Is Spinach a Good Source of Iron? Cooked Better Than Raw?

Touted as a high iron food, spinach jumped to center stage when it appeared in every episode of Popeye the Sailor Man from 1930s to 60s. So, should Popeye stick to eating his canned spinach? Or should he eat it raw?

Iron Content: Raw Spinach vs. Cooked Spinach

Spinach is a source of non-heme iron, which is found in vegetable sources. Non-heme iron is not as bioavailable to the body as the heme iron found in animal products.

Plus, spinach shrinks like crazy once it’s cooked! For cup-to-cup comparison, you’re likely eating 5 times more spinach if you choose to eat cooked!

Cooking Spinach Helps Reduce Inhibitor Oxalate Content

Spinach contains an inhibitor³ called oxalic acid or oxalate⁴. Oxalate naturally binds with minerals like calcium and iron, making them harder for the body to absorb⁵. As oxalate is water-soluble, cooking spinach helps reduce the amount of oxalate, and can help unlock these iron absorption inhibitors and hence increase iron bioavailability. In other words, cooking spinach helps make iron more available to your body.

Remember, men need 8 mg of iron per day, while pre-menopausal women need 18 mg (pregnant women need 27 mg). So, cooked spinach does provide a significant source of iron!

Should You Stop Eating Raw Spinach?

No, unless you have kidney disease, or your doctor recommended you to avoid it. Oxalate is naturally present in many foods; whole grains such as buckwheat and amaranth, vegetables such as chard and rhubarb, beans, and nuts all contain oxalate. If you are going to eat spinach (raw or cooked) and other iron-rich foods, pair them with the following iron absorption enhancers:

• Meat, fish, or poultry
• Fruits: Oranges, orange juice, cantaloupe, strawberries, grapefruit, and other Vitamin-C-rich fruits
• Vegetables: Broccoli, Brussels sprouts, tomatoes, tomato juice, potatoes, and green and red peppers
• White wine

The Bottom Line

It turns out that Popeye made the right decision eating his canned cooked spinach. Certainly, we have more fresh produce available now than in the ’20s, when the cartoon was first created. As water-soluble vitamins are lost during boiling, the best way to cook spinach is steaming or dry cooking like microwave cooking or stir-frying.

Tell Us: How do you cook your spinach?

1. U.S. Department of Agriculture. “Spinach, raw” FoodData Central, SR Legacy, National Agricultural Library, https://fdc.nal.usda.gov/food-details/168462/nutrients. Accessed 15 July 2025. ↩︎
2. U.S. Department of Agriculture. “Spinach, cooked, boiled, drained, without salt” FoodData Central, SR Legacy, National Agricultural Library, https://fdc.nal.usda.gov/food-details/168463/nutrients. Accessed 15 July 2025. ↩︎
3. Noonan, S C, and G P Savage. “Oxalate content of foods and its effect on humans.” Asia Pacific journal of clinical nutrition vol. 8,1 (1999): 64-74. https://pubmed.ncbi.nlm.nih.gov/24393738/ ↩︎
4. Mirahmadi, Seyed Fazel et al. “High and low oxalate content in spinach: an investigation of accumulation patterns.” Journal of the science of food and agriculture vol. 102,2 (2022): 836-843. https://doi.org/10.1002/jsfa.11419 ↩︎
5. Salgado, Neuza et al. “Oxalate in Foods: Extraction Conditions, Analytical Methods, Occurrence, and Health Implications.” Foods (Basel, Switzerland) vol. 12,17 3201. 25 Aug. 2023, https://doi.org/10.3390/foods12173201 ↩︎