Two cups of raw spinach (about 60g) delivers over 240% of your vitamin K, half your vitamin A, and a meaningful dose of lutein for under 15 calories. Its dietary nitrates help lower blood pressure. Pair it with vitamin C or fat to absorb the iron and carotenoids.
Nutritional Snapshot (per 100g raw)
Active Compounds & How They Work
Lutein & Zeaxanthin — Eye Protectors
Spinach is one of the richest dietary sources of lutein and zeaxanthin, carotenoids that accumulate in the macula of your eye and filter damaging blue light. In the landmark AREDS2 trial, supplementation with lutein and zeaxanthin reduced progression to advanced age-related macular degeneration in people with low dietary intake.1 Food sources like spinach remain the preferred first-line approach.
Dietary Nitrates — Natural Blood Pressure Support
Spinach is one of the highest-nitrate vegetables (roughly 500–900mg per 100g fresh weight). Dietary nitrates convert to nitric oxide in the body, dilating blood vessels and reducing blood pressure. Nitrate-rich vegetable intake is consistently associated with lower blood pressure and fewer cardiovascular events in cohort studies.2
Folate & Vitamin K — The Quiet Workhorses
Folate supports DNA synthesis and is critical in pregnancy for preventing neural tube defects. Vitamin K1 activates proteins involved in blood clotting and bone mineralization — population studies link higher vitamin K intake with stronger bones and fewer fractures.3
Health Benefits by Condition
Eye Health
Higher dietary intake of lutein and zeaxanthin is associated with a lower risk of cataracts and age-related macular degeneration. One serving of spinach provides roughly 6–12mg of lutein+zeaxanthin — squarely in the range associated with protection in observational studies.4
Blood Pressure & Heart Health
Beyond nitrates, spinach delivers potassium (558mg per 100g cooked), magnesium, and fiber — a mineral trio with established blood-pressure benefits. Controlled studies of nitrate-rich vegetables show measurable blood pressure reductions within weeks.2
Bone Health
Spinach combines vitamin K1, calcium, magnesium, and vitamin A — all involved in bone metabolism. While its high oxalate content reduces calcium absorption somewhat, the overall package still supports bone health as part of a varied diet.3
Energy & Anemia Prevention
Spinach provides non-heme iron plus folate and vitamin C — a combination that supports red blood cell production. The vitamin C in the leaf itself (28mg per 100g) actually enhances absorption of its own iron. Cooking concentrates the iron per serving.5
The Oxalate & Absorption Caveats
Spinach is high in oxalates, which bind calcium and iron and can contribute to kidney stones in susceptible people. Practical workarounds:
- Pair with vitamin C — a squeeze of lemon on spinach salad boosts non-heme iron absorption several-fold
- Add a fat source — carotenoids (lutein, beta-carotene) are fat-soluble; dress salads with olive oil
- Blanch or steam — brief cooking reduces soluble oxalates by 30–50% and concentrates nutrients per bite
- Rotate your greens — alternate spinach with lower-oxalate options like kale, arugula, and bok choy
Kidney stones: If you've had calcium oxalate stones, talk to your doctor about portion size and preparation — boiling and discarding the water removes the most oxalate.6
Best Ways to Eat Spinach
1. The Daily Big-Bowl Salad
Two to three cups raw with olive oil, lemon juice, and a protein source. Raw preserves vitamin C and folate (both heat-sensitive), while the oil and lemon solve the absorption problem.
2. Lightly Wilted, Not Boiled to Death
Throw a handful into hot pasta, soups, or stir-fries in the last 60 seconds. Brief heat softens oxalates while keeping texture and most folate intact.
3. The Green Smoothie Trick
Blend raw spinach with citrus or kiwi — the vitamin C dramatically increases iron absorption, and the fruit masks the grassy flavor. Two handfuls disappear into a smoothie almost undetectably.
4. Frozen Chopped Spinach
Frozen spinach is blanched before freezing, which reduces oxalates, and it's remarkably cheap per serving. Squeeze out the water and add to curries, frittatas, and dals.
Safety & Side Effects
- Blood thinners: Spinach's very high vitamin K directly counteracts warfarin. If you take warfarin, keep spinach intake consistent day-to-day and coordinate with your prescriber7
- Kidney stones: High oxalate content makes large daily servings risky for people prone to calcium oxalate stones
- Thyroid function: Raw spinach contains goitrogenic compounds. Normal servings are fine; people with hypothyroidism on iodine-sufficient diets don't need to avoid it, but cooking reduces the concern further
- Pesticide residue: Spinach tops the EWG's Dirty Dozen list — strongly consider organic
Related Guides
References
- Age-Related Eye Disease Study 2 Research Group. Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: the AREDS2 randomized clinical trial. JAMA. 2013;309(19):2005-2015.
- Bondonno CP, et al. Vegetable nitrate intake, blood pressure and incident cardiovascular disease: Danish Diet, Cancer, and Health Study. Eur J Epidemiol. 2017;32(9):811-822.
- Fusaro M, et al. Vitamin K, bone fractures, and vascular calcifications in chronic kidney disease: an important but poorly studied relationship. J Nephrol. 2011;24(4):385-392.
- Ma L, et al. Lutein and zeaxanthin intake and the risk of age-related macular degeneration: a systematic review and meta-analysis. Br J Nutr. 2012;107(3):350-359.
- Teucher B, Olivares M, Cori H. Enhancers of iron absorption: ascorbic acid and prebiotic carbohydrates. Eur J Clin Nutr. 2004;58(9):1168-1180.
- Chai W, Liebman M. Effect of different cooking methods on vegetable oxalate content. J Agric Food Chem. 2005;53(8):3027-3030.
- Crowther MA, et al. Warfarin antagonism and vitamin K: the role of consistent vitamin K intake in managing anticoagulation. J Thromb Thrombolysis. 2000;10(2):141-146.