Lactose Intolerance – High-Yield Notes

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Lactose Intolerance – High-Yield Notes

🔹 Definition
→ Inability to digest lactose (a disaccharide sugar in milk) due to deficiency or absence of lactase enzyme in the small intestine.
→ Leads to gastrointestinal symptoms after consuming lactose-containing foods.

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🔹 Causes
✔️ Primary Lactase Deficiency (most common)
→ Genetically programmed decrease in lactase after weaning (adult hypolactasia).
✔️ Secondary Lactase Deficiency
→ Due to injury to the small intestine (e.g., gastroenteritis, celiac disease, Crohn’s disease, chemotherapy).
✔️ Congenital Lactase Deficiency (rare)
→ Autosomal recessive disorder, seen in neonates.
✔️ Developmental Lactase Deficiency
→ In premature infants (<34 weeks gestation).

🔹 Symptoms (30 min–2 hours after lactose ingestion)
→ Bloating
→ Abdominal pain/cramping
→ Flatulence
→ Diarrhea (osmotic, watery)
→ Nausea

🔹 Diagnosis
✔️ Clinical diagnosis
→ Symptom correlation with lactose ingestion & relief on elimination.
✔️ Hydrogen Breath Test (gold standard)
→ ↑ Hydrogen in exhaled air after lactose load.
✔️ Lactose Tolerance Test
→ Monitor blood glucose after lactose ingestion (less reliable).
✔️ Stool Acidity Test (infants)
→ Fermentation products (lactic acid) cause acidic stool (pH <5.5).

🔹 Management
✔️ Dietary modification
→ Lactose-free or low-lactose diet.
✔️ Lactase enzyme supplements
→ Oral lactase before meals (e.g., Lactaid).
✔️ Probiotics
→ May help in some patients.
✔️ Calcium and Vitamin D supplementation
→ For those avoiding dairy.

🔹 Foods to Avoid
→ Milk (cow, goat, sheep)
→ Cream, ice cream, soft cheeses (e.g., ricotta, cream cheese)
→ Butter (large amounts)
→ Yogurt (if not tolerated)
→ Whey and milk-based protein powders
→ Processed foods with hidden lactose (e.g., baked goods, salad dressings, instant soups).

🔹 Prevention & Patient Education
→ Introduce lactose gradually to increase tolerance in some cases.
→ Use lactose-free alternatives (e.g., almond, soy, oat milk).
→ Read labels for “milk solids,” “whey,” “curds.”
→ Hard cheeses & fermented yogurts often better tolerated.

⭐ Key Takeaway
Lactose intolerance is common, especially in non-European populations. Diagnosis is clinical and supported by breath test. Management focuses on dietary changes and enzyme replacement.

1. What is lactose intolerance?

✅ Answer: Lactose intolerance is the inability to digest lactose, a sugar found in milk and dairy products, due to a deficiency of the enzyme lactase in the small intestine. It causes gastrointestinal symptoms after consuming lactose-containing foods.

2. What causes lactose intolerance?

✅ Answer: The main causes are:

Primary lactase deficiency (most common): genetic reduction in lactase after childhood.
Secondary lactase deficiency: due to intestinal damage (e.g., gastroenteritis, celiac disease).
Congenital lactase deficiency (rare): present from birth.
Developmental lactase deficiency: in premature infants.

3. What are the symptoms of lactose intolerance?

✅ Answer: Symptoms appear 30 min to 2 hours after consuming lactose and include:
→ Bloating
→ Abdominal cramps
→ Diarrhea (watery)
→ Flatulence (gas)
→ Nausea

4. How is lactose intolerance diagnosed?

✅ Answer:

Clinical diagnosis: based on symptoms after lactose ingestion and improvement after avoiding lactose.
Hydrogen breath test (gold standard): detects hydrogen in breath after lactose load.
Lactose tolerance test: checks blood glucose rise after lactose ingestion.
Stool acidity test: used in infants.

5. Can lactose intolerance be cured?

✅ Answer: No, there’s no cure. But symptoms can be controlled by avoiding lactose, using lactase supplements, and trying lactose-free alternatives.

6. What foods should people with lactose intolerance avoid?

✅ Answer: Avoid or limit:
→ Milk (cow, goat, sheep)
→ Cream, ice cream, butter (large amounts)
→ Soft cheeses (ricotta, cream cheese)
→ Whey and milk-based products
→ Processed foods with hidden lactose (check labels).

7. Are there any lactose-free dairy options?

✅ Answer: Yes! You can try:
→ Lactose-free milk and dairy products
→ Plant-based milk (almond, soy, oat, coconut)
→ Hard cheeses (cheddar, parmesan) which are naturally low in lactose
→ Fermented yogurt (better tolerated by some people).

8. Why is calcium important for lactose-intolerant people?

✅ Answer: Since they avoid dairy (a major calcium source), they are at risk for calcium and vitamin D deficiency. Supplements or calcium-rich alternatives (tofu, spinach, fortified plant milk) are recommended.

9. Can probiotics help with lactose intolerance?

✅ Answer: Yes, some probiotics (especially those containing Lactobacillus and Bifidobacterium) may improve digestion of lactose and reduce symptoms in some individuals.