More Details on Dairy: A2 Beta Casein Milk Raises Glutathione Levels

Sometimes dairy gets a bad wrap, being one of the top 8 common food allergens. There has been research and debate as to the health benefits of consuming raw milk dairy products many naturopaths and health enthusiasts swear by non pasteurized, cultured milk products. But new research into a specific protein in milk may be adding a new component to this conversation, which may be of interest whether consuming either raw or conventionally sold milk.

In a study looking at the effects of A1 and A2 types of Beta casein (B-casein), in milk, it was found that milk containing predominantly A2 type B-casein actually significantly raised glutathione levels(1). This is remarkable because it is known that Beta-casomorphin-7 (BCM-7), a peptide derived from B-casein A1, actually downregulates glutathione production in the digestive tract as well as neural cells by limiting cysteine uptake(1). The effects of A1 B-casein may not be limited to antioxidant production. There is support for concluding that A1 B-casein is a primary culprit in gut inflammation and gastric upset for individuals with dairy sensitivity (2,3).

Milk containing only A2 B-casein is nothing new. Goat, sheep, camel, buffalo, yak, and donkey milk all contain mostly, or only A2 B-casein. Many people who cannot consume cow’s milk, find that they can eat these other types of milk. Genetically, cows produce varying levels and ratios of A1/A2 B-casein containing milk. Older breeds of cows, such as Jersey, Asian, African cows, produce predominantly A2 containing milk. About 5,000 years ago there was genetic mutation which led to breeds of cows with more A1 in their milk; breeds such as the Holstein(4,5). The genetic mutation led to a change in the 229 amino acid structure of b-casein, where proline had previously attached to BCM-7. With the mutation, A1 b-casein attaches to BCM-7 through a linkage to histidine, which is far less stable than the proline bond of A2 b-casein, causing more BCM-7 to end up in the GI tract. BCM-7 is implicated in immune and neurological changes(5). BCM-7 is not found in high levels in blood, or urine of cows, or humans consuming A2 predominant milk.

  1.  Deth R, et al. Clinical evaluation of glutathione concentrations after consumption of milk containing different subtypes of β-casein: results from a randomized, cross-over clinical trial.Nutr J. 2016 Sep 29;15(1):82.
  2. 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.
  3. 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.
  4. Yang S,et al. Identification of Genetic Associations and Functional Polymorphisms of SAA1 Gene Affecting Milk Production Traits in Dairy Cattle. PLoS One. 2016 Sep 9;11(9):e0162195. doi: 10.1371/journal.pone.0162195. eCollection 2016.
  5. Woodford K. Devil in the Milk: Illness, Health and Politics: A1 and A2 Milk. Wellington New Zealand: Craig Potton Publishing 2007.

email-photoNode Smith, associate editor for NDNR, is a fifth year naturopathic medical student at NUNM, where he has been instrumental in maintaining a firm connection to the philosophy and heritage of naturopathic medicine amongst the next generation of docs. He helped found the first multi-generational experiential retreat, which brings elders, alumni, and students together for a weekend campout where naturopathic medicine and medical philosophy are experienced in nature. Three years ago he helped found the non-profit, Association for Naturopathic ReVitalization (ANR), for which he serves as the board chairman. ANR has a mission to inspire health practitioners to embody the naturopathic principles through experiential education. Node also has a firm belief that the next era of naturopathic medicine will see a resurgence of in-patient facilities which use fasting, earthing, hydrotherapy and homeopathy to bring people back from chronic diseases of modern living; he is involved in numerous conversations and projects to bring about this vision. 

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