Wheatgrass is the freshly sprouted first leaves of the common wheat plant, used as a food, drink, or dietary supplement. Wheatgrass is served freeze dried or fresh, and so it differs from wheat malt, which is convectively dried. Wheatgrass is allowed to grow longer and taller than wheat malt.
Like most plants, wheatgrass contains chlorophyll, amino acids, minerals, vitamins and enzymes. Claims about the health benefits of wheatgrass range from providing supplemental nutrition to having unique curative properties, but these claims have not been scientifically proven.
Wheatgrass juice is often available at juice bars, and some people grow and juice their own in their homes. It is available fresh as produce, in tablets, frozen juice, and powder. Wheatgrass is also sold commercially as a spray, cream, gel, massage lotion, and liquid herbal supplement. Because it is extracted from wheatgrass sprouts, i.e. before the wheat seed or "berry" used in flour begins to form, wheatgrass juice is gluten-free, but some dietitians recommend that those with celiac disease avoid it due to a high risk of cross contamination. url=| archive-date
The consumption of wheatgrass in the Western world began in the 1930s as a result of experiments conducted by Charles Schnabel in his attempts to popularize the plant. By 1940, cans of Schnabel's powdered grass were on sale in major drug stores throughout the United States and Canada.
Ann Wigmore was also a strong advocate for the consumption of wheatgrass as a part of a raw food diet. Wigmore, founder of the Hippocrates Health Institute, believed that wheatgrass, as a part of a raw food diet, would cleanse the body of toxins while providing a proper balance of nutrients as a whole food. She also taught that wheatgrass could be used to treat those with serious ailments. 
Wheatgrass can be grown indoors or outdoors. A common method for sprout production indoors is often on trays in a growth medium such as a potting mix. Leaves are harvested when they develop a "split" as another leaf emerges. These can then be cut off with scissors and allow a second crop of shoots to form. Sometimes a third cutting is possible, but may be tougher and have fewer sugars than the first.
Schnabel's research was conducted with wheatgrass grown outdoors in Kansas. His wheatgrass required 200 days of slow growth, through the winter and early spring, when it was harvested at the jointing stage. He claimed that at this stage the plant reached its peak nutritional value; after jointing, concentrations of chlorophyll, protein, and vitamins decline sharply. Wheatgrass grown is harvested, dehydrated at a low temperature and sold in tablet and powdered concentrates for human and animal consumption. Indoor grown wheatgrass is used to make wheatgrass juice powder.
Proponents of wheatgrass make many claims for its health properties, ranging from promotion of general well-being to cancer prevention. However, according to the American Cancer Society, "available scientific evidence does not support the idea that wheatgrass or the wheatgrass diet can cure or prevent disease". Some research was done on drug-induced diabetic rates, suggesting it has an insulin raising effect in type two diabetic rats. 
Extracting wheatgrass juice with a manual juicing machine.
Wheatgrass 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).
The nutrient content of wheatgrass juice is roughly equivalent to that of dark leafy vegetables (see table 1).