The World's Healthiest Foods
Spinach

Calorie for calorie, leafy green vegetables like spinach with its delicate texture and jade green color provide more nutrients than any other food. Although spinach is available throughout the year their season runs from March through May and from September through October when it is the freshest, has the best flavor and is most readily available.

 


Health Benefits

Anti-Cancer Compounds in Spinach

Researchers have identified at least 13 different flavonoid compounds in spinach that function as antioxidants and as anti-cancer agents. (Many of these substances fall into a technical category of flavonoids known as methylenedioxyflavonol glucuronides.) The anticancer properties of these spinach flavonoids have been sufficiently impressive to prompt researchers to create specialized spinach extracts that could be used in controlled studies. These spinach extracts have been shown to slow down cell division in stomach cancer cells (gastric adenocarcinomas), and in studies on mice, to reduce skin cancers (skin papillomas). A study on adult women living in New England in the late 1980s also showed intake of spinach to be inversely related to incidence of breast cancer.

Spinach Carotenoid Combats Prostate Cancer

A carotenoid found in spinach and other green leafy vegetables fights human prostate cancer two different ways, according to research published in the September 2004 issue of the Journal of Nutrition. The carotenoid, called neoxanthin, not only induces prostate cancer cells to self-destruct, but is converted in the intestines into additional compounds, called neochromes, which put prostate cancer cells into a state of stasis, thus preventing their replication. (December 13, 2004)

We all know that Popeye made himself super strong by eating spinach, but you may be surprised to learn that he may also have been protecting himself against osteoporosis, heart disease, colon cancer, arthritis, and other diseases at the same time.

Helping You Bone Up

The vitamin K provided by spinach - almost 200% of the Daily Value in one cup of fresh spinach leaves and over 1000% of the Daily Value in one cup of boiled spinach (which contains about 6 times as much spinach) - is important for maintaining bone health. Vitamin K1 activates osteocalcin, the major non-collagen protein in bone. Osteocalcin anchors calcium molecules inside of the bone. Therefore, without enough vitamin K1, osteocalcin levels are inadequate, and bone mineralization is impaired.

Cardiovascular Protection from Spinach

For atherosclerosis and diabetic heart disease, few foods compare to spinach in their number of helpful nutrients. Spinach is an excellent source of vitamin C and vitamin A, the latter notably through its concentration of beta-carotene. These two nutrients are important antioxidants that work to reduce the amounts of free radicals in the body; vitamin C works as a water-soluble antioxidant and beta-carotene as a fat-soluble one. This water-and-fat-soluble antioxidant team helps to prevent cholesterol from becoming oxidized. Oxidized cholesterol is able to stick to and build up in blood vessel walls, where it can cause blocked arteries, heart attack or stroke. Getting plenty of vitamin C and beta-carotene can help prevent these complications, and a cup of boiled spinach can provide you with 294.8% of the daily value for vitamin A along with 29.4% of the daily value for vitamin C. Spinach is also an excellent source of folate. Folate is needed by the body to help convert a potentially dangerous chemical called homocysteine that can lead to heart attack or stroke if levels get too high, into other benign molecules. In addition, spinach is a very good source of magnesium, a mineral that can help to lower high blood pressure and protect against heart disease as well. A cup of boiled spinach contains 65.6% of the daily value for folate and 39.1% of the daily value for magnesium.

In addition to its hefty supply of cardioprotective vitamins and minerals, a study published in the August 2003 issue of the Journal of Agriculture and Food Chemistry has revealed that spinach Rubisco contains four peptides (protein components) that inhibit angiotensin I-converting enzyme—the same enzyme blocked by ACE inhibitor drugs, which are used to lower blood pressure. When given to rats bred to be hypertensive, spinach produced a blood pressure lowering effect within two to four hours. How much spinach did the rats have to eat to get this beneficial effect? Just 20 to 30 mg of these powerful spinach peptides for each kilogram (2.2 pounds) of their body weight. In human terms, what this suggests is that an entrée-sized spinach salad for lunch or a serving of steamed spinach as part of the evening meal may have a salutary effect on blood pressure two to four hours later.(October 1, 2003)

Colon Cancer Prevention

Spinach can also help prevent colon cancer. The vitamin C and beta-carotene in spinach help to protect the colon cells from the damaging effects of free radicals. And the folate in spinach helps to prevent DNA damage and mutations in colon cells, even when they are exposed to cancer-causing chemicals. Studies show that people who eat foods high in vitamin C, beta-carotene, and/or folate are at a much lower risk of getting colon cancer than those who don't.

Anti-Inflammatory Nutrients

The nutrients in spinach can also help with conditions in which inflammation plays a role. For example, asthma, osteoarthritis, and rheumatoid arthritis are all conditions that involve inflammation. Since beta-carotene and vitamin C have anti-inflammatory properties, they can be helpful for reducing symptoms in some patients. In addition, the magnesium and riboflavin in spinach, two nutrients of which it is an excellent source, may help to reduce the frequency of migraine attacks in people who suffer from them.

A Smarter Brain with Spinach

In animal studies, researchers have found that spinach may help protect the brain from oxidative stress and may reduce the effects of age-related related declines in brain function. Researchers found that feeding aging rats spinach-rich diets significantly improved both their learning capacity and motor skills.

Protect the Brain from Damage After a Stroke

Eating plenty of spinach may significantly lessen brain damage from strokes and other neurological disorders, suggests a study published in the May 2005 issue of the Journal of Experimental Neurology.

Neuroscientists at the University of South Florida College of Medicine, James A. Haley Veterans' Hospital and the National Institute on Drug Abuse found that rats fed diets enriched with spinach, blueberries or spirulina (a type of algae) suffered the loss of much fewer brain cells and recovered significantly more of their ability to move following a stroke.

The researchers studied four groups of rats. All were fed equal amounts of food for one month. The control (untreated) group ate chow only. A second group was given rat chow supplemented with blueberries, the third got chow with spinach, and the fourth received chow with spirulina.

After four weeks, an ischemic stroke with reperfusion was induced in the rats. (An ischemic stroke occurs when a blood clot blocks an artery, cutting off the supply of oxygen to the brain with the result that brain cells can be severely damaged and die). When the clot is cleared, the pent up oxygenated blood quickly rushes back in. Known as reperfusion, this restoration of blood flow can also result in brain damage as it causes cellular swelling, edema and the production of free radicals.

Rats given spinach or blueberry along with their chow, however, were protected: the size of the area of their brains damaged by the stroke was half that seen in the brains of the control rats.

Rats fed spirulina-enriched diets did even better; their stroke lesions were 75 per cent smaller than those of controls. In addition, but not surprisingly, rats pretreated with the spinach, blueberry or spirulina diets also showed regained more of their abilities to move after the stroke than rats in the control group. Neuroscientists think the reason for the improved outcome in spinach, blueberry or algae-treated rats is the same as that demonstrated in previous University of Florida/Veterans Administration research, which revealed that diets enriched with spinach, blueberries or spirulina reversed normal age-related declines in memory and learning in old rats. All these foods are exceptionally rich in antioxidants, which neuroscientists believe able to largely counteract the burst of free radicals triggered in brain cells by an ischemic stroke. It is this sudden excessive production of free radicals that damages the lipids, proteins and DNA in brain cells, causing their death.

Spinach leaves contain high levels of antioxidant flavonoids, p-coumaric acid, 9-cis-β-carotene, and other water-soluble natural antioxidants. Several ingredients in blueberries, including their flavonoids and anthocyanins, have also been shown to have strong antioxidant activity. Just how powerful these compounds are is suggested by the fact that spinach and blueberries were each given as only 2% of the two supplemented rat diets.

Better Eyesight from Spinach

Lutein, a carotenoid protective against eye diseases such as age-related macular degeneration and cataract, is found in green vegetables, especially spinach, as well as kale and broccoli. But egg yolks, although they contain significantly less lutein than spinach, are a much more bioavailable source whose consumption increases lutein concentrations in the blood many-fold higher than spinach,shows a human study published in the August 2004 issue of the Journal of Nutrition.

Although the mechanism by which egg yolk increases lutein bioavailability is not yet known, it is likely due to the fats (cholesterol and choline) found in egg yolk. Lutein, like other carotenoids, is fat-soluble, so cannot be absorbed unless fat is also present. To maximally boost your lutein absorption, we suggest enjoying your spinach, whether steamed, sautéed or fresh in spinach salad, with a little olive oil and a topping of chopped hard-boiled egg. For a flavorful, quick and easy recipe featuring eggs and spinach, try our Poached Eggs over Spinach and Mushrooms.(October 10, 2004)

Iron for Energy

Cooked spinach is an excellent source of iron. Although Popeye ate spinach to boost his strength, it's more important for menstruating women, who are more at risk for iron deficiency. Boosting iron stores with spinach is a good idea, especially because, in comparison to red meat, a well known source of iron, spinach provides iron for a lot less calories and is totally fat-free. Iron is an integral component of hemoglobin, which transports oxygen from the lungs to all body cells, and is also part of key enzyme systems for energy production and metabolism. And, if you're pregnant or lactating, your needs for iron increase. Growing children and adolescents also have increased needs for iron. In one cup of boiled spinach, you'll be provided with 35.7% of the daily value for iron.

So while spinach probably won’t make you super strong the minute you eat it, it may be able to help you avoid some very serious health conditions. It seems like Popeye was pretty smart after all.

Description

Spinach belongs to the same family (Chenopodiaceae) as chard and beets. It shares a similar taste profile with these two other vegetables - it has the bitterness of beet greens and the slightly salty flavor of chard.

Popeye popularized spinach, but it’s too bad he ate it out of a can. Fresh spinach retains the delicacy of texture and jade green color that is lost when spinach is processed. Raw spinach has a mild, slightly sweet taste that can be refreshing in salads, while its flavor becomes more acidic and robust when it is cooked.

There are three different types of spinach generally available. Savoy has crisp, creased curly leaves that have a springy texture. Smooth-leaf has flat, unwrinkled, spade-shaped leaves, while semi-savoy is similar in texture to savoy but is not as crinkled in appearance. Spinacia oleracea is the scientific name of this leafy vegetable.

History

Spinach is thought to have originated in ancient Persia (Iran). Spinach made its way to China in the 7th century when the king of Nepal sent it as a gift to this country. Spinach has a much more recent history in Europe than many other vegetables. It was only brought to that continent in the 11th century, when the Moors introduced it into Spain. In fact, for a while, spinach was known as “the Spanish vegetable” in England.

Spinach was the favorite vegetable of Catherine de Medici, a historical figure in the 16th century. When she left her home of Florence, Italy, to marry the king of France, she brought along her own cooks, who could prepare spinach the ways that she especially liked. Since this time, dishes prepared on a bed of spinach are referred to as “a la Florentine.”

Spinach grows well in temperate climates. Today, the United States and the Netherlands are among the largest commercial producers of spinach.

How to Select and Store

Choose spinach that has vibrant deep green leaves and stems with no signs of yellowing. The leaves should look fresh and tender, and not be wilted or bruised. Avoid those that have a slimy coating as this is an indication of decay.

Store fresh spinach loosely packed in a plastic bag in the refrigerator crisper where it will keep fresh for about four days. Do not wash it before storing as the moisture will cause it to spoil. Avoid storing cooked spinach as it will not keep very well. Spinach can be frozen after being blanched for two minutes, although this will cause its texture to become very soft, so do not completely thaw it before cooking.

How to Enjoy

For some of our favorite recipes, click Recipes.

Tips for Preparing Spinach:

Spinach, whether bunched or prepackaged, should be washed very well since the leaves and stems tend to collect sand and soil. Before washing, trim off the roots and separate the leaves. Place the spinach in a large bowl of tepid water and swish the leaves around with your hands as this will allow any dirt to become dislodged. Remove the leaves from the water, empty the bowl, refill with clean water and repeat this process until no dirt remains in the water (usually two to three times will do the trick). Cut away any overly thick stems to ensure for more even cooking. If you are going to use the spinach in a salad, you can dry it in either a salad spinner or by shaking it in a colander. If you are going to cook it, you do not need to worry about drying it well as the remaining water will serve to help it cook.

A Few Quick Serving Ideas:

Add layers of steamed spinach to your next lasagna recipe.

Toss steamed spinach with pressed garlic, fresh lemon juice and olive oil. Sprinkle with a little Parmesan cheese.

Safety

Allergic Reactions to Spinach

Although allergic reactions can occur to virtually any food, research studies on food allergy consistently report more problems with some foods than with others. Common symptoms associated with an allergic reaction to food include: chronic gastrointestinal disturbances; frequent infections, e.g. ear infections, bladder infections, bed-wetting; asthma, sinusitis; eczema, skin rash, acne, hives; bursitis, joint pain; fatigue, headache, migraine; hyperactivity, depression, insomnia.

Individuals who suspect food allergy to be an underlying factor in their health problems may want to avoid commonly allergenic foods. Spinach is one of the foods most commonly associated with allergic reactions. Other foods commonly associated with allergic reactions include: cow's milk, wheat, soy, shrimp, oranges, eggs, chicken, strawberries, tomato, peanuts, pork, corn and beef. These foods do not need to be eaten in their pure, isolated form in order to trigger an adverse reaction. For example, yogurt made from cow’s milk is also a common allergenic food, even though the cow’s milk has been processed and fermented in order to make the yogurt. Ice cream made from cow’s milk would be an equally good example.

Spinach and Pesticide Residues

Virtually all municipal drinking water in the United States contains pesticide residues, and with the exception of organic foods, so do the majority of foods in the U.S. food supply. Even though pesticides are present in food at very small trace levels, their negative impact on health is well documented. The liver’s ability to process other toxins, the cells’ ability to produce energy, and the nerves’ ability to send messages can all be compromised by pesticide exposure. According to the Envirionmental Working Group's 2003 report "Shopper's Guide to Pesticides in Produce", spinach is among the 12 foods on which pesticide residues have been most frequently found. Therefore, individuals wanting to avoid pesticide-associated health risks may want to avoid consumption of spinach unless it is grown organically.

Spinach and Oxalates

Spinach is among a small number of foods that contain any measurable amount of oxalates, naturally-occurring substances found in plants, animals, and human beings. When oxalates become too concentrated in body fluids, they can crystallize and cause health problems. For this reason, individuals with already existing and untreated kidney or gallbladder problems may want to avoid eating spinach. Oxalates may also interfere with absorption of calcium from the body. For this reason, individuals trying to increase their calcium stores may want to avoid spinach, or if taking calcium supplements, may want to eat spinach 2-3 hours before or after taking their supplements.

Spinach and Goitrogens

Spinach contains goitrogens, naturally-occurring substances in certain foods that can interfere with the functioning of the thyroid gland. Individuals with already existing and untreated thyroid problems may want to avoid spinach for this reason. Cooking may help to inactivate the goitrogenic compounds found in food. However, it is not clear from the research exactly what percent of goitrogenic compounds get inactivated by cooking, or exactly how much risk is involved with the consumption of spinach by individuals with pre-existing and untreated thyroid problems.

Spinach and Purines

Spinach contain naturally-occurring substances called purines. Purines are commonly found in plants, animals, and humans. In some individuals who are susceptible to purine-related problems, excessive intake of these substances can cause health problems. Since purines can be broken down to form uric acid, excess accumulation of purines in the body can lead to excess accumulation of uric acid. The health condition called “gout” and the formation of kidney stones from uric acid are two examples of uric acid-related problems that can be related to excessive intake of purine-containing foods. For this reason, individuals with kidney problems or gout may want to limit or avoid intake of purine-containing foods such as spinach.

Nutritional Profile

Introduction to Food Rating System Chart

The following chart shows the nutrients for which this food is either an excellent, very good or good source. Next to the nutrient name you will find the following information: the amount of the nutrient that is included in the noted serving of this food; the %Daily Value (DV) that that amount represents (similar to other information presented in the website, this DV is calculated for 25-50 year old healthy woman); the nutrient density rating; and, the food's World's Healthiest Foods Rating. Underneath the chart is a table that summarizes how the ratings were devised. For more detailed information on our Food and Recipe Rating System, please click here.

 

Spinach (boiled, with salt)
1.00 cup
41.40 calories
Nutrient Amount DV
(%)
Nutrient
Density
World's Healthiest
Foods Rating
vitamin K 888.50 mcg 1110.6 482.9 excellent
vitamin A 14742.00 IU 294.8 128.2 excellent
manganese 1.68 mg 84.0 36.5 excellent
folate 262.44 mcg 65.6 28.5 excellent
magnesium 156.60 mg 39.1 17.0 excellent
iron 6.43 mg 35.7 15.5 excellent
vitamin C 17.64 mg 29.4 12.8 excellent
vitamin B2 (riboflavin) 0.42 mg 24.7 10.7 excellent
calcium 244.80 mg 24.5 10.6 excellent
potassium 838.80 mg 24.0 10.4 excellent
vitamin B6 (pyridoxine) 0.44 mg 22.0 9.6 excellent
tryptophan 0.07 g 21.9 9.5 excellent
dietary fiber 4.32 g 17.3 7.5 very good
copper 0.31 mg 15.5 6.7 very good
vitamin B1 (thiamin) 0.17 mg 11.3 4.9 very good
protein 5.35 g 10.7 4.7 very good
phosphorus 100.80 mg 10.1 4.4 very good
zinc 1.37 mg 9.1 4.0 very good
vitamin E 1.72 mg 8.6 3.7 very good
omega 3 fatty acids 0.15 g 6.0 2.6 good
vitamin B3 (niacin) 0.88 mg 4.4 1.9 good
selenium 2.70 mcg 3.9 1.7 good
World's Healthiest
Foods Rating
Rule
excellent DV>=75% OR Density>=7.6 AND DV>=10%
very good DV>=50% OR Density>=3.4 AND DV>=5%
good DV>=25% OR Density>=1.5 AND DV>=2.5%

References

  • Asai A, Terasaki M, Nagao A. An epoxide-furanoid rearrangement of spinach neoxanthin occurs in the gastrointestinal tract of mice and in vitro: formation and cytostatic activity of neochrome stereoisomers. J Nutr. 2004 Sep;134(9):2237-43.
  • Chung HY, Rasmussen HM, Johnson EJ. Lutein bioavailability is higher from lutein-enriched eggs than from supplements and spinach in men. J Nutr. 2004 Aug;134(8):1887-93.
  • Edenharder R, Keller G, Platt KL, Unger KK. Isolation and characterization of structurally novel antimutagenic flavonoids from spinach (Spinacia oleracea). J Agric Food Chem 2001 Jun;49(6):2767-73.
  • Ensminger AH, Ensminger, ME, Kondale JE, Robson JRK. Foods & Nutriton Encyclopedia. Pegus Press, Clovis, California.
  • Ensminger AH, Esminger M. K. J. e. al. Food for Health: A Nutrition Encyclopedia. Clovis, California: Pegus Press; 1986.
  • Fortin, Francois, Editorial Director. The Visual Foods Encyclopedia. Macmillan, New York.
  • He T, Huang CY, Chen H, Hou YH. Effects of spinach powder fat-soluble extract on proliferation of human gastric adenocarcinoma cells. Biomed Environ Sci 1999 Dec;12(4):247-52.
  • Joseph JA, Shukitt-Hale B, Denisova NA et al. Long-term dietary strawberry, spinach or vitamin E supplementation retards the onset of age-related neuronal signal-transduction and cognitive behavioral deficits. J Neurosci 1998 Oct 1;18(19):8047-55.
  • Joseph JA, Shukitt-Hale B, Denisova NA, et al. Reversals of age-related declines in neuronal signal transduction, cognitive, and motor behavioral deficits with blueberry, spinach, or strawberry dietary supplementation. J Neurosci 1999 Sep 15;19(18):8114-21.
  • Longnecker MP, Newcomb PA, Mittendorf R, et al. Intake of carrots, spinach, and supplements containing vitamin A in relation to risk of breast cancer. Cancer Epidemiol Biomarkers Prev 1997 Nov;6(11):887-92.
  • Nyska A, Lomnitski L, Spalding J, et al. Topical and oral administration of the natural water-soluble antioxidant from spinach reduces the multiplicity of papillomas in the Tg.AC mouse model. Toxicol Lett 2001 May 31;122(1):33-44.
  • Wang Y, Chang CF, Chou J, Chen HL, Deng X, Harvey BK, Cadet JL, Bickford PC. Dietary supplementation with blueberries, spinach, or spirulina reduces ischemic brain damage. Exp Neurol. 2005 May;193(1):75-84.
  • Wood, Rebecca. The Whole Foods Encyclopedia. New York, NY: Prentice-Hall Press; 1988.
  • Yang Y, Marczak ED, Yokoo M, Usui H, Yoshikawa M. Isolation and antihypertensive effect of angiotensin I-converting enzyme (ACE) inhibitory peptides from spinach Rubisco. J Agric Food Chem. Aug 13;51(17):4897-902.

This page was updated on: 2005-05-26 23:36:10
© 2002 The George Mateljan Foundation