Lactose Intolerance

Definition

Lactose intolerance is a common digestive problem where the body is unable to digest lactose, a type of sugar mainly found in milk and dairy products. It occurs due to a deficiency of lactase, an enzyme produced in the small intestine that is necessary for breaking down lactose.

Aetiology

The causes of lactose intolerance can include:

Primary lactase deficiency: A genetically determined reduction in lactase production that begins after weaning and becomes more pronounced with age.
Secondary lactase deficiency: Occurs due to injury to the small intestine from illness, surgery, or conditions such as coeliac disease or Crohn's disease.
Congenital lactase deficiency: A rare inherited disorder where infants are born with little or no lactase enzyme.
Developmental lactase deficiency: Can occur in premature infants, but typically improves as the infant matures.

Pathophysiology

Lactose intolerance results from a deficiency of lactase, the enzyme responsible for hydrolysing lactose into glucose and galactose in the small intestine. Undigested lactose passes into the colon, where it is fermented by bacteria, producing gas and causing osmotic water retention, leading to symptoms such as bloating, diarrhoea, and abdominal pain.

Risk Factors

Age (more common in adults than in children)
Ethnic background (more common in people of Asian, African, Native American, and Mediterranean descent)
Family history of lactose intolerance
Premature birth
Diseases affecting the small intestine (e.g., coeliac disease, Crohn's disease)
History of gastrointestinal surgery

Signs and Symptoms

Symptoms of lactose intolerance typically occur within a few hours of consuming lactose-containing foods or drinks and can include:

Bloating
Diarrhoea
Abdominal pain or cramps
Flatulence
Nausea

Investigations

Clinical history and dietary review

Management

Primary Care Management

Dietary modification: Advising patients to reduce or eliminate lactose-containing foods and drinks from their diet.
Lactase enzyme supplements: These can be taken with meals to help digest lactose.
Calcium and vitamin D supplementation: Important for patients who avoid dairy to prevent deficiencies.
Education: Informing patients about lactose intolerance, how to read food labels, and identifying hidden sources of lactose.
Referral: To a dietitian for specialised dietary advice or to a gastroenterologist if symptoms persist despite dietary modifications.

Specialist Management

Treating underlying conditions: If secondary lactose intolerance is due to another condition like coeliac disease or Crohn's disease, managing the primary condition can improve lactose tolerance.
Probiotics: In some cases, probiotics may help improve symptoms by modifying the gut microbiota.

Example Management for Lactose Intolerance

A patient presenting with symptoms of bloating, diarrhoea, and abdominal pain after consuming dairy products can be diagnosed by restricting lactose from diet for about 6 weeks and then a gradual re-introduction of lactose; if symptoms restart then lactose intolerance in the likely diagnosis. Initial management includes advising the patient to avoid lactose-containing foods and drinks. The patient is also provided with lactase enzyme supplements to take with meals containing lactose. Dietary counselling is offered to ensure adequate intake of calcium and vitamin D from non-dairy sources. Follow-up appointments are scheduled to monitor symptoms and dietary adherence.

References

NICE. (2024). Food Allergy and Intolerance: Assessment and Management. Retrieved from NICE
NHS. (2023). Lactose Intolerance. Retrieved from NHS
British Dietetic Association (BDA). (2022). Guidelines for the Management of Lactose Intolerance. Retrieved from BDA
World Gastroenterology Organisation (WGO). (2021). Global Guidelines on Lactose Intolerance. Retrieved from WGO