Wheat grass is a source of potassium, dietary fiber, vitamin A, vitamin C, vitamin E (alpha tocopherol), vitamin K, thiamin, riboflavin, niacin, vitamin B6, pantothenic acid, iron, zinc, copper, manganese and selenium. Wheatgrass is also a source of protein (less than one gram per 28 grams). Adding other foods with complementary amino acid profiles to this food may yield a more complete protein source and improve the quality of some types of restrictive diets.
Wheatgrass proponent Charles Schnabel claimed in the 1940s that "fifteen pounds of wheatgrass is equal in overall nutritional value to 350 pounds of ordinary garden vegetables" a ratio of espite claims of vitamin and mineral content disproportional to other vegetables, the nutrient content of wheatgrass juice is roughly equivalent to that of dark leafy vegetables
Contrary to popular[who?] belief, vitamin B12 is not contained within wheatgrass or any vegetable; rather it is a byproduct of the microorganisms living on plants. Some analyses of B12 content in wheatgrass have confirmed that it contains negligible amounts of the compound even though the source of this analysis remains unclear. The USDA National Nutrient Database reports that wheatgrass contains no vitamin B12. Because vitamin B12 is not made by plants, any of this vitamin would have to be produced by bacteria found in the preparation :