You don’t have to be a genius to like chocolate, but geniuses are more likely to eat lots of chocolate, at least according to a new paper published in the august New England Journal of Medicine. Franz Messerli reports a highly significant correlation between a nation’s per capita chocolate consumption and the rate at which its citizens win Nobel Prizes.
Building on research raising the possibility that the flavanols in chocolate may enhance cognitive performance, Messerli “wondered whether there would be a correlation between a country’s level of chocolate consumption and its population’s cognitive function.” Using the success of a country in winning Nobel Prizes as a surrogate for “the proportion with superior cognitive function” in a country, he analyzed the relationship between the number of Nobel laureates per capita in a country with that country’s per capita chocolate consumption.
Messerli reported “a close, significant linear correlation (r=0.791, p<0.0001) between chocolate consumption per capita and the number of Nobel laureates per 10 million persons in a total of 23 countries.” The relationship was even stronger when Sweden, the home of the Nobel Prize, was removed from the calculations, as it appeared to have won more Nobel prizes than expected based on its chocolate consumption. Switzerland, on the other hand, “was the top performer in terms of both the number of Nobel Laureates and chocolate consumption.” (It should perhaps be noted at this point that Messerli, a hypertension expert who lives in New York City, was born in Switzerland and reports in his disclosure statement that he consumes chocolate daily, “mostly but not exclusively in the form of Lindt’s dark varieties.”)
Messerli duly points out that correlation does not prove causation, but, he writes, “since chocolate consumption has been documented to improve cognitive function, it seems most likely that in a dose-dependent way, chocolate intake provides the abundant fertile ground needed for the sprouting of Nobel laureates. Obviously, these findings are hypothesis-generating only and will have to be tested in a prospective, randomized trial.”
Regarding Sweden’s status as an outlier, Messerli writes that “one cannot quite escape the notion that either the Nobel Committee in Stockholm has some inherent patriotic bias when assessing the candidates for these awards or, perhaps, that the Swedes are particularly sensitive to chocolate, and even minuscule amounts greatly enhance their cognition.” Messerli also raises the possibility that reverse causation may explain the main finding, “that is, that enhanced cognitive performance could stimulate countrywide chocolate consumption.”
Sanjay Kaul provided the following comment to CardioBrief:
This article highlights, with a touch of whimsy, caveats that challenge the interpretation of findings of observational studies. From the use of surrogate endpoints (based on biological plausibility and the results of preclinical studies) to the distinction between correlation and causation, confounding (whether the effect size is too large to be explained away by confounding), and the hypothesis-generating nature of the inferential process. Careful consideration of these issues is likely to help navigate through the labyrinth of misinformation and disinformation these types of studies are particularly prone to generating.
A randomized controlled trial is warranted to validate the hypothesis raised by this study. The pressing question, in my opinion, is who would sponsor such a study – the chocolate makers or the Nobel Committee?