Here's a nutritional inkblot test: When you look at an orange and consider its healthfulness, do you think about it as a whole food or do you think about its vitamin C? A creative new study published in the Journal of Health Psychology suggests that most of us think of the latter, and that even though looking at nutrients instead of foods is common, it's also problematic.
Americans have long been barraged with information about specific nutrients and micronutrients in foods. We're told to love bananas for their potassium, for instance, instead of for the many other compounds and fiber that make the whole food so healthy. But that's missing the nutritional forest for the trees, says Jonathon P. Schuldt, author of the new study and assistant professor of communication at Cornell University. "When we go through our everyday lives, we get conflicting nutritional advice," he says. "Even though more nutrition experts are really emphasizing that we eat whole foods that have nutrients embedded in their natural contexts, these results suggest that when it comes to perceptions of long-term disease outcome, nutrients still hold a lot of sway in people’s judgments."
To find out to what extent people think that nutrients—and not the foods they come from—help stave off disease, Schuldt rounded up more than a hundred people and asked them to judge a fictional man's risk for disease. The study participants read a description about a fictional man named Steve Thompson: a young, healthy middle-class American who enjoys cooking, playing poker and hitting the local pub. For half of the group, however, the last paragraph about Steve was different. Half of the people read about Steve’s diet rich in healthy nutrients—potassium, omega-3 fatty acids, vitamin C, calcium and iron—while the other group read about his diet rich in whole foods—bananas, fish, oranges, milk and spinach. (The whole foods, you’ll notice, correspond to their most prominent nutrients.)
They were then asked to judge how healthy Steve was, compared to the average American. They also estimated Steve’s likelihood of five diet-related diseases: heart disease, diabetes, stroke, cancer and obesity.
Those who learned that Steve had a diet rich in healthy nutrients (like omega-3s) rated his risk for all diseases, but not obesity, lower than those who learned that Steve ate a lot of whole foods (like fish). And those with higher test scores were more likely to value nutrients over food than students with lower test scores—possibly because they'd be more attuned to scientific links between things like omega-3 fatty acids and heart disease.
The findings may help explain why the supplement industry is so profitable, while simple fruits and vegetables struggle to make their way to the plates of Americans. "The whole industry is built on this idea that there are studies out there linking vitamin C to healthy outcomes, and therefore you should just eat vitamin C," Schuldt says. "What we lose there is the fact that we should probably be eating oranges. One cannot live off of vitamin C alone."