What Is Lactose? What Is Lactose Intolerance? Symptoms and Management

What Is Lactose?

Lactose is a type of sugar naturally found in milk and dairy products. It is also known as “milk sugar.” It is present especially in cow, goat and sheep milk.

Lactase enzyme, produced in the small intestine, is needed to digest lactose. When lactose is not digested adequately, digestive complaints such as gas, bloating, abdominal pain and diarrhea may occur.

What Is Lactase?

Lactase is an enzyme found in the intestines that helps digest lactose. It breaks lactose down into smaller sugars such as glucose and galactose, allowing the body to absorb them.

What Is Lactose Intolerance?

Lactose intolerance occurs when the body cannot produce enough lactase enzyme or lactase activity decreases, resulting in incomplete digestion of lactose. It is not an allergy; it is a digestive system problem.

When lactose-containing foods are consumed, undigested lactose may ferment in the intestine and cause gas, bloating, abdominal pain or diarrhea. Symptom severity depends on the amount of lactose consumed and individual tolerance.

What Are the Symptoms of Lactose Intolerance?

After consuming lactose-containing foods, the following complaints may occur:

• Gas, bloating and discomfort
• Cramp-like abdominal pain
• Diarrhea
• Nausea
• Abdominal rumbling or urgent need to use the toilet

If one or more of these complaints repeatedly occur in relation to milk and dairy products, consulting a specialist may be useful for diagnosis and nutrition planning.

What Causes Lactose Intolerance? What Are the Types?

Lactose intolerance is caused by low lactase enzyme levels or reduced lactase activity. It has different types:

• Primary lactose intolerance: The most common form. It is related to genetic tendency and develops as lactase production decreases with age.
• Secondary lactose intolerance: It may occur after intestinal infections, celiac disease or inflammatory bowel diseases such as Crohn’s disease. In some patients, tolerance may improve when the underlying condition is treated.
• Congenital lactose intolerance: Very rare. It occurs when infants are born without lactase production and requires medical follow-up.
• Developmental lactose intolerance: It may be temporary in premature infants because lactase production has not yet fully developed.

How Is Lactose Intolerance Diagnosed?

Diagnosis is based on symptoms, the relationship between dairy intake and complaints, dietary history and test results when needed. One of the commonly used methods is the hydrogen breath test.

In some situations, stool acidity testing and a supervised elimination-reintroduction diet may also be used. If symptoms improve when lactose is limited and return when lactose is reintroduced, lactose intolerance may be suspected. However, similar complaints may also be caused by irritable bowel syndrome, celiac disease, inflammatory bowel disease or other food intolerances, so evaluation should be individualized.

What Should People With Lactose Intolerance Do?

The goal is not always to eliminate all dairy products unnecessarily, but to determine the amount a person can tolerate and suitable alternatives.

• Lactose-free milk and lactose-free dairy products may be preferred.
• Yogurt, kefir and aged cheeses may be better tolerated by some people; tolerance varies individually.
• If plant-based beverages such as almond, soy or oat drinks are used, calcium- and vitamin D-fortified options may be preferred.
• Labels should be read carefully for processed foods, ready-made sauces, some medications or supplements that may contain hidden lactose.
• Lactase enzyme supplements may be considered if recommended by a physician or dietitian.

Does Lactose Intolerance Affect Quality of Life?

If not controlled, lactose intolerance may affect social life, dietary routine and daily comfort. However, quality of life can be maintained with the right nutrition plan, portion control, appropriate product selection and supportive supplements when needed.

If dairy products are restricted, calcium and vitamin D intake should be reviewed. Children, pregnant and breastfeeding individuals, older adults, people at risk of osteopenia/osteoporosis and those with chronic diseases may benefit from dietitian support.

Frequently Asked Questions

References

1. NIDDK. Lactose Intolerance
2. NIDDK. Eating, Diet, & Nutrition for Lactose Intolerance
3. Mayo Clinic. Lactose Intolerance - Symptoms and Causes
4. Mayo Clinic. Lactose Intolerance - Diagnosis and Treatment