BABY'S FIRST CHOICES: New research suggests that if infants are exposed to more complex and healthful-tasting flavors, they might be more inclined to eat better later in life. Image: iStockphoto/Kobyakov
Our diets are unhealthy, that much is clear. Now, an increasing number of scientists and physicians wonder if our propensity for unhealthy, obesity-inducing eating might be tied to the food choices made during our first weeks and months of life. Indeed, the latest research indicates that what we learn to like as infants paves the way for what we eat as adults. If true, we might be able to tackle the obesity epidemic in a new and more promising way, one that starts with the very first spoonful.
Today, unfortunately, most of those early lovin' spoonfuls contain more sugar and salt than is nutritionally wise. A recent study in the Journal of Public Health found that 53 percent of processed baby and toddler foods lining supermarket shelves (at least in Canada) have an excessive number of calories from simple sugars, and 12 percent of them have too much sodium. The authors, noting how overindulgence on both of these nutrients is tied to cardiovascular disease and diabetes, suggest that early exposure to overly sweet or salty meals could promote a taste for these unhealthy ingredients in the future.
There are, of course, some very real, deeply rooted evolutionary affinities for salt and sugar. Basic tastes are largely hardwired, predetermined by genetics and our primordial drive to stay alive. In the wild most herbivores and omnivores have developed ways to quickly sort the good foods from the potentially harmful ones. Sugars in fruits, for example, are natural sources of energy. And because of that, animals have strong inclinations for—and receive great pleasure from—eating sweet foods.
Rather than focus on limiting the unhealthful aspects of diet, Gary Beauchamp, a biopsychologist and a leading expert on chemosensory science, prefers to study the promotion of good-for-you foods. Based on data he has collected in the past 40 years, Beauchamp thinks ''that complex multisensory flavor profiles—even more so than individual tastes such as sweet or bitter—are influenced by our experiences during the first few months of life." And if parents introduce healthful tastes and flavors, such as carrots or broccoli, early on, an infant will not only rapidly adapt, but will also develop a preference for these flavors that could persist for a lifetime.
To be clear, there is a marked difference between tastes and flavors. Tastes are one-dimensional, whereas flavors are multimodal. The five basic tastes (sweet, salty, sour, bitter and umami) activate specific receptors—the taste buds—of the sensory system, which map directly to cranial nerves. Flavors, on the other hand, arise when information from both the mouth and the nose is combined, and it can be difficult to tease out the contribution of the smells from the assortment of tastes that describe the essence of a flavor. Think about the experience of enjoying a glass of fine wine. Describing the vintage as sweet would be a disservice to the complexity of the liquid before you. While the taste of supple fruit may dominate the varietal, sweet does not exactly describe the flavors from the subtle vanilla undertones or the smoky oak finish. Nor does it explain the lush aroma that hits your nose as you sip.
Situated between the campuses of the University of Pennsylvania and Drexel University in West Philadelphia, the Monell Center is the world's only independent, non-profit institute studying the science of taste and smell. "Our hypothesis is that flavors associated with various vegetables, could be influenced by early exposure," says Beauchamp, who is the organization's director. So now he and his team are trying to figure out how exposure to certain tastes and flavors early in life influences the foods we choose to eat as we get older."
More of a bad thing
At first blush, it seems logical that increasing the amount of sugar in an infant's diet would cause the evolutionary drive to kick into high gear, intensifying his or her fervor for sweets. But even though science supports our evolutionary inclination for certain tastes, the evidence is mixed on whether altering exposure to individual tastes can trump the biological components.
Children do have an increased affinity for sweet foods compared to adults, presumably due to their nutritional needs required for active growth. But there has been little evidence to support the idea that increased sugar intake will affect preferences as an adult. "The liking for sweets," Beauchamp says, "is a particularly strong case where you [have] a very big biological component."
As we have developed an innate liking for sweet to get the energy we need, our reactions to other tastes have developed to protect us. Bitter tastes often signal a food might be toxic or poisonous, whereas a sour zing may hint that something has fermented or spoiled, both of which seem to be evolutionary aversions that kept foragers safe when dining in the wild.
Nevertheless, many plants that are good for us are quite bitter. Could our aversion to these tastes also be leading to health problems? In a 2010 review article, researchers at the Monell Center questioned whether over-consumption of bad foods is fully to blame for many diet-related health problems. Although most are quick to point the finger at high-sugar and salt diets as the causative agent for many diseases, the team wondered whether our decreased intake of bitter vegetables—those that are known to regulate the metabolic system—could be exacerbating the problems.