❤️ Lactose intolerance

Lactose intolerance is when milk or dairy products cause bloating, gas, abdominal pain, rumbling, nausea or diarrhoea. The small intestine makes too little lactase, the enzyme that digests milk sugar (lactose). Undigested lactose reaches the large intestine, where bacteria break it down into fluid and gas (NIDDK). Symptoms start minutes to hours after eating (NHS).

NIDDK estimates that about 68% of people worldwide, and about 36% in the US, digest lactose poorly. They are the majority in Africa and Asia, while in northern Europe many carry a gene that keeps lactase active after childhood. EFSA calls lactase decline after early childhood normal and genetically determined. Not everyone who digests lactose poorly has symptoms; it is intolerance only when they do. Secondary intolerance follows gut infections or comes with coeliac or Crohn’s disease; treating the cause may restore lactose digestion.

Do not confuse intolerance with milk allergy, an immune reaction to milk proteins that can cause difficulty breathing, itching, swelling of the lips and face and can even be life-threatening (NHS). Intolerance is unpleasant, but its main risk lies elsewhere: cutting out dairy entirely can leave you short of calcium and vitamin D (NIDDK).

Lactose intolerance or milk allergy? Intolerance comes from too little lactase, the enzyme that digests milk sugar, so undigested lactose reaches the large intestine and causes bloating, gas or diarrhoea. Allergy is an immune reaction to milk proteins and can be dangerous. Primary or secondary? Lactase often declines normally after early childhood, but secondary intolerance follows gut infections or comes with coeliac or Crohn's disease, and treating the cause may restore lactose digestion. Having a gene variant that keeps lactase active, as many northern Europeans do, means no intolerance.

Look for “lactose-free” on the pack of milk, yoghurt and other dairy products, which NIDDK describes as equally nutritious. They sit in the chilled dairy aisle of a supermarket, next to ordinary dairy. Lactose-free does not mean free of milk proteins, so it is not suitable for milk allergy. Hard cheeses such as cheddar have lower lactose. Lactase supplements are sold in pharmacies, but young children and pregnant or breastfeeding women should ask a doctor first.

Why it matters to you. There is no single threshold, but per EFSA the vast majority of people with reduced lactase tolerate up to 12 g of lactose at a time, about a glass of milk, with no or mild symptoms; larger amounts are easier spread over the day. NIDDK advises drinking milk in small portions with meals and choosing yoghurt, lower-lactose hard cheeses such as cheddar, or equally nutritious lactose-free products. Lactase supplements help some people, but young children and pregnant or breastfeeding women should ask a doctor first. The NHS advises against cutting out dairy without a doctor’s or dietitian’s advice.