Spinach (Spinacia oleracea) is an edible flowering plant in the family of Amaranthaceae. It is native to central and southwestern Asia. It is an annual plant (rarely biennial), which grows to a height of up to 30 cm. Spinach may survive over winter in temperate regions. The leaves are alternate, simple, ovate to triangular-based, very variable in size from about 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 diameter, maturing into a small, hard, dry, lumpy fruit cluster 5–10 mm across containing several seeds.

Common spinach, Spinacia oleracea, was long considered to be in the Chenopodiaceae family, but in 2003, the Chenopodiaceae family was combined with the Amaranthaceae family under the family name 'Amaranthaceae' in the order Caryophyllales. Within the Amaranthaceae family, Amaranthoideae and Chenopodioideae are now subfamilies, for the amaranths and the chenopods, respectively.

Etymology

Spinach plant in November, Castelltallat

The English word "spinach" dates to the late 14th century, and is from espinache (Fr. épinard), of uncertain origin. The traditional view derives it from O.Prov. espinarc, which perhaps is via Catalan espinac, from Andalusian Arabic asbinakh (اسبيناخ), from Arabic es-sabaanikh (السبانخ), from Persian اسپاناخ aspanakh, meaning roughly "green hand",^[1] but the multiplicity of forms makes the theory doubtful.^[2]

History

Spinach is thought to have originated in ancient Persia (modern Iran and neighboring countries). Arab traders carried spinach into India, and then the plant was introduced into ancient China, where it was known as "Persian vegetable" (bōsī cài; 波斯菜; present:菠菜). The earliest available record of the spinach plant was recorded in Chinese, stating it was introduced into China via Nepal (probably in 647 AD).^[3]

In AD 827, the Saracens introduced spinach to Sicily.^{[citation needed]} The first written evidence of spinach in the Mediterranean was recorded in three 10th-century works: the medical work by al-Razi (known as Rhazes in the West) and in two agricultural treatises, one by Ibn Wahshiya and the other by Qustus al-Rumi. Spinach became a popular vegetable in the Arab Mediterranean and arrived in Spain by the latter part of the 12th century, where the great Arab agronomist Ibn al-'Awwam called it the "captain of leafy greens". Spinach was also the subject of a special treatise in the 11th century by Ibn Hajjaj.^[4]

The prickly-seeded form of spinach was known in Germany by no later than the 13th century, though the smooth-seeded form was not described until 1552. (The smooth-seeded form is used in modern commercial production.)^[3]

Spinach first appeared in England and France in the 14th century, probably via Spain, and it gained quick popularity because it appeared in early spring, when other vegetables were scarce and when Lenten dietary restrictions discouraged consumption of other foods. Spinach is mentioned in the first known English cookbook, The Forme of Cury (1390), where it is referred to as spinnedge and/or spynoches.^[5] Smooth-seeded spinach was described in 1552.^[3]

In 1533, Catherine de' Medici became queen of France; she so fancied spinach, she insisted it be served at every meal. To this day, dishes made with spinach are known as "Florentine", reflecting Catherine's birth in Florence.^[6]

During World War I, wine fortified with spinach juice was given to French soldiers weakened by hemorrhage.^[7]

Culinary information

Nutrition

Spinach has a high nutritional value and is extremely rich in antioxidants, especially when fresh, steamed, or quickly boiled. It is a rich source of vitamin A (and especially high in lutein), vitamin C, vitamin E, vitamin K, magnesium, manganese, folate, betaine, iron, vitamin B₂, calcium, potassium, vitamin B₆, folic acid, copper, protein, phosphorus, zinc, niacin, selenium and omega-3 fatty acids. Recently, opioid peptides called rubiscolins have also been found in spinach.

Polyglutamyl folate (vitamin B₉ or folic acid) is a vital constituent of cells, and spinach is a good source of folic acid. Boiling spinach can more than halve the level of folate left in the spinach, but microwaving does not affect folate content.^[8] Vitamin B₉ was first isolated from spinach in 1941.^[9]

Iron

Spinach, along with other green leafy vegetables,^[10] is considered to be rich in iron. For example, the United States Department of Agriculture states that a 180-g serving of boiled spinach contains 6.43 mg of iron, whereas a 170-g ground hamburger patty contains at most 4.42 mg.^[11] However, spinach contains iron absorption-inhibiting substances, including high levels of oxalate, which can bind to the iron to form ferrous oxalate and render much of the iron in spinach unusable by the body.^[12] In addition to preventing absorption and use, high levels of oxalates remove iron from the body.^[13] But some studies have found that the addition of oxalic acid to the diet may improve iron absorption in rats over a diet with spinach without additional oxalic acid.^[14]

Calcium

Spinach also has a high calcium content. However, the oxalate content in spinach also binds with calcium, decreasing its absorption. Calcium and zinc also limit iron absorption.^[15] The calcium in spinach is the least bioavailable of calcium sources.^[16] By way of comparison, the body can absorb about half of the calcium present in broccoli, yet only around 5% of the calcium in spinach.

Pureed spinach and homemade cheese with spiced flatbread (makki di roti) from India

Types of spinach

A distinction can be made between older varieties of spinach and more modern ones. Older varieties tend to bolt too early in warm conditions. Newer varieties tend to grow more rapidly, but have less of an inclination to run up to seed. The older varieties have narrower leaves and tend to have a stronger and more bitter taste. Most newer varieties have broader leaves and round seeds.

The three basic types of spinach are:

• Savoy has dark green, crinkly and curly leaves. It is the type sold in fresh bunches in most supermarkets in the United States. One heirloom variety of savoy is 'Bloomsdale', which is somewhat resistant to bolting. Other common heirloom varieties are 'Merlo Nero' (a mild variety from Italy) and 'Viroflay' (a very large spinach with great yields).
• Flat- or smooth-leaf spinach has broad, smooth leaves that are easier to clean than Savoy. This type is often grown for canned and frozen spinach, as well as soups, baby foods, and processed foods.
• Semi-savoy is a hybrid variety with slightly crinkled leaves. It has the same texture as Savoy, but it is not as difficult to clean. It is grown for both fresh market and processing. 'Five Star', a widely grown variety, has good resistance to running up to seed.

Production, marketing and storage

Spinach output in 2005

Spinach is sold loose, bunched, packaged fresh in bags, canned, or frozen. Fresh spinach loses much of its nutritional value with storage of more than a few days.^[17] While refrigeration slows this effect to about eight days, spinach will lose most of its folate and carotenoid content, so for longer storage, it is blanched and frozen, cooked and frozen, or canned. Storage in the freezer can be for up to eight months.

The Environmental Working Group reported spinach is one of the dozen most heavily pesticide-contaminated produce products.^[18] The most common pesticides found on spinach are permethrin, dimethoate, and DDT.^{[citation needed]} Spinach is high in cadmium contamination. An FDA study found more in boiled spinach in the early 90's (0.125 mg/kg) than in the 320 other foods studied.^[19]

Spinach is packaged in air, or in nitrogen gas to extend shelf life. Some packaged spinach is exposed to radiation to kill any harmful bacteria that may be on the leaves. The Food and Drug Administration approves of irradiation of spinach leaves up to 4.0 kilograys; however, using radiation to sanitize spinach is of concern because it may deplete the leaves of their nutritional value. Researchers at the Agricultural Research Service experimentally tested the concentrations of vitamins C, E, K, B₉, and four other carotenoids in packaged spinach following irradiation. They found with increasing level of irradiation, four nutrients showed little or no change. Those nutrients include vitamins B₉, E, K, and the carotenoid neoxanthin. This study showed the irradiation of packaged spinach to have little or no change to the nutritional value of the crop, and the health benefits of irradiating packed spinach to reduce harmful bacteria seem to outweigh the loss of nutrients.^[20]

In popular culture

The cartoon character Popeye the Sailor Man is portrayed as having a strong affinity for spinach, becoming physically stronger after consuming it. The commonly accepted version of events states this portrayal was based on faulty calculations of the iron content.^[21] In the version, German scientist Emil von Wolff misplaced a decimal point in an 1870 measurement of spinach's iron content, leading to an iron value ten times higher than it should have been, and this faulty measurement was not noticed until the 1930s. This caused the popular misconception that spinach is high in iron that makes the body stronger.^[22]

Criminologist Mike Sutton wrote an article in the Internet Journal of Criminology, claiming the Popeye and iron link is just another long-standing myth, and spinach was chosen and promoted in Popeye for its vitamin A content alone.^[23] In the cited article, he also disputes the above — what he calls the Spinach Popeye Iron Decimal Error Story (SPIDES) — due to lack of verifiable sources, although he found a different reference of ten times the actual iron content from the twenties. Further research by Sutton presents more evidence for the SPIDES being a myth which is cited as veracious evidence in the official errata pages for Samuel Arbesman's book, The Half-life of Facts.^[24]

Spinach, along with Brussels sprouts and other green vegetables, is often portrayed in the media, including children's shows, as being undesirable. For example, early Popeye movies played on the gag that Popeye's nephews never liked spinach but ate it anyway to grow up big and strong.^[25] The same theme is depicted in an even earlier classic cartoon from the New Yorker magazine.^[26]

See also

• Spinach in the United States

References

Further reading

• D. Maue, S. Walia, S. Sahore, M. Parkash, S. K. Walia, S. K. Walia (2005). "Prevalence of Multiple Antibiotic Resistant Bacteria in Ready-to-Eat Bagged Salads". American Society for Microbiology meeting. June 5–9. pp. Atlanta. Abstract
• Rogers, Jo. What Food is That?: and how healthy is it?. The Rocks, Sydney, NSW: Lansdowne Publishing Pty Ltd, 1990. ISBN 1-86302-823-4.
• Cardwell, Glenn. Spinach is a Good Source of What?. The Skeptic. Volume 25, No 2, Winter 2005. Pp 31–33. ISSN 0726-9897
• Blazey, Clive. The Australian Vegetable Garden: What's new is old. Sydney, NSW: New Holland Publishers, 1999. ISBN 1-86436-538-2
• Stanton, Rosemary. Complete Book of Food and Nutrition. Australia, Simon & Schuster, Revised Edition, 1995. ISBN 0-7318-0538-
• Sutton, M. (2010) The Spinach Popeye Iron Decimal Error Myth is Finally Busted. Best Thinking.Com: http://www.bestthinking.com/articles/science/chemistry/biochemistry/the-spinach-popeye-iron-decimal-error-myth-is-finally-busted