Management of Lactose Intolerance
Confirm the diagnosis objectively with a hydrogen breath test rather than accepting patient self-report, then implement dietary lactose restriction while preserving yogurt and hard cheese consumption to prevent unnecessary calcium deficiency. 1
Diagnostic Confirmation
Patient self-reports of lactose intolerance correlate poorly with actual lactase deficiency and cannot be relied upon for diagnosis. 1, 2 The hydrogen breath test is the gold standard diagnostic method across all major gastroenterology societies. 1, 2
Hydrogen Breath Test Protocol:
- Administer 25-50g lactose dissolved in 200-500ml water after overnight fasting 2
- Collect end-expiratory breath samples every 15-30 minutes for three hours 1, 2
- A rise in hydrogen concentration >20 parts per million from baseline confirms lactose malabsorption 1, 2
- Be aware that false negative rates reach 25%, often due to hydrogen non-excretion in approximately 18% of subjects 2
Alternative Diagnostic Approach:
- A 2-week dietary restriction trial with symptom resolution serves as a simple, economical alternative when breath testing is unavailable 1, 2
- Only test patients consuming more than 280ml (0.5 pint) of milk or dairy equivalent daily, as those below this threshold rarely experience symptoms even with lactase deficiency 2
Dietary Management Strategy
Primary Intervention:
- Avoid fresh milk and most dairy products during symptomatic periods 1
- Most adults with lactose intolerance tolerate up to 12-15g of lactose (approximately 1 cup of milk) without symptoms 3
Critical Preservation of Tolerated Foods:
- Yogurt and firm/hard cheeses contain negligible lactose and should NOT be eliminated unnecessarily 1, 2
- These foods are generally well-tolerated even in lactose-intolerant individuals and help prevent calcium deficiency 1, 2
Hidden Lactose Consideration:
- Most lactose-containing medications contain <12g lactose and rarely cause symptoms—do not unnecessarily avoid these 2
- Check labels on processed foods, baked goods, breakfast cereals, and processed meats for hidden lactose 4
Addressing Secondary and Reversible Causes
Before finalizing a lactose intolerance diagnosis, evaluate for reversible secondary causes: 1, 2
- Celiac disease 1, 2
- Acute gastroenteritis 1, 2
- NSAID use 1, 2
- Small bowel disease 1, 2
- Chemotherapy (causes reversible lactose intolerance in up to 35% of cancer patients) 2
For cancer patients on chemotherapy: Avoid milk and dairy products except yogurt and firm cheeses to reduce symptom intensity and duration 1
For infants with acute diarrhea: Use lactose-free or lactose-reduced formulas immediately upon rehydration 1
Broader Differential Diagnosis
At least 50% of patients with presumed lactose intolerance actually have broader FODMAP intolerance (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols). 1, 2
Algorithm for Persistent Symptoms:
- If lactose restriction alone doesn't resolve symptoms after 2 weeks, trial a low FODMAP diet 1, 2
- This addresses the broader spectrum of fermentable carbohydrate intolerance affecting at least half of IBS patients 2
Adjunctive Therapies
Probiotics:
- Consider Lactobacillus acidophilus CL1285 + Lactobacillus casei LBC80R for 4-12 weeks to induce colon microbiome adaptation 1, 2
- Discontinue if no improvement after 12 weeks 2
Lactase Enzyme Supplements:
- May be helpful as adjunctive therapy, though evidence quality is limited 3
Common Pitfalls to Avoid
- Don't rely on symptoms alone—visceral hypersensitivity in IBS can cause identical symptoms independent of lactose malabsorption 2
- Don't eliminate all dairy unnecessarily—this increases risk of osteopenia and osteoporosis from calcium deficiency 4
- Don't ignore negative breath tests completely—false negative rates are high; if symptoms are suggestive, still trial lactose-free diet 2
- Don't assume lactose intolerance is permanent—treat underlying conditions as secondary lactose intolerance is often reversible 1, 2