Enhanced Verifiable CPD from the
University of Birmingham

Dentaljuce Shorts: 500 words, 10 MCQs, on general medicine and surgery.

Lactose Intolerance

Lactose intolerance is the inability to digest lactose, a sugar found in dairy products, due to a deficiency of the enzyme lactase. This condition affects approximately 65% of the global population with varying prevalence among different ethnic groups.

Lactose molecule structure
Lactose is made up of two simple sugars: glucose and galactose.

Signs and Symptoms

The primary symptoms of lactose intolerance include abdominal pain, bloating, diarrhoea, flatulence, and nausea, typically occurring 30 to 120 minutes after consuming lactose-containing foods. The severity of symptoms depends on the amount of lactose ingested and individual tolerance levels. Unlike milk allergy, lactose intolerance does not cause immune reactions such as itching, hives, or anaphylaxis.


Lactose intolerance results from a deficiency of lactase, an enzyme produced in the small intestine that breaks down lactose into glucose and galactose for absorption. This deficiency can be genetic or acquired. There are four types of lactose intolerance:

  1. Primary Lactose Intolerance: Common and genetically determined, it occurs as lactase production decreases after childhood.
  2. Secondary Lactose Intolerance: Caused by injury to the small intestine due to infections, celiac disease, Crohn's disease, or other conditions.
  3. Developmental Lactose Intolerance: Occurs in premature infants but usually improves over time.
  4. Congenital Lactose Intolerance: A rare genetic disorder present from birth, characterised by a complete lack of lactase.
Lactose intolerance prevalence
An estimate of the percentage of adults that can digest lactose in the indigenous population of the Old World.


Diagnosis of lactose intolerance involves several steps to confirm the condition:

  • Hydrogen Breath Test: Measures hydrogen levels in breath after ingesting lactose. High levels indicate lactose intolerance.
  • Lactose Tolerance Test: Monitors blood glucose levels after lactose ingestion. A flat glucose rise suggests lactose malabsorption.
  • Stool Acidity Test: Used for infants, it tests stool acidity after lactose ingestion. Acidic stools indicate intolerance.
  • Intestinal Biopsy: Confirms lactase deficiency through tissue samples.
  • Genetic Testing: Identifies specific mutations associated with primary lactose intolerance.


Management primarily involves dietary adjustments and supplements:

  • Dietary Avoidance: Limiting lactose intake to avoid symptoms. Individuals vary in their tolerance levels, and many can consume small amounts of lactose without significant issues.
  • Lactase Supplements: Over-the-counter lactase enzyme supplements can help digest lactose when consuming dairy products.
  • Lactose-Free Products: Use of lactose-free milk and dairy products as substitutes.
  • Calcium Intake: Ensuring adequate calcium intake through non-dairy sources or supplements to maintain bone health.


Lactose intolerance varies significantly across populations:

  • High Prevalence: East Asian, West African, Jewish, and Arab descent populations, with up to 90-100% affected.
  • Low Prevalence: Northern European populations, with about 5% affected due to historical dairy farming and genetic adaptations.

Historical Context

Lactase persistence, the ability to digest lactose into adulthood, evolved in populations with a history of dairy farming, such as in Europe, Scandinavia, and parts of Africa. This genetic adaptation occurred independently in various regions due to the benefits of digesting milk from domesticated animals. The understanding of lactose intolerance has evolved, recognising it as common globally rather than an anomaly limited to certain populations.

Other Animals

Most mammals, including humans, typically lose the ability to produce lactase after weaning. This natural decline in lactase production is also observed in other mammals, driven by genetic and epigenetic factors such as DNA methylation.

Self-assessment MCQs (single best answer)

What enzyme is deficient in individuals with lactose intolerance?

Which symptom is NOT typically associated with lactose intolerance?

Which type of lactose intolerance is present from birth and results from a complete lack of lactase?

Which diagnostic test measures hydrogen levels in the breath after lactose ingestion?

Which population has the highest prevalence of lactose intolerance?

What is the primary management strategy for lactose intolerance?

What is the main difference between lactose intolerance and a milk allergy?

Which of the following is NOT a common method for diagnosing lactose intolerance?

What historical development contributed to lactase persistence in certain populations?

Why is it important for individuals with lactose intolerance to ensure adequate calcium intake?


Dentaljuce provides Enhanced Continuing Professional Development (CPD) with GDC-approved Certificates for dental professionals worldwide.

Founded in 2009 by the award-winning Masters team from the School of Dentistry at the University of Birmingham, Dentaljuce has established itself as the leading platform for online CPD.

With over 100 high-quality online courses available for a single annual membership fee, Dentaljuce offers comprehensive e-learning designed for busy dental professionals.

The courses cover a complete range of topics, from clinical skills to patient communication, and are suitable for dentists, nurses, hygienists, therapists, students, and practice managers.

Dentaljuce features Dr. Aiden, a dentally trained AI-powered personal tutor available 24/7 to assist with queries and provide guidance through complex topics, enhancing the learning experience.

Check out our range of courses, or sign up now!

Membership Options

Dentaljuce offers a range of membership options…

Regular Membership

With enhanced CPD Certificates. Dentaljuce is brought to you by the award winning Masters team from the School of Dentistry, University of Birmingham, UK. All have won awards for web based learning and teaching and are recognised as leaders and innovators in this field, as well as being highly experienced clinical teachers. Full access to over 100 courses, no extras to pay.

Buy Now

£89.00 per year

Student Membership

No Certificates. With universities cutting down on traditional lectures, many students are currently having to rely more on online resources. If you don't need CPD Certificates, we are offering an amazing discount on your Dentaljuce personal membership fee. Special student price just £29 for 12 months individual membership.

Buy Now

£29.00 per year

Dr. Aiden has transformed my CPD. I've learned more in the past month than I have in the last year.

© Dentaljuce 2024 | Terms & Conditions | Privacy Policy

Recording CPD time: recorded.