Superfood Spotlight: Spinach

Originating in central and southwestern Asia, spinach (Spinacia oleracea) is a leafy green flowering plant that grows annually and is of the Amaranthaceae family, just like beetroot and chard.1–3 Similar to its relatives, spinach has a mild, bitter, and somewhat salty taste. There are three types of spinach: savoy, semi-savoy, and smooth leaf. A spinach plant can grow up to 30 centimeters in height,3 and its leaves can be anywhere from 2 to 30 centimeters in length and 1 to 15 centimeters in width.3 Spinach was introduced to the United States by people from Spain during the eighth century.2

 
HIGH FIBER CONTENT

Spinach contains high amounts of insoluble fiber. Increased intake of fiber has been correlated to lowered recurrence of colon polyps and an overall reduced incidence of colon cancer.4–7 Fiber stimulates butyrogenic activity in the gut microbiome, which has antineoplastic properties, protecting the colon from tumor development.4–7 The insoluble fiber found in spinach provides the gut microbiome with an energy source while helping to keep things moving along efficiently in the gastrointestinal track. Fiber is particularly beneficial to those who suffer from constipation; irregular bowel movements allow prolonged contact between carcinogens in the stools and the gut wall.6,7 Fiber helps regulate blood sugar, aids in digestion, and has anti-inflammatory properties.4–7 Lower levels of tumor necrosis factor-alpha (TNF-a) and interleukin-6 (IL-6), pro-inflammatory immunity cells (cytokines) that signal immune/inflammatory responses, have been reported in those who maintain a higher intake of fiber.5–8

LOADED WITH ANTIOXIDANTS

The abundance of vitamin C, kaempferol, and quercetin in spinach combats oxidative stress that can occur throughout the body in reaction to lifestyle factors such as poor diet or smoking, metabolic diseases such as obesity, and/or environmental factors such as air or water pollutants.8,9 Oxidative stress can damage cells and tissue and trigger chronic systemic inflammation in the body, which in turn can promote the development of other chronic conditions, such as lung disease, diabetes, and cancer.10–12 The antioxidants in spinach can counteract the effects of oxidative stress.12 Vitamin C also plays a significant role in optimizing tissue and cell construction and iron absorption, destroying harmful pathogens, and boosting overall immune health.12

CONTAINS CANCER-PREVENTING COMPOUNDS

The monogalactosyl diacylglycerol and sulfoquinovosyl diacylglycerol components found in spinach can prevent cancer/tumor growth or slow its progression, according to data from clinical trials.13,14 Researchers have identified a positive association between increased spinach intake and reduced occurrence of prostate and breast cancers.13,14

IMPROVES AND MAINTAINS EYE AND HEART HEALTH

The plant pigments lutein and zeaxanthin, which provide many vegetables with their red, orange, or yellow color, have been linked to better eye health.15 Leafy green vegetables, such as spinach, are good sources of these pigments. These pigments are already located in human eyes, and consuming more spinach can boost their functions, including protection from sun damage and prevention of macular degeneration and cataracts.16,17 Moreover, higher intakes of spinach have even been reported to reverse pre-existing sun damage.15

Making a habit of integrating spinach into your meals can enhance overall heart health.3 Spinach is a good source of nitrates, which moderate blood pressure and can decrease heart disease risk.1–4 Spinach is also a good source of calcium, which influences the muscle walls of the heart (vascular contraction and vasodilation).18 Calcium is also responsible for the transmission of nerves, cellular signaling, and hormone secretion.18

BENEFITS COGNITIVE AND MUSCULAR FUNCTIONING

Spinach contains Vitamin K1 and folate, which are important nutrients for brain health. Vitamin K1 ensures the brain has enough calcium, exhibits anti-inflammatory effects, and improves cognitive performance. Folate is vital for fetal brain development and continues to play an important role in cognitive functioning throughout life.19,20 Folate deficiency can lead to cognitive dysfunction and has been linked to Alzheimer’s disease, depression, and even epilepsy.20

Spinach is also an excellent source of iron. Iron is an essential mineral due to its role in the oxygen delivery process and regulation of many biochemical reactions throughout the body.21 Iron deficiency can lead to anemia, muscular problems, fatigue, high blood pressure, mental disorders, and osteoporosis.21

SPINACH AND WORKOUTS26

Did you know the nitrates in spinach can help increase the effectiveness of your muscles during physical activity? Findings from a study published in Cell Press indicated that participants who were given a small dose of inorganic nitrate (the amount found in a few handfuls of spinach) over the course of three days required less oxygen while working out on an exercise bike. Consuming less oxygen while working out improves overall workout performance, researchers surmised. And, with the assistance of  “good” oral bacteria, dietary nitrites create nitric oxide in our bodies, a molecule that opens up blood vessels, which can lower blood pressure, allow more blood to be sent to muscles and tissue, and combat inflammation.27

EASILY PREPARED AND ADAPTABLE

Spinach is commonly purchased fresh (raw) or cooked (e.g., canned, frozen). Typically, fresh spinach is sold loosely or bunched in bags or containers and has a shelf life of approximately eight days. However, purchasing frozen or canned spinach can increase its shelf life and preserve its folate and carotenoid content.22 There are numerous preparation methods for this hearty vegetable, including chopped (raw), steamed, sautéed, or blanched. Spinach can be added to soups, dips, burritos, and pasta dishes, or just function as a side dish. Often, fresh spinach serves as the foundation for a variety of salad and smoothie combinations. Plus, given its mild flavor, spinach effortlessly harmonizes with other reagents.

Editor’s Note: Due to high levels of calcium and oxalates, increased spinach intake could lead to the development of kidney stones, especially in those who are prone to the condition.23,24 The vitamin K1 in spinach might also impede blood-thinning medication.25 Consult with your healthcare provider prior to adding more spinach to your diet.

SOURCES

  1. Lewin J. Top 5 health benefits of spinach. Updated 17 FEB 2021.  https://www.bbcgoodfood.com/howto/guide/ingredient-focus-spinach. Accessed 4 APR 2021.
  2. New World Encyclopedia site. Spinach.  https://www.newworldencyclopedia.org/entry/Spinach. Accessed 4 APR 2021.
  3.  Encyclopedia Britannica site. Spinach. Updated 6 NOV 2020. https://www.britannica.com/plant/spinach.
    Accessed 4 APR 2021.
  4. Pahwa R, Singh A, Jialal I. Chronic inflammation. In: StatPearls [Internet]. Treasure Island (Florida):
     StatPearls Publishing; 2020.
  5. Mayo Clinic site. Nutrition and healthy eating.  https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/high-fiber-foods/art-20050948.
    Accessed 4 APR 2021.
  6. Kojima M, Wakai K, Tokudome S, et al. Bowel movement frequency and risk of colorectal cancer in a large cohort study of Japanese men and women. Br J Cancer.
    2004;90(7):1397–1401.
  7. Harvard Health Publishing site. Surprising sources of dietary fiber. DEC 2020.  https://www.health.harvard.edu/staying-healthy/surprising-sources-of-dietary-fiber.
    Accessed 4 APR 2021.
  8. Ocvirk S, Wilson AS, Appolonia CN, et al. Fiber, fat, and colorectal cancer: new insight into modifiable dietary risk factors. Curr Gastroenterol Rep. 2019 Dec 2;21(11):62.
  9. Valko M, Leibfritz D, Moncol J, et al. Free radicals and antioxidants in normal physiological functions and human disease. Int J Biochem Cell Biol. 2007;39(1):44–84.
  10. Aruoma OI. Free radicals, oxidative stress, and antioxidants in human health and disease. JAOCS. 1998(75):1–14.
  11. Maeda N, Hada T, Yoshida H, Mizushina Y. Inhibitory effect on replicative DNA polymerases, human cancer cell proliferation, and in vivo anti-tumor activity by glycolipids from spinach. Curr Med Chem. 2007;14(9):955–967.
  12. Kirsh VA, Peters U, Mayne ST,et al. 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):1200–1209.
  13. 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):887–892.
  14. Maeda N, Yoshida H, Mizushina Y. Spinach and health: anticancer effect. In: Watson RR, Preedy VR (eds.) Bioactive Foods in Promoting Health. Cambridge Massachusetts): Academic Press; 2010:393–405.
  15. Roberts RL, Green J, Lewis B. Lutein and zeaxanthin in eye and skin health. Clin Dermatol. 2009 Mar-Apr;27(2):195–201.
  16. Liu R, Wang T, Zhang B, et al. Lutein and zeaxanthin supplementation and association with visual function in age-related macular degeneration. Invest Ophthalmol Vis Sci. 2014 Dec 16;56(1):252–258.
  17. Vu HT, Robman L, Hodge A, et al. Lutein and zeaxanthin and the risk of cataract: the Melbourne Visual Impairment Project. Invest Ophthalmol Vis Sci. 2006 Sep;47(9):3783–3786.
  18. National Institutes of Health site. Calcium. https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/. Accessed 4 APR 2021.
  19. Alisi L, Cao R, De Angelis C, et al. The relationships between vitamin K and cognition: a review of current evidence. Front Neurol. 2019;10:239.
  20. Reynolds EH. Folic acid, ageing, depression, and dementia. BMJ. 2002;324(7352):1512–1515.
  21. National Institutes of Health site. Iron. https://ods.od.nih.gov/factsheets/Iron-Consumer/. Accessed 4 Apr 2021.
  22. Science Daily site. Storage time and temperature affects nutrients in spinach. 23 MAR 2005. https://www.sciencedaily.com/releases/2005/03/050323124809.htm. Accessed 4 APR 2021.
  23.  Marsh BM, Sathianathen N, Tejpaul R, et al. Public perceptions on the Influence of diet and kidney stone formation. J Endourol.
    2019 May;33(5):423–429.
  24. Nutrition Facts site. Kidney stones. https://nutritionfacts.org/topics/kidney-stones/. Accessed 4 APR 2021.
  25. Chang CH, Wang YW, Yeh Liu PY, Kao Yang YH. A practical approach to minimize the interaction of dietary vitamin K with warfarin. J Clin Pharm Ther. 2014 Feb;39(1):56–60.
  26. Eurekalert! Site. Want more efficient muscles? eat your spinach. 11 FEB 2011. https://www.eurekalert.org/pub_releases/2011-02/cp-wme012611.php. Accessed 4 APR 2021.
  27. Whitworth G. Is vasodilation good? 2 NOV 2018. https://www.healthline.com/health/vasodilation. Accessed 4 APR 2021.  

Latest Recipes

Sign up for NHR’s FREE E-Newsletter!

          • Receive notifications when a new issue of NHR is available
          • Get free recipes, tips on healthy living, and the latest health news
Email(Required)

Subscribe to NHR Print for only $18 a year!

Get unlimited access to content plus receive 6 eye-appealing, information-packed print issues of NHR delivered to your mailbox.