuable therapy, because it frees the body to focus its energy on cleansing and healing. Similarly, dieticians sometimes advise people to follow detoxification diets in order to gradually cleanse the body of substances that are thought to be causing ill health.
Practitioners of natural medicine have long believed that dietary therapies can be used to encourage the body to heal and repair itself, and scientists are becoming increasingly knowledgeable about the power of food to promote health. With strong evidence that certain foods can help to protect against cancer and encourage a healthy heart, nutrition and medicine have become allies in the fight against disease.
Sensitivities to Food
Abnormal reactions to food were recorded in ancient Greece by Hippocrates, but it was not until 1906 that the term ‘allergy’ was first used. Awareness of the range of food sensitivities has grown, and scientists and doctors have carried out a great deal of research in this field, in an effort to understand why foods that can be enjoyed by most people can cause adverse reactions in others.
Food allergies and intolerances can result in similar symptoms, but they occur for different reasons; food allergies are immune-based reactions to a certain substance, whereas intolerances occur when an individual lacks the enzymes needed to digest a particular substance. Physical signs of food sensitivity take a number of forms, including problems such as asthma, irritable bowel syndrome and migraine. Infants and children under the age of five are particularly prone to food sensitivity problems. Various food allergy tests help specialists to identify the foods that are most likely to be causing a problem. A course of action to prevent a recurrence of the allergic reaction is then tailored to the individual’s needs.
FOOD ALLERGIES AND INTOLERANCES
Food allergies and intolerances can produce similar symptoms, although intolerances are generally less severe in their effects. An allergy can be defined as an idiosyncratic reaction to a substance involving an immune response. An intolerance is an idiosyncratic reaction to a substance, but with no apparent immune basis. In both cases, avoiding ‘trigger’ substances is the key to staying well. Because the foods that often have to be avoided are basics such as milk and wheat, it is important to get advice on how to adapt the diet, so that it remains nutritionally balanced.
Research shows that people with food allergies and intolerances often become addicted to the food that is causing a reaction, and that the food has a drug-like effect upon them, making them feel drowsy or mildly euphoric. Food cravings can, therefore, provide valuable clues to food sensitivities.
A food allergy occurs when the body’s immune system believes that a normally harmless food is an ‘invader’. It then produces antibodies that attack the food cells as if they were toxins, triggering the release of body chemicals, such as histamine, that cause allergic symptoms. These symptoms include sneezing, asthma, skin rashes, nausea, diarrhoea, swelling and headaches. In rare cases, usually involving peanuts or shellfish, the allergic reaction can be life-threatening. The most common food allergens have proved to be wheat, dairy products, eggs, fish, crustaceans and molluscs, nuts, peanuts, soya beans, yeast and meat, especially beef and pork. One of the most common allergens is the protein gluten.
Immediate-onset food allergies
Some food allergies, known as immediate-onset food allergies, are triggered by the antibody IgE. These antibodies attach themselves to mast cells (reactive cells in the lining of the gut). When the offending allergen combines with its specific IgE antibody, the IgE molecule triggers the mast cell to release granules containing histamine and other chemicals that cause the classic symptoms of allergy. IgE-based reactions tend to occur very quickly after the trigger food has been consumed, which makes the cause relatively easy to identify.
Delayed-onset food allergies It is thought that the more common delayed-onset, or hidden, food allergies usually involve a second antibody, called IgG. It is thought that the reaction is caused by the inability of the digestive tract to prevent large quantities of partially digested and undigested food from seeping through the gut wall and entering the bloodstream. This causes a substantial production of reaction-triggering antibodies, most of which are IgG.
Delayed-onset allergic reactions may occur from one hour to up to three days after the allergen has been consumed, making the allergen more difficult to identify.
People with a gluten allergy (also known as coeliac disease) suffer from impaired nutrient absorption because the protein gluten damages the lining of the small intestine. This causes an IgG or related antibody based allergic reaction. Symptoms include bloating, diarrhoea, anaemia and. Gluten is found in cereals such as wheat, rye, barley and oats. Hundreds of everyday foods contain gluten, including bread, cakes, biscuits, pasta, breakfast cereals, foods coated in batter, sauces and soups, and possibly some brewed drinks made with barley, such as beer.
Once diagnosed, people with a gluten allergy are put on a strict gluten-free diet. A gluten-free diet should be balanced with fresh fruit and vegetables, gluten-free cereals such as quinoa, eggs, milk and cheese, as well as meat, poultry and fish. A marked improvement in health is usually achieved within a few weeks or months.
Wheat allergy is more common than total gluten sensitivity and many people who are not made ill by gluten contained in other foods have an adverse reaction to wheat gluten. Once diagnosed, people with a wheat allergy are put on a wheat-free diet.