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Millions of years ago, a child was born whose body did not understand the difference between harmless substances normally found in the environment (allergens) and agents that carried infections. As a result, the child reacted to allergens in the same way he reacted to infections-by producing antibodies (protective substances) against them. With these new antibodies, he fought the allergens in various organs of his body, causing an inflammation there. This inflammation is known as allergy. As allergic men and women got married, this weakness was compounded in their offspring. They became known as allergy-prone or atopic children.

Explanation of Terms

Atopy (or allergy proneness). This is susceptibility to a group of illnesses that develop naturally after contact with allergens. It has the following characteristics:

a. A family history of allergy. An atopic child will not inherit a specific allergic disease. He does inherit, however, the tendency to develop sensitivity to any allergen when he comes in contact with it. This contact cannot be avoided realistically, and it may take place months or years after birth.

b. A reaction to an injected allergen. This may be a swelling and an itch in the skin where an allergen, to which one is sensitive, has been injected.

Sensitization. When an atopic child is exposed to an allergen, he may become sensitive to it. Sensitization can be active or passive. An example of active sensitization is when an allergic child develops allergy to ragweed when he is exposed to it. An example of passive sensitization is illustrated in the following historic experiment. Blood serum from Dr. Kustner, who was sensitive to fish, was injected into the skin of Dr. Prausnitz, who was not. A few hours later, an extract of fish was injected into the skin of Dr. Prausnitz. Within thirty minutes, an inflammation and itching developed in the skin of Dr. Prausnitz, who had never before been sensitive to fish. The skin of Dr. Prausnitz, which did not contain antibodies against fish, acquired them through a passive transfer from Dr. Kustner’s blood serum, which did contain them. Passive transfer causes a local sensitivity that lasts only a short time, in contrast to active sensitivity which lasts much longer.

Sensitization can be immediate or delayed. One child may develop hay fever minutes after exposure to ragweed; this is an immediate type of sensitivity. Another child may develop poison ivy dermatitis days after exposure to poison ivy; this is the delayed type of sensitivity. The distinction between the two kinds of sensitivity is based upon the time required for an allergic reaction to develop following exposure to an allergen.

Some factors influence the type and likelihood of allergy:

a.     The route through which the allergen enters the body. Some allergens are more dangerous when given by injection and less dangerous when given by mouth. An example is penicillin.

b.     The presence of the allergen in the environment in quantity. Ragweed may cause allergies in children while they are in America because ragweed is present in abundance here; it does not cause allergies in the same children when they are in Europe because it is less abundant there.

ñ     Some substances have a stronger allergenic power than others and are therefore more likely to cause an allergy. The egg white has stronger allergenic power than the yolk,

d.     The capacity of a person to acquire an allergy. Twins growing up in the same environment may develop different kinds of allergies; also, one twin may develop an allergy, while the other may never develop an allergy.

Toxicity. Toxicity is not allergy; it is the reaction of the body to a substance given to it in quantity (such as the reaction of a person who is stung by many bees). Allergy, on the other hand, may result from an injection of a very small quantity of bee venom. Therefore, one definition of allergy would be an extreme sensitivity to a substance which is harmless to most persons when given to them in the same amount.

Shock Organ. The organ of the body which becomes inflamed in allergy is called the shock organ. In asthma, the shock organ is the lung; in hay fever, it is the nose; in eczema, it is the skin.

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Many other symptoms have been attributed to food intolerance over the years. Those discussed below are ones that are mentioned fairly regularly in connection with food.

Ulcerative colitis

Ulcerative colitis is an inflammatory disease that affects the large intestine (also called the colon – hence colitis, inflammation of the colon). It causes bouts of abdominal pain and diarrhoea, often with blood and mucus in the stools. There were reports in the 1960s and 1970s that ulcerative colitis patients ‘recovered’ on a milk-free diet, and this was attributed to food intolerance. But subsequent experience has not borne this out.

Dr John Hunter, who pioneered the study of food intolerance in Crohn’s disease, has had little success in treating ulcerative colitis by the same methods. When all food is withdrawn, and elemental diets or intravenous feeding used instead, the ulcerative colitis patients do not make a sustained recovery’. Perhaps the milk-free diets in the original studies seemed to be effective because the patients were short of lactase, the enzyme that breaks down milk sugar. Diarrhoea often makes the gut deficient in

lactase temporarily, and by drinking milk the patients may have been perpetuating their attacks of colitis.

One form of ulcerative colitis, known as proctitis, produces inflammation mainly in the lower part of the large intestine, near where it opens at the anus. It is possible that food allergy7 plays a part in this disorder, as a great many IgE antibodies have been found in the vicinity. So far, however, there has been little investigation of this possibility.

There is one type of colitis which is commonly due to food, and that is infant colitis, especially when if affects children under a year old. This rare condition is regarded as a form of ulcerative colitis by some doctors, but not by others. The main symptom is diarrhoea containing blood and mucus. A sample is taken and examined under the microscope (a biopsy) to assess the degree of inflammation in the gut. Dr Peter Milla, of the Institute of Child Health in London, has made a special study of infant colitis, and finds that the symptoms are caused by food in about 75 per cent of cases. There are clear signs of immune-system involvement, so this is in fact food allergy. In some babies, IgE and mast cells are involved, in others it is a different type of immune reaction.

This condition is known as food-allergic colitis or FAC and most of the babies suffering from it are are bottle-fed. However, some are breast-fed infants responding to foods that the modier is eating. For bottle-fed infants, switching to a hydrolysate feed (see p213)is the usual treatment. For those being breast-fed, it is usually enough for the mother to eliminate certain foods from her diet – the most common culprits being milk, egg, soya and wheat. Where this alone does not work, the mother can also be treated with the drug, sodium cromoglycate to reduce absorption of intact food molecules by suppressing her own allergic reactions to them. Some babies are best treated by taking them off the breast and giving a hydrolysate feed instead.

A few babies with colitis have a type of autoimmune disease – they are making antibodies to their own cells. These antibodies start to attack various body cells, including those in the large intestine, and this sets off the inflammation that causes the bleeding and diarrhoea. By looking for autoantibodies in the blood, doctors can tell if colitis is being caused in this way. Interestingly enough, Dr Milla has found that changing to a hydrolysate feed or chicken-based feed helps these babies considerably. Some still need im-muno-suppressant drugs to control the inflammation, but others do not. It would seem that immune reactions to foods are aggravating the autoimmune reaction in such cases. Some babies with food-allergic colitis grow out of it, but others are still sensitive to the same foods five or more years later. For other causes of diarrhoea in babies and children.

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