Nutrition experts have long warned about the health risks associated with eating too many ultra-processed foods, including obesity, cardiovascular disease and diabetes, while encouraging people to choose more natural foods. But how do shoppers decide whether a food is natural? New research from the UBC Sauder School of Business suggests many consumers use a surprisingly simple clue: shelf life.

The study, Naturalness against environment-friendliness: The impact of shelf life on food perceptions and purchase decisions, found that consumers tend to view foods with shorter shelf lives as more natural and healthier, even when shelf life is not a reliable indicator of either. At the same time, products with longer shelf lives are often seen as more environmentally friendly because they are less likely to be wasted.

In one experiment, participants compared potato chips with five-month and nine-month shelf lives. They rated the five-month chips as more natural and healthier, while viewing the longer-lasting chips as better for reducing food waste. In another experiment involving pasta sauces, nearly 70 per cent chose the sauce with a one-year shelf life when researchers emphasized naturalness. When environmental protection was emphasized, only 43 per cent chose it.

The preference persisted even when researchers explained why a product lasted longer. Participants were told that one mayonnaise had a longer shelf life solely because of a high-performance seal, yet those focused on naturalness still preferred the shorter-lasting product. Similarly, when two granola bars had almost identical ingredients and nutritional information, consumers continued to favour the one with the shorter shelf life.

Researchers believe consumers are using shelf life as a mental shortcut for judging naturalness. “We provide ingredient lists. We provide nutritional facts. But it’s a lot to process,” explains UBC Sauder Associate Professor Dr. Yann Cornil, who co-authored the study with Dr. Dan Liu of Jinan University and Dr. Xiaobing Xu of Hainan University. Instead, shoppers may rely on cues such as shelf life, packaging and marketing.

The findings are particularly relevant as ultra-processed foods make up a substantial portion of modern diets. Roughly 46 per cent of Canadians’ daily caloric intake comes from ultra-processed foods, compared with about 55 per cent in the United States. Dr. Cornil says consumers increasingly associate “natural” foods with healthiness and often assume that products lasting longer have undergone more processing.

While that assumption can sometimes be correct, it is not always so. Advances in packaging can significantly extend shelf life without changing a food’s ingredients or nutritional value. “Foods with a longer shelf life could be just as good, and just as healthy and natural,” says Dr. Cornil. Yet consumers may still avoid them because they associate longevity with artificial processing.

That perception can have unintended environmental consequences. By choosing foods with shorter shelf lives, consumers may increase the likelihood that products spoil before they are eaten, contributing to unnecessary food waste. The researchers say the study demonstrates a tension between consumers’ desire for natural foods and their environmental goals, while highlighting how strongly shelf life can influence purchasing decisions—even when shoppers are given information showing that their assumptions may be misleading.

More information: Dan Liu et al, Naturalness against environment-friendliness: The impact of shelf life on food perceptions and purchase decisions, Journal of Consumer Psychology. DOI: 10.1002/jcpy.70034

Journal information: Journal of Consumer Psychology Provided by University of British Columbia