Spinach

Spinach (Spinacia oleracea) is a leafy green flowering plant native to central and Western Asia. It is of the order Caryophyllales, family Amaranthaceae, subfamily Chenopodioideae. Its leaves are a common edible vegetable consumed either fresh, or after storage using preservation techniques by canning, freezing, or dehydration. It may be eaten cooked or raw, and the taste differs considerably; the high oxalate content may be reduced by steaming.

It is an annual plant (rarely biennial), growing as tall as 1 ft. Spinach may overwinter in temperate regions. The leaves are alternate, simple, ovate to triangular, and very variable in size: 2–30 cm long and 1–15 cm broad, with larger leaves at the base of the plant and small leaves higher on the flowering stem. The flowers are inconspicuous, yellow-green, 3–4 mm in diameter, and mature into a small, hard, dry, lumpy fruit cluster 5–10 mm across containing several seeds.

In 2022, world production of spinach was 33 million tonnes, with China alone accounting for 93% of the total.

Etymology
Originally from Persian aspānāḵ, the name entered European languages from Latin spinagium, which borrowed it from Arabic isbanakh. The English word "spinach" dates to the late 14th century from OF espinache.

Taxonomy
Common spinach (S. oleracea) was long considered to be in the family Chenopodiaceae, but in 2003 that family was merged into the Amaranthaceae in the order Caryophyllales. Within the family Amaranthaceae sensu lato, Spinach belongs to the subfamily Chenopodioideae.

Description
As opposed to the great majority of the flowering plants or plants used as vegetables, spinach is a dioicous plant, meaning different plants can have either female or male flowers.

The flowers are small, green and unattractive to pollinators. Rather, pollination occurs via wind anemophily, for which the pollen has evolved to be very small and light so it can be carried large distances, often miles away.

History
Spinach is thought to have originated about 2,000 years ago in ancient Persia from which it was introduced to India and later to ancient China via Nepal in 647 AD as the "Persian vegetable". In AD 827, the Arabs introduced spinach to Sicily. The first written evidence of spinach in the Mediterranean was recorded in three 10th-century works: a medical work by al-Rāzī (known as Rhazes in the West) and in two agricultural treatises, one by Ibn Waḥshīyah and the other by Qusṭus al-Rūmī. Spinach became a popular vegetable in the Arab Mediterranean and arrived in the Iberian Peninsula by the latter part of the 12th century, where Ibn al-ʻAwwām called it , 'the chieftain of leafy greens'. Spinach was also the subject of a special treatise in the 11th century by Ibn Ḥajjāj.

Spinach first appeared in England and France in the 14th century, probably via Iberia, and gained common use because it appeared in early spring when fresh local vegetables were not available. Spinach is mentioned in the first known English cookbook, the Forme of Cury (1390), where it is referred to as 'spinnedge' and 'spynoches'. During World War I, wine fortified with spinach juice was given to injured French soldiers with the intent to curtail their bleeding.

Culinary use, consumption and nutrition
Spinach is eaten both raw, in salads, and cooked in soups, curries, or casseroles. Notable dishes with spinach as a main ingredient include spinach salad, spinach soup, spinach dip, saag paneer, pkhali, and spanakopita.

Nutrients
Raw spinach is 91% water, 4% carbohydrates, 3% protein, and contains negligible fat (table). In a 100 g serving providing only 23 calories, spinach has a high nutritional value, especially when fresh, frozen, steamed, or quickly boiled. It is a rich source (20% or more of the Daily Value, DV) of vitamin A, vitamin C, manganese, and folate (31-52% DV), with an especially high content of vitamin K (403% DV) (table). Spinach is a moderate source (10–19% of DV) of the B vitamins, riboflavin and vitamin B6, vitamin E, potassium, iron, magnesium, and dietary fiber (table).

Due to the dense content of vitamin K, individuals taking the anticoagulant warfarin, which acts by inhibiting vitamin K, are instructed to minimize consumption of spinach (and other dark green leafy vegetables) to avoid blunting the effect of warfarin.

Although spinach contains moderate amounts of iron and calcium, it also contains oxalates, which may inhibit absorption of calcium and iron in the stomach and small intestine. Cooked spinach has lower levels of oxalates, and its nutrients may be absorbed more completely.

Cooking spinach significantly decreases its vitamin C concentration, as vitamin C is degraded by heating. Folate levels may also be decreased, as folate tends to leach into cooking liquid.

Spinach is rich in nitrates and nitrites, which may exceed safe levels if spinach is over-consumed.

Production
In 2022, world production of spinach was 33 million tonnes, with China alone accounting for 93% of the total.

Marketing and safety
Fresh spinach is sold loose, bunched, or packaged fresh in bags. Fresh spinach loses much of its nutritional value with storage of more than a few days. Fresh spinach is packaged in air, or in nitrogen gas to extend shelf life. While refrigeration slows this effect to about eight days, fresh spinach loses most of its folate and carotenoid content over this period of time. For longer storage, it is canned, or blanched or cooked and frozen.

Some packaged spinach is exposed to radiation to kill any harmful bacteria. The Food and Drug Administration approves of irradiation of spinach leaves up to 4.0 kilograys, having no or only a minor effect on nutrient content.

Spinach may be high in cadmium contamination depending on the soil and location where the spinach is grown.

In popular culture
The comics and cartoon character Popeye the Sailor Man is portrayed as gaining strength by consuming canned spinach. The accompanying song lyric is: "I'm strong to the finich [sic], 'cuz I eats me spinach." This is usually attributed to the iron content of spinach, but in a 1932 strip, Popeye states that "spinach is full of vitamin A" and that is what makes people strong and healthy.