Story URL: http://news.medill.northwestern.edu/chicago/news.aspx?id=214244
Story Retrieval Date: 6/19/2013 1:10:58 PM CST
You may want to heed your mother’s advice to “drink your milk.”
Researchers in the Department of Neurology at Gloucester Royal Hospital in Gloucester, U.K. recently found a strong correlation between a country’s milk consumption per capita and its number of Nobel prize winners.
Sweden was found to have the highest correlation between Nobel prize winners and milk consumption, with 33 Nobel laureates and 340 liters of milk consumed each year.
China had the lowest number of Nobel laureates and the lowest milk consumption, 25 liters per year, of the 22 countries included in the study.
Researcher Sarah Linthwaite and colleagues from Gloucester obtained their data from the Food and Agriculture Organization of the United Nations Statistics and from an earlier study on chocolate consumption and the prize. Their results were published this week in the journal Practical Neurology.
However, there is a “ceiling effect,” or limit, to the association between drinking milk and winning Nobel prizes, said Linthwaite, head researcher on the study. After drinking approximately 300 liters of milk, the correlation between milk consumption and Nobel prize winners becomes weaker.
“You won’t win more Nobel prizes if you drink more milk,” Linthwaite said.
She added that the studies do not just apply to drinking milk, but also dairy products such as yogurt. She said there was one exception: butter.
The Gloucester researchers were inspired by a study by Dr. Franz Messerli, professor of medicine at St. Luke’s-Roosevelt Hospital in New York.
Messerli originally sought to examine how chocolate consumption could improve cognitive function. His nationality inspired him to study the correlation between chocolate consumption and Nobel prize winners.
“Being Swiss myself, I knew Switzerland had the highest chocolate consumption in the world per capita, and the highest number of Nobel prize winners,” Messerli said.
He found a strong correlation between chocolate consumption and production of Nobel prize winners. He said Vitamin D could account for both chocolate and milk’s beneficial effect on cognitive function.
“Milk and chocolate contain vitamin D, and vitamin D by itself has been shown to improve cognitive function,” Messerli said. “So vitamin D could be a common denominator.” His study appeared in the New England Journal of Medicine last October.
Common denominators, or third variables, play a large role in both the correlation of milk consumption and Nobel winners, and chocolate consumption and Nobel laureates, said Robert Hurley, post-doctoral researcher in cognitive neurology at Northwestern University.
“You can never say that ‘x’ causes ‘y,’ you can only say that they’re associated in some way,” said Hurley. “It might be that certain people who are healthier and drink more milk have better cognitive abilities, but you’re not looking at the third variable.”
James Dignam, professor of biostatistics at the University of Chicago, shared Hurley’s opinion that third variables in a study must be examined to determine causality.
“In observational studies, relating ‘x’ to ‘y’, there’s ‘u,’ a third factor. Once you account for the third thing, the correlation between the first two factors could go away.”
However, Dignam also said geography was an important factor in the studies’ findings. He said the Nobel prize’s Swedish origins could account for the high number of Northern European Nobel prize winners.
"Japan in the 1900s wasn’t industrialized yet, and Sweden and other northern European countries would have more scientific resources,” Dignam said. “Now, the countries might look similar in terms of education level and people engaged in science.”
Both Linthwaite and Messerli acknowledged that more research needs to be done to determine the role milk and chocolate consumption plays in cognitive function.
“I have not yet found the common denominator,” Messerli said. “I’m interested in the explanation and co-variants. There will be a follow-up.”
Linthwaite said those aiming for Nobel recognition might try this recipe: "Not only eat more chocolate but perhaps drink milk too: or strive for synergy with hot chocolate?"