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Milking more benefit from dairy: A2 milk and glutathione

We’ve written about A2 milk before, comparing it to A1/A2 milk for GI symptoms. Turns out that the powerful antioxidant glutathione may also be affected by which milk you drink

Study under review: Visceral adiposity and metabolic syndrome after very high-fat and lowfat isocaloric diets: a randomized controlled trial

Introduction

Glutathione (GSH), a small peptide consisting of the amino acids L-glutamine, L-cysteine, and glycine, is present in every cell and tissue and is one of the most powerful antioxidants in the body. Reductions in GSH levels have been correlated with inflammation and a number disease states and processes including neurodegenerative disease[1]. One of the major routes for GSH production in the body is through dietary intake of the amino acid cysteine. Cysteine absorption in the gut is inhibited by β-casomorphin-7 (BCM-7), an opioid-like peptide derived from bovine β-casein, a component of cow’s milk. In vitro studies using cultured cells have shown that opioid peptides decrease intracellular GSH levels[2] in part by suppressing cysteine uptake into the cell.

Although milk is great source of dietary cysteine source due to its high whey content, BCM-7 is derived from certain variants of β-casein, which can reduce cysteine uptake. BCM-7 is derived from the A1, but not A2, variant of β-casein. Depending on the genetic makeup of the cow, A1, A2, or both types of β-casein are present in milk. Preliminary studies have shown that milk containing A1, but not A2 β-casein increased gut inflammation and discomfort, and reduced cognitive function in individuals with self-reported lactose intolerance[3]. To examine whether this may occur through increased BCM-7 levels derived from A1 β-casein in cow’s milk, a clinical trial was performed and published in a recent issue of Nutrition Journal[4].

Cow’s milk contains two subtypes of β-casein protein, A1 and/or A2, depending on the the genetic makeup of the cow. A1 β-casein can be processed by the body to produce BCM-7, a small peptide shown to decrease glutathione (GSH) absorption and promote inflammation.

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