Was the Spinach-Iron Myth Really Caused by a Misplaced Decimal Point?
By now the spinach-and-iron story has a twist ending built in: yes, Popeye ate spinach for iron, but no, spinach isn't actually that rich in iron — someone misplaced a decimal point in a 19th- or early-20th-century measurement, inflating the number tenfold, and nobody caught it for decades. It's a satisfying correction, the kind that makes you feel like you've seen behind the curtain. We went looking for the decimal point itself. Nobody we found has ever produced one — including the two academics most responsible for making the story famous.
The claim
A 19th-century scientist misplaced a decimal point when recording spinach's iron content, inflating the published figure roughly tenfold; the error went uncorrected for decades, and it is the real reason spinach acquired its popular reputation as an unusually iron-rich vegetable.
Source trail
The trail has two layers, and most retellings only chase the first one. Layer one: nutritionist Arnold E. Bender floated the decimal-point idea, tentatively, in a 1972 lecture and a 1977 magazine piece. Hematologist Terence Hamblin then restated it as settled fact in a 1981 British Medical Journal Christmas article, and that's the version that spread through decades of textbooks, trivia columns and classroom asides. Layer two, much less repeated: criminologist Mike Sutton went looking for Bender's and Hamblin's actual sources starting around 2010, found neither could produce one, and traced the real 20th-century measurement discrepancies to ordinary bad lab technique instead of any single slipped decimal. A 2014 peer-reviewed paper by sociologist Ole Bjørn Rekdal, hosted on PubMed Central, independently covers the same investigation and is the closest thing to a primary account of the myth's own history that we could directly read.
What's confirmed
- The decimal-point idea traces to Arnold Bender, stated as a possibility, not a fact — a 1972 lecture followed by a 1977 magazine article, not a single source both later retellings agree on. Rekdal's 2014 paper, fetched directly via PubMed Central (checked 2026-08-22), attributes the phrase "the fame of spinach may well have grown from a misplaced decimal point" to Bender's 1972 inaugural lecture at Queen Elizabeth College, University of London, and describes it as a deliberately hedged suggestion, not an assertion. Mike Sutton's own account, fetched directly from his Dysology blog (checked 2026-08-22), separately dates the same idea's first appearance in print to a 1977 Spectator magazine piece by Bender — a different document than the 1972 lecture, five years later. Both sources point to Bender as the origin; neither points to the same document as the earliest written trace.
- Hamblin's 1981 BMJ article is the one that turned Bender's hedge into an accepted fact, and it was written as a joke. Per Rekdal's paper (PubMed Central, checked 2026-08-22), Hamblin's piece — titled "Fake!", a Christmas-edition article about fabricated academic claims — restated Bender's tentative wording as settled history. Rekdal's own framing: "The decisive moment was most likely when Bender's 'appears to have been' became replaced by Hamblin's assertive statement." The McGill University Office for Science and Society's account, fetched directly from mcgill.ca/oss (checked 2026-08-22), independently confirms the 1981 BMJ date and the "Fake!" framing, and adds that author Joe Schwarcz had himself repeated the decimal-point story in his own earlier writing before retracting it.
- When directly asked for his source, Hamblin couldn't produce one — and said so on the record. Rekdal's paper (PubMed Central, checked 2026-08-22) quotes Hamblin's reply to Sutton's inquiry: he was "sure he had not made it up" but could not remember where he had first read it, guessing it might have been Reader's Digest. Rekdal also quotes Hamblin's later public acknowledgment: "Thanks for pointing out my mistake of 29 years ago. I never could remember where I had first seen the decimal point story." Both quotes come from the same paper, not from us contacting Hamblin directly.
- Popeye's creator never had the character credit iron — the strip's own dated timeline names Vitamin A instead. CBR's dated review of the original strips, fetched directly from cbr.com (checked 2026-08-22), places the first spinach-for-strength joke on June 26, 1931, the first time Popeye is shown actually eating spinach for strength on February 28, 1932, and the strip's own explanation — "Vitamin A in spinach" — arriving by July 1932. The McGill OSS account above independently corroborates the vitamin A detail and adds that E.C. Segar's choice fit spinach's early-20th-century reputation as a vitamin-rich food, a separate and, on this evidence, more accurate reputation than the iron one.
- Spinach's reputation as iron-rich predates any single decimal-point incident by decades. A 2019 peer-reviewed paper by Michael Mielewczik and J. Moll, "Spinach in Blunderland," published in Annals of the History and Philosophy of Biology (volume 21, pages 61–142) and listed on the Rothamsted Research institutional repository (checked 2026-08-22), states in its own abstract that popular promotion of spinach as an iron-rich food dates to the 1850s — roughly two decades before the 1870 date Bender's account blames, and long before anyone claims a decimal point moved.
What isn't
- Nobody we found, including Sutton and Rekdal, has produced the actual text of Bender's 1972 lecture. Every account of it, including the two we cite above, quotes Bender's wording secondhand, through later papers and retrospectives — not from a transcript or recording of the lecture itself. We could not independently verify Bender's exact original phrasing.
-
What actually caused inflated early-20th-century iron readings for spinach is described,
not pinned to one paper we could read ourselves. Sutton's own blog summary states the
likely explanations are lab contamination and confusion between fresh- and dried-spinach weights,
crediting a 1907 analysis by chemist Henry Sherman. We could not read Sutton's underlying
peer-reviewed paper directly — the PDF hosted at Nottingham Trent University's institutional
repository (
irep.ntu.ac.uk) returned unreadable binary content to our fetcher rather than extractable text — so this detail rests on Sutton's own secondary summary of his research, not the paper itself. - Bender's own claimed source for the decimal error — a scientist he names as "Dr E. von Wolff," corrected in 1937 by a "Professor Schupan" — does not hold up under Sutton's checking, per Sutton's own account, but we could not verify this against Sutton's peer-reviewed paper directly for the same PDF-access reason above. Sutton's blog states the real data traces to a different, earlier scientist (Haensel, 1908), meaning Bender's own citation for his own claim was reportedly wrong — but this is currently a secondhand claim about a claim, and we are naming it as one rather than asserting it as independently confirmed.
- We could not read the full text of the 2019 Mielewczik and Moll paper — only its abstract, via the Rothamsted repository listing page. Its finding that the iron-rich reputation predates 1870 is reported here as the abstract states it, not checked against the paper's own underlying evidence, which we did not access.
Verdict
The specific mechanism — one scientist, one slipped decimal, one identifiable correction — has no documented source anyone has produced, including the two people most responsible for spreading it as fact. Bender floated it as a guess in 1972; Hamblin turned it into settled history in 1981 without a citation and later admitted, on the record, that he couldn't remember where he'd gotten it. What is solidly documented is almost the opposite of a tidy correction: real measurement errors did happen, ordinary bad lab technique explains them better than any single misplaced digit, and the belief that spinach is iron-rich predates the supposed decimal error by decades. The "decimal point" story debunks a real myth using a mechanism that is, on the evidence available to us, itself unverified — a myth about a myth, built the same way as the one it corrects.