Glutathione is an important cellular antioxidant in animals. In humans, glutathione concentrations are associated with mortality, and evidence suggests that cellular levels of glutathione are pivotal to good health. Glutathione does not work as an antioxidant in isolation, but forms an intricate network of antioxidants with other antioxidant nutrients such as vitamin C, vitamin E, carotenoids, ubiquinone (coenzyme Q10) and flavonoids. Increasing cellular levels of glutathione is not practical by taking supplements of glutathione, because as a peptide the glutathione is hydrolysed during digestion, absorption rates of the parent compound are low. Oral glutathione therefore does not raise blood levels. However, increasing intakes of other antioxidants has been shown to be effective at increasing cellular glutathione levels, and in particular, vitamin C is beneficial in this respect. Dietary habits and lifestyle strategies to increase cellular glutathione concentrations are of interest because of the possible health effects.
Dairy consumption is associated with lower body weights and a reduced risk of developing insulin resistance. The health benefits of dairy have been well studied and a number of mechanisms for these health effects have been described. Recently, milk consumption has been shown to be associated with increased levels of glutathione in the brains of humans, which may suggest that milk consumption is associated with a reduced risk of oxidative stress and neurodegeneration. In one study1, brain levels of glutathione were associated with the amount of daily servings of dairy, and a particularly strong correlation was found for milk. However, both cheese intake and calcium intake were also associated with increased glutathione brain concentrations. The authors concluded that dairy foods might increase brain glutathione concentrations because they serves as a precursor to glutathione synthesis in the brain tissue. Alternatively, milk may be a marker for tea intake which may also increase glutathione levels.