ผู้ใช้:GEEK-Pol/กระบะทราย

สำหรับความหมายอื่น ดูที่ ผู้ใช้:GEEK-Pol/กระบะทราย (แก้ความกำกวม)

Indoor grown wheatgrass 8-10 days before harvest.

Extracting wheatgrass juice with a manual juicing machine.

Wheat Grass Juice

Wheatgrass is a food prepared from the cotyledons of the common wheat plant, Triticum aestivum (subspecies of the family Poaceae). It is sold either as a juice or powder concentrate. Wheatgrass differs from wheat malt in that it is served freeze-dried or fresh, while wheat malt is convectively dried. Wheatgrass is allowed to grow longer than malt. Like most plants, it 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, though few, if any, have been scientifically proven. It is often available in juice bars, and some consumers grow and juice wheatgrass in their homes. It is available as fresh produce, tablets, frozen juice and powder. Wheatgrass is also available in spray, cream, gel, massage lotion, and a concentrated drink. Wheatgrass contains no wheat gluten.

History

Wheat grass can be traced back in history over 5000 years, to ancient Egypt and perhaps even early Mesopotamian civilizations. It is purported that ancient Egyptians found sacred the young leafy blades of wheat and prized them for their positive effect on their health and vitality.

The consumption of wheatgrass in the Western world began in the 1930s as a result of experiments conducted by Charles F. 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

Anne 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 disease. Wigmore's recommendations and reputation as a health practitioner have been heavily criticized, but many health institutes still endorse her teachings.

Cultivation

Extracting wheatgrass juice with a manual juicing machine.

Outdoor grown wheat grass grows slowly through the winter in a climate like that of Kansas in the United States.

Wheatgrass can be grown indoors or out. 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 less 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. Harvested grass was dehydrated and made into powders and tablets for human and animal consumption. Wheatgrass grown indoors in trays for ten days contains similar nutritional content. Wheatgrass grown outdoors is harvested, dehydrated at a low temperature and sold in tablet and powdered concentrates. Wheat grass juice powder is also available either spray-dried or freeze-dried. Unfortunately, wheatgrass juice can be very bitter and retain the grittiness of the powder which has led to innovation in the marketplace with Nutrifiz launching an effervescent tablet form, improving the flavour, reducing the cost and adding convenience to consumption.

Health claims

Table 1. Nutrient comparison of 1 oz (28.35 g) of wheatgrass juice, broccoli and spinach.
Nutrient	Wheatgrass Juice	Broccoli	Spinach
Protein	860 mg	800 mg	810 mg
Beta-carotene	120 IU	177 IU	2658 IU
Vitamin E	880 mcg	220 mcg	580 mcg
Vitamin C	1 mg	25.3 mg	8 mg
Vitamin B12	0.30 mcg	0 mcg	0 mcg
Phosphorus	21 mg	19 mg	14 mg
Magnesium	8 mg	6 mg	22 mg
Calcium	7.2 mg	13 mg	28 mg
Iron	0.66 mg	0.21 mg	0.77 mg
Potassium	42 mg	90 mg	158 mg
Data on broccoli and spinach from USDA database. Data on Wheatgrass juice from indoor grown wheatgrass.

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". There is some limited evidence of beneficial pharmacological effects from chlorophyll, though this does not necessarily apply to dietary chlorophyll.

A small 2002 study showed some evidence that wheatgrass might help with the symptoms of ulcerative colitis, but without further work the significance of this work cannot be determined. Another small 2002 study suggested wheatgrass might help with the side-effects of breast cancer chemotherapy.

Nutritional content

Wheatgrass is a good source of potassium, a very good source of 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, and has negligible amount 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 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 1:23. Despite claims of vitamin and mineral content disproportional to other vegetables, the nutrient content of wheatgrass juice is roughly equivalent to that of common vegetables (see table 1).

Contrary to popular belief, B₁₂ is not contained within wheat grass or any vegetable; rather it is a byproduct of the microorganisms living on plants. Some analyses of B₁₂ content in wheatgrass has 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.

See also

• List of ineffective cancer treatments

External links

• Wheatgrass Juice: Is the magical mystery juice all it's blended up to be? Skeptoid: Critical Analysis of Pop Phenomena November 6, 2009
• Wheatgrass Juice & Folk Medicine Michael Shermer, Scientific American, 299, 42 (2008)