Food Intolerance

Question 1

Define food intolerances

Answer 1

Non-immune adverse reactions to food and/or food additives that are distinct from food allergy

Question 2

Which food intolerances are most common

Answer 2

Lactose (most common)
Wheat

Question 3

What is the aetiology of lactose intolerance

Answer 3

Lactase enzyme not expressed on the microvilli of the intestine → lactose cannot be broken down into glucose + galactose → lactose ferments in the gut → waste gas
May be primary, congenital, secondary/acquired hypolactasia (gastroenteritis, giardiasis, coeliac disease)

Question 4

What are the risk factors for food intolerances

Answer 4

Recent gastroenteritis (post gastroenteritis syndrome)
Irritable bowel syndrome (Crohn’s)
Family history (congenital lactose intolerance)
Coeliac disease

Question 5

What are the symptoms of food intolerance

Answer 5

Symptoms arise with the consumption of lactose-containing products - Often a delay in onset (minutes to hours) and prolonged symptomatic phase
Often presents later in life than CMPA

GI symptoms: bloating, abdominal pain, vomiting, diarrhoea, constipation
Foul smelling ‘yeasty’ stool: Explosive, bulky, frothy, watery
Headache
Fatigue
Musculoskeletal symptoms
Failure to thrive, faltering growth

Question 6

What are the signs of food intolerance on examination

Answer 6

Weight and height
Obs
Abdominal: Abdominal tenderness, Abdominal distension

Question 7

What are the differentials for food intolerances

Answer 7

Coeliac disease
Sucrase-isomaltase deficiency
CMPA
Giardiasis
Irritable bowel syndrome
Tropical sprue

Question 8

What investigations should be done for lactose intolerance

Answer 8

Clinical diagnosis → 2 week trial of dietary lactose elimination

If inconclusive:
Lactose hydrogen breath test
Stool for reducing substances and pH: +ve with low pH
FBC (anaemia from secondary lactase deficiency from coeliac)
Small bowel biopsy (persistent symptoms)
Lactose intolerance test: measures serum glucose after lactose administration

Question 9

What is the management for lactose intolerances

Answer 9

1. 2-week dietary lactose elimination trial followed by reintroduction
   → Resolution of symptoms followed by resumption after lactose is re-introduced is diagnostic

Dairy-free exclusion diet + referral to dietician
± Lactase supplements (although easily denatured by the stomach)
± lactase-treated dairy products
± calcium supplements

Question 10

What are the complications of lactose intolerance

Answer 10

Osteoporosis
Rickets
Malnutrition
Faltering growth

Question 11

What is the prognosis for lactose intolerance

Answer 11

Will resolve after several months of the dairy-free diet, when lactase starts to be expressed again
Excellent prognosis
Persistent symptoms in a small number of patients is due to ongoing inadvertent lactose exposure, IBS, or poorly controlled underlying disorders
Treatment is lifelong and adherence can be an issue, especially in children