What are the active medicinal properties in barley grass?

Nutritional
In 1940, it was explained how the vitamins, minerals, and protein in the cereal grasses are essential to animals and humans. A dehydrated preparation of cereal grass called “cerophyl” was approved as an “accepted food” by the Council of Foods of the American Medical Association in 1939. Later, synthetic nutrients were added to a number of foods, and multivitamins gained popularity. The juice of barley grass contains beta carotene, vitamins B1, B2, B6, B12, pantothenic acid, and folic acid. Minerals present include potassium, calcium, iron, phosphorus, and magnesium. Other constituents are chlorophyll, amino acids, protein, fiber, and enzymes. Cobalamin or vitamin B12 deficiency may be avoided in vegetarian diets by supplementation with dehydrated barley grass juice.

Antioxidant activity
Barley leaf extract has the ability to scavenge free radicals. Reactive oxygen species have been shown to play an important part in mediating the production of pro-inflammatory cytokines and can be instrumental in the pathogenesis of diseases such as rheumatoid synovitis, arthritis, and gout. Animal data shows an increased production of oxygen-free radicals with barley leaf extract added to the diet. Clinical studies show blood levels of oxygen-free radicals were reduced by supplementation with 15 g/day barley leaf extract in patients with type 2 diabetes mellitus. Similar results were noted in nondiabetic, hyperlipidemic patients. More clinical studies are needed to show the extent of benefits in humans.