Health Benefits of Spinach


Spinach

We all know the cartoon character Popeye, who is “strong to the finch (finish). The reason, as he puts it, “Cause I eats me spinach.” But did you know that spinach also fights inflammation; helps build healthy bones, relieves certain cardiovascular conditions, and reduces the risk of cancer, all at the same time? Not only is spinach one of the most nutritional vegetables on the planet, but it tastes good, too, that's if it's properly stored and prepared.

What Is Spinach?

Spinach is a leafy green vegetable of an edible plant in the Amaranth Family.  This is a group of plants which includes beets and quinoa. Spinach probably originated several thousand years ago in ancient Persia, and was introduced to countries all over, including India, China (where it became known as the “Persian vegetable”), the Arabian Peninsula, and on to Europe via Moorish Spain. A sixteenth-century queen of France named Catherine de' Medici, who was born in Florence, insisted on eating spinach at every meal, hence dishes made with this vegetable are now known as “Florentine.”

What Are the Key Nutritional Benefits of Spinach?

Spinach is proven to be an excellent source for a long list conventional nutrients. These include vitamin B2 (riboflavin), vitamin B6 (pyridoxine), folic acid, niacin, vitamin C, vitamin E, and the bone-building vitamin, vitamin K1. It contains calcium, potassium, manganese, and magnesium, as well as copper, zinc, and selenium. Spinach provides small amounts of heart-healthy omega-3 essential fatty acids, but not so many that they would tend to oxidize (excesses even of essential fatty acids are not always healthy). Spinach is also a good source of fibre and many of the amino acids the human body needs to build proteins.

In addition to the nutrients that are found in many other foods, spinach is one of the best sources of the antioxidants lutein and zeaxanthin, which are extremely important to eye health, especially in preventing cataracts and age-related macular degeneration, and the methylenedioxyflavonol glucuronides, 13 chemical compounds that function as anti-cancer agents . Spinach is also a source of two compounds related to beta-carotene, violaxanthin and neoxanthin (which the plant makes from violaxanthin). These compounds are what give plants an orange colour and can be converted by the human body into vitamin A.

What Health Issues Are Especially Responsive to Spinach?

Popeye was pretty smart. One of the reasons he could take a bruising from Bluto in every episode is because he ate his spinach. Every serving of cooked spinach he ate provided him with 1000% of the Recommended Daily Intake (RDI) of vitamin K1, an essential nutrient for bone health. Vitamin K1 regulates the osteoclasts, the cells that break down bone so it does not accumulate brittle areas.  It also removes damaged bone, so that they don't become more active than the osteoblasts, which are the cells that constantly create new bone as and when it's needed.

The probiotic bacteria in our intestines can convert vitamin K1 into vitamin K2, a compound that regulates the flows of calcium in the body, making sure that it goes into bones, where it is needed, but stays out of cholesterol deposits in the arteries, where it would be become potentially fatal.

Scientific studies have found that eating foods like spinach is actually better than drinking milk for maintaining healthy bones, especially in women, both young women and women who have past menopause. Several studies have found that consuming more spinach is linked to lower rates of occurrence of several types of cardiovascular disease, both high blood pressure and hardening of the arteries.

Other Health Conditions Directly Affected by Spinach

Cleft palate: In many cases, this devastating birth defect can be prevented by consuming folate during early pregnancy. Spinach is a good source of folate (folic acid) especially when it is consumed raw, stir-fried, or steamed.

Esophageal cancer: A study that followed the dietary patterns and health outcomes of 292,898 men and 197,904 women, found that those who ate the most spinach (about once a week, on average) had a 33% lower risk of esophageal cancer.

Gallbladder cancer: A study in India found that people who ate spinach three or more times per week were slightly more than 50% less likely to develop gallbladder cancer. (Amaranth, a plant related to spinach, offered even better protection).

Liver cancer: Flavonoids from spinach and peppers are associated with lower rates of progression for viral liver infection to liver cancer.

Prostate cancer: Aggressive cancerous tumours of the prostate are 24-78% less likely in men who eat more broccoli and spinach. Just one serving a week is enough to protect against this cancer.

Spina bifida: Like cleft palate, this birth defect is preventable by adequate consumption of folate from foods like spinach during pregnancy.

In the interest of accuracy, we also need to report three conditions where the consumption of spinach may be problematic:

E. coli: Outbreaks of E. coli are rare, but when there is an E. coli outbreak in the United States, often the culprit is found to be spinach (most outbreaks of E. coli in Europe have been traced back to sprouts). All that is necessary to get rid of the bacterium, however, is thorough washing (by placing the spinach in a sink or basin filled with water and agitating it thoroughly, then rinsing the leaves for a second time) or by cooking.

Kidney stones: Most kidney stones contain oxalates, and spinach contains oxalates. It would seem logical to limit consumption of foods that are high in oxalic acid, such as almonds, beet greens, bran, chocolate, rhubarb, spinach, strawberries, and tea. No study, however, has found that restricting the consumption of these foods increases the risk of kidney stones. Some studies have found that the consumption of leafy greens, peanuts, and tea, actually reduce the risk of kidney stones. The vitamin K in green leafy vegetables may be one reason vegetarians have a lower incidence of kidney stones. One study did find a 30% greater risk of kidney stones in men and a 34% greater risk of kidney stones in women, when more than two servings per week were consumed, but this would be equivalent to eating spinach every other day.

Where Does Spinach Fit in the Families of Vegetables?

In addition to beets and quinoa, spinach is also related to amaranth, sugar beets, and Swiss chard. Combining these vegetables in the same dish usually results in an excessively “earthy” flavour, but they are all delicious when eaten separately.

What Is the Best Way to Eat Spinach Raw?

Spinach, especially bunch spinach, requires special care both before and after purchase. Don't buy spinach that is yellow, wilted, or moldy. Don't buy bagged spinach with any water in the bag. This is usually a sign of spoilage.

Don't wash spinach as soon as you get it home. It is important to keep it as dry as possible in the crisper section of the refrigerator. If you store spinach in an open plastic bag, squeeze out as much air as possible. This isn't necessary if you buy prewashed spinach in a sealed plastic bag at the market. Most of the time the bag is filled with nitrogen to prevent spoilage, and the individual leaves have been washed several times before being carefully dried and  packed. Bagged spinach is nearly always higher quality that bunch spinach, unless you are purchasing it directly from the farmer or grew it yourself.

Washing Spinach

It is not necessary to wash bagged spinach, but it is necessary to wash bunch or loose leafs of spinach bought from a produce bin. Wash off visible mud or dirt under cold running water before placing the spinach into a large bowl of lukewarm water. Stir the leaves around with your hands. Next pour out the water and clean out any sediment at the bottom of the bowl. Wash the spinach one more time, or until there is no sediment left at the bottom of the bowl. Once it's thoroughly washed, dry the spinach with a salad spinner before adding it to salads, or use damp spinach directly in cooking.

Note: Do not let the spinach stand in water after the washing is done, or it will lose its nutritional value.

What Is the Best Way to Use Spinach in Salads?

A much-loved perennial favourite is the spinach and bacon combination. Serve wilting spinach with hot bacon and add lemony vinaigrette with a little salt and black pepper to taste. This is likely to be a huge hit with your non-vegan and non-vegetarian friends. Some higher-protein spinach salads also use boiled eggs and/or anchovies.

If you prefer a meat-free spinach salad, consider combining your spinach with some of these:

  • Avocado slices and mango chunks.
  • Bean sprouts, sliced mushrooms, and red onion.
  • Dried cranberries and toasted almonds in any tangy vinaigrette.
  • Frisée and tangerines.
  • Grapefruit and avocado.
  • Grapefruit and red onion.
  • Raisins, slivers of toasted almonds, chopped carrots, and quartered cherry tomatoes.
  • Shallots, black olives, sliced almonds, red peppers or paprika, red wine vinegar, and olive oil.
  • Sliced strawberries, chunks of avocado, crumbled Blue cheese, toasted pecans, and English peas or fava beans.
  • Tomatoes, cooked peas, and onion.

What Is the Best Way to Cook Spinach?

Don't steam spinach, boil it, and then discard the cooking liquid. Boiling spinach leaches out acidic compounds and creates a sweeter taste. Don't be concerned about nutritional losses. The lutein and zeaxanthin content of spinach actually increases when it is boiled, and the available calcium content increases nearly 800%.

Always boil spinach in a large pot, preferably about three quarts (three litres) of water for three ounces (84 grams) of leaf spinach. The water has to be boiling rapidly before the spinach is added, after which time it should only need to cook for one to two minutes, or until it is thoroughly wilted. Leaving the pot uncovered helps more oxalates escape from the leaves, so it is less likely to cause problems for those who are sensitive to them. Spinach should be removed from its cooking liquid the moment it's cooked, and the liquid should not be saved for future use in soups.

What Are Some Ways to Make Spinach More Interesting?

Spinach is a great accompaniment to some favourite meat entrees, notably steak and scallops. Eggs and spinach go together well in frittatas, omelettes, and even in scrambled eggs.

How Do I Get Kids to Like Spinach?

During the 1920s, 1930s, 1940s, and 1950s, Popeye the Sailor Man did wonders for American spinach consumption. Giant statues of this cartoon fictional character were erected, which soon became tourist attractions for his adoring young fans.

In the twenty-first century, however, something more than a cartoon character is needed to get kids interested in spinach. The single most important thing you can do to get your offspring attracted to spinach is to make sure you do not overcook it, or let it stand in cooking water. Sweeter spinach will be appreciated more. It also helps to “dilute” the taste in these kid-friendly ways:

  • Fruit smoothies: A little spinach probably won't even be noticed.
  • Green bread: Add spinach to your zucchini bread recipe.
  • Potato spinach casserole: Add a little chopped spinach instead of parsley to your favourite scalloped potato dish.
  • Spinach balls: These fried balls of spinach and Parmesan cheese are great for special occasions.
  • Spinach bars: Combine chopped spinach with cheese, milk, butter, onion, mushrooms, and flour to make a savoury green treat with one of children's all-time favourite foods, cheese.
  • Spinach casserole: Cover with gooey cheese.
  • Spinach dip: As long as your children don't eat too many chips, the net benefits of spinach dip and tortilla chips will be positive. You can make the dip from thawed frozen spinach, water chestnuts, mayonnaise, sour cream, and Knorr onion soup mix.
  • Spinach fritters: Make with spinach, matzo meal or cracker meal, egg, cheese, salt and pepper, and a little baking powder. Kids will eat them like the proverbial pancakes.

If you children are into sports, simply point out an important fact about the benefits of spinach. Tell them their muscles work much better when they eat it!

Muscles are powered by mitochondria. These energy-producing centers found in every muscle cell are especially suited for generating energy, with or even without a ready supply of oxygen.

One of the fuels muscle mitochondria can use when they don't have enough oxygen, meaning when you work out really hard, is inorganic nitrates (that is, nitrates that aren't bound to carbon, even though they are found in food), such as the nitrates in spinach. The difference for muscles provided with the nitrates from spinach is a little like the difference between a conventional car and a hybrid. The hybrid can go a lot farther with a lot less fuel, and so can muscles of young athletes who eat their spinach.

How Long Does Spinach Keep?

Fresh spinach keeps for five days at most and only then if it is stored in a dry condition. Bagged spinach seldom lasts longer than the printed expiration date.

Cooked spinach dishes begin to ooze and generate acidic, bitter compounds, just 24 hours after cooking unless they are frozen. Frozen spinach and frozen spinach dishes generally taste good for one to two months.

Tips for Frugal Use of Spinach

Don't be afraid to use frozen spinach in cooking. It is a great deal less expensive than fresh spinach, it won't spoil, and it actually has a higher nutritional content than when fresh. A serving of frozen spinach offers 18,921 International Units (IU) of vitamin A, while a serving of fresh spinach offers only 2,813 IU. A serving of frozen spinach contains 580 micrograms of vitamin K, while a serving of fresh spinach contains only 145 micrograms. A serving of frozen spinach provides 117 mg of magnesium, 540 mg of potassium, 0.9 mg of zinc, 0.2 mg of copper, and 9.4 micrograms of selenium, while a serving of fresh spinach provides only 24 mg of magnesium, 167 mg of potassium, 0.2 mg of zinc, no measurable copper, and 0.3 micrograms of selenium.

The freezing process “unlocks” between 5-30 times more micronutrients from frozen spinach than are found in fresh.  If it's really the nutrition you want, skip fresh spinach, and cook from frozen.

References

Anonymous. Want More Efficient Muscles? Eat Your Spinach. Science News. 4 February 2011.

Freedman ND, Park Y, Subar AF, Hollenbeck AR, Leitzmann MF, Schatzkin A, Abnet CC. Fruit and vegetable intake and esophageal cancer in a large prospective cohort study. Int J Cancer. 2007 Dec 15; 121(12): 2753-60.

Fujii H, Noda T, Sairenchi T, Muto T. Daily intake of green and yellow vegetables is effective for maintaining bone mass in young women. Tohoku J Exp Med. 2009 Jun; 218(2): 149-54. PMID: 19478471.


Giaconi JA, Yu F, Stone KL, Pedula KL, Ensrud KE, Cauley JA, Hochberg MC, Coleman AL; Study of Osteoporotic Fractures Research Group. The association of consumption of fruits/vegetables with decreased risk of glaucoma among older African-American women in the study of osteoporotic fractures. Am J Ophthalmol. 2012 Oct; 154(4): 635-44. doi: 10.1016/j.ajo.2012.03.048. Epub 2012 Jul 20. PMID: 22818906.

Iritani N, Nogi J. Effect of spinach and wakame on cholesterol turnover in the rat. Atherosclerosis. 1972 Jan-Feb; 15(1): 87-92.

Kirsh VA, Peters U, Mayne ST, Subar AF, Chatterjee N, Johnson CC, Hayes RB; Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Prospective study of fruit and vegetable intake and risk of prostate cancer. J Natl Cancer Inst. 2007 Aug 1; 99(15): 1200-9. Epub 2007 Jul 24.

Lagiou P, Rossi M, Lagiou A, Tzonou A, La Vecchia C, Trichopoulos D. .Flavonoid intake and liver cancer: a case-control study in Greece. Cancer Causes Control. 2008 Oct; 19(8): 813-8. doi: 10.1007/s10552-008-9144-7. Epub 2008 Mar 19. PMID: 18350370.

Rai A, Mohapatra SC, Shukla HS. Correlates between vegetable consumption and gallbladder cancer. Eur J Cancer Prev. 2006 Apr; 15(2): 134-7.

Shohag MJ, Wei Y, Yu N, Lu L, Zhang J, He Z, Patring J, Yang X. Folate content and composition of vegetables commonly consumed in China J Food Sci. 2012 Nov; 77(11): H239-45. doi: 10.1111/j.1750-3841.2012.02939.x. Epub 2012 Nov 5. PMID: 23127121.

Taylor EN, Curhan GC. Oxalate intake and the risk for nephrolithiasis. J Am Soc Nephrol. 2007 Jul; 18(7): 2198-204. Epub 2007 May 30. PMID: 17538185.

 

 


About Andy Williams

Andy Williams has a Ph.D. in biology and a strong interest in health and nutrition. The Paleo Gut web site was created to explore the health benefits of the Paleo diet and see how it is changing lives. Also, get our free daily Paleo Gut newspaper delivered to your inbox. Please feel free to contact me and let me know about your Paleo experiences or favorite recipes.

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