Overview
Lactose intolerance is a condition where a person's body is unable to fully digest the sugar (lactose) found in milk and dairy products. As a result, undigested lactose reaches the colon, where it ferments, causing symptoms such as diarrhea, gas, and bloating. Lactose intolerance can occur due to a deficiency in the digestive enzyme lactase, which is responsible for breaking down lactose in the small intestine. There are three types of lactose intolerance: primary, secondary, and congenital or developmental. Primary lactose intolerance is the most common, and it's caused by a decrease in lactase production as a person ages. Secondary lactose intolerance is the result of an illness, injury, or surgery affecting the small intestine, such as celiac disease or Crohn's disease. Congenital or developmental lactose intolerance is rare and involves an inherited lack of lactase production.
Understanding the disease
Symptoms
The symptoms of lactose intolerance include diarrhea, gas, and bloating, which usually begin within 30 minutes to two hours after consuming dairy products. These symptoms occur when the small intestine doesn't produce enough lactase enzyme to digest lactose, leading to undigested lactose reaching the colon where bacteria cause the symptoms. Lactose intolerance is usually harmless but can be uncomfortable.
Risk Factors
Risk factors for developing lactose intolerance include:
- Increasing age: Lactose intolerance usually appears in adulthood, as the body's production of the lactase enzyme decreases with age.
- Ethnicity: Lactose intolerance is most common in people of African, Asian, Hispanic, and American Indian descent.
- Premature birth: Infants born prematurely might have reduced levels of lactase due to delayed development of lactase-producing cells in the small intestine.
- Diseases affecting the small intestine: Conditions such as bacterial overgrowth, celiac disease, and Crohn's disease can cause lactose intolerance by damaging the small intestine or disrupting lactase production.
- Certain cancer treatments: Radiation therapy for cancer in the stomach area or certain intestinal complications from chemotherapy can increase the risk of developing lactose intolerance. Remember that managing lactose intolerance often involves adjusting your diet and may not require complete avoidance of dairy products. Consult your healthcare provider for personalized advice and recommendations.
Development
The various types of lactose intolerance develop in different ways.
- Primary lactose intolerance: This is the most common type, where people start life producing enough lactase. As children replace milk with other foods, the amount of lactase they produce normally drops, but usually remains high enough to digest the amount of dairy in a typical adult diet. By adulthood, lactase production falls off sharply, making milk products difficult to digest.
- Secondary lactose intolerance: This form of lactose intolerance occurs when the small intestine decreases lactase production after an illness, injury, or surgery involving the small intestine. Diseases associated with secondary lactose intolerance include intestinal infection, celiac disease, bacterial overgrowth, and Crohn's disease. Treatment of the underlying disorder might restore lactase levels and improve signs and symptoms, though it can take time.
- Congenital or developmental lactose intolerance: It's rare for babies to be born with lactose intolerance caused by a lack of lactase. This disorder is passed from generation to generation in a pattern of inheritance called autosomal recessive. Premature infants can also have lactose intolerance because of an insufficient lactase level. In summary, primary lactose intolerance occurs as an individual ages and their body produces less lactase. Secondary lactose intolerance is caused by underlying disorders, while congenital or developmental lactose intolerance is rare and inherited.
Assessment and Diagnosis
Triage
You should see a doctor if you frequently have symptoms of lactose intolerance after eating dairy foods, particularly if you're worried about getting enough calcium.
Diagnosis
To diagnose lactose intolerance, your doctor may suspect it based on your symptoms and response to reducing dairy foods in your diet. They can confirm the diagnosis by conducting one or more of the following tests:
- Hydrogen breath test: Measures the amount of hydrogen in your breath after consuming a lactose-rich liquid. Increased hydrogen levels indicate poor lactose digestion.
- Lactose tolerance test: Measures your blood glucose levels two hours after drinking a lactose-rich liquid. A lack of glucose rise suggests poor lactose absorption.
- Lactose intolerance tests: Evaluates your body's response to lactose by removing milk and milk products from your diet for several weeks or performing a breath test.
- Stool tests: Examines your stool for bacteria, parasites, or the presence of bile acid. Remember to consult your healthcare professional for accurate diagnosis and appropriate treatment options.
Management and Treatment
Treatment
To treat lactose intolerance, you can follow these steps:
- Limit milk and other dairy products.
- Include small servings of dairy products in your regular meals.
- Eat and drink lactose-reduced or lactose-free products.
- Use lactase enzyme tablets or drops.
- Experiment with different dairy products, as some have less lactose than others.
- Maintain good nutrition by consuming calcium-rich foods such as broccoli, leafy green vegetables, calcium-fortified products, canned salmon or sardines, milk substitutes like soy milk and rice milk, and almonds, Brazil nuts, and dried beans. Remember that individual responses to lactose may vary, so it might take some trial and error to determine the best approach for managing your lactose intolerance.
Preparing for medical consultation
To prepare for an appointment for lactose intolerance, you should:
- Make an appointment with your family doctor if you have symptoms that suggest lactose intolerance.
- Ask if there are any specific preparations you need to make before the appointment, such as restricting your diet or fasting before a specific test.
- Create a list of your symptoms, including any that may seem unrelated to lactose intolerance.
- Note down any key personal information, such as recent life changes, major stresses, and family medical history.
- Gather a list of all medicines, vitamins, or supplements you are taking, including the doses.
- Bring a family member or friend with you to help remember important details and ask questions.
- Prepare a list of questions to ask your doctor, such as the cause of your symptoms, possible tests needed, dietary suggestions, restrictions, and the best course of action. Remember to share any information about your daily dairy intake and how different dairy products affect your symptoms with your doctor.