Lactose Intolerance

Introduction

Lactose intolerance is usually due to a deficiency of the digestive enzyme in the small bowel mucosa, resulting in lactose malabsorption.



Symptoms

Incompletely absorbed lactose is subsequently fermented by bacteria in the large bowel causing

Symptoms associated with lactose ingestion are not always due to lactose deficiency; they may be due to rapid transit of lactose through the small bowel.

Lactase deficiency can be primary with delayed onset (i.e. adult lactase deficiency), secondary or congenital. Delayed-onset primary lactase deficiency may begin from 7 years of age.



Differential Diagnosis

The diagnosis is suspected based on dietary history.

  • The differential diagnosis includes physiologically incomplete absorption of simple carbohydrates (e.g., sorbitol, mannitol, xylitol, fructose, FODMAP) and therapeutic inhibitors of carbohydrate absorption (e.g., acarbose), which can cause symptoms of carbohydrate intolerance.

Allergy to cow's milk protein is distinct to lactose intolerance.

  • Symptoms of cow's milk allergy include hives, blotchy skin rashes, facial swelling, diarrhoea and wheeze; anaphylaxis may occur.
  • Symptoms may occur rapidly after ingestion of cow's milk; however, some symptoms (e.g. diarrhoea, vomiting, worsening eczema) can occur hours or days after exposure.
  • Cow's milk allergy is common in infancy (2%), but most children outgrow it by 3 or 4 years of age; it is rare in adulthood.



Management

The goal of management in patients with lactose intolerance is to eliminate symptoms while maintaining calcium intake and vitamin D intake.

  • Patients who avoid dairy products and have an inadequate intake of calcium and vitamin D should be encouraged to increase their consumption of calcium-rich foods or consider using calcium and vitamin D supplementation.

Since intolerance is a dose-dependent phenomenon, patients usually respond to restriction of lactose without having to avoid lactose-containing products altogether.

  • Individuals with lactose intolerance may start with more strict dietary restriction and then work up to their individually tolerated limit of ingestion of lactose-containing food.
  • Most individuals with lactose malabsorption tolerate a dose of at least 12 g lactose without problems because of persisting residual lactase activity. Larger doses may be tolerated if consumed with food or spread over a whole day.

Options for dietary modification include:

  • Choosing low-lactose and lactose-free products where possible, e.g. soy milk replacing cow's milk.
  • Consuming smaller quantities of lactose-containing products more frequently over the day (rather than large quantities at a time).
  • Using lactase enzyme drops or tablets before ingesting lactose-containing products.



Lactose-free Medicines

Lactose is an ingredient widely used by the pharmaceutical industry in the formulation of tablets and capsules, as a diluent or filler. It can also be used in lyophilised products, as a carrier in dry-powder inhalers, and can be found in liquid formulations.

The amount of lactose used in medicinal products is small in comparison to dairy products and the dose provided is usually less than 2 g/day.

  • Hence, GI symptoms may not be experienced by all lactose intolerant patients.

One may have to check the list of excipients in product leaflet or contact manufacturer to know the quantity of lactose in a medicinal product.

The eMC website can be used to search for a lactose-free medicine.

  • Click advanced search option and select search documents "by SmPC section"
  • Select section to search by 6.1 List of excipients.
  • Select "does not contain" and type in lactose in search query.
  • You may click add to further refine the search (e.g. 1 Name of medicinal product, 4.1 Therapeutic indications)
  • Click search.



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