Glutathione is an important antioxidant found in the plasma and throughout the cells of the body, which plays a central role in maintaining health. Drinking cow’s milk helps to enhance cellular glutathione levels. However, a new clinical trial has shown that a novel type of milk, free from A1 β-casein, can produce a greater increase in glutathione and may therefore be a healthier option1.
Either or both types of β-casein may be found in cows’ milk, depending on the genetic make-up of the cow. However standard milk from modern European herds (Bos Taurus) contain both A1 and A2 types of β-casein. For example, a holstein friesian cow produces A1:A2 in its milk in an approximately 60:40 ratio. But milk is also now being supplied from herds that only produce milk containing A2 type β-casein by selectively breeding these cows to only produce this type of β-casein. Interestingly, other mammalian species (e.g. goat, sheep, human) and many other cattle breeds of native Asian or African origin (Bos Indicus) do not produce A1 β-casein in their milk.
A new double-blind, randomised, controlled 2×2 crossover study1 has examined the effects of these different types of milk. The study measured glutathione concentrations in healthy participants after they consumed either regular cows’ milk containing both A1 and A2 β-casein or cows’ milk with A2 type β-casein alone.
The study demonstrated that consumption of milk containing only A2 β-casein was associated with a significantly greater increase in plasma glutathione concentrations. Levels of glutathione were two-fold higher compared with the consumption of milk containing both β-casein types. The study also noted that there was no increase in plasma BCM-7 concentrations in the a2 Milk™ group compared with the washout diet in the study participants. Thus, milk containing only A2 β-casein and not A1 β-casein has a greater potential to promote the production of the antioxidant glutathione in humans than conventional milk.
Deth R, Clarke A, Ni J, Trivedi M. Clinical evaluation of glutathione concentrations after consumption of milk containing different subtypes of β-casein: results from a randomized, cross-over clinical trial. Nutrition Journal. 2016; 15:82 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5041571/