Lactose is the sugar found in milk and dairy products and it needs the enzyme lactase to break it down. Without enough lactase, the lactose is broken down by bacteria in the small bowel, causing bloating, flatulence, stomach cramps, diarrhoea and nausea. Globally, around 70% of us don’t continue producing lactase after we have finished breast or formula feeding. Genetically, babies need milk – adults not so much. But northern Europeans, who thousands of years ago got into cattle farming, have adapted to cow’s milk and have a genetic mutation so that only between 2 and 15% have a degree of lactase deficiency. This rises to 23% in central Europeans and 95% in Asian populations. So is lactase deficiency the normal state?
Not really – it made sense to drink milk at one time, so we adapted to do so. And cow’s milk is nutritious – it contains calcium, vitamins A and D and riboflavin, as well as protein and isn’t heavy on calories.