Spinach is an edible flowering plant placed in the family Amaranthaceae. It’s scientifically called Spinacia oleracea. It’s an annual plant reaching a length of 30 cm. The plant is rarely biennial. In the temperate regions the plant could even survive in the winter months. The leaves are alternate, simple, and ovate to triangular-based. They may be 2-30 cm long and 1-15cm wide. The larger leaves are present at the base of the plant while little leaves are found around the flowering area. The flowers are inconspicuous, yellow-green and 3-4 millimeters in diameter. They mature into a tiny, hard, dry, lumpy fruit cluster which measures 5-10 mm.
The word spinach comes from an Arabic word. Spinach is of substantial importance from nutritional point of view. It’s full of antioxidants especially if fresh, steamed or quickly boiled. It’s a potent source of vitamin A, 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. A present study has indicated that spinach also contains opioid peptides known as rubiscolins. Polyglutamyl folate is a vital component of cells and spinach is a rich source of folic acid. Boiling the spinach leaves reduces folate content but microwaving doesn’t impact the folate content.
Spinach alongside other green leafy vegetables is regarded as a good source of iron. According to an estimate of United States Department of Agriculture 180 g of boiled spinach comprises 6.43 milligrams of iron, whereas a 170 g ground hamburger patty contains at most 4.42 mg. The bioavailability of iron depends upon its absorption which is affected by a range of factors. Iron enters body in two forms either heme or non-heme iron. All the iron present in vegetables, grains and three-fifth of the animal foods comprises non-heme iron. The remaining fraction of meats contains heme iron. The iron in spinach is consumed unless and until absorbed by a supply of vitamin C. spinach contains iron absorption inhibiting factors along with high levels of oxalate which creates ferrous oxalate upon binding with iron. This form is unstable and can not be absorbed in body.
Spinach also has high calcium content. However oxalate in spinach also binds with calcium ands thus declines its absorption. Calcium and zinc also limit iron absorption. Calcium in spinach is bioavailable of calcium resources. There are three forms of spinach available commercially. These are savoy, semi-savoy and flat or smooth leaf spinach. Savoy spinach has dark green, crinky and curly leaves. It’s marketed in fresh bunches. They are resistant to bolting. The flat or smooth leaf spinach bears smooth leaves and it’s not hard to clean this variety as compared to savoy variety. This is very popularly used in soups, processed foods and baby foods. Semi-savoy is a hybrid variety with slightly crinkled leaves. It has the same texture like that of the savoy spinach and is a lot easier to be cleaned out. It is grown for fresh and processed foods. Spinach is sold in loose, bunched, prepackaged bags, canned or frozen forms. Fresh spinach loses much of its nutrient value after being stores in refrigerator for few days. Much of the folate and carotenoid content of spinach becomes lost upon storage. The cartoon character Popeye the Sailor Man is depicted as having a strong affinity for spinach, becoming physically stronger after consuming it.