Research suggests that eating a breakfast low in carbohydrates could make you a happier and more tolerant person.
A study, conducted by the University of Lübeck in Germany, found that people who ate fewer carbohydrates for breakfast were more likely to make forgiving decisions in a game they played later.
It is thought that the increased tolerance is due to low-carb meals being higher in protein, which stimulates the release of dopamine in the brain.
For years, medical advice has promoted a diet based on starchy carbohydrates such as pasta, potatoes and bread, however people are increasingly turning towards low-carb diets.
Protein consumed in food affects amino-acid levels, in particular one that is a precursor to dopamine release; following this discovery, and knowing that dopamine is a key part of decision-making, Soyoung Park and her team wondered whether a low-carb diet would impact people’s behaviour.
In order to test their theory, people were asked to take part in the “ultimatum game”, which saw people split into pairs, with one given money and the power to decide how much to share.
If the offer is accepted, both participants would receive the cash, but if the offer is rejected then neither participant would receive anything.
Logic would dictate that all offers should be accepted, as even a small amount of money is better than none at all. Despite the logic however, many people rejected the lower offer.
Park says that this is down to a desire to ‘punish’ those who do not split money fairly, even if it impacts negatively on themselves.
“It’s trying to punish cheaters and is supposed to foster a good society,” she says.
Park’s team asked 87 participants what they had eaten for breakfast that morning, and then got them to take part in the game. They found that those who had eaten a low-carb breakfast were considerably more likely to accept ‘unfair’ offers, with 76 per cent doing so; just 47 per cent of the high-carb group took the offers.
Following this, the research group asked 24 people to come in for breakfast before taking part in the game over two different days. These volunteers were given either a high-carb meal or a low-carb meal, with them then switching to the other option for the next day.
This study once again found that people were more likely to accept lower offers after a low-carb meal, with around 40 per cent of ‘unfair’ offers accepted compared to around 31 per cent after a high-carb breakfast.
After taking blood samples from the participants, they found that a low-carb meal increased the levels of tyrosine, a compound that is the precursor to dopamine.
It is speculated that dopamine may cause these behavioural changes because it acts as a reward signal, and people that had higher dopamine levels following breakfast may have been more satisfied by the lower offer.
There are other possible explanations for accepting lower offers though, as it is the rational thing to do. Regardless of the reason however, there was a clearly link between diet and behaviour.
Bahador Bahrami of University College London says that although this study did show a clear link, it is unclear as to whether it would still be evident in other situations.
“This is a very specific probe of human cost-benefit analysis. We need the same to be shown in a number of other social decisions,” he says.