Despite an avalanche of evidence pointing to the health and environmental benefits of plant-based diets, researchers have uncovered an unexpected obstacle preventing many of us from making any significant shift from meat and animal products.

In an experiment involving more than 7,300 participants, people were far more likely to choose the meat and dairy-free option if it wasn't referred to as vegan.

'Plant-based' labels didn't fare much better. Food with this label was chosen 27 percent of the time, compared to the food labeled vegan being chosen only 20 percent of the time.

"This labeling effect was consistent across socio-demographics groups but was stronger among self-proclaimed red-meat eaters," writes the team from the University of Southern California.

Led by decision psychologist Patrycja Sleboda, the researchers presented study participants with a choice between two gourmet food baskets; one with meat and dairy and one without.

Unknown to them, the individuals had been randomly assigned into five experimental conditions where the meat and dairy-free basket was labeled vegan, plant-based, healthy, sustainable, or healthy and sustainable.

Regardless of the experimental conditions, the meat and dairy basket was chosen most of the time. However, in the groups where the meat and dairy-free basket had been labeled "healthy and sustainable", the vegan option was chosen a lot more often (44 percent) than those actually labeled "vegan" (just 20 percent).

The study took place online, so it may only reflect online shopping choices, but the results reflect the cultural resistance against veganism seen broadly within the wider community. Anti-vegan groups have sprung up across the internet and the bias against vegans is so strong only those stigmatized with drug-use disorders elicit the same degree of negativity.

Yet at the same time, multiple studies suggest most regular consumers of meat do actually support the health, environmental, and ethical principles behind veganism. What's more, there's no denying the wealth of evidence pointing towards clear health benefits including weight loss, reduced blood pressure, lower diabetes risks, and heart problems across different ethnic groups.

Psychologists suspect these irrational contradictions are a consequence of trying to placate our cognitive dissonance – when your beliefs don't align with your actions. This specific form has been termed moral schizophrenia – such as the conflict between eating meat and knowing that veganism is more sustainable.

So vegans make us uncomfortably aware of our own internal contradictions. For this we resent them.

"[Moral] rebels are resented when their implicit reproach threatens the positive self-image of individuals who did not rebel," Stanford University psychologists concluded in a 2008 study.

As a consequence of this widespread anti-vegan bias, some researchers suggest that instead of focusing on hardline veganism, encouraging flexitarianism – a reduction but not complete elimination of animal products – is a more attainable and sustainable goal. Merely reducing meat still has health benefits without requiring a quantum leap into a meat-free lifestyle.

Early signs suggest shifting focus to health and environmental benefits work.

This also leaves room for those of us with dietary health conditions that make strict plant-based diets difficult to achieve.

Findings from Sleboda and her team's study suggest a practical step towards universally improving our food choices.

"Labels provide a low-cost intervention for promoting healthy and sustainable food choices," the researchers conclude.

This research was presented at the Society for Risk Analysis 2023 Annual conference and has been published in the Journal of Environmental Psychology.