Everything you need to know about lactose intolerance
- Sayuki
- Jul 24, 2014
- 1 min read
Not everyone who consumes milk regularly can digest it, and people who think they are lactose intolerant may not be.
The ability to digest lactose, the main sugar in milk, requires an enzyme called lactase. All baby mammals produce it, but it is normally switched off around the time of weaning. In people who lack this enzyme, lactose passes into the colon where it feeds bacteria that generate gas and fluid, resulting in painful bloating, cramps and diarrhoea – a condition known as lactose intolerance or malabsorption.A mutation which allowed adults to keep producing lactase emerged around 7000 years ago, and now 35 per cent of people can digest milk as adults – although there are marked geographical variations (see map below). In China and South-East Asia, more than 90 per cent of people are thought to be lactose intolerant, compared with between 2 and 20 per cent of those of northern European descent.
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