A lot of people will have already made up their mind about whether humans need dairy in their diet and will be thinking that the answer is obviously “yes” or obviously “no”. But nutrition is based on science not opinion – so, here’s the latest research on the matter.
Milk is an interesting foodstuff. The sugar in it is called lactose and lactose requires a chemical or enzyme called lactase to allow it to pass across the walls of the gut into the blood stream. When we are babies, we all produce plenty of the lactase enzyme which allows us to absorb our mother’s milk. In populations where milk consumption has been historically low, such as Japan and China, most children will have stopped producing lactase soon after weaning and – producing almost entire populations that may be unable to absorb the lactose in milk – this we call “lactose intolerance”.
In populations where milk consumption has always been high, such as in Europe, most adults continue to produce lactase for their whole lives and can digest milk quite happily with only around 5% of the population being lactose intolerant.
Continuing to produce lactase into adulthood is actually an inherited genetic variation which has become so common because being able to tolerate milk has a selective advantage. Milk is a useful source of protein, energy, calcium, phosphate, B vitamins and iodine, meaning that those with the mutation were generally healthier and produced more children than those who couldn’t tolerate milk, and so the presence of the mutation increased.
The symptoms of lactose intolerance include wind, bloating and diarrhoea so if you don’t experience any of those after drinking milk or eating ice cream then you’re fine.