Spinach is a fast growing vegetable plant whose leaves are consumed, always dark green and smooth or blistered. Depending on the variety, it’s annual or biennial. Spinach is grown in all temperate regions.
In Asia, the water spinach (ngo choy in Chinese, kangkung in Indonesian) grows in the water of ponds. In Japan, horenso is a small, tender and soft variety. The spinach, also known as New Zealand spinach or summer spinach is close to the spinach, but it does not belong to the same family. Its leaves are fleshier.
The story of spinach
Originally from Central Asia, spinach didn’t grew in other regions until the beginning of the Christian era. Unlike many other edible plants, it was not known either of the Greeks or the Romans, or only in a marginal way. No mention is made before the 7th century.
It was reportedly introduced to Sicily following the invasion of the Saracens of North Africa in the 8th century. However, it will be necessary to wait until the fifteenth century before kitchen books mention it, either because it has taken all this time to spread to the rest of Europe, or because it had little culinary significance. It is known, however, it was cultivated in the gardens of the monasteries in the 14th century.
It is not known when exactly it was introduced to America, but it is thought that it was before the nineteenth century. A century will pass before it acquires some popularity.
A few words about spinach
Spinach belongs to the family of chenopodiaceae, which includes other edible plants such as beet, chard, goosefoot (or cabbage), atriplex, quinoa and saunicorn. According to the varieties, its leaves are curly or flat, the first being often sold in fresh condition, the seconds canned or frozen.
In the popular language, various other edible green leaf plants took the name “spinach”, this leads to some confusion: Malabar spinach (saddle), New Zealand spinach (spinach), Southeast Asian Spinach (morning), spinach from China (amaranth), etc. In principle, only the plant belonging to the genus Spinacia, and referred to in this article, should bear that name.
Spinach health profile
Well known for its high iron content, spinach also provides an exceptional amount of other vitamins and minerals. Some of its antioxidants would be particularly beneficial to the eyes. And people can prepare it in a thousand ways.
The benefits of spinach
Spinach with curly leaves and smooth leaves
Cancer. Researchers observed that regular use of spinach (at least one ½ cup per week) was associated with a lower risk of breast cancer. A prospective study also indicated spinach consumption was related to a low risk of esophagus cancer. Two studies, in vitro and among animals, showed among several plants, spinach had the greatest ability to inactivate certain enzymes associated with the onset of cancer and to prevent the growth of cancer cells.
• Eye health. A steady intake of carotenoids, which can come from regular spinach consumption, is associated with a lower risk of macular degeneration, cataracte, and pigmentary retinitis. The main carotenoids of spinach (lutein and zeaxanthin) have the ability to accumulate in the macula and retina of the eye, thereby protecting it from oxidative stress could be damaging to it.
• Oxidative stress. A clinical study among humans concluded daily consumption of cooked spinach (about ¾ cup) resulted in better resistance of white blood cells to oxidative stress, thus demonstrating an antioxidant potential4.
Several epidemiological studies have shown high consumption of vegetables and fruit decreases the risk of cardiovascular diseases, certain cancers and other chronic diseases. The presence of antioxidants in vegetables and fruits could play a role in these protective effects.
What does spinach contain?
Cooked spinach is more nutritious
For equivalent portions, cooked spinach contains about 6 times more lutein, zeaxanthin and betaine than raw spinach. In addition, boiled spinach usually provides more vitamins and minerals per serving than raw spinach.
Spinach contains various antioxidants, including large amounts of lutein and zeaxanthin, compounds of the carotenoid family. Antioxidants, in general, can neutralize free radicals of the body and thus prevent the onset of cardiovascular diseases, certain cancers and various chronic diseases.
Lutein and zeaxanthin would have beneficial effects on eye health, and could help prevent certain cancers, including those of the breast and lung. However, more research is needed to confirm the specific contribution of lutein and zeaxanthin to the prevention of these diseases.
Spinach also contains ferulic acid, an antioxidant compound that protects human cells from oxidative stress and possibly the formation of some cancers. According to the researchers, a large proportion of the ferulic acid (or other antioxidants of the same family) present in the food would reach the large intestine, which would protect the cells of the colon cancer.
Betaine is a naturally occurring nitrogenous compound in several species of plant and animal kingdom. The use of betaine could include helping to treat certain liver diseases, such as fatty liver. It would also reduce the blood concentration of homocysteine, an amino acid that, when its concentration is too high in the blood, is a risk factor for cardiovascular disease. The consumption of betaine could also improve athletic performance, particularly through better endurance and effort. Spinach would be one of the foods containing the most betaine.
About 1% of the dry matter of spinach consists of chlorophyll, a green pigment present in several leafy vegetables. According to one study, chlorophyll would have the ability to inhibit the growth of cancer cells. However, little is known about the potential effect of spinach chlorophyll in humans.
Spinach would be one of the plants that contain the most glycolipids (after green tea and parsley). These compounds would have some potential anticancer effect, but also properties against inflammation. Most of the research carried out to date has been in vivo and animal studies, rather than clinical studies; it is difficult to say whether these properties can be applied to humans by eating spinach.
The legend of Popeye: does eating spinach make you stronger?
One remembers this sailor who became exceptionally strong after swallowing a box of spinach.
Even today, many associate this food with an energy boost. This idea could come from its iron content; a mineral protecting against certain forms of anemia and the ensuing fatigue symptoms.
However, even if spinach contains a good amount of it, the iron of the plant foods is less well assimilated than the iron from an animal source.
However, the assimilation of the iron of the plants can be increased by consuming foods rich in vitamin C (citrus, peppers, etc.) or proteins at the same time.
Persons at risk of urinary lithiasis (kidney stones consisting of oxalate and calcium, also known as renal gallstones) should limit their consumption of foods rich in oxalate. Oxalates are compounds that are naturally found in several foods, including spinach. In some cases, these people are recommended to avoid eating spinach.
Vitamin K and anticoagulants
Spinach contains a high amount of vitamin K. This vitamin, necessary among other things to blood coagulation, can be manufactured by the body in addition to be found in certain foods. Persons taking anticoagulant medications (Coumadin, Warfilone and Sintrom for example) must adopt a diet with relatively stable vitamin K content from one day to the next. Spinach is part of a list of foods and must be consumed at most 1 times per day and each time in a maximum quantity of 1 cup (250 ml) if it is believed, or about 60 ml (¼ cup) if cooked. It is highly recommended for people under anticoagulation to consult a dietitian/nutritionist or physician to learn about vitamin K food sources and to ensure that the most stable daily intake is possible.
Choice and conservation
Spinach is offered year-round in most grocery stores, usually in plastic bags, more rarely in fresh bouquets. Choose crisp, dark green and shiny leaves, smooth or not (depends on the varieties). Avoid faded, damaged leaves, stained with black or yellow.
One can also find in the trade of frozen spinach or canned. Preferably choose the first to the second ones, which are often overcooked and take on a metallic taste.
Refrigerator. A few days in a perforated plastic bag.
Freezer. Have steam whiten 1 to 2 minutes, wring and put in freezer bags where they will keep a few months.
Spinach prefers sandy soils rich in organic matter.
Ph: 6.4 to 6.8. Particularly intolerant to soil acidity, it will grow poorly if the ph is less than 6.0.
Fertilizers: Its nitrogen requirements are high. Bury a good amount of decomposed manure before planting or, better yet, grow a nitrogen-rich green manure (peas, fava, alfalfa, etc.) the year before the spinach crop. In addition, the spinach must not run out of boron. Remember, however, it is a trace element and the quantities required remain minimal.
Spinach prefers fresh climates (10 °C to 17 °C) and short days (less than 14 hours of light per day, which means before mid-may or after July under our climates). It is therefore necessary to sow it as early as possible in the spring and around mid-August for the fall harvest. There are a few varieties with some heat tolerance, but it is better to protect them with a shade that only leaves 50% of the light.
Spacing: 1 cm or 2 cm in row and 25 cm to 30 cm between rows.
Spinach requires regular and abundant irrigation. In case of drought, give it about 2.5 cm of water every 7 to 10 days.
To protect the plant against the beet fly, the spinach flea beetle and the spinach aphid, cover it with a geotextile at planting time.
In the family garden, spinach should be relatively safe from diseases such as downy mildew. However, if they occur, choose resistant varieties.
Harvest by cutting the stem about ten centimeters above the crown. The plant will form new leaves that can be harvested three or four weeks later.
Under our climates, spinach can be planted between late August and mid-September to obtain a harvest in the following spring. There is a risk that the plants will not survive the cold, especially in the case of refreshment followed by large gels. But during the good years, when the snow cover stays all winter, they will be among the first plants to come out of the ground in the spring.
Ecology and environment
Spinach is among the fruits and vegetables that display the highest concentrations of pesticide residues. If we cannot fully feed on products from organic farming, it would be at least interesting to consume organic foods which, in industrial agriculture, are the most contaminated with chemicals.
On the other hand, it was discovered that, like cauliflower, table grapes, peas and lettuce, spinach travelled very far distances between its production and sales locations, which is inevitably a source of pollution. In studies conducted in Iowa, it was determined, to be sold in this state, it had to travel on average more than 3 200 km. In North America, this vegetable is produced on a very large scale in just a few places on the mainland (especially in California). In season it is therefore preferable to choose local products.
The concepts of “food miles” and “food odometer” have been put forward to make consumers aware of the environmental costs associated with the purchase of foods that are not locally produced (whether organic or not).
A learned calculation is used to establish the “weighted average distance” of any food (or other product) between its point of production and its point of sale. In environmental settings, there is an increasing view that this average should be part of the criteria used by organic food certification bodies. In fact, air or land transport is one of the major causes of carbon monoxide pollution. Further stress the greater the distance, the less the product is fresh, tasty and nutritious.