Lactose Intolerance: Symptoms, Causes, and Management


Lactose intolerance is a common digestive disorder that affects a significant portion of the global population. It occurs when the body is unable to fully digest lactose, a sugar found in milk and dairy products. While lactose intolerance can be uncomfortable and inconvenient, it is not a life-threatening condition. In this article, we will delve into the details of lactose intolerance, including its symptoms, causes, diagnosis, and management options.

What is lactose intolerance?

Lactose intolerance is characterized by the body’s inability to produce sufficient amounts of lactase, an enzyme responsible for breaking down lactose into simpler sugars—glucose and galactose. When lactose is not fully digested, it remains in the digestive system and can cause various uncomfortable symptoms.

Symptoms of lactose intolerance

The symptoms of lactose intolerance can vary in severity and typically manifest within a few hours after consuming lactose-containing foods or drinks. Common symptoms include:

  1. Abdominal pain and cramps: These are among the most common symptoms and can range from mild to severe.
  2. Bloating: Lactose intolerance can lead to excess gas production in the digestive system, causing bloating and discomfort.
  3. Diarrhea: The undigested lactose can draw water into the intestine, resulting in loose stools or even diarrhea.
  4. Nausea and vomiting: In some cases, lactose intolerance can trigger feelings of nausea and lead to vomiting.

Lactose intolerance is different from milk allergy, which involves an immune system response to proteins found in milk rather than lactose.

Causes of lactose intolerance

There are 3 primary types of lactose intolerance, each with its own underlying cause:

  1. Primary lactose intolerance: This is the most common type and occurs when the body gradually produces less lactase with age. This reduction in lactase production is genetically determined and commonly affects individuals of African, Asian, Hispanic, or Native American descent.
  2. Secondary lactose intolerance: This type is caused by damage to the small intestine, which can result from conditions such as celiac disease, Crohn’s disease, or intestinal infections. In these cases, lactose intolerance is usually temporary and improves as the underlying condition is treated.
  3. Congenital lactose intolerance: This is a rare condition in which infants are born with an inability to produce lactase. It is an inherited disorder and requires immediate medical attention, as infants are unable to tolerate lactose in breast milk or standard infant formulas.

Which infections and conditions may cause secondary lactose intolerance?

Secondary lactose intolerance can occur as a result of certain infections and conditions that damage the small intestine. The following are some examples of infections and conditions that may lead to secondary lactose intolerance:
  1. Gastroenteritis: This is an infection or inflammation of the gastrointestinal tract, often caused by viruses, bacteria, or parasites. Gastroenteritis can damage the lining of the small intestine, leading to temporary lactose intolerance until the intestinal lining recovers.
  2. Celiac disease: Celiac disease is an autoimmune disorder in which the consumption of gluten triggers an immune response that damages the small intestine. This intestinal damage can result in lactose intolerance until the condition is properly managed through a gluten-free diet.
  3. Crohn’s disease: Crohn’s disease is a chronic inflammatory bowel disease that can affect any part of the digestive tract. Inflammation and ulceration in the small intestine may disrupt lactase production and cause secondary lactose intolerance.
  4. Intestinal infections: Infections such as bacterial overgrowth, parasitic infections (e.g., giardiasis), or viral infections can cause inflammation and damage to the intestinal lining, leading to temporary lactose intolerance.

Diagnosis and management of lactose intolerance

If you suspect lactose intolerance, consult a gastroenterologist for an accurate diagnosis. Diagnosis is typically done through a combination of medical history assessment, physical examination, and lactose intolerance tests such as lactose tolerance test, hydrogen breath test, or stool acidity test.

While there is no cure for lactose intolerance, several management strategies can help individuals cope with the condition:

  1. Dietary adjustments: The most common approach involves reducing or eliminating lactose-containing foods and drinks from the diet. This includes milk, cheese, ice cream, and other dairy products. Fortunately, there are numerous lactose-free or lactose-reduced alternatives available in the market.
  2. Lactase supplements: Over-the-counter lactase enzyme supplements are available and can be taken prior to consuming lactose-containing foods or drinks. These supplements help digest lactose and may alleviate symptoms in some individuals.
  3. Gradual reintroduction of lactose: In certain cases, individuals with lactose intolerance can tolerate small amounts of lactose without experiencing symptoms. Gradually reintroducing lactose-containing foods under the guidance of a gastroenterologist can help determine individual tolerance levels.
  4. Nutritional guidance: Removing dairy products from the diet can impact calcium and vitamin D intake. Seek nutritional guidance to ensure an adequate intake of these nutrients through alternative sources or supplements.

Bottom line

Lactose intolerance is a common digestive disorder that affects individuals worldwide. Understanding its symptoms, causes, and management options is essential for individuals with lactose intolerance to live comfortably and maintain a healthy diet. By making dietary adjustments and considering lactase supplements, those with lactose intolerance can continue to enjoy a well-balanced and satisfying diet while minimizing discomfort. Consultation with a gastroenterologist is crucial for an accurate diagnosis and personalized management plan.

How can I contact gastroenterologist Dr. Zavos for an appointment?

Dr. Chris Zavos is a board-certified gastroenterologist and hepatologist, located in Thessaloniki Greece, and specifically in Kalamaria suburb, about 7 kilometres (4 miles) southeast of downtown Thessaloniki. His private office is at: Fanariou 8 street (near Aigaiou and Adrianoupoleos avenues), Kalamaria (Thessaloniki), Greece.

Thessaloniki International Airport is only 10 km away from his private office in Kalamaria and can be reached by taxi within 13 minutes from the airport.

Dr. Chris Zavos performs endoscopies at Bioclinic private hospital in downtown Thessaloniki (Mitropoleos 86 street).

You can contact Dr. Zavos at phone numbers: (+30)-6976596988 and (+30)-2311283833, or you can email him at Dr. Zavos responds to Greek and English languages.

Last update: 26 September 2023, 18:59


Gastroenterologist - Hepatologist, Thessaloniki

PhD at Medical School, Aristotle University of Thessaloniki, Greece

PGDip at Universitair Medisch Centrum Utrecht, The Netherlands

Ex President, Hellenic H. pylori & Microbiota Study Group