The vitamin A and vitamin K abundant in kale juice help support the function of your red blood cells. Vitamin A guides blood cell development, from immature blood stem cells in your bone marrow into mature and functional blood cells. It boosts red blood cell production, which supports healthy oxygen circulation and also supports the development of white blood cells needed for a robust immune system. Vitamin K controls the function of platelets, helping to ensure that they can aggregate and form blood clots. A serving of kale juice offers 496 micrograms of vitamin K several times your daily vitamin K intake requirement.