Spinach (Spinacia oleracea) is one of incredible green-leafy vegetable often recognized as one of the functional foods for its health benefiting nutritional, antioxidants and anti-cancer composition. Its tender, crispy, dark-green leaves are one of the favorite ingredients of chefs all around the world.
Botanically, it belongs to the Amaranthaceae family, and its scientific name: Spinacia oleracea.
Spinacia plant grows to about 1 foot in height. Although it can be grown year round, its fresh greens are best available soon after the winter season from March through May in the Northern Hemisphere, and from September until November in the South of the equator.
At least, two varieties of spinach are cultivated for their edible leaves; Savoy type with dark-green crinkle (wrinkled) leaves and flat-leaf variety with smooth surfaced leaves.
Health Benefits of Spinach
Spinach is a storehouse for many phytonutrients that have health promotional and disease prevention properties.
It is very low in calories and fats (100 g of raw leaves provide just 23 calories). Also, its leaves hold a good amount of soluble dietary fiber; no wonder why this leafy greens often recommended by dieticians in the cholesterol controlling and weight reduction programs!
Fresh 100 g of spinach contains about 25% of daily intake of iron, one of the highest for any green leafy vegetables. Iron is an essential trace element required by the human body for red blood cell production and as a co-factor for an oxidation-reduction enzyme, cytochrome oxidase during the cellular metabolism.
Fresh leaves are a rich source of several vital antioxidant vitamins like vitamin-A, vitamin-C, and flavonoid polyphenolic antioxidants such as lutein, zeaxanthin, and β-carotene. Together, these compounds help act as protective scavengers against oxygen-derived free radicals and reactive oxygen species (ROS) that play a healing role in aging and various disease processes.
Zeaxanthin, an important dietary carotenoid, is selectively absorbed into the retinal macula lutea in the eyes where it thought to provide antioxidant and protective UV light-filtering functions. It thus helps protect from “age-related macular related macular disease” (ARMD), especially in the older adults.
Further, vitamin-A is required for maintaining healthy mucosa and skin and is essential for night vision. Consumption of natural vegetables and fruits rich in vitamin-A and flavonoids are also known to help the body protect from lung and oral cavity cancers.
Spinach leaves are an excellent source of vitamin-K. 100 g of fresh greens provides 402% of daily vitamin-K requirements. Vitamin-K plays a vital role in strengthening the bone mass by promoting osteoblastic activity in the bones. Additionally, it also has an established role in patients with Alzheimer’s disease by limiting neuronal damage in the brain.
This green leafy vegetable also contains good amounts of many B-complex vitamins such as vitamin-B6 (pyridoxine), thiamin (vitamin B-1), riboflavin, folates, and niacin. Folates help prevent neural tube defects in the newborns.
100 g of farm fresh spinach has 47% of daily recommended levels of vitamin-C. Vitamin-C is a powerful antioxidant, which helps the body develop resistance against infectious agents and scavenge harmful oxygen-free radicals.
Its leaves also contain a good amount of minerals like potassium, manganese, magnesium, copper and zinc. Potassium is an important component of cell and body fluids that helps controlling heart rate and blood pressure. The human body uses manganese and copper as a co-factor for the antioxidant enzyme, superoxide dismutase. Copper is also required for the production of red blood cells. Zinc is a co-factor for many enzymes that regulate growth and development, digestion and nucleic acid synthesis.
It is also a small source of omega-3 fatty acids.
Regular consumption of spinach in the diet helps prevent osteoporosis (weakness of bones), iron-deficiency anemia. Moreover, its soft leaves are believed to protect the human body from cardiovascular diseases and cancers of colon and prostate.
Selection and storage
Spinach is best available during the winter season. In the markets, buy fresh leaves featuring dark-green color, vitality, and crispiness. Avoid those with dull/sunken leaves, yellow discoloration, and spots.
Once at home, wash them thoroughly in clean running water, and rinse in salt water for about 30 minutes in order to remove dirt and any insecticide residues.
Although it can be stored in the refrigerator for up to a week, fresh leaves should be eaten at the earliest in order to get maximum nutrition benefits.
Preparation and serving methods
Wash leaves in cold water before using in cooking. Gently pat them dry using a tissue or soft cloth. Trim away tough stems. Raw leaves can be either chopped or used as they are in a variety of recipes.
Here are some serving tips:
Fresh, tender spinach leaves (baby spinach) can be eaten raw either in salad and vegetable burgers or as juice. Antioxidant properties may decrease significantly on steaming, frying and boiling for longer periods.
Along with other vegetables, its leaves are used in the preparation of noodles, pie, pasta, pilaf (pulao), and soups as well as in the preparation of baby foods.
In India and Pakistan, where it is popular as “palak,” spinach features in a variety of delicious cooking such as “palak paneer” (with cottage cheese), aloo-palak (with potato), fried rice, chicken and meat preparations.
In India and Bangladesh spinach is mixed with other seasonal greens like goosefoot (Chenopodium album), fenugreek, mustard greens, Malabar spinach (Basella alba), etc., to prepare “saag” which is eaten with unleavened bread (roti), and rice.
Reheating of spinach left-over may cause conversion of nitrates into nitrites and nitrosamines by certain bacteria that thrive on pre-prepared nitrate-rich foods, such as spinach and many other green vegetables. These harmful compounds may be bad for health, especially in children.
Phytates and dietary fiber present in the leaves may interfere with the bioavailability of iron, calcium, and magnesium.
Because of its high vitamin-K content, patients taking anti-coagulants such as “warfarin” are encouraged to avoid spinach in their food since it interferes with drug metabolism.
Spinach contains oxalic acid, a naturally-occurring substance found in some vegetables, which may crystallize as oxalate stones in the urinary tract in some people. Individuals with known oxalate urinary tract stones are advised to avoid eating certain vegetables belonging to Amaranthaceae and Brassica family. Adequate intake of water is therefore advised to maintain normal urine output.
It may also contain goitrogens, which may interfere with thyroid hormone production and can cause thyroxin hormone deficiency in individuals with thyroid dysfunction.