08 Dec 2016 --- According to an innovative, new investigation published in Nutrition Journal, cow's milk containing only A2 protein has been shown to increase an essential antioxidant that may help strengthen the body's disease-fighting power. In the first human clinical trial of its kind, scientists found that milk naturally containing only the A2 type of beta-casein protein – rather than both the A1 and A2 found in most ordinary milk – doubled the concentration of glutathione (GSH) in healthy adults.