Lactose Intolerance
Lactose intolerance is the malabsorption of the sugar present in milk and dairy products due to a deficiency of the enzyme responsible for breaking it down during digestion.
Symptoms and Causes
Lactose intolerance is a digestive disorder caused by a deficiency of lactase, the enzyme responsible for breaking down lactose (the sugar present in milk and its derivatives). When the small intestine does not produce enough lactase, lactose passes into the large intestine without being fully digested. Consequently, bacterial fermentation causes abdominal issues.
Although often confused, lactose intolerance is not the same as a milk allergy. The former is a digestive condition, whereas the latter is an abnormal immune system response.
The prognosis for lactose intolerance is generally good, as it can be managed through dietary and lifestyle modifications.
Symptoms
Symptoms typically appear between 30 minutes and 2 hours after ingesting lactose-containing foods, although onset may be slightly delayed. The most characteristic symptoms in adults include:
- Diarrhea
- Nausea
- Occasionally, vomiting
- Abdominal pain of variable intensity, ranging from mild discomfort to severe colicky pain
- Bloating
- Increased intestinal gas, manifested as belching or flatulence
- Stomach rumbling
Symptoms of lactose intolerance in infants include:
- Uncontrollable crying
- Irritability
- Occasionally, weight loss
- Stomach rumbling after feedings
- Gas
- Abdominal distension
- Colic
- Diarrhea
- Vomiting
Causes
Lactose intolerance occurs when the small intestine is unable to produce sufficient lactase to digest lactose. It can be classified into three types:
- Primary lactose intolerance: the most common type. In healthy individuals, lactase production decreases after the introduction of foods other than milk. However, intolerant individuals excessively reduce lactase production due to a genetic predisposition.
- Secondary lactose intolerance: lactase deficiency results from injury, surgery, or a secondary disease, such as:
- Intestinal infection
- Celiac disease
- Crohn’s disease
- Bacterial overgrowth
- Congenital lactose intolerance: infants are born without the ability to produce the lactase necessary for lactose digestion. It is inherited in an autosomal recessive pattern (both parents must carry the same genetic mutation).
Risk Factors
The risk of developing lactose intolerance increases in the following situations:
- Advanced age: this condition is rare in infants and children, as it typically develops over time
- Premature birth: lactase-producing cells form during the third trimester, so premature infants may be born before their development
- Small intestine diseases
- Oncological treatments: may occur as a side effect of chemotherapy
Complications
Lactose intolerance can lead to severe diarrhea, resulting in:
- Dehydration
- Malnutrition
- Calcium deficiency
Prevention
Lactose intolerance cannot be prevented.
Which Specialist Treats Lactose Intolerance?
Lactose intolerance is diagnosed within the specialties of Family and community medicine, Pediatrics, Gastroenterology, or Allergology.
Diagnosis
Diagnosis of lactose intolerance typically includes the following procedures:
- Medical history: the specialist suspects the disorder based on the patient’s symptoms, which are highly specific. A detailed review of medical history and lifestyle is also performed.
- Hydrogen breath test: commonly known as the breath test, it measures the amount of hydrogen in the patient’s breath after ingesting a lactose solution. Inadequate digestion results in increased hydrogen levels.
- Lactose tolerance test: a lactose-containing liquid is administered, and after a set period, blood glucose levels are measured. Poor digestion results in lower blood glucose levels.
- Fecal pH test: undigested lactose increases lactic acid in the stool, resulting in acidic pH.
Treatment
There is no specific treatment for lactose intolerance, but symptoms can be prevented by modifying dietary habits:
- Monitor the body’s response to dairy consumption, allowing patients to adjust their diet and reduce difficult-to-digest products
- Reduce lactose intake without complete elimination
- Consume small portions of dairy
- Drink milk with other foods to slow digestion
- Use lactose-free dairy products
For occasions when lactose ingestion is unavoidable, specialists may prescribe lactase-containing medications, typically in drops or tablets taken before meals.
Patients with lactose intolerance secondary to an underlying disease should receive targeted treatment.
