Human health implications of A1 versus A2 beta-casein: theory and current evidence

 

Human health implications of A1 versus A2 beta-casein: theory and current evidence

Posted on April 2, 2014 by Keith Woodford

[On March 21 2014 I presented a paper at a conference organised by UK charity Food and Behaviour Research and held at the Royal College of Surgeons, London. The abstract is copied below]

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Human Health Implications of A1 versus A2 beta-casein: theory and current evidence

Keith Woodford
Professor of Farm Management and Agribusiness
Lincoln University, New Zealand

The health implications of A1 beta–casein relative to A2 beta-casein are controversial. At times the scientific debate can become clouded by the reality that milk is a commercial product. Conversion of all herds so as to replace A1 beta-casein with A2 beta-casein over one to two cow generations (4 – 12 years) is technically straight forward. Accordingly, the beta-casein issue can be presented as either a threat to, or an opportunity for, the mainstream industry, with elements of each perspective being valid.

The Key Science.

• All bovine beta-casein was originally of the A2 type. A1 beta-casein is now produced by a considerable proportion of cows that have European bloodlines. In contrast, goats, sheep, buffalo, camels and humans produce beta-casein of the A2 type.
• On digestion, A1 beta-casein releases the peptide beta-casomorphin-7 (BCM7) which has opioid characteristics. This is scientifically proven and is no longer controversial. The level of release has been shown to be consistent with pharmacological effects (Boutrou et al 2013)
• A1 beta-casein has been implicated in a range of human health conditions, many of which have an auto-immune element to them. The health conditions include Type 1 diabetes, heart disease, mental health conditions, behaviour, child development, sudden infant death syndrome, and milk intolerances.
• The evidence in humans is largely epidemiological (population studies, cohort studies, case-control) and observational, plus in vitro for human tissues, and randomised trials with animals.
• New research with rats (Barnett et al 2014) has shown, with major and statistically significant effect sizes, that A1 beta-casein inhibits gastric transit of food relative to A2 beta casein, that the enzyme DPP4 is up-regulated in the small intestine, and that in the colon there is an increase in the inflammatory marker myeloperoxidase (MPO).
• A recent study with mice (Haq et al 2013) found that in response to A1 beta-casein ingestion there were major effects (both size and statistical significance) in immune responses (antibodies and Th2 cell production) and intestinal myeloperoxidase (MPO). These effects did not occur with A2 beta-casein.
• This recent research can help provide theoretical underpinnings for the prior epidemiological findings and further justify the revisiting thereof.
• It is feasible for all dairy herds to be bred to remove the A1 allele relating to the specific gene that produces A1 beta-casein. Total herd conversion can take anywhere from four years to about twelve years, depending on the breeding strategy.

Recent references
Barnett MPG, McNabb WC, Roy NC, Woodford KB, and Clarke AJ 2014. “Dietary A1 beta-casein affects gastrointestinal transit time, dipeptidyl peptidase-4 activity, and inflammatory status relative to A2 b-casein in Wistar rats”. International Journal of Food Sciences and Nutrition. In press.

Boutrou R, Gaudichon C, Dupont D, Jardin J, Airinei G, Marsset-Baglieri A, et al. Sequential release of milk protein-derived bioactive peptides in the jejunum in healthy humans. American Journal of Clinical Nutrition. 2013;97(6):1314-23. Epub 2013/04/12.

Haq MR, Kapila R, Sharma R, Saliganta V, Kapila S. 2013 “Comparative evaluation of cow β-casein variants (A1/A2) consumption on Th2-mediated inflammatory response in mouse gut”. European Journal of Nutrition. Epub 2013/10/10.

Further Information:
Keith Woodford writes extensively on the topic of A1 versus beta-casein. His archived writings including detailed references on this topic can be found at http: //keithwoodford.wordpress.com within the website category ‘A1 and A2 milk’.

Disclosure of Interest
On occasions Keith Woodford consults in a professional capacity for A2 Corporation and other agri-food companies as an independent adviser. However he does not represent any   of these companies and he retains total independence in anything that he writes.

About Keith Woodford
Keith has been Professor of Farm Management and Agribusiness at Lincoln University, New Zealand, since 2000. His professional interests span from farm decisions though to food and health outcomes. This current semester he is teaching into a new Lincoln University course in global food systems. He has supervised 12 PhD students and more than 20 Masters students through to completion. Previously he was Reader in Rural Management at University of Queensland in Australia. He has worked on agri-food projects in many Asian and Pacific countries, working for national and international development agencies and also commercial firms. He has been studying and writing on the science and politics of A1 and A2 beta-casein for more than 10 years. His book ‘Devil in the Milk.’ was published in 2007, with an updated version in 2010. Outside of agri-food systems, his lifelong passions include mountaineering and skiing.