Lactose Intolerance: Symptoms, Causes, and Treatment

What is Lactose Intolerance?

Lactose intolerance is a common digestive problem where the body is unable to digest lactose, a type of sugar mainly found in milk and dairy products. This occurs when the small intestine does not produce enough of an enzyme called lactase, which is needed to break down lactose into simpler forms that can be absorbed into the bloodstream.

When lactose moves through the large intestine (colon) without being properly digested, it can cause uncomfortable symptoms such as bloating, diarrhea, and gas. Lactose intolerance is not the same as a milk allergy, which is an immune response to the proteins in milk. Instead, lactose intolerance is a digestive issue and is generally not life-threatening, though it can be quite bothersome.

Source: Mayo Clinic, National Institutes of Health (NIH)

Common Causes

Lactose intolerance can develop for several reasons. Here are some of the most common causes:

• Primary Lactose Intolerance: This is the most common type and is caused by a natural decline in lactase production as people age. It often begins in childhood or adolescence and becomes more noticeable in adulthood. This type is more common in people of African, Asian, Hispanic, and Native American descent.
• Secondary Lactose Intolerance: This occurs when the small intestine decreases lactase production after an illness, injury, or surgery involving the small intestine. Conditions such as celiac disease, bacterial overgrowth, or Crohn's disease can damage the lining of the intestine and lead to this type of lactose intolerance.
• Congential Lactase Deficiency: A rare genetic disorder where a baby is born with little or no lactase enzyme. This condition is inherited and requires infants to be fed lactose-free formula.
• Developmental Lactase Deficiency: Sometimes seen in premature infants, this condition occurs when the small intestine is not fully developed at birth. It usually improves as the infant grows.
• Infections: Gastrointestinal infections, such as viral gastroenteritis (stomach flu) or bacterial infections, can temporarily damage the lining of the intestines, leading to lactose intolerance.
• Celiac Disease: An autoimmune disorder where the ingestion of gluten leads to damage in the small intestine, which can reduce lactase production.
• Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause inflammation in the digestive tract, leading to lactose intolerance.
• Chemotherapy and Radiation Therapy: Cancer treatments can damage the intestinal lining, leading to temporary or permanent lactose intolerance.
• Small Intestinal Bacterial Overgrowth (SIBO): An increase in the number of bacteria or changes in the type of bacteria in the small intestine can interfere with lactose digestion.
• Aging: As people age, the production of lactase can naturally decrease, making lactose intolerance more common in older adults.

Source: Centers for Disease Control and Prevention (CDC), World Health Organization (WHO)

Associated Symptoms

Symptoms of lactose intolerance typically begin 30 minutes to 2 hours after consuming foods or drinks containing lactose. The severity of symptoms can vary depending on the amount of lactose consumed and the amount of lactase your body produces. Common symptoms include:

• Bloating
• Diarrhea
• Gas
• Stomach cramps
• Stomach rumbling or gurgling
• Nausea, and sometimes vomiting

In some cases, people may also experience:

• Headaches
• Fatigue
• Loss of concentration or "brain fog"
• Joint or muscle pain
• Eczema or other skin reactions

These symptoms can range from mild to severe and can significantly impact a person's quality of life if not managed properly.

Source: Cleveland Clinic

When to See a Doctor

It's important to see a doctor if you experience persistent or severe symptoms after consuming dairy products. You should seek medical advice if:

• Your symptoms are causing significant discomfort or disrupting your daily life.
• You experience unexplained weight loss.
• You have persistent diarrhea or vomiting, which can lead to dehydration.
• You notice blood in your stool.
• Your symptoms do not improve after avoiding dairy products.
• You have symptoms of lactose intolerance along with other concerning symptoms, such as fever, severe abdominal pain, or signs of an allergic reaction (e.g., hives, difficulty breathing).

A healthcare provider can help determine if your symptoms are due to lactose intolerance or another condition, such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), or a milk allergy.

Source: Mayo Clinic

Diagnosis

If lactose intolerance is suspected, your doctor may recommend one or more of the following tests to confirm the diagnosis:

• Lactose Tolerance Test: This test measures your body's reaction to a liquid containing high levels of lactose. After drinking the liquid, blood samples are taken over a period of time to measure how much glucose (a byproduct of lactose digestion) is in your bloodstream. If your glucose levels do not rise, it suggests that your body is not digesting lactose properly.
• Hydrogen Breath Test: This test measures the amount of hydrogen in your breath after consuming a lactose-rich drink. Normally, very little hydrogen is detectable in the breath. However, if your body is not digesting lactose, it will ferment in the colon, producing hydrogen and other gases that can be detected in your breath.
• Stool Acidity Test: This test is often used for infants and young children who cannot undergo other tests. It measures the amount of acid in the stool, which can be elevated if lactose is not being digested properly.
• Genetic Test: This test can identify the genetic variant associated with primary lactose intolerance. It is a simple blood test that can confirm the diagnosis without requiring you to consume lactose.
• Endoscopy or Biopsy: In some cases, particularly if another condition like celiac disease is suspected, your doctor may perform an endoscopy to examine the lining of your small intestine and take a small tissue sample (biopsy) for analysis.

Your doctor may also recommend keeping a food diary to track your symptoms and identify patterns related to dairy consumption.

Source: National Institutes of Health (NIH)

Treatment Options

There is no cure for lactose intolerance, but symptoms can be managed through dietary changes and other treatments. Here are some options:

Dietary Changes

• Limit or Avoid Lactose: Reduce or eliminate dairy products from your diet. Many people with lactose intolerance can tolerate small amounts of lactose, so you may not need to avoid dairy completely.
• Choose Lactose-Free or Low-Lactose Products: Many stores carry lactose-free milk, cheese, and other dairy products that are treated with lactase to break down the lactose.
• Try Dairy Alternatives: Consider plant-based milks such as almond, soy, oat, or coconut milk. Be sure to choose fortified options to ensure you're getting enough calcium and vitamin D.
• Eat Lactose-Reduced Foods: Some aged cheeses (like cheddar and Swiss) and yogurts with live cultures are lower in lactose and may be easier to digest.

Enzyme Supplements

• Lactase Supplements: Over-the-counter lactase enzyme tablets or drops (such as Lactaid) can help digest lactose. These are taken just before consuming dairy products.

Probiotics

• Probiotic Supplements: Probiotics are beneficial bacteria that can help improve digestion. Some studies suggest that certain probiotic strains may help reduce symptoms of lactose intolerance.

Nutritional Considerations

• Calcium and Vitamin D: Since dairy is a primary source of calcium and vitamin D, it's important to ensure you're getting enough of these nutrients from other sources. Leafy greens, fortified foods, and supplements can help.

Gradual Reintroduction

• Slowly Reintroduce Dairy: Some people find that they can gradually reintroduce small amounts of dairy into their diet over time, allowing their digestive system to adjust.

Source: Mayo Clinic, Cleveland Clinic

Prevention Tips

While lactose intolerance cannot always be prevented, especially in cases of primary lactose intolerance, there are steps you can take to manage symptoms and reduce discomfort:

• Know Your Limits: Pay attention to how your body reacts to different amounts of lactose. Some people can tolerate small amounts of dairy without symptoms.
• Read Labels: Lactose is found in many processed foods, including bread, cereals, lunch meats, salad dressings, and even some medications. Always check ingredient labels for hidden sources of lactose.
• Eat Dairy with Other Foods: Consuming dairy products as part of a meal rather than on an empty stomach can help slow digestion and reduce symptoms.
• Try Fermented Dairy: Fermented dairy products like yogurt and kefir contain beneficial bacteria that can help digest lactose.
• Stay Hydrated: Drinking plenty of water can help ease digestive discomfort and prevent dehydration, especially if you experience diarrhea.
• Consult a Dietitian: A registered dietitian can help you create a balanced diet that avoids lactose while ensuring you get all the necessary nutrients.

If you have secondary lactose intolerance due to an underlying condition, treating that condition may help improve your lactose tolerance over time.

Source: Centers for Disease Control and Prevention (CDC)

Emergency Warning Signs

While lactose intolerance is generally not life-threatening, certain symptoms may indicate a more serious condition that requires immediate medical attention. Seek emergency care if you experience any of the following:

• Severe Dehydration: Signs include extreme thirst, dry mouth, little or no urination, severe weakness, dizziness, or confusion. Dehydration can occur due to persistent diarrhea or vomiting.
• Blood in Stool or Vomit: This can indicate a more serious gastrointestinal issue, such as an infection, inflammatory bowel disease, or internal bleeding.
• Severe Abdominal Pain: Intense or persistent abdominal pain could be a sign of a blockage, appendicitis, or another serious condition.
• Signs of an Allergic Reaction: If you experience hives, swelling of the face or throat, difficulty breathing, or a rapid heartbeat after consuming dairy, you may be having an allergic reaction (anaphylaxis), which requires immediate medical attention.
• High Fever: A fever over 101°F (38.3°C) accompanied by digestive symptoms could indicate an infection that needs prompt treatment.
• Persistent Vomiting: Vomiting that lasts more than 24 hours can lead to dehydration and electrolyte imbalances, which can be dangerous.

If you or someone else experiences these emergency warning signs, call 911 or go to the nearest emergency room immediately.

Source: World Health Organization (WHO), Mayo Clinic