History
This nutrient-packed vegetable is thought to have originated in Iran. In the 7th century, China began growing spinach after receiving it as a gift from the king of Nepal. Not until the 11th century did the Europeans begin cultivating the vegetable.
During the 16th century, the queen of France, Catherine de Medici, grew to love spinach as a young girl. Upon leaving her hometown of Florence, Italy to marry the king of France, she actually brought her own cooks with her because they knew exactly how she liked her spinach prepared. Catherine de Medici made spinach so popular that now when food is served on a bed of spinach it is called "a la Florentine." Perhaps the queen of France was partly responsible for the spread of spinach all over Europe during the 18th century.
Now, the Netherlands and the United States are the two countries responsible for most of the spinach production. Spinach thrives well in cool, damp climates and is able to withstand temperatures that dip into the twenties. Spinach is available throughout the year, but fresh spinach tastes the best from March to May and September to October.
Selection / Storage / Preparation
Selection - Select spinach with leaves and stems that are free of damage and have a deep green, uniform color. It is best to avoid spinach that has yellow or brown spots. The leaves should look fresh and be free of wilting. Check the leaves to make sure they are not slimy, as this is a sign of spoilage.
Storage - Fresh spinach can be stored in the refrigerator in a plastic bag for up to four days. Avoid packing a lot of spinach leaves into one plastic bag as well as washing the leaves before storage because this could cause the spinach to spoil. Cooked spinach does not refrigerate well. Instead, try blanching the leaves for two minutes and then freezing.
Preparation - Since spinach leaves collect dirt, it is best to wash both bunched and prepackaged spinach by putting the leaves into a bowl and washing with water two to three times. The difference between bunched and prepackaged spinach is that the bunched leaves may come with roots. Make sure to trim away roots before washing. If you plan on using the leaves for a lettuce salad, you can dry them by placing them on a paper towel to dry or in a salad spinner. If you plan on cooking the leaves, drying is not necessary.
Nutrition
Spinach and other green leafy vegetables are classified as the most nutrient dense of all foods, meaning spinach is packed with vitamins and minerals but low in calories. Spinach has been identified as providing protection against cancer and atherosclerosis because it contains approximately 13 different flavonoids and is an excellent source of both vitamin C and beta carotene, all of which function as antioxidants to decrease oxidative damage to cells by free radicals. A decrease in oxidative damage reduces the risk for developing atherosclerosis, inflammatory diseases and certain forms of cancer. A study looking at human stomach cancer cells revealed that spinach extract slowed the division of these cells, therefore decreasing tumor growth. Another study conducted in New England showed adult women who consumed spinach had a decreased incidence of breast cancer. Numerous studies have also documented the effects of antioxidants on decreasing cholesterol build-up in arteries, which decreases risk for heart attack and stroke.
Spinach is also an excellent source of folate, which can also decrease risk of heart attack and stroke. An adequate intake of folate decreases homocysteine levels in the blood, which at high levels can increase risk of cardiovascular disease.
A one cup serving of fresh spinach leaves also provides 190.5% of the daily value of vitamin K, which plays an important role in blood clotting and bone health. However, those who are on anticoagulants should limit their consumption of spinach and other green leafy vegetables.
It is important not to consume large amounts of spinach everyday because the oxalic acid in the spinach can interfere with mineral absorption, particularly calcium absorption in the small intestine. Therefore, too much spinach could interfere with bone mineralization.
Nutrient Analysis of 1 cup spinach (raw): calories: 7, fat: <1g, cholesterol: 0mg, protein: 1g, carbohydrate: <1g, sodium: 38mg, fiber: 3g, vitamin C: 8mg, vitamin A: 1690 IU, folate: <1mcg
Adapted from: http://www.whfoods.com/genpage.php?tname=foodspice&dbid=43 and http://www.ces.ncsu.edu/depts/hort/hil/hil-17.html