Common names confusion
• Amaranthus dubius: Red spinach or Chinese spinach.
• Atripex hortensis: Mountain spinach or French spinach.
• Basella alba: Malabar spinach or red vine spinach, creeping spinach, or climbing spinach.
• Beta vulgaris: Chard, spinach beet, silverbeet, perpetual spinach.
• Cleome serrulata: Navajo spinach.
• Cleome bonus-henricus: Lincolnshire spinach.
• Ipomoea aquatica: Water spinach, river spinach, or Chinese spinach.
• Rumex acetosa: Spinach dock.
• Spinacia oleracea: Common spinach.
• Tetragonia tetragonioides: New Zealand spinach, sea spinach.
• Wild spinach: Common names to many plants with edible leaves.
• Others: Morogo or African spinach. (12)
Spinacia oleracea is an annual, succulent-leaved plant growing to a height of 50 centimeters. Leaves are alternate, simple, ovate or triangular-based, varying in sizes from 2 to 30 centimeters long and up to 15 centimeters wide, larger at the base of the plant, smaller higher on flowering stems. Flowers are inconspicuous, yellow green, 3 to 4 millimiters in diameter, maturing to a small, hard, dry and lumpy fruit cluster about 5-10 millimeters across, containing several seeds. (6)
There are two main types of spinach leaves: the crinkled savory-leaf spinach and the smooth or flat-leaf spinach.
- Cultivated everywhere.
- In the U.S., California is the largest producer of spinach, followed by Arizona and New Jersey.
Per capita consumption in the US for 2016 was estimated to be 1.7 pounds.(9)
- Nutrient analysis of raw spinach per 100 g: (Proximates) water 91.40 g, energy 23 kcal, protein 2.86 g, total lipid (fat) 0.39 g, carbohydrate by difference 3.63 g, total dietary fiber 2.2 g, total sugars 0.42 g; (Minerals) calcium 99 mg, iron 2.71 mg, magnesium 79 mg, phosphorus 49 mg, potassium 558 mg, sodium 79 mg, zinc 0.53 mg; (Vitamins) vitamin C (total ascorbic acid) 28.1 mg, thiamin 0.078 mg, riboflavin 0.189 mg, niacin 0.724 mg, vitamin B6 0.195 mg, folate 194 µg, vitamin A 9377 IU, vitamin E 2.03 mg, vitamin K 482.9 µg; (Lipids) total saturated fatty acids 0.063 g, total monosaturated FA 0.010 g, total polyunsaturated FA 0.165 g. (1)
Phytochemical screening yielded phlobatannin, saponins, phenol, tannins, glycosides, flavonoids, steroids, terpenes, and cardenolides. (see study below) (5)
- Important compounds are: phenolics (ortho-coumaric, para-coumaric, and ferulic acid); flavonoids (apigenin, glucuronide, flavone, jaceidin, kaempferol, myricetin, methoxyflavone, patuletin, quercetin, and spinacetin); carotenoids (lutein, ß-carotene, violaxanthin, and neoxanthin). Vitamin yield includes vitamin A, E, K, and C, along with folate, folic acid, and oxalic acid; minerals includes calcium, copper, iron, magnesium, manganese, phosphorus, potassium, and zinc. (6)
- Phytochemical analysis of dried and powdered plant yielded phytosterols, proteins, glycosides, flavonoids, carbohydrates, quinones, and terpenoids. (7)
- Two major carotenoids present in spinach leaves are lutein and beta-carotene, comprising 65% of total carotenoids content.
- Studies have suggested antioxidant, antibacterial, anti-inflammatory, anti-osteoarthritis, anti-obesity, anti-diabetic, anti-osteoporosis, anti-Alzheimer, radioprotective, radioprotective, hepatoprotective properties.
Leaves and seeds.
Edibility / Nutrition
- Spinach is one of the most nutritious leaf vegetables. It is high in protein, low in carbohydrate and fat.
- It is a nutrient-dense source of vitamins and minerals, and maintains its nutritional value even after cooking.
- Considered one of nature's perfect foods.
- Historically, spinach leaves have been used as laxative, diuretic, antidote against poison or infection, as treatment for asthm and other breathing difficulties, sore throad and kidney stones. (9)
- Seeds have been used for fever, back pain, and as diuretiic.
- In Indian traditonal medicine, used to treat liver injury, infection, and jaundice.
- In Iranian medicine, prescribed as antidepressant. Because of high iron and chlorophyll content, used a therapeutic food for patients with anemia.
• Anti-Osteoarthritis / Attenuation of Disease Progression: Study evaluated the anti-osteoarthritic and chondro-protective effects of S. oleracea extract on chemically (monosodium iodoacetate) induced osteoarthritis by measures of biomarkers viz. micro-CT, mRNA, and protein expression of pro-inflammatory and chondrogenic genes. In vitro cell free and cell based assays showed the extract to be a strong antioxidant and anti-inflammatory agent. Results suggest SOE has potential to alleviate MIA induced deleterious effects. (4)
• Antibacterial / Leaves: Study evaluated various extracts of leaves for antibacterial activity against selected bacteria viz. Staphylococcus aureus and Pseudomonas aeruginosa. The ethyl acetate crude extract showed effective antibacterial activity at 100% concentration. Ethanol crude extract and aqueous extract showed no activity. (see constituents above) (5)
• Anti-Alzheimer / Review: Study conducted a review on various ethnomedicinal use of spinach and its influence on the pathophysiology of Alzheimer's disease. Its pathophysiology is related to neurotoxic events triggered by the ß-amyloid cascade and by cytoskeletal abnormalities due to hyperphosphory-lation of microtubule-associated Tau protein in neurons, causing many of the hallmarks of AD viz. formation of neuritic or senile plaques and neurofibrillary tangles, oxidative and inflammatory processes, neurotransmitter disturbances, and cholinergic deficits. The review delves on the potential of spinach-enriched diet and extracts as natural therapeutic or adjuvant options for Alzheimer's disease treatment. (6)
• Antidiabetic / Leaves: Study evaluated the hypoglycemic activity of ethanolic and aqueous extracts of S. oleracea in alloxan induced diabetic rats. The extracts produced a significant reduction in fasting blood glucose, significant changes in serum lipid profiles. Histopathological study of the pancreas showed regeneration of the pancreas earlier necrosed by alloxan. (8)
• Radioprotective: Study investigated the radioprotective efficacy of spinach against radiation induced oxidative stress in the testis of Swiss albino mice exposed to 5 Gy of gamma radiation. Radiation induced augmentation in lipid peroxidation, glycogen and cholesterol values were significantly ameliorated by supplementation of SE extract. The leaves are rich in antioxidants like carotenoids (ß-carotene, lutein and zeaxanthin), along with high content of proteins, minerals, and vitamin C. Spinach extract pretreatment provided protection against various biochemical changes in mice testis which may be due to the synergistic effect of antioxidant constituents. (10)
• Amelioration of Abnormalities Associated with Metabolic Syndrome: Study evaluated the protective effects of antioxidant rich extract of Spinacia oleracea (NAOE) in abnormalities associated with the metabolic syndrome (MetS) in rats. Results showed NAOE (400 mg/kg) treatment combined with aerobic exercise for 45 days to fructose-fed rats was more effective than NAOE or AE alone. The protective effect may be attributed to potent antioxidant activity of its abundant NAO, especially flavonoids. (11)
• Comparative Antioxidative Study: Study evaluated the phytochemical constituents of three very commonly used leafy vegetables of West Bengal i.e., Bacopa monnieri (Brahmi sak), Lagenaria siceraria (Lau sak) and Spinacia oleracea (Palong sak). Antioxidant potential of raw and boiled leaf and stem was studied. Results showed higher amounts of phenol, flavonoid, vitamin C, vitamin E were found in the leaf samples. Raw samples contained higher amounts of flavonoid, vitamin C and vitamin E, while boiled samples yielded higher amount of phenols. Of the three vegetables, S. oleracea was richest in phenol, flavonoid, and vitamin E content and was more active as free radical scavenger with low IC50 of 140 µg/ml compared to Bacopa and Lagenaria. (12)
• Spinach as Natural Food-Grade Antioxidant in Flour Dough: Study evaluated the addition of spinach powder in flour dough as a natural antioxidant. Spinach powder decreased the lipid content in fried dough, reduced conjugated diene and aldehyde formation, and improved lipid oxidative stability in fried products during storage. (13)
• Effects of Pre- and Post-Harvest Factors on Bioactive Compounds of Baby Spinach: Study evaluated the pre- and post-harvest factors--sowing time, growth stage at harvest, use of shade nettings, post-harvest storage temperature and duration--on the concentrations of bioactive compounds of baby spinach. Ascorbic acid and flavonoids decreased during plant growth. Plant growth has greatest impact on carotenoid concentration. Early harvesting may benefit increased concentrations of bioactive compounds. There were considerable losses of ascorbic acid during storage, whereas carotenoids and flavonoids were stable and sometimes increased. Ascorbic acid concentration at harvest time may have protective effect on plant tissue against oxidative stress and subsequent deterioration. (14)
• Phytochemical Screening: Study confirmed the presence of fats, carbohydrates (reducing sugars, pentoses, and hexoses), glycosides, particularly anthraquinone (-o- and -c-form) and coumarin glycosides. Solvent extraction was more in water compared to alcohol, with reduced extractability in dried leaves compared to fresh leaves. Study found no change in phytochemical constituents in fresh and dried leaves. Loss of water content showed no effect on extractive vales of leaves and phytoconstituents, suggesting dried leaves can be stored for medicinal use. (15)
• Comparison of Nutritional
Composition / Raw Fresh and Shade Dried Leaves: Study evaluated the proximate and mineral composition of raw fresh and shade dried spinach leaves. Raw fresh spinach showed vegetable protein content of (11.10%) and fiber (21.38%). Powder from shade dried leaves yielded a vegetable protein content of 19.10%. The protein content in both forms presents as a rich source of vegetable protein over other lesser known vegetables and can be recommended for children with malnutrition. The low carbohydrate content and high fiber content present benefits for diabetic patients. (16)
• Leaf Mucilage as Suspending Agent: Study evaluated the mucilage isolated from S. oleracea leaves as an innovative suspending agent using parameters like sedimentation profile, degree of flocculation, and redispersibility. Results showed the leaf mucilage could be a suspending agent, with a performance superior to both tragacanth and bentonite. (17)
• Antacid Effect: Study compared the antacid effect of raw spinach juice and an antioxidant-rich methanolic extract of spinach (NAOE) in an artificial stomach model. Effect was compared with sodium bicarbonate (SB) and a marketed antacid preparation ENO. While highest antacid activity was demonstrated by ENO and SB, spinach showed significant antacid activity whether in raw juice form as as methanol extract. (18)
• Nanoparticles / Leaves / Antimicrobial: Study reports on the rapid, ecofriendly method of synthesis of silver nanoparticles from Eruca sativa and Spinacia oleracea and their bacterial impact on Streptococcus pneumonia and Pseudomonas aeruginosa and their pharmaceutical and other biomedical applications. (19) Study reports on the synthesis of silver nanoparticles using Spinacia oleracea and Lactuca sativa leaves and the efficacy of the synthesized NPs as antimicrobial agents against B. subtilis, S. aureus, K. pneumonia and E. faecalis strains. (20)
• Anti-Inflammatory / Leaves: Study evaluated the anti-inflammatory activity of ethanolic and aqueous extracts of leaves of S. oleracea using carrageenan induced rat paw edema for acute inflammation and cotton pellet granuloma method for chronic inflammation. In both methods, the extracts showed significant activity comparable to indomethacin standard. (21)
• Antioxidant Effect on Testicular and Epididymal Weight: Study evaluated the antioxidant effects of spinach on the weight of testes and epididymis in obese Sprague Dawley rats. Results showed intake of spinach supplemented diet had ameliorative effects on the weight of testes and epididymis in response to deleterious effects caused by obesity-induced oxidative stress. (22)
• Effect on Chronic Restraint Stress-Induced Memory Deficit and Anxiety: Study evaluated the effect of a hydroalcoholic extract of spinach on chronic restraint stress-induced spatial learning and memory deficit and anxiety in adult male rats. Results showed improvement in spatial learning and memory and reduced anxiety, which was attributed to rich antioxidant content in the ethanol extract. (23)
• Hepatoprotective / Carbon Tetrachloride Induced Toxicity / Seeds: Study evaluated the in vitro and in vivo protective effects of S. oleracea seeds on CCl4-induced hepatic toxicity. Results showed significant in vitro and in vivo hepatoprotective activity of n-butanol fraction. HPTLC analysis confirmed the presence of 20-hydroxyecdysone (20-HE), which may explain the effects. (24)
Regulatory Effect on Appetite / Control of Obesity / CCK: Nutrients and gastrointestinal peptide hormones such as cholecystokinin (CCK), GLP-1, and peptide YY are involved in short term regulation of food intake, interacting with long term regulators like insulin, leptin, and ghrelin. This study evaluated the appetite suppressing effect of a flavonoid rich extract of spinach leaf in rats. Results showed a promising appetite suppressing effect by inducing a quicker than normal release of CCK, which elicits earlier onset of satiety in rats. (25)
Acceleration of Bone Regeneration / Alleviation of Postmenopausal Osteoporosis: Study evaluated the efficacy of S. oleracea extract in reversing bone loss induced by ovariectomy and bone healing properties in a drill-hole fracture model in rats. The extract treatment effectively prevented ovariectomy-induced bone loss and stimulated fracture healing in adult rats. A dried granular form of extract was also effective in fracture healing at the same dose. (26)
• Protective Effect in Experimental Inflammatory Bowel Disease: Study evaluated the protective effect of an aqueous extract of S. oleracea leaves in inflammatory bowel disease using acetic acid- and ethanol-induced colitis in mice and indomethacin-induced enterocolitis in rats. AESO at 1,000 mg/kg showed the most prominent effects. Results showed AESO was effective in attenuating almost all the symptoms of IBD in the experimental models, which may be attributed to antioxidant activity of flavonoids in the AESO. In acute oral toxicity, the AESO did not show any sign of toxicity and mortality at 5,000 mg/kg p.o. (27)
- Extracts in the cybermarket.