Milk Intake and the Brain Antioxidant Glutathione  

Glutathione is an important antioxidant that is protective against oxidative stress in the brain. Consequently, increasing cerebral glutathione levels may be of interest, particularly because these levels decrease with age. A study sought to investigate if increasing milk intake, which contains important substrates for glutathione synthesis, would increase these levels after a 3-month intervention.

Older woman reading at her kitchen table

Glutathione is a key antioxidant in the brain, as it is the first line of defence in protecting against reactive oxygen species, which are cellular by-products that can lead to cellular damage, oxidative stress, and DNA damage. In fact, glutathione is critical to the brain’s antioxidant defence system: there is no other known enzymatic defence that prevents or reduces the damages caused by these reactive oxygen species.  A decrease in cerebral glutathione has been observed in brain tissue undergoing oxidative stress both in aging and neurodegeneration. Importantly, increases in brain glutathione levels cannot be achieved through direct administration but rather through biosynthesis using amino acid substrates (cysteine, glutamate, and glycine). 

Milk contains all three amino acids, in addition to calcium and riboflavin which aid in glutathione maintenance. In a preliminary study of 60 older adults (60-85 years), higher cerebral glutathione concentrations were associated with greater dairy consumption.1 

In light of these previous findings, researchers designed a randomized controlled trial to assess if increasing milk intake to 3 cups a day in adults with low habitual dairy intake (less than 1.5 servings of total dairy per day) affected cerebral glutathione levels after 3 months in 73 older adults (60–89 years).2 At the end of the 3-month trial, the intervention group had increases in overall glutathione brain concentrations, while no change was observed in the control group.  
While research on the topic remains scarce and more research is warranted, the authors note that these results are promising as dietary approaches may limit adverse effects and that milk, specifically, is a widely available and accessible healthy beverage option.

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