Signs And Symptoms Of Lactose Intolerance In Children


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If your child complains of abdominal cramps, loose stools, or nausea after ingesting a cup of milk or ice cream, it could be lactose intolerance. The condition occurs due to the absence or insufficiency of lactase, an enzyme produced in the small intestine. Lactase helps convert lactose, a type of milk sugar, into simpler sugars, which can be easily absorbed by the body.

The undigested lactose moves into the colon (large intestine), where it is fermented by colonic bacteria, triggering symptoms, such as excessive burping and flatulence (1). Regulating dairy intake and treatment of underlying cause in some cases can help avoid symptoms of lactose intolerance.

This post shares about lactose intolerance in children, its causes, symptoms, diagnosis, and treatment.

Are Lactose Intolerance And Milk Allergy The Same?

Although lactose intolerance and milk allergy have similar symptoms, they are different conditions. Lactose intolerance is a digestive disorder characterized by an inability to digest lactose sugar. It usually manifests itself in late childhood, teenage, or adulthood and is seldom life-threatening.

Milk allergy is an immune system-related condition involving an allergic reaction to one or more milk proteins. It is common in infants and young children. Since it is a type of allergy, it may cause a severe allergic reaction known as anaphylaxis (2).

What Are The Causes Of Lactose Intolerance In Children?

There are three different forms of lactase deficiency that can lead to lactose intolerance (3) (4) (5).

  1. Primary lactase deficiency: It is also called lactase non-persistence and is the most common cause of lactose intolerance. It happens due to a gradual decline in the production of lactase after infancy. Its symptoms usually develop gradually and manifest in late childhood, teenage, or early adulthood. Genetic predisposition is the fundamental reason behind primary lactase deficiency.
  1. Secondary lactase deficiency: It can lead to temporary lactose intolerance among children. This form of lactase deficiency occurs due to damage to the inner lining of the small intestines due to infections (Rotavirus and Giardia), autoimmune diseases (Crohn’s and Celiac disease), or severe malnutrition. Certain medicines and surgeries also cause intolerance. Most reasons can be treated to restore normal lactase production.
  1. Congenital lactase deficiency: In this rare genetic condition, the baby’s small intestine produces little to no lactase from birth. Children with congenital lactase deficiency usually do not tolerate breast milk as well.

What Are The Symptoms Of Lactose Intolerance In Children

The symptoms and their intensity depend on several factors, including the type of lactase deficiency and the quantity of lactose ingested. The following are some of the common symptoms of lactose intolerance (3) (6).

  • Nausea or vomiting
  • Abdominal pain or cramps
  • Bloating
  • Gas or flatulence
  • Excess burping
  • Loud bowel sounds
  • Diarrhea or loose stools

These symptoms can emerge from 30 minutes to two hours after ingesting milk or dairy products.
The symptoms of lactose intolerance are similar to other gastrointestinal problems and infections. Therefore, consult a pediatrician to determine the exact cause.

How Is Lactose Intolerance Diagnosed In Children?

The doctor will collect family, medical, and diet history, along with a detailed discussion of the child’s symptoms. Various tests, such as blood test, endoscopy, or biopsy, might be conducted to rule out the presence of infections, autoimmune diseases, or malnutrition.

If other tests turn out negative, and the doctor suspects lactose intolerance, then the following tests can be conducted to confirm the diagnosis (2) (6) (7).

  1. Elimination diet test: You will be asked to eliminate lactose-containing foods from your child’s diet, note improvement in symptoms, and re-introduce the foods. If the symptoms reappear, lactose intolerance is the most likely cause.
  1. Hydrogen breath test: The child drinks a small amount of liquid with a known amount of lactose. Then, the child breathes out into a balloon-like bag every 15 to 30 minutes for a few hours. If a high amount of hydrogen is detected in the air inside the bag and lactose intolerance symptoms are observed, a positive diagnosis is made.
  1. Stool acidity test: This test is usually recommended for young children who cannot perform the hydrogen breath test. The test checks the acidity (pH) of the stool. An acidic stool can indicate lactose malabsorption.

The doctor may order multiple tests to determine the presence of lactose intolerance. Based on the diagnosis, your child will be recommended dietary changes to alleviate symptoms.

How Is Lactose Intolerance Treated In Children?

Lactose intolerance due to primary and congenital lactase deficiency does not have a cure, but the symptoms can be managed by avoiding lactose in the diet. Secondary lactase deficiency due to autoimmune diseases, such as Crohn’s disease, can be managed with dietary changes.

Secondary lactase deficiency due to infections, medications, or poor nutrition can be cured with appropriate treatment modalities.

The following are the various forms of management and treatment for lactose intolerance (2) (8) (9).

1. Dietary changes

If the child has primary and congenital lactase deficiency or secondary lactase deficiency due to autoimmune diseases, then avoid lactose. You may try following dietary modifications (10) (11) (12).

  • Eliminate all lactose-containing foods if the child has a low threshold of tolerance. Lactose is found in many products beyond dairy, such as bread, cereal, salad dressings, and confectionery items. Check the ingredient list of a product carefully to avoid lactose and dairy products.
  • Milk and dairy products provide calcium, vitamin D, and vitamin B12. However, there are other sources of these nutrients, too. Meat and eggs are excellent sources of vitamin B12. Calcium can be obtained from fish, oranges, beans, and broccoli. Vitamin D can be found in fish and eggs. These nutrients can also be adequately found in most fortified cereals and lactose-free health drinks for children.
  • Milk can be replaced with fortified lactose-free milk or plant-based milk, such as soy milk and almond milk.

Some lactose-intolerant children can consume a small quantity (about one cup) of milk or have yogurt and cheese, which contain low amounts of lactose. However, the safe limit can vary depending on the severity of lactose intolerance and the underlying cause of lactase deficiency. Avoid serving lactose-containing products to the child without consulting the doctor. Discuss with the doctor the best dietary changes to provide optimum nutrition to the child.

2. Lactase enzyme tablets or drops

The pediatrician can recommend adding a lactase enzyme tablet or drop formulation in a specific dosage to lactose-containing foods (13). It will help pre-digest lactose and alleviate symptoms associated with its intolerance. Lactase enzyme tablets and lactase-treated milk are available over-the-counter. Since the effect of these formulations varies from case-to-case, consult your healthcare provider before using them.

3. Treatment of infections

Infections, such as gastroenteritis that cause secondary lactase deficiency, can be cured with appropriate medications, such as antibiotics. Several infections can be prevented through precautions. For instance, giardiasis can be prevented by drinking clean water, and rotavirus infections can be avoided through vaccination.

What Are The Possible Complications Of Lactose Intolerance?

Poor management of lactose intolerance may increase the risk of the following complications (14).

  1. Osteopenia is a condition where the bone’s mineral density declines, making the bones fragile.
  1. Juvenile osteoporosis is characterized by the thinning and weakening of bones due to excessive bone loss. It usually occurs as osteopenia progresses.
  1. Malnutrition is a state that develops due to the inadequate supply of nutrients, in general.

These complications are rare and usually occur when the child’s only source of calcium and vitamin D is milk. Supplementation with appropriate food items can balance the loss of any nutrients due to the absence of milk and dairy in the diet.

Lactose intolerance is not life-threatening. Encourage your child to follow dietary and general management steps. Several dietary alternatives are available to effectively replace dairy in the child’s diet. Timely diagnosis and appropriate dietary management can help alleviate the symptoms and improve the quality of life.


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