Food Intolerances (Milk Protein / Lactose)

Food allergy vs food intolerance

Conditions causing symptoms after food ingestion include:

• IgE-mediated food allergy — can cause severe reactions including hives, asthma, facial swelling, and anaphylaxis.
• Non-IgE-mediated allergy syndromes — e.g. coeliac disease.
• Mixed IgE- and non-IgE-mediated reactions — e.g. eosinophilic oesophagitis.
• Food intolerance — e.g. lactose intolerance.

Food intolerance must be distinguished from food allergy: it does not involve the immune system, does not cause severe allergic reactions (anaphylaxis), and is dose-dependent. It’s a common complaint with varied symptoms — IBS-type symptoms, bloating, headache, “brain fog”, skin rashes, lethargy.

Investigation

If food intolerance is clinically suspected, the only appropriate investigation is a trial of an exclusion diet, undertaken with guidance from a medical practitioner and a specialist Accredited Practising Dietitian. If symptoms don’t improve after 4 weeks, food intolerance is unlikely and alternative causes should be considered.

Skin-prick testing and allergen-specific IgE blood tests should not be used unless allergy is suggested by the clinical history — false- positive results are common and can lead to inappropriate dietary restrictions, with nutritional implications (particularly in children) and unnecessary fear/anxiety for the patient or family. There is no skin or blood test that accurately diagnoses food intolerance.

Cow’s milk/soy protein allergy (infants)

Consider non-IgE-mediated cow’s milk/soy protein allergy in infants who are unsettled and crying, have poor weight gain, significant feeding problems throughout the day and night, diarrhoea with blood or mucus, or widespread eczema.

Diagnosis: eliminate cow’s milk from the mother’s diet (if breastfeeding) or use an extensively hydrolysed formula (usually needs a paediatric consult). Diagnosis is supported if symptoms improve on elimination and reappear when cow’s milk protein is reintroduced.

Lactose overload / intolerance (infants)

Consider lactose overload if a baby is having very frequent feeds with frothy/watery diarrhoea and perianal excoriation. Primary lactose intolerance is rare in infants.

Treatment: space feeds >3 hours apart, or trial a lactose-free formula (or lactase-treated breast milk).