Food Intolerance

Food Intolerance

It involves any reaction to food without involvement of immune system.

Food intolerance is often diagnosed by an elimination diet.

Skin prick tests or specific IgE measurements are not appropriate or helpful for the diagnosis of food intolerance.

The most common food intolerances are: lactose intolerance and monosaccharide intolerance, both of which are characterised by

• Persistently fluid stool.
• Excessive flatus.
• Excoriation of the buttocks.
• Typically, these infants appear well.
  

Lactose intolerance
Following infectious diarrhoea, infants may have temporary lactose intolerance.

Management

• Breast-feeding should continue unless there are persistent symptoms with buttock excoriation and failure to gain adequate weight.
• Formula-fed infants should be placed on a lactose-free formula for 3–4 weeks.

Note: A clinical response after change to soy formula may indicate either post-infectious lactose intolerance or allergy to cow’s milk protein, as soy formulae available in Australia are lactose-free.

Monosaccharide intolerance

Infrequently, infants with severe bowel damage secondary to gastroenteritis may be unable to absorb normal amounts of monosaccharide such as glucose or fructose. Diarrhoea will continue even with a lactose-free formula. Monosaccharide intolerance requires specialist consultation.

Food Allergy

A food allergy is an adverse reaction to a generally harmless substance within a food (usually a protein) that is mediated by the immune system.

Cow’s milk, egg, peanut, tree nuts, fish, shellfish, soy and wheat cause more than 90% of food allergies in children.

There are essentially three main types of food allergy: IgE mediated; IgE and non-IgE mediated; and non-IgE mediated.

IgE-mediated food allergy

The commonest IgE-mediated food allergens are egg, peanuts and milk.

Wheat, soy, fish and tree nuts are the next most common. Many food allergic children will have more than one food allergy.

Diagnosis is made on the history and confirmed by skin-prick testing.

The main principle of management is avoidance of the offending antigen.

• Oral allergy syndrome

Some patients with seasonal allergic rhinitis/conjunctivitis experience itch and irritation of the tongue, mouth and throat after ingestion of some fresh fruits and vegetables.

• Anaphylaxis

Non-IgE and IgE mediated Food Allergy

Atopic dermatitis and food allergy

Many parents perceive that food allergy is the underlying cause of their child’s atopic dermatitis and will try vigilantly to pinpoint the cause. Evidence would suggest that only about 40% of children with moderate to severe atopic dermatitis have a true food allergy.

Eosinophilic oesophagitis

Non-IgE-mediated food allergy

• Cow’s milk protein intolerance / soy intolerance

Infants are irritable and have blood or mucous in their stool typically some hours after the ingestion of these proteins.

Most resolve by 3 years old.

First-line treatment is usually a formula containing cow’s milk protein hydrosylate. Soy-based formulas should not be used in infants under 6 months old as many are also soy protein intolerant.

• Food protein-induced enterocolitis syndrome

In acute presentations, the child ingests the food and typically within 1.5 to two hours vomits profusely and may become shocked. It is frequently misdiagnosed as sepsis or bowel obstruction.

In chronic forms, young infants exposed to these proteins on a daily basis typically manifest symptoms of daily vomiting, diarrhoea, failure to thrive and, occasionally, melaena.

The pathophysiology of FPIES is unclear but skin tests are negative.

Diagnosis is based on history and management involves strict avoidance of the food.

Cow’s milk and soy FPIES usually resolve between the ages of 1 and 2 years and resolution is established by formal supervised food challenge.