MixedFoodLast updated: July 10, 2026

Spinach is exceptionally high in iron

Spinach does contain meaningful iron, but it is not exceptionally high compared with many other common foods, and a persistent legend attributes today's spinach reputation to a decimal-point error that historians of the claim have found little solid documentary evidence for. Spinach's iron is also less absorbable than iron from meat sources due to compounds that inhibit uptake.

Written by Iggy Pomp · Reviewed by Igor Pomper · Last updated July 10, 2026

What we know

Spinach has a long-standing reputation, reinforced by the cartoon character Popeye, as an exceptionally iron-rich food capable of imparting significant strength. Spinach does contain iron, and is a reasonably good plant source, but nutritional databases, including USDA FoodData Central, show its iron content, roughly 2.7 milligrams per 100 grams cooked, is comparable to or lower than many other common foods, including lentils, beans, tofu, and red meat, undermining the idea that spinach is uniquely or exceptionally iron-dense compared with typical dietary sources.

A widely repeated explanation for the exaggerated reputation claims that a 19th century German chemist misplaced a decimal point in a published iron measurement, inflating spinach's apparent iron content by a factor of ten, an error supposedly repeated for decades until discovered in the 1930s. This decimal-point story has been investigated by researchers and science historians, including a frequently cited 2010 analysis published in the British Medical Journal by Mike Sutton, who found no solid documentary evidence that such a specific transcription error actually occurred as commonly described; earlier iron measurement methods from that era were generally less precise and produced somewhat higher readings than later, more accurate analytical techniques for a variety of methodological reasons, but the specific, colorful decimal-point anecdote appears to be a later embellishment without a clearly traceable original source, similar in pattern to several other popular science legends.

Separately from the measurement-error story, there is a genuine and well documented nutritional distinction relevant to spinach's actual usefulness as an iron source: the type of iron matters. Iron exists in two dietary forms, heme iron, found in animal products like red meat, poultry, and fish, and non-heme iron, found in plant sources including spinach, beans, and fortified grains. Heme iron is absorbed by the body considerably more efficiently, typically cited at around 15 to 35 percent absorption, compared with non-heme iron, typically absorbed at only about 2 to 20 percent depending on other dietary factors, according to research reviewed by the National Institutes of Health Office of Dietary Supplements. Spinach specifically also contains oxalic acid (oxalates), compounds that bind to iron and further reduce its bioavailability, meaning the iron spinach does contain is absorbed even less efficiently than the already lower non-heme absorption rate would suggest on its own.

None of this makes spinach nutritionally unimportant; it remains a genuinely healthy vegetable, providing vitamin K, vitamin A, folate, and other beneficial nutrients and antioxidants, and it can meaningfully contribute to iron intake as part of a varied diet, particularly when consumed alongside vitamin C-rich foods, which measurably improve non-heme iron absorption, a pairing recommended by dietitians for exactly this reason. The accurate nutritional picture is more modest than Popeye's cartoon strength boosts suggest, but spinach is not nutritionally worthless as an iron source either; it is simply one moderate, less efficiently absorbed plant-based option among many, not an outlier food that towers over other common iron sources the way its popular reputation implies. Nutrition educators sometimes use the spinach story specifically as a teaching example in science literacy contexts, since it illustrates how an appealingly simple explanation, a single transcription error, can spread and persist even when the more mundane, methodologically varied explanation, older and less precise measurement techniques generally, is closer to what limited historical evidence actually supports.

Common claims

Spinach is one of the best dietary sources of iron.Misleading. Its iron is poorly absorbed due to oxalates; meat is far more bioavailable.
A decimal-point error caused the spinach iron myth.Partly supported. Historical evidence is mixed, but early nutritional data did overstate spinach iron.
Spinach has no useful nutritional value.False. Spinach is rich in folate, vitamin K, and antioxidants.

Evidence hierarchy

01USDA FoodData Central nutrient composition data for spinach and comparison foodsGovernment nutrient database showing spinach's iron content is moderate, comparable to or below several other common foods.02Spinach, iron and popeye: ironic lessons from biochemistry and history on the importance of healthy skepticism of claimsMike Sutton's investigation into the decimal-point legend, finding no solid documentary evidence for the commonly repeated version of the story.03NIH Office of Dietary Supplements Iron fact sheetComparison of heme versus non-heme iron absorption rates and the effect of oxalates on plant-based iron bioavailability.

Spinach is exceptionally high in iron

What we know

Common claims

Evidence hierarchy

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