That Glass of Milk Does Not Agree With You
Within an hour of consuming dairy, your stomach rebels – bloating, cramping, gas, and sometimes urgent diarrhoea. If this scenario is familiar, you are likely among the estimated 65-75% of the global adult population with some degree of lactose intolerance. At our practice in Zürich Seefeld, I help patients confirm the diagnosis, understand its implications, and manage it effectively.
What Is Lactose Intolerance?
Lactose is the sugar found in milk and dairy products. To digest it, your small intestine produces an enzyme called lactase, which breaks lactose into glucose and galactose for absorption. Lactose intolerance occurs when lactase production is insufficient – undigested lactose reaches the colon, where bacteria ferment it, producing gas, bloating, and fluid shifts that cause diarrhoea.
Types of Lactose Intolerance
Primary lactose intolerance: The most common type. Lactase production naturally declines after weaning in the majority of the world’s population. This is genetically determined and is the normal state for most humans – lactase persistence (the ability to digest lactose lifelong) is actually the genetic variant, common mainly in Northern European populations.
Secondary lactose intolerance: Temporary lactase deficiency caused by damage to the small intestinal lining from conditions like coeliac disease, Crohn’s disease, gastroenteritis, SIBO, or chemotherapy. Treating the underlying condition often restores lactase production.
Congenital lactase deficiency: Extremely rare – a genetic condition present from birth where no lactase is produced at all.
Symptoms
Symptoms typically appear 30 minutes to 2 hours after consuming lactose-containing foods: bloating and abdominal distension, cramping, flatulence, diarrhoea (sometimes explosive), nausea, and abdominal rumbling. The severity depends on the degree of lactase deficiency and the amount of lactose consumed. Most people with lactose intolerance can tolerate small amounts of dairy.
Diagnosis
The hydrogen breath test is the gold standard. After drinking a lactose solution, breath hydrogen is measured at intervals – elevated hydrogen indicates malabsorption. At our practice, I also distinguish lactose intolerance from other causes of similar symptoms (SIBO, fructose malabsorption, IBS) by testing for these conditions simultaneously when appropriate.
What We Do: Managing Lactose Intolerance Effectively
Confirm the diagnosis: Not all dairy-related symptoms are lactose intolerance – milk protein sensitivity, for example, has different implications.
Identify your threshold: Most people with lactose intolerance can tolerate some lactose. Fermented dairy (yoghurt, aged cheese) contains less lactose and is often well tolerated.
Lactase supplementation: Taking lactase enzyme before dairy consumption allows many people to enjoy dairy without symptoms.
Ensure calcium and vitamin D adequacy: If dairy is significantly reduced, these nutrients need alternative sources or supplementation to protect bone health.
Investigate secondary causes: If lactose intolerance appeared suddenly in adulthood, I investigate for underlying conditions causing secondary lactase deficiency.
Gut health support: Optimising the microbiome can improve lactose tolerance, as certain colonic bacteria can help metabolise lactose more favourably.
Conclusion
Lactose intolerance is common, easily diagnosed, and manageable. You do not necessarily need to eliminate all dairy – understanding your personal threshold and using enzyme support allows most people to continue enjoying dairy products. If dairy is causing you problems, book a breath test at our practice in Zürich Seefeld for a definitive answer.
