Humans don’t just eat for calories, but have ‘nutritional wisdom’ to seek micronutrients, study shows

Article content

Ordering a perfectly seared steak and fries or spooning creamy dal over rice could be a sign of something other than an enjoyable meal. Revolutionary new research suggests humans have “nutritional wisdom,” which helps us navigate the “hidden complexity” in food choices.

Article content

Food composition — not just a need for calories — plays into our preferences, according to a paper published in the journal Appetite. As has been shown in other animals, humans “seem to possess a discerning intelligence”: the ability to select foods based on their micronutrients (vitamins and minerals).

The international collaboration between University of Bristol psychology professor Jeff Brunstrom and author Mark Schatzker, Toronto-based writer-in-residence at the Modern Diet and Physiology Research Center (affiliated with Yale University) began with a shared curiosity and interest — but different points of view.

In 2018, Schatzker was in Florida giving a lecture on his book, The Dorito Effect, in which he counters the commonly held belief that humans seek food purely for the calories. After all, he points out, wild mushrooms and truffles are highly prized yet low in calories, and fruit widely enjoyed.

Article content

“If it’s just calories that turn us on, why do we pay so much money for wines from Burgundy, which have no more calories than an $8-bottle of red wine out of some crappy factory?” says Schatzker.

“I think there’s so much more to it. And I think the experience of eating suggests that it just can’t possibly be that simple.”

Brunstrom was intrigued by Schatzker’s presentation but skeptical. “I went to see him at the end and basically said: ‘Great talk, but I think you’re probably wrong. Do you want to test it?’”

Instead of sparking an argument, their differing opinions launched a four-year research project. As it turns out, the study supports Schatzker’s original proposition: Our mealtime decision-making is influenced, in part, by micronutrients.

Article content

Scientists tend to think of food choice as being governed by a single factor, says Brunstrom — whether an attraction to highly calorific foods or sweetness. But their research shows that it’s more nuanced than that.

“It demonstrates that food, cuisine, our interactions with food, are meaningful in the sense that it looks like we are seeking out complex interactions between micronutrients,” Brunstrom explains.

“It’s a bit of a game changer, I suppose, because it makes us recognize what chefs might have known all along. But as scientists, it should make us recognize that there’s a hidden complexity to food choice that we need to understand.”

Though other animals, such as livestock and rodents, are known to select foods for their micronutrients, little is known about how food composition sways human preferences.

Article content

In the 1930s, American pediatrician Clara Davis’ research on babies’ food choices suggested “nutritional wisdom”; Davis allowed a group of 15 babies to eat whatever they wanted from 33 food items. However, due to its methods — which would be considered unethical today — replicating it isn’t an option.

Demonstrating nutritional intelligence in humans is more complicated than in other animals, Brunstrom explains. While in rodents, for example, researchers can tightly control their environment and diet, the same isn’t possible for people.

Over video calls during COVID lockdowns, Brunstrom and Schatzker arrived at a new technique to home in on the influence of micronutrients.

“We hit upon this idea of, ‘Hang on. If people are showing nutritional intelligence, then maybe that’s exposed and expressed in combinations of foods — the foods that they prefer to pair together,’” recalls Brunstrom.

Article content

“And the moment we started to do that, and to look at the evidence that way, things started to come alive. And we started to see these sorts of patterns in these data.”

The paper presents the findings of three studies. For the first, adult participants chose between images of two pairs of fruits and vegetables (apple, banana, blackberries, carrots, celery and cucumber). Fruits and vegetables vary widely in their micronutrient composition, the researchers note, making them a better comparison than foods such as grains and meat.

They found “a significant tendency” for people to choose pairings that offered both greater amounts of micronutrients and a better balance (‘micronutrient complementarity’).

To confirm their findings, Brunstrom and Schatzker ran a second image-based study, with different foods, followed by a third, real-world study.

Article content

In analyzing a national U.K. nutrition survey of 1,086 people, they found a similar pattern in two-component meals. The range of micronutrients in steak and fries or curry and rice, for example, was wider than would be predicted by chance. People also seemed to avoid excess micronutrients — “a form of foraging efficiency.”

Schatzker was especially interested in the subtlety revealed in the results.

“We’re not just looking for vitamins and minerals just for their own sake — hoovering them up. But there seems to be some added level of intelligence … to avoid excesses of one and make sure we get the full spread,” says Schatzker. “Which seems particularly intelligent, and a particularly efficient way of foraging, if you think about how we would have been in an evolutionary context.”

Article content

With its alternating focus on low-fat, high-protein and low-carb regimes in recent decades, diet culture tends to emphasize macronutrients (carbohydrates, fat and protein).

But people don’t choose carbohydrates, fat or protein, Brunstrom underscores — they choose food.

While they are important, “if we only focus on those macronutrients, then I think we arrive at an impoverished understanding of the underlying everyday interaction that we have with food,” says Brunstrom.

Article content

As their research shows, the way we interact with food is more complex than macronutrients or calories — and micronutrients potentially play a role in that complexity.

If we were only interested in meeting macronutrient needs, Brunstrom adds, we would simply eat mixtures of fat and sugar. Along with culture and conviviality, micronutrient content could contribute to our enjoyment of certain dishes.

“Food comes with it a whole set of beliefs, anticipation of the effects of food, a sense of enjoyment, a sense of occasion. All of these things are intimately bound up in the everyday experience of interacting with food,” says Brunstrom.

“And so I think it makes sense to ask questions about real foods. And about whether or not there are underlying patterns that govern the real foods that we consume.”

Article content

Brunstrom and Schatzker are both interested in understanding the cultural implications of nutritional wisdom. Recipes and cuisine, they say, may be one way nutritional intelligence is passed through generations.

“We know what combinations work and we share them. That’s one of the reasons we like to talk about recipes. We’re kind of in it for the flavour, but there’s something deeper going on,” says Schatzker.

“Maybe there’s a kind of wisdom in how we cook and the recipes that have been passed down from previous generations that we should pay more attention to. And I think that’s what our research will start to look at as a next move.”

The researchers present the possibility that though strong in other animals, nutritional wisdom could be diminishing in humans.

Article content

Today’s diets rich in processed products are markedly different from those of our evolutionary past. The foods we eat may have the hallmarks of nutritional value, says Brunstrom, but those sensory cues are the product of artificial flavourings and colourings.

“In a sense, then you’ve got a corruption of a system that would have otherwise conferred significant benefit, but now is being adopted perhaps by the food industry to generate foods that are attractive, but hold little nutritional value,” he adds.

In The Dorito Effect, Schatzker explores flavour and how animals use it as a guide to nutrition. The multi-billion dollar flavour industry puts additives in a wide range of food, including potato chips and soft drinks.

Article content

“If flavour has some connection to how the brain seeks out or finds value in food in terms of micronutrients, we could really be messing things up by adding these things to junk food,” says Schatzker.

“I think it’s obvious on some level that adding flavouring to junk food makes it more desirable. But it could be even worse in the sense that it appears we have this flavour-sensing ability for a very good reason.”

The conventional wisdom for many decades has been that humans evolved to seek energy-dense foods; we ensure a balanced diet by eating a range of different items.

Brunstrom and Schatzker’s research challenges the prevailing model of what drives our appetite.

“We tend to think of ourselves as these hungry, simple-minded apes that come out of the womb on a lifetime mission just to stuff our faces with calories. And I think that’s wrong,” says Schatzker. “That can seem right when you look at some of the disordered eating, but there are so many cultural counterexamples to that.”

He references his recent book, The End of Craving: Northern Italy, with its widely appreciated cuisine, has an obesity rate of less than 10 per cent.

The paper is just the beginning, Schatzker adds — a new “opening volley” in an age-old discussion. “There might actually be some rays of light that are exciting, and reasons to be hopeful and think that there’s a good way out of our predicament.”

When it comes to eating in a complicated world, we may be smarter than we thought.