Study says A1 protein may spark milk intolerance
A clinical trial conducted in China and involving 600 adult Han Chinese participants with self-reported lactose intolerance has reported that consumption of a2 Milk containing only A2 beta casein reduced acute gastrointestinal symptoms compared to consuming conventional milk containing A1 and A2 beta casein proteins, according to The a2 Milk Company.
The study was run through international contract research organisation (CRO) SPRIM and was sponsored by The a2 Milk Company. Authors say that their findings demonstrate that, in some individuals with self-reported lactose intolerance, the adverse gastrointestinal symptoms following consumption of regular milk may be related to the presence of A1 beta casein protein rather than lactose itself.
The double-blind, randomised, cross-over and peer-reviewed study, published in the UK-based Nutrition Journal, investigated the “acute” impacts of drinking 300ml of milk on symptoms often associated with milk intolerance, with the effects being measured at 1, 3 and 12 hours.
All of the participants were non-regular milk drinkers who had not consumed milk for at least four weeks prior to the trial, and who self-reported as lactose intolerant. Participants who drank A1 protein-free milk (a2 Milk) during the clinical trial showed improvements in gastrointestinal symptoms when they consumed milk containing only A2 beta casein as compared with their consumption of conventional milk.
The participants were chosen from 1,200 consumers who had self-diagnosed lactose intolerance and digestive discomfort after consuming conventional milk. 200 participants were then selected from each of three major Chinese cities: Shanghai, Beijing and Guangzhou. Of the 600 self-diagnosed participants, 71% were confirmed as lactose malabsorbers, reflecting a compromised ability to digest lactose.
The authors conclude, “Milk-related gastrointestinal symptoms may result from the ingestion of A1 beta casein rather than lactose in some individuals”. They also state that, “These results suggest that the elimination of A1 beta casein from the diet was associated with reduced severity of acute gastrointestinal symptoms after milk intake in this population.”
Dr Anton Emmanuel, consultant gastroenterologist and director of the GI Physiology Unit at University College Hospital commenting on the study, says, “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 an intolerance – around 60% of the world’s population.
“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.”
Lead investigator of the research Yue Xin Yang, says, “It is interesting to see this data showing that dairy proteins can influence digestive symptoms, especially because we know 70% of the world’s population report as being lactose intolerant. Put simply, the study suggests consuming conventional milk may trigger lactose intolerance type symptoms in those people.”
