Oat grass juice comes from the young green leaves of the oat plant, harvested before the grain appears. Unlike oat grain or bran, the grass is juiced fresh or dried into a powder. It supplies small amounts of chlorophyll, certain B vitamins, and vitamin K, but is not a concentrated source of vitamins or minerals.
Many people take oat grass juice as a daily wellness tonic for vitality and energy. It is typically consumed as a liquid shot (1-2 oz) or mixed with water or juice (1-2 g powder). Some take it on an empty stomach for absorption, though it can also be taken with meals.
Oat grass contains vitamin K, which can interfere with blood thinners like warfarin. If you take anticoagulant medication, talk to your doctor before adding this supplement.