CHINA – A1 beta-casein protein in cow’s milk is the root cause of lactose intolerance, and not the lactose itself, according to a new clinical trial

The trial, which was conducted in China and published in Nutrition Journal, involved 600 adults who said they were lactose-intolerant.

According to FoodBev, the Chinese researchers investigated the ‘acute’ impacts of drinking 300ml of milk on symptoms often associated with milk intolerance, with the effects being measured after one, three and 12 hours.

Those symptoms included flatulence, bloating, abdominal pain, and both the frequency and consistency of stool.

The study concluded that “milk containing A2 beta-casein attenutated acute gastrointestinal symptoms of milk intolerance, while conventional milk containing A1 beta-casein reduced lactase activity and increased gastrointestinal symptoms”.

The results were good news for a2 Milk, the Australian dairy company, which separates the two proteins found in natural cows’ milk in order to offer products that are easier to digest for consumers who would otherwise be lactose-intolerant.

Depending on a cow’s genetic make-up, milk traditionally contains either A1 or A2 proteins, or a mix of both – but simple genetic tests can determine whether individual members of the herd produce milk that is A1/A1, A1/A2, or A2/A2.

The A2 brand has already received a vote of confidence in the form of a study, which suggested that A2 protein doubles the concentration of the essential antioxidant glutathione – a critical part of the body’s defence system.

The latest research also added weight to similar but smaller clinical trials that also found a link between the two beta-casein proteins in cow’s milk and lactose intolerance.

The first – conducted at Curtin University in Australia – showed that milk with only the A2 protein is easier on the digestive system.

Another small-scale study in China last year showed that those with lactose intolerance can drink A2 milk with no digestive discomfort.

“This is the largest human trial to date examining the differences between the impact of the A1 and A2 protein.

It suggests that proteins found in dairy can have a significant impact on digestion, and that lactose may not be the only cause of gastrointestinal issues in those with intolerance – around 60% of the world’s population,” said Dr Anton Emmanuel, a consultant gastroenterologist at University College Hospital in London.

“Given that the underlying biochemistry and symptoms of lactose intolerance are identical in Asian and Caucasian/British populations, these results are highly significant to both regions.”