Spinach (Spinacia oleracea)

Spinach (Spinacia oleracea) is a leafy green vegetable that grows in many geographic regions. It is nutrient-dense and offers many health benefits. Spinach comes in several varieties and may be eaten either when it is very young or after it has been allowed to mature. Spinach can have a bitter taste; some people have a hereditary tendency to be more sensitive to this bitterness. However, this ancient green is considered a healthy addition to diets and may be eaten raw, cooked, combined with other ingredients, or blended into smoothies.

Background

Spinach is thought to have originated as a human food source in Nepal. A wild green plant known as Spinacia tetrandra is believed to have been cultivated and consumed about 1,400 years ago. By the middle of the seventh century, the Chinese were eating spinach carried from Nepal. This "Persian green" was then introduced to the Moors, who brought it with them on their travels and crusades. During the eleventh century, the Moors introduced spinach to the Spanish; from there, it spread throughout Europe, where it often was known as the "Spanish vegetable."

By the fifteenth century, spinach was common in the Mediterranean region, where it was popular among royalty. It was particularly desirable because it matured so early in spring, when few fresh vegetables were available and winter stores were depleted. During the eighteenth century, new varieties were discovered, including one native to New Zealand that could withstand heat and dry conditions better than the types grown in Europe and Asia. This type of spinach became important in South America and the southern United States, where dry, hot conditions made growing traditional versions difficult.

For part of its early history, spinach was considered a medicinal herb. Sometimes the young leaves were cooked in a small amount of water, salted, and then fed to the sick as a way of strengthening them. Although it was not known then, spinach contains iron in a significant enough quantity to serve as a substitute for those who could not eat or digest meat. For example, according to the United States Department of Agriculture, 180 grams of spinach contains more than 2 milligrams more iron than a comparably sized serving of hamburger. As a result, it can conceivably help the ill recover their strength.

The idea that spinach is a powerful source of iron—as promoted by early-twentieth-century cartoon character Popeye the Sailor—was at one time exaggerated. During the late nineteenth century, German chemist Erich von Wolf misplaced a decimal point when he recorded the results of his tests on the vegetable's iron content. Instead of 3.5 milligrams per 100 grams, von Wolf recorded 35 milligrams. His mistake, made in 1870, was not corrected until 1937 when an unknown person double-checked his math.

Overview

Spinach is green and leafy. Sometimes the leaves are picked, but the plant is left in the ground to produce more leaves. Young leaves are tender and have a mild taste. They are often consumed in salads. Mature leaves are somewhat more fibrous and are often used in cooking. The leaves come in both curly and flat varieties and in a few varieties with subtle differences in taste and texture.

During the twentieth century, horticulturists began seriously working to improve the spinach plant. While the plant is easy to grow, it is susceptible to heat and prefers the shorter, cooler days of spring and fall to the heat of summer. For this reason, it is often grown in two growing seasons. One crop will be planted as soon as the ground can be worked, and the other will go in a few weeks before the last expected frost. Properly protected, the plants can winter in the ground and produce an early crop the following spring.

One challenge in growing spinach is its tendency to "bolt," or grow very tall and sprout flowers. Heat and overcrowding often cause this to occur, and when it does, the leaves become tough and bitter. This is one reason why spinach is generally grown in cooler weather.

Spinach has become a popular vegetable for salads and for use in cooked recipes because it provides many nutrients but has few calories. In addition to iron, spinach provides vitamins A and C, and one cup of spinach provides more than 200 percent of the recommended daily allowance of vitamin K. The vitamins found in spinach promote heart and bone health. Spinach contains antioxidants that can help prevent cell damage. These include Coenzyme Q10 (CoQ10), which protects muscles, including those in the cardiovascular system. In addition, spinach contains carotenoids, or substances that can help prevent cancer.

Spinach contains oxalate, or oxalic acid, a substance that can cause kidney stones in susceptible individuals and that might impede the absorption of iron and calcium in some circumstances. Cooking helps to minimize the effects of oxalate and free up the iron in spinach, allowing the body to absorb it better. Oxalate is also responsible for the bitter, astringent taste some people notice when eating spinach. Some people have a hereditary tendency to notice the bitter taste, while others do not. The bitterness can be minimized by certain cooking techniques, such as the addition of oil, spices, or salt during preparation. Some people add spinach to smoothies, combining it with sweeter-tasting fruits such as mangoes and strawberries to help minimize the bitterness.

Some of the nutrients in spinach are more available when it is raw, while others are more prevalent when the food is cooked. In addition to iron and calcium, the body can absorb more vitamin A, vitamin E, fiber, zinc, thiamin, and protein and several carotenoids from cooked spinach than from raw spinach. On the other hand, vitamin C, niacin, folate, potassium, and riboflavin are more easily absorbed from raw spinach.

Bibliography

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