Doctor’s view of food allergies, intolerances

Press, 6 October 1989, Page 12

Doctor’s view of food allergies, intolerances

By

MAVIS AIREY

Increased education of doctors by nutritionists is needed, Dr Douglas Wilson told the New Zealand Guild of Foodwriters Conference in Auckland last week-end. Nutrition is not a compulsory part of medical training in New Zealand, except for paediatricians, he said. Dr Wilson, formerly of the Auckland Medical School, is the medical director of Boehringer Ingelheim and in private practice specialises in allergies and intolerances. The distinction between food allergies and intolerances is important, he said. Whereas true food allergies are uncommon, chemical intolerances are much more widespread — affecting up to 10 per cent of the population — and involve wider disease patterns. Quote a lot is known about allergies, but little

is known about chemical intolerances, he said.

Allergies tend to involve proteins rather than simple chemicals. Common culprits are peanuts, eggs, celery, shellfish, milk in children under two years old, and cod in Scandinavia. The reaction is immediate and major. Antibodies interact with the food a person eats, affecting certain cells: in the nose, causing hay fever; in the stomach, causing cramps or colic; or in the eyes, causing itchy eyes, for example. People allergic to eggs may find their lips swell and they start wheezing; a baby with milk allergy may fail to gain weight, and have puffy eyes and stomach cramps.

Doctors know there are

hereditary aspects to allergies; they also know allergies tend to fade with age, he said. Milk allergy has usually faded by the age of two, for example. With intolerances, small chemicals, not proteins, are involved. The most common intolerant chemicals are added, particularly as preservatives or colourings, but they also occur naturally in foods, he said. Salicycates are aspirin related, but occur also in apples, citrus fruit, tomaties, strawberries, and some wines. Amines occur in cheese, chocolate, bananas, avocados, tomaoes, and some wines. Other culprits include nitrates, which can affect

behaviour, monosodium glutamate, tartrazine, which is used for yellow colouring, brewer’s yeast, gluten and anti-oxidants. Most people are not sensitive to these substances, he emphasises, and while new processes of preservation may be needed people .should not forget its essential purpose. “The majority of young people who died last century died because of bad food,” he said. Anti-oxidants' may also be beneficial, he added, apparently, they may protect against intestinal cancer.

People with chemical intolerances may get skin eruptions, such as hives, or aggravated excema. Other symptoms are migraines and other headaches, asthma, and gastro-intestinal reactions, such as heartburn or abdominal cramps; Chemicals may also be blamed for behavioural

reactions, such as hyperactivity, or. neurotic behaviour. A chemical intolerance may not always be the cause of the condition, but it can make it worse, Dr Wilson said. People who think they have chemical intolerances need to beware of allowing “anecdote to steamroller over science,” he warned. “There are no good, consistent tests. I rely on the slowest approach to the problem. The symptoms may be chronic, or they may fluctuate from day to day. “I have to check that the sysmptoms could be due to chemical intolerance, and exclude organic disease or true allergy.” This done, his method is to put the person on an exclusion diet, sometimes known as the “caveman

diet,” and then if the symptoms resolve, challenge each suspect substance by reintroducing it, either openly Or blind, using a food capsule. The follow-up may involve long-term dietary modification.

Even this painstaking method is difficult to prove scientifically, he admitted.

In a study of 300 people with sinus trouble done in Auckland, excluding milk brought the number of sufferers down to 30. However, when they were challenged with milk that had been coloured and flavoured so that they would not know what it was, the symptoms came back in only one case.

“This demonstrates that when you try and challenge scientifically, there are difficulties,” he said.

Whether the number of sensitive people is growing or not, he does not know.

‘There are no good consistent tests. 1 rely on the slowest approach to the problem/