Food allergies and intolerances

Food allergies and food intolerances are becoming increasingly common, but how do you tell one from the other and are they really a problem?

Although official figures suggest only two per cent of adults, and up to eight per cent of children have an accepted food allergy, as many as one in three people recognise that eating certain foods consistently triggers unwelcome symptoms.

Food allergies

Why allergies are more prevalent remains unknown. Most seem to result from ill-understood interactions between our immune system and our 21st-century diet, lifestyle and environment. One popular theory is that over cleanliness and excessive use of antibiotics has caused our 'T helper' immune cells to move away from anti-infective, antigen-tolerant reactions towards allergic type sensitivity reactions.

Substances that trigger a classic allergic reaction are known as allergens and involve a type of antibody known as IgE. IgE interacts with immune cells in the skin, intestines and respiratory tract to cause the release of powerful chemicals, such as histamine. Foods that can trigger an Ig-E mediated 'classic' food allergy include:

• Eggs
• Cow's milk
• Peanuts
• Tree nuts
• Shell fish
• Fin fish
• Wheat
• Soy
• Beef
• Chicken
• Citrus fruits
• Tomatoes

In some people, these can cause a severe, life-threatening, anaphylactic reaction with falling blood pressure, constriction of airways, facial/tongue swelling and collapse. These symptoms tend to come on quickly, usually within minutes of exposure.