Lactose intolerance: should you cut out all dairy products?

Lactose intolerance results from a decrease in the activity of lactase, the enzyme that digests lactose (milk sugar). It affects 20 to 80% of the population depending on ethnic origin.

Mechanism

Without sufficient lactase, undigested lactose ferments in the colon, producing gas, bloating, pain, and sometimes diarrhea.

Diagnosis

• Hydrogen breath test: reference method, measures exhaled hydrogen after lactose ingestion
• Genetic test: identifies predisposition but does not predict symptom severity
• Elimination-reintroduction test: pragmatic and accessible

What you can probably still consume

• Aged cheeses: Comté, Gruyère, Parmesan — contain very little lactose
• Yogurts: lactic bacteria pre-digest some of the lactose
• Small amounts: up to 12 g of lactose (one glass of milk) are tolerated by most intolerant people when taken with a meal
• Lactose-free milk: same nutritional value, pre-digested lactose

Beware of deficiencies

Completely eliminating dairy products exposes you to a risk of calcium deficiency. Alternatives: calcium-rich mineral waters, green vegetables (broccoli, kale), almonds, canned sardines (with bones).