Spinach

Among the World's Healthiest vegetables, spinach comes out at the top of our ranking list for nutrient richness. Rich in vitamins and minerals, it is also concentrated in health-promoting phytonutrients such as carotenoids (beta-carotene, lutein, and zeaxanthin) and flavonoids to provide you with powerful antioxidant protection. Enjoy baby spinach in your favorite salads or make a salad made exclusively of baby spinach. Spinach is one of only three vegetables that we recommend boiling to help reduce its concentration of oxalic acid. We recommend boiling for just 1 minute to minimize loss of nutrients and flavor. For more on the Healthiest Way of Cooking Spinach, see the How to Enjoy section below. Foods belonging to the chenopod family—including beets, chard, spinach and quinoa—continue to show an increasing number of health benefits not readily available from other food families. The red and yellow betalain pigments found in this food family, their unique epoxyxanthophyll carotenoids, and the special connection between their overall phytonutrients and our nervous system health (including our specialized nervous system organs like the eye) point to the chenopod family of foods as unique in their health value. While we have yet to see large-scale human studies that point to a recommended minimum intake level for foods from this botanical family, we have seen data on chenopod phytonutrients, and based on this data, we recommend that you include foods from the chenopod family in your diet 1-2 times per week. In the case of a leafy food like spinach, we recommend a serving size of at least 1/2 cup, and even more beneficial, at least one full cup.

This chart graphically details the %DV that a serving of Spinach provides for each of the nutrients of which it is a good, very good, or excellent source according to our Food Rating System. Additional information about the amount of these nutrients provided by Spinach can be found in the Food Rating System Chart. A link that takes you to the In-Depth Nutritional Profile for Spinach, featuring information over 80 nutrients, can be found under the Food Rating System Chart.

• Health Benefits
• Description
• History
• How to Select and Store
• Tips for Preparing and Cooking
• How to Enjoy
• Individual Concerns
• Nutritional Profile
• References

Health Benefits

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 helping to protect himself against inflammatory problems, oxidative stress-related problems, cardiovascular problems, bone problems, and cancers at the same time.

Anti-Inflammatory and Anti-Cancer Benefits from Spinach Phytonutrients

Even though virtually all vegetables contain a wide variety of phytonutrients—including flavonoids and carotenoids—spinach can claim a special place among vegetables in terms of its phytonutrient content. Researchers have identified more than a dozen different flavonoid compounds in spinach that function as anti-inflammatory and anti-cancer agents. (Some 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 laboratory studies. These spinach extracts have been shown to slow down cell division in human stomach cancer cells (gastric adenocarcinomas), and in studies on laboratory animals, 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.

Excessive inflammation, of course, typically emerges as a risk factor for increased cancer risk. (That's why many anti-inflammatory nutrients can also be shown to have anti-cancer properties.) But even when unrelated to cancer, excessive inflammation has been shown to be less likely following consumption of spinach. Particularly in the digestive tract, reduced inflammation has been associated not only with the flavonoids found in spinach, but also with its carotenoids. Neoxanthin and violaxanthin are two anti-inflammatory epoxyxanthophylls that are found in plentiful amounts in the leaves of spinach. While these unique carotenoids may not be as readily absorbed as carotenoids like beta-carotene or lutein, they still play an important role in regulation of inflammation and are present in unusual amounts in spinach.

Decreased risk of aggressive prostate cancer is one health benefit of spinach consumption that should not be overlooked when talking about the anti-cancer properties of spinach. "Aggressive prostate cancer" is defined as stage III or IV prostate cancer which carries with it a Gleason score of at least 7. (Gleason scores are prostate cancer rating measurements that require lab studies of prostate tissue and evaluation of common tumor-related patterns.) Interestingly, in a recent study that evaluated possible prostate cancer-prevention benefits from a variety of vegetables including spinach, broccoli, cauliflower, cabbage, Brussels sprouts, mustard and turnip greens, collards, and kale — only spinach showed evidence of significant protection against the occurrence of aggressive prostate cancer.

Antioxidant Benefits of Spinach

Most of the flavonoid and carotenoid nutrients found in spinach that provide anti-inflammatory benefits provide antioxidant benefits as well. Given the fact that spinach is an excellent source of other antioxidant nutrients — including vitamin C, vitamin E, vitamin A (in the form of carotenoids), and manganese —as well as a very good source of the antioxidant zinc and a good source of the antioxidant selenium—it's no wonder that spinach helps lower risk of numerous health problems related to oxidative stress. Our blood vessels, for example, are especially susceptible to damage from oxidative stress, and intake of spinach has been associated with decreased risk of several blood vessel-related problems, including atherosclerosis and high blood pressure. (Interestingly, the blood pressure benefits of spinach may be related not only to its antioxidants, but also to some of its special peptides. Peptides are small pieces of protein, and researchers have discovered several peptides in spinach that can help lower blood pressure by inhibiting an enzyme called angiotensin I-converting enzyme.)

Two of the carotenoids that are especially plentiful in spinach — lutein and zeaxanthin — are primary antioxidants in several regions of the eye, including the retina and the macula. Although we haven't seen specific studies on spinach intake and prevention of eye-related problems like macular degeneration, we have seen studies showing that human blood levels of lutein can be increased by consumption of spinach in everyday amounts. We've also seen at least one group of researchers suggesting that spinach has a likely role to play in prevention of eye problems, including age-related macular degeneration.

Helping You Bone Up

The wealth of vitamin K provided by spinach is important for maintaining bone health. Vitamin K1 helps prevent excessive activation of osteoclasts, the cells that break down bone. Additionally, friendly bacteria in our intestines convert vitamin K1 into vitamin K2, which activates osteocalcin, the major non-collagen protein in bone. Osteocalcin anchors calcium molecules inside of the bone. All of these vitamin K-related mechanisms point to the importance of vitamin K-rich foods for bone health, and it is difficult to find vegetables that are richer in vitamin K than spinach. (On our World's Healthiest Foods list, only kale provides more micrograms of vitamin K per cup.) Spinach is also an excellent source of other bone-supportive nutrients including calcium and magnesium.

So while spinach probably won't make you super strong the minute you eat it, as it did for Popeye, it will promote your health and vitality in many other ways. It seems like Popeye was pretty smart after all.

Description

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, its 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. Spinach belongs to the same family (Amaranthaceae-Chenopodiaceae) as Swiss chard and beets and has the scientific name, Spinacia oleracea. It shares a similar taste profile with these two other vegetables, having the bitterness of beet greens and the slightly salty flavor of Swiss chard.

Popeye popularized spinach, but it's too bad he ate it out of a can. Fresh spinach retains the delicacy of texture and 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. Baby spinach is great for use in salads owing to its taste and delicate texture.

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.

Do not wash spinach before storing as the exposure to water encourages spoilage. Place spinach in a plastic storage bag and wrap the bag tightly around the spinach, squeezing out as much of the air as possible. Place in refrigerator where it will keep fresh for up to 5 days.

Avoid storing cooked spinach as it will not keep very well.

Tips for Preparing and Cooking

Tips for Preparing Spinach

Spinach 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). Do not leave spinach soaking in the water as water-soluble nutrients will leach into the water.

Spinach sold in bags has been pre-washed and only needs to be rinsed. If you are going to use it in a salad, dry it using a salad spinner or by shaking it in a colander.

The Healthiest Way of Cooking Spinach

Spinach is only one of three vegetables we recommend boiling to free up acids and allow them to leach into the boiling water; this brings out a sweeter taste from the spinach. Discard the boiling water after cooking; do not drink it or use it for stock because of its acid content.

Use a large pot (3 quart) with lots of water and bring to a rapid boil. Add spinach to the boiling water and boil for 1 minute. Begin timing as soon as you place the spinach in the pot if you are using 1 pound or less of spinach. If you are cooking larger quantities of spinach bring the water back to a boil before beginning timing the 1 minute. Do not cover the pot when cooking spinach. Leaving the pot uncovered helps to release more of the acids with the rising steam. Research has shown that the boiling of spinach in large amounts of water helps decrease the oxalic acid content.

Remove spinach from pot, press out liquid with a fork, place in a bowl, toss with our Mediterranean Dressing, and top with your favorite optional ingredients. For details see 1-Minute Spinach.

How to Enjoy

A Few Quick Serving Ideas

• Add layers of spinach to your next lasagna recipe.
• Pine nuts are a great addition to cooked spinach.
• Spinach salads are a classic easy and delicious meal or side dish.

WHFoods Recipes That Feature Spinach

• Poached Egg over Spinach
• Poached Eggs over Spinach & Mushrooms
• Mediterranean Baby Spinach Salad
• Warm Spinach Salad with Tuna
• Indian-Style Lentils
• Figs, Walnuts and Spinach Salad
• 1-Minute Spinach
• Golden Spinach and Sweet Potato Healthy Sauté

Individual Concerns

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 Environmental Working Group's 2014 report "Shopper's Guide to Pesticides," conventionally grown spinach is among the top 12 fruits and vegetables 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 E. coli

Several national recalls of spinach-containing products between 2006-2013 have raised consumer concerns about the risk of spinach contamination with E. coli bacteria. Of special concern have been Shiga toxin-producing E. coli (STEC), including E. coli 0157:H7. Thorough washing of contaminated spinach cannot remove E. coli 0157:H7. However, as summarized by the U.S. Food and Drug Administration (FDA), "Cooking fresh spinach at 160°F (71°C) for 15 seconds will kill any E. coli 0157:H7 present." The cooking method we recommend on our website for spinach—a quick boil for approximately 1 minute—greatly exceeds this safety standard.

Because many people enjoy spinach in raw form (especially baby spinach), we are often asked about the level of risk involved with consumption of raw spinach. While we have not seen enough data to provide you with an exact risk level here, there is definitely some level of risk involved—although it might be very small—with consumption of raw spinach. If your goal is to remove this risk entirely, your best approach is to follow our quick boil cooking method for spinach.

In the case of certified organic raw spinach (and other certified organic raw vegetables), there is one regulation working to help lower contamination risk: raw animal manure cannot be used less than 120 days prior to harvest of a certified organic food if the food (like spinach) has an edible portion that comes into contact with the soil or soil surface. This restriction on the use of raw animal manure can help prevent crops like spinach from being contaminated with bacteria like E. coli 0157:H7. In the case of non-organic raw spinach, there can also be reduction of risk due to irradiation of the spinach—a practice allowed by the FDA since 2008. (Since irradiation is a prohibited practice in the production of certified organic foods, however, certified organic raw spinach is not irradiated.)

Spinach and Oxalates

Spinach is among a small number of foods that contain measurable amounts 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. Although early studies on spinach suggested possible interference of oxalates with iron absorption, more recent studies suggest that absorption of non-heme iron (iron from plants) is not significantly impacted by the oxalates contained in spinach. Laboratory studies have shown, however, that oxalates may interfere with absorption of calcium from the body. Exactly how much interference takes place in the case of spinach and calcium absorption is not clear, but at a minimum, you should expect to absorb a minimum of about 10% of the calcium from the spinach that you eat. For example, in one cup of boiled spinach containing about 285 milligrams, you can expect to absorb about 25-30 milligrams. For adults, the Adequate Intake (AI) level for calcium falls between 1,000 and 1,200 milligrams. This recommended amount assumes an absorption rate of about 30%. In other words, about 300-360 milligrams of absorbable calcium are expected each day. While 25-30 milligrams is not an overwhelming amount of calcium from a serving of food, a cup of spinach is extremely low-calorie and can provide you with about 10% of the recommended calcium intake for very few (about 40) calories. Those circumstances make spinach a worthwhile addition to your diet with respect to calcium, even though spinach is not an outstanding source of this nutrient and should not be counted on to boost your calcium intake by large amounts. For more on this subject, please see "Can you tell me what oxalates are and in which foods they can be found?"

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. For more on this subject, please see "What are purines and in which foods are they found?"

Nutritional Profile

Spinach is an excellent source of vitamin K, vitamin A (in the form of carotenoids), manganese, folate, magnesium, iron, copper, vitamin B2, vitamin B6, vitamin E, calcium, potassium, and vitamin C. It is a very good source of dietary fiber, phosphorus, vitamin B1, zinc, protein, and choline. Additionally, spinach is a godo source of omega-3 fatty acids, niacin, pantothenic acid, and selenium. While this mixture of conventional nutrients gives spinach a unique status in the antioxidant and anti-inflammatory department, it is the unusual mixture of phytonutrients in spinach that "seals the deal" in terms of its antioxidant and anti-inflammatory components. In terms of flavonoids, spinach is a unique source of methylenedioxyflavonol glucuronides, and in terms of carotenoids, its difficult to find a more helpful source of lutein and zeaxanthin. The epoxyxanthophyll carotenoids neoxanthin and violaxanthin are also welcomed constituents of spinach leaves.

For an in-depth nutritional profile click here: Spinach.

In-Depth Nutritional Profile

In addition to the nutrients highlighted in our ratings chart, an in-depth nutritional profile for Spinach is also available. This profile includes information on a full array of nutrients, including carbohydrates, sugar, soluble and insoluble fiber, sodium, vitamins, minerals, fatty acids, amino acids and more.

Introduction to Food Rating System Chart

In order to better help you identify foods that feature a high concentration of nutrients for the calories they contain, we created a Food Rating System. This system allows us to highlight the foods that are especially rich in particular nutrients. The following chart shows the nutrients for which this food is either an excellent, very good, or good source (below the chart you will find a table that explains these qualifications). If a nutrient is not listed in the chart, it does not necessarily mean that the food doesn't contain it. It simply means that the nutrient is not provided in a sufficient amount or concentration to meet our rating criteria. (To view this food's in-depth nutritional profile that includes values for dozens of nutrients - not just the ones rated as excellent, very good, or good - please use the link below the chart.) To read this chart accurately, you'll need to glance up in the top left corner where you will find the name of the food and the serving size we used to calculate the food's nutrient composition. This serving size will tell you how much of the food you need to eat to obtain the amount of nutrients found in the chart. Now, returning to the chart itself, you can look next to the nutrient name in order to find the nutrient amount it offers, the percent Daily Value (DV%) that this amount represents, the nutrient density that we calculated for this food and nutrient, and the rating we established in our rating system. For most of our nutrient ratings, we adopted the government standards for food labeling that are found in the U.S. Food and Drug Administration's "Reference Values for Nutrition Labeling." Read more background information and details of our rating system.

In-Depth Nutritional Profile for Spinach

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. 2004. PMID:15333710.
• Asai A, Yonekura L and Nagao A. Low bioavailability of dietary epoxyxanthophylls in humans. Br J Nutr. 2008 Aug;100(2):273-277. 2008.
• 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. 2004. PMID:15284371.
• 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. 2001. PMID:12950.
• Gates MA, Tworoger SS, Hecht JL, De Vivo I, Rosner B, Hankinson SE. A prospective study of dietary flavonoid intake and incidence of epithelial ovarian cancer. Int J Cancer. 2007 Apr 30; [Epub ahead of print]. 2007. PMID:17471564.
• genannt Bonsmann SS, Walczyk T, Renggli S et al. Oxalic acid does not influence nonhaem iron absorption in humans: a comparison of kale and spinach meals. Eur J Clin Nutr. 2008 Mar;62(3):336-41. Epub 2007 Apr 18. 2008.
• 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. 1997. PMID:12980.
• Lucarini M, Lanzi S, D'Evoli L et al. Intake of vitamin A and carotenoids from the Italian population--results of an Italian total diet study. Int J Vitam Nutr Res. 2006 May;76(3):103-9. 2006.
• Makiko I, Mutsuko T, and Takashi N. Influence of the Amount of Boiling Water on the Sensory Evaluation, Oxalic Acid and Potassium Content of Boiled Spinach. Journal of Cookery Science of Japan 2005, 38(4):343-349. 2005.
• Manach C, Scalbert A, Morand C, Rémésy C, Jiménez L. Polyphenols: food sources and bioavailability. Am J Clin Nutr. 2004 May;79(5):727-47. 2004. PMID:15113710.
• Morris MC, Evans DA, Tangney CC, Bienias JL, Wilson RS. Associations of vegetable and fruit consumption with age-related cognitive change. Neurology. 2006 Oct 24;67(8):1370-6. 2006. PMID:17060562.
• Okazaki K, Oka N, Shinano T et al. Differences in the metabolite profiles of spinach (Spinacia oleracea L.) leaf in different concentrations of nitrate in the culture solution. Plant Cell Physio. 2008 Feb;49(2):170-7. Epub 2007 Dec 17. 2008.
• Song W, Derito CM, Liu MK et al. Cellular antioxidant activity of common vegetables. J Agric Food Chem. 2010 Jun 9;58(11):6621-9. 2010.
• Tang G, Qin J, Dolnikowski GG et al. Spinach or carrots can supply significant amounts of vitamin A as assessed by feeding with intrinsically deuterated vegetables. Am J Clin Nutr. 2005 Oct;82(4):821-8. 2005.
• 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. 2005. PMID:15817266.
• 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. 2003.