Two new studies link A1 (but not A2) milk to gut inflammation

In the first study, researchers found that mice fed A1 beta casein (but not A2 beta casein) had increased levels of inflammation in the gut and associated immune effects .  This is the first study to demonstrate conclusively that consumption of A1 beta casein leads to physiological responses by the immune system.

The second study confirmed the inflammatory effect of A1 beta casein in the gut.  Rats fed A1 showed an increase of about 65% in the inflammatory marker MPO.  Researchers also found that A1 beta casein slowed down transit of food through the digestive system compared to A2 beta-casein. Slower transit time can lead to digestive discomfort, abdominal bloating and/or constipation.

A1 milk is the ‘normal’ milk we find in supermarkets.

Milks that are free of A1 beta casein include:

  • cows milk from some European herds particularly in France and Spain
  • A2 brand cows milk in Australia, New Zealand and most recently, the UK
  • all milk from other animals including goats, sheep, buffalo, pure Asian cattle, camels and yaks
  • human breastmilk


The findings of this new research would appear to explain the following success story we received from a reader in 2010:

For the past 18+ months my wife has suffered from an increasing problem with gut issues and chronic diarrhea and related symptoms. She has tried various milks and milk substitutes (soy, etc). None have made any difference to her gut problems. Her GP has not found any specific cause and has recommended a range of tests and indicated it was probably "irritable bowel syndrome" which I'm sure you know is one of the catch-all medical labels which basically means "we don't really know".

On pure chance my wife (who had seen your report a couple of years ago on A2) decided about 6 weeks ago she had nothing to lose by trying A2 milk.

Our life has been transformed and this happened literally overnight! Gut patterns are back to normal, a far far cry from many daily urgent dashes to the loo, usually immediately after eating or drinking almost anything but particularly things containing dairy products. Literally life became normal within 4 hours of her first bowl of oatmeal with A2 milk. Absolutely amazing. The transformation has been astounding and we are very grateful to the people that have figured out the A2 story – from story [955].


And another excerpt:

Oh and the whole family have switched to A2 milk, and I have now just realized how sick and bloated normal milk makes me feel!!! – from story [861]

Scientific references and further reading

Haq MR et al. Comparative evaluation of cow β-casein variants (A1/A2) consumption on Th2-mediated inflammatory response in mouse gut. Eur J Nutr. 2013 Oct 29. [Epub ahead of print]
http://www.ncbi.nlm.nih.gov/pubmed/24166511

Barnett MP et al. Dietary A1 β-casein affects gastrointestinal transit time, dipeptidyl peptidase-4 activity, and inflammatory status relative to A2 β-casein in Wistar rats. Int J Food Sci Nutr. 2014 Mar 20. [Epub ahead of print]
http://www.ncbi.nlm.nih.gov/pubmed/24649921

Blog by Professor Keith Woodford, author of Devil in the Milk: Illness, health and politics
http://keithwoodford.wordpress.com/category/a1-and-a2-milk/

Our A2 factsheet with more reader reports

A2 milk in Australia http://a2milk.com.au

A2 milk introduced into the UK http://www.telegraph.co.uk/finance/businessclub/10410044/Allergy-free-milk-firm-reaches-1m-sales.html