When you’re feeling too ill to eat, or have indigestion, what could be better than a gentle, thick glass of milk to settle your stomach? It’s soothing to drink, and at least you are getting something nutritious inside you. This remedy has been around for years in countries where milk is popular. Until the 1980s, doctors would sometimes recommend milk to patients with duodenal ulcers (in the intestine just beyond the stomach) to help ease their discomfort.
Milk is in fact slightly acidic, but far less so than the gastric acid naturally produced by the stomach. So it was long thought that milk could neutralise this stronger acid and relieve the pain. Milk does help provide a temporary buffer to gastric acid, but studies have shown that milk stimulates acid production, which can make you feel sick again after a short period of relief.
In 1976, ten hardy research participants put themselves forward to test this out. They had their stomachs emptied and were then fed milk through a tube up their nose. An hour later the contents of their stomachs were sucked out again and then gastric acid secretion was measured every five minutes. The researchers found that milk caused an increase in the secretion of gastric acid for the next three hours, which could explain why people with ulcers typically experience pain a few hours after a meal.
It’s not just milk, though. Studies comparing coffee, tea, beer and milk found they all stimulated the secretion of acid. Beer and milk have the greatest effect, which suggests, somewhat surprisingly, that the pH of a drink is irrelevant when it comes to acid production.