Truth be told, there is iron in spinach, but not significantly more than in other green vegetables, and few people can consume spinach in large quantities. A larger problem with the idea of spinach as a good source of iron, however, is that it also contains substances that strongly inhibit the intestinal absorption of iron (see e.g. Garrison, 2009: 400). Simply put, spinach should not at all be the first food choice of those suffering from iron deficiency.
...
We find the following in Hamblin (1981):
The discovery that spinach was as valuable a source of iron as red meat was made in the 1890s … German chemists reinvestigating the iron content of spinach had shown in the 1930s that the original workers had put the decimal point in the wrong place and made a tenfold overestimate of its value. … For a source of iron Popeye would have been better off chewing the cans. (p. 1671)
The myth about the iron content of spinach was not born in the 1930s, as told by Larsson. The decimal point error was made 40 years earlier, but was disclosed in the 1930s, and Hamblin makes it perfectly clear that he himself was not the one who made the discovery. The third, and greatest surprise is not immediately clear from the quote above: Hamblin does not provide a reference to support his claim that a decimal point error actually was made; nor does he give any names, dates, or other information that could help us verify how the error was made and by whom, or who should be credited for its discovery and correction.
... [D]espite the vagueness and complete lack of documentation that characterize Hamblin’s account of the decimal point error, the story has been picked up by numerous authors who have redistributed it through journal articles and books, turning it into a full-blown and still blooming academic urban legend.
...
Sutton (2010b) argues convincingly that there were entirely other reasons, such as contamination during the analysis or the confusion between fresh and dried spinach, that caused the exaggerated figures in the 19th century. He also criticizes Hamblin for perpetuating another related misconception: that Popeye was created in order to promote spinach for its iron content. According to Sutton (2010a: 13–14), Elzie Crisler Segar had an entirely different nutrient, vitamin A, in mind when he invented Popeye and contributed to a massive increase in spinach consumption in the United States during the 1930s.
...
Bender’s suggestion about a possible decimal point error has now turned into an assertion linked to a specific year, two decades earlier than Hamblin’s purported date. But again, the statement still lacks a reference or any other type of documentation. It is therefore difficult to know if Bender’s (1982) increase in certainty could be a result of his own more thorough investigations on the issue or whether he had been influenced by Hamblin’s (1981) article. A third possibility is that Bender’s gradual change of wording, consistently without any precise documentation, could be a consequence of a common human weakness which allegedly has a particularly high prevalence among anglers telling stories about their past catches.
Bender and Hamblin have not just provided us with examples of how even top-level academics can sometimes be careless in their attitude to references and documentation. These publications between 1972 and 1982 have also given us an excellent opportunity to study the birth of an academic urban legend and to explore the micro dynamics behind the often dramatic outcomes of the whisper game. The decisive moment was most likely when Bender’s ‘appears to have been’ became replaced by Hamblin’s assertive statement. In other words, Hamblin had certainly heard about the decimal point error from someone, but accidentally turned Bender’s suggestion into a piece of fact, which then was blessed with the stamp of reliability associated with British Medical Journal.
...
When academics plagiarize from each other, whether it is an idea or a reference, a single (and highly erroneous, as in this case) interpretation will appear as two or more mutually independent statements, reinforcing the reliability or truth value of each other in a way that is entirely undeserved. This is likely an important part of the explanation behind the fact that some academics no longer find it necessary to refer to a source when telling the story about the decimal point error. In the past 30 years, a large number of apparently independent sources have mutually confirmed the ‘fact’ that a decimal point error was made, whether it was in 1870, in the 1890s, or in the 1930s. Nothing indicates that the decimal point error ever was made, but the account about it will most likely live a long and colorful life, just like its parent myth, the belief that spinach is a good source of iron.
From the article:
...
...
...
...