Our brains often misjudge which foods impact the planet most

Consumers routinely over- or underestimate the environmental impact of common foods. In a study of 168 adults, scientists traced these errors to two underlying cognitive shortcuts.

The findings from the University of Nottingham suggest that simple, standardized labeling could bridge the gap between perception and scientific reality.

How the research worked

Participants performed a digital card-sorting task that covered 44 common supermarket items. They then viewed product-level scientific impact estimates and reported whether any were higher or lower than expected.

“We created an online task to explore how people understand food’s environmental impact. Participants said they’d change future purchases after seeing which products had higher or lower impacts,” said Daniel Fletcher, a postdoctoral researcher at the University of Nottingham.

The published study confirmed two hidden dimensions in the way people sorted foods. It also measured changes in participants’ stated purchasing intentions after the surprises were revealed.

Hidden patterns in food thinking

People split foods by animal or plant origin. They also sorted by level of processing, from simple staples to ready to eat snacks.

To map those judgments, researchers used multidimensional scaling, a statistical technique that positions similar items closer together. The technique showed clear separation by origin and by processing level.

Packaging and factory steps often loom large in memory. Farming impacts like feed, manure, and enteric methane are less obvious during a quick shop.

These dimensions also feel qualitatively different to many people. When harms seem unlike one another, comparing a sausage to a soda becomes a judgment call rather than a calculation.

When instinct gets food wrong

Participants often overestimated the environmental cost of highly processed snacks. They underestimated foods tied to scarcity-weighted water use – a measure of water demand adjusted for local stress levels.

Nuts and rice were common blind spots, and many participants were surprised that beef carries a much higher footprint than chicken.

A global analysis shows that ruminant meat far outpaces poultry across emissions and land use, helping explain the surprise many participants reported.

The UK product-level dataset integrates ingredient lists and four indicators to score items. It highlights how water stress can dominate for nuts and rice, while processing adds less than people assume.

Measuring food’s real impact

Environmental impact estimates come from life cycle assessment, a cradle to grave method that adds up resources used and pollution created. It sums what happens from farm inputs through packaging, transport, and retail.

Four indicators typically matter most for food systems. Those are greenhouse gas emissions, land use, eutrophication, and water stress.

This approach helps make sense of confusing trade offs. For example, a snack can be unhealthy yet still carry a lower environmental score than cheese.

In this project, scientists showed people a focused set of the lowest and highest scoring products after the sorting task. That design made it easier to notice mismatches between guesses and scientific estimates.

Labels will not solve every barrier to sustainable eating. They can, however, align intuition with evidence at the moment of choice.

Helping shoppers go green

The results suggest people struggle to compare meat with highly processed plant foods. A single front-of-pack grade from A to E could make cross-category choices easier.

A systematic review finds that environmental labels can nudge selection and purchasing in controlled tests. Designs that compress multiple impacts into one clear score are easier to use.

Broader context matters, too. An international commission links healthier, more plant-based diets with lower pressure on land and water.

If a label uses one common scale across categories, trade-offs become clearer at a glance. The same grade can appear on cheese, nuts, biscuits, and tea without sending mixed signals.

The road ahead for labels

These results come from UK shoppers working with images and summaries on a screen. Real-world choices include price, habits, and culture, which can blunt good intentions.

Scientific impact estimates also focus on the path to the store and often exclude cooking and disposal. Even so, the main signals here point to agriculture and water stress as the drivers that matter most.

The sample was modest in size and drawn from a single country. Cultural food norms, supply chains, and farming systems vary widely, so replication will be useful.

Water impacts also depend on where and when crops are grown. A nut orchard in a dry basin tells a different story from one in a rainy zone.

The study is published in the Journal of Cleaner Production.

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