New German research has found that introverts may be more likely to be vegetarian than those with a more extroverted personality.
Carried out by researchers at the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS) along with the University Hospital of Leipzig, the new study looked at 8,943 participants and assessed their personality traits and any symptoms of depression via questionnaires.
The participants were also asked to complete questionnaires on their diet, reporting on how often they had eaten certain animal products in the last 12 months -- from "several times a day" to "never."
The findings, published in the journal Nutrients, showed that following a vegetarian or vegan diet appears to be related to personality, with the participants who ate a predominantly plant-based diet more likely to be introverted, while those who mainly ate animal products were more likely to be extroverts.
"It is difficult to say what the reason for this is," says study leader Veronica Witte. "It could be because more introverted people tend to have more restrictive eating habits or because they are more socially segregated because of their eating habits."
However, despite previous studies finding an association between a plant-based diet and a more neurotic personality, the researchers found no such link. "Earlier analyses had found that more neurotic people were generally more likely to avoid certain groups of foods and to behave more restrictively. We focused here solely on the avoidance of animal products and could not observe any correlation," says Witte.
Previous studies have also found that a predominantly plant-based diet is associated with depressive moods, although again, the researchers failed to find any correlation between the two factors. "It is possible that in previous analyses other factors had blurred the results, including the BMI or conspicuous personality traits that are known to be associated with depression. We accounted for them," said Witte.
The researchers did find another association though. The results showed that the lower the amount of animal products in a person's diet, the lower their body mass index (BMI) on average, which the researchers say could be due to a plant-based diet also having a lower proportion of heavily processed foods.
Moreover, eating predominantly primary animal products such as meat, sausage and fish, tends to be linked with a higher BMI than eating mainly secondary animal products, like eggs, milk, dairy products, cheese and butter.
"Products that are excessively rich in fat and sugar are particularly fattening. They stimulate the appetite and delay the feeling of satiety. If you avoid animal foods, you consume fewer such products on average," explains Evelyn Medawar, first author of the study. She adds that the dietary fibers found in vegetarian food have a positive effect on the microbiome in the intestine, which also increases feelings of satiety (fullness). "People who eat predominantly vegetable foods may therefore absorb less energy," says Medawar.