Made a Bad Decision? Blame Cap'n Crunch

The decisions you make, and how well you negotiate, could very well be affected by what you had for breakfast.


That's the conclusion of a preliminary study out of the University of Luebeck, in Germany. It all boiled down – as so much in human nutrition does – to the mix of carbs and proteins.

The researchers observed that volunteers in the study were more likely to reject an unfair financial offer if they'd filled up on carbs that morning. However, if their morning meal's mix skewed more toward lower-carb/higher-protein, they were more inclined to take the money instead of having nothing.

What's the science? One researcher posits that people tend to have lower levels of an amino acid called tyrosine after a high-carb breakfast. Tyrosine is a critical component in the production of dopamine, which is part of the brain's "reward system." It is possible that a lower-carb/protein-rich meal might allow for higher levels of tyrosine, which in turn would reinforce the brain's reward pathway. The end result could render a person more accepting of a decision he might otherwise discount as "unfair.”

There were two phases to the study. In the first, 87 college studentsplayed a game that gave players the opportunity to either accept or reject a clearly unfair financial offer from an opponent. After the results were tabulated, the participants reported what they had had for breakfast. Unfair offers were rejected by 53 percent of people who'd eaten a high-carb breakfast, compared with only one-quarter of students who had eaten a lower-carb breakfast.

In phase two, 24 men were fed a controlled breakfast consisting of 80 percent carbs and 10 percent protein on the first day, and 50 percent carbs and 25 percent protein on the second day. The results – a greater likelihood to reject unfair offers after a high-carb breakfast – mirrored the first phase of the study.

It's worth noting that the study is very preliminary and ripe for improvement. For example, only men were tested, and a small sampling at that. Only levels of carbs and protein were tracked, leaving the role that fat plays still a mystery. And the conditions under which the study was conducted did not account for participants' long-term diet, which would influence their short-term response to a high- or lower-carb meal.

The study was published in the Proceedings of the National Academy of Sciences.