New A2 milk research provides digestive and cognitive evidence in young children

A new paper relating to A2 milk has been published this month in the Journal of Pediatric Gastroenterology and Nutrition (JPGN). The paper provides strong evidence from a clinical trial with pre-school children in China that A1 beta-casein relative to A2 beta-casein has negative effects on both digestion and cognitive performance.

The evidence is sufficiently strong that those who have argued until now that A2 milk is just a marketing gimmick will find it increasingly difficult to sustain that argument.  This has major implications for the mainstream dairy industry which continues to downplay the A1 versus A2 issue.

For those new to the debate, A2 milk comes from A2 cows, with these cows naturally producing milk free of A1 beta-casein. As background, there is no A1 beta-casein in human milk or goat milk or sheep milk. Cows are the only species that produce A1 beta-casein, and it is found in a high proportion of cows of European origin.

The strength of this latest paper is not just what is new but how it builds on prior research. Through confirmation, it provides credibility to that prior research.

The paper also gains credibility from where it is published. The JPGN, where this latest paper is published, is the official journal of the European and North American Societies of Pediatric Gastroenterology, Hepatology and Nutrition.  

The authors of this new paper come from Shanghai Jiao Tong and Peking Universities in China, together with an Australian collaborator. Peking University is ranked by Times Higher Education as the Number One university in China and Jiao Tong as number 7.

The trial was with 80 pre-school-age children. The trial compared ordinary milk containing a mix of A1 and A2 beta casein (hereafter called ‘A1’) with a milk product where all of the beta-casein was A2.  Most of the children were showing early signs of intolerance to conventional milk prior to the study.

It was a crossover trial, with all of the children having five days of consuming one milk product and then, following a nine-day washout, another five days of the other milk. The children, their parents, and the supervising staff were all blinded as to which milk was which. Half the children had the A1 milk first and the other half had the A2 milk first.

The trial provided exceptionally strong evidence across a wide range of measures. When the children were consuming the A1 milk, they had more digestive discomfort, their faeces were of a different consistency, they produced less of the desirable fatty acids in their digestive system, they had elevated  beta-casomorphin in their blood, they had increased inflammatory markers in their blood, and their cognitive performance on a  standardised computerised test of response times was inferior. The paper is available here

For those who are statistically minded, many of the results were at significance levels of p<.001. This is much higher – more than 50 times – what is normally required to provide acceptance of a genuine effect. The crossover design is the ideal method for reducing chance effects, and double-blinding of both participants and scientific supervisors is also best practice.

None of the results came as a surprise. All results were hypothesised based on prior research and with the biochemical pathways increasingly understood. However, this trial has tested those hypotheses in a rigorous setting and with pre-school children. This was the first time such a trial had been undertaken with children of any age.

I had been waiting for the publication of this paper for two years. The trial itself was in 2016. It is the third of three major related pieces of research conducted in China.

It has been a frustrating wait for publication. When I inquired, all I could find out was that a key researcher was very ill and this was causing the delay.  I had to hope that the health issue would be solved and that this was indeed the full story. It now seems that it was.

The first of these Chinese studies, which I call ‘China1’ was published in April 2016 with Jianqin Sun from Shanghai’s Fudan University as the lead author. It provided very powerful evidence, also from a crossover design, that A1 beta-casein slowed down the transit of food through the digestive system, that it caused inflammation, and that there were cognition effects using the computerised test of response rates and response accuracy.

Unfortunately, the China1 paper is not easy to read. Even scientists can get confused and misinterpret the strength of the results unless they spend many hours exploring the detail. Also, although the design was very strong, those who did not understand the strength of the crossover design were always going to be sceptical because the trial only involved 45 people.  Hence, I always knew that trial would not have the public impact that it deserved.

As a consequence, although I have written about ‘China1’ for scientific audiences, and discussed it at seminars, I have never discussed it in the mainstream media. I decided to wait for ‘China2’ and ‘China3’.

China2, also known as the ‘Three Cities Study’ involved more than 600 people in Beijing, Shanghai and Guangzhou who were tested for intolerance for A1 versus A2 beta-casein. The paper is available here.   

China2, like China 1, provided strong evidence of intolerance but given the number of people involved, the design was much simpler and only limited measurements were taken. It had more impact in the public arena than China1, in part because it was easy to understand, and also because people were impressed by the large number of participants. But there was less science.

Despite studying and writing about the science behind A1 and A2 milk for fifteen years, I still chose to say nothing in public about China2. I wanted to wait for China3 with its in-depth study of pre-school children.

In the meantime, there was another published paper from the China-based studies. Blood samples from China1 were sent to American researchers who analysed them for their beta-casomorphin7 content and also their levels of antioxidant glutathione. Once again, they found important differences that gave scientific insights beyond the immediate clinical effects. That paper is available here

Taking all of the China studies together, I now have the confidence to say publicly that this is a very impressive body of evidence from a range of scientists from top-level Chinese institutions and international collaborators. The combined effect will be to influence all Chinese dairy companies and also international dairy companies with a China-focus to commit themselves to A2 dairy products. Their success in China now depends on it.

In Western countries, there will still be scepticism, with more evidence required from studies undertaken in Western countries before the sceptics are convinced. However, while that debate will continue, there are now increasing quantities of A2 dairy products in supermarkets of the world. That includes all across Australia, much of the USA and the United Kingdom, increasingly in New Zealand and even in Moscow.

Of course, the evidence for dairy products free of A1 beta-casein goes well beyond the clinical effects investigated in the China studies. It is now well over 20 years since Professor Bob Elliott from Auckland University and Professor Robert Cade from Florida started writing independently about the effects of the A1-derived beta-casomorphin7 on wide ranging medical conditions.  Back in 2007, I wrote a book about their work and that of other scientists who followed, which I called ‘Devil in the Milk’. At least now, when I write about the ‘milk devil’, I know that people in many Western countries do have the opportunity to buy A2 dairy products should they wish to. Until recently that was not the case.


About Keith Woodford

Keith Woodford is an independent consultant, based in New Zealand, who works internationally on agri-food systems and rural development projects. He holds honorary positions as Professor of Agri-Food Systems at Lincoln University, New Zealand, and as Senior Research Fellow at the Contemporary China Research Centre at Victoria University, Wellington.
This entry was posted in A1 and A2 milk, China, Dairy, Uncategorized. Bookmark the permalink.

16 Responses to New A2 milk research provides digestive and cognitive evidence in young children

  1. Louise Coats says:

    Hi Keith,
    Great to finally have these trials out for perusal. I have been waiting too! I have been steadily removing the A1 cows from the dairy herd for 18 years now (is a slow process when cows live into their teens)!
    I have been patiently waiting for a milk company to pick up A2 milk in the Hauraki Plains & was lucky enough to be close enough to the Fonterra factory for this to happen for this coming season.
    I have often spoken with my clients over many years encouraging them to only use A2 semen and quietly clean up the dairy genetics but have largely been unsuccessful. Now there is even more robust science and now no excuse not to tackle the issue with urgency. To not do so leaves a risk to the NZ dairy industry especially when other countries are attending to the matter and actively seeking A2 milk products.
    There is a some research work done in Australia indicating meat tenderness possibly being linked with A2. Would be interesting to see if this could be validated too. Perhaps another explanation for my observations over many years with Jersey (greater likelihood to be A2A2) crossed over a beef breed having such tender meat! (Not all beef breeds are A2 though from my limited testing however).
    I certainly appreciate you keeping your interest in this topic and spreading the word.

    Louise Coats


    • Brian Renwick says:

      Those who are not actively converting their herds to A2 are going to find themselves stuck with cows that will have to go to the works. They won’t be worth the trouble of milking; they will only have meat value.

  2. Rod McKenzie says:

    Great long term work and new report

  3. douglaslinehamjnr says:

    The issue is now beyond doubt, surely. Watch the company value go now.

    • Brian Renwick says:

      Yes, company share price might rise, but when all cattle milk is A2, I expect it will fall to it’s inherent value

      • Keith Woodford says:

        That could take some time. At that time they could still have a lead position such as that held currently in the conventional milk market by Nestle. In the meantime, their focus is on further building their brand without building the greater A2 category. Within the company, there will be lots of interesting debates around this.

  4. Daniel Viotti says:


  5. Jay Carter says:

    Interesting that you are highlighting the benefits of these studies, proclaiming their strength and powerful findings. What of the HVN funded studies out of University of Auckland. Are these not strong? Why are their findings dribbled out as abstracts in the MDPI publication “Proceedings” rather than providing a full publication? Why are you not highlighting their strength? Or was their findings not as positive as the p-hacking masterpieces produced by S.P.R.I.M (no conflict of interest, really? Sprim does nothing free of charge) and the Chinese teams?

    • Keith Woodford says:

      All I have seen is a conference presentation which was not peer reviewed and seemed like it might contain internal anomalies. I wrote to the lead author but from there it went quiet. I like to see full papers before I comment publicly as I like to get into the detail. As for the SPRIM involvement in the China studies, I have seen no evidence of p-hacking. I have spent many hours poring over those studies. From what I could see, there was no p-hacking, but the way that China1 was written meant that most readers underestimated the power of that study ,and could have falsely come to that conclusion.
      If you have abstracts for the HVN studies then please flick a link to me

  6. David Renwick says:

    Hello again and thank you Keith. I have just now asked A2 Corp why a summary of this research has not been provided to the NZX and ASX. Pacific Edge Biotechnology (PEB.NZ) continually keep the markets informed of new science and compulsory regulatory approval advances regarding their products, and for A2 Corp not to puzzles and frustrates me.
    The NBR reported it this morning and The Australian on 22 July.

    • Keith Woodford says:

      I too have been surprised over the years that a2 Millk has not flagged new research to the NZX and ASx but some legal eagle has probably said that it is best to let the science do the talking. I think they are ‘gun shy’ about getting caught in a firefight and so they stand back and let others carry the debate.

  7. Max Bowyer says:

    There is an item in a recent NBR daily email titled ‘Sceptical reception for A2 milk research’. Do you have any comments about it?

    • Keith Woodford says:

      Professor Mann has always been forthright in his criticism both of A2 and of me.
      Here is a fascinating example from 2007.
      It is worth a read.
      I don’t expect he will ever change his view.
      I have never been able to get him to discuss the science with me.
      His comments in the NBR article such as ‘garbage’ do not actually advance the debate.
      As for the other quoted researcher, Andrew Reynolds, who is a colleague of Professor Mann at Otago Uni, his comments that it was a ‘small study that does not mean much’ would seem to indicate he does not understand the crossover design, nor is he willing to acknowledge the very high levels of statistical significance.
      Of course this is just one of mutiple papers and he is choosing to look at it in isolation.

  8. Thanks for sharing this amazing blog on A2 milk. Nowadays milk is important for a kid’s growth.

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