Why we eat what we eat: one (molecular) perspective

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Don’t feel alone if when you’re feeling sluggish, your taste buds tell you to choose a chocolate bar over a plateful of cruciferous vegetables. When we need energy, we’re all biologically wired to prefer sweet and fatty over bitter — at least, that’s what I’ve learned in my Molecular Basis of Taste class over the past few weeks.

Our professor, Gabriella Morini, helped us decode the language of taste. We learned about how our taste buds are considered by some scientists to be the primary factor in what we choose to eat — taste can override matters of cost, convenience, and health. When presented with a choice, we eat what tastes good to us, and those preferences were established long before culture and marketing started telling us what to eat.

Professor Morini explained that taste is a chemical sense, developed so that humans could recognize what was safe to eat and discern toxic substances. Humans can detect five primary different tastes: sweet, salty, umami (savory/meaty), bitter, and sour. Fatty doesn’t have taste receptors all its own, but it is also an important taste indicator for humans. Some of these tastes are invitations to eating: they tell the brain that food is safe and good for us. Other tastes are warnings that deter us from eating further.

So that chocolate bar? When we feel its sweet, buttery, fatty flavors on our tongues, our taste receptors send signals to keep eating — sugar and fat are important sources of energy. If the chocolate bar also contains salt and shards of bacon, all the better: we like salt because it is important for metabolizing food, and umami because it signals that the food contains amino acids. But that plate of kale? Its pungent, slightly bitter flavor can turn us off — bitter sensations warn us that the food might be toxic for humans. Some bitter compounds, though, are very healthful for humans. They can contain polyphenols, which often have an antioxidant effect (think red wine and black tea).

The language of taste was wired this way because up until recently, scarcity of food led us to develop preferences for energy-laden foods, i.e. those rich in fats and sugars. This has led to a globalized taste for fast food, which is salty, fatty, meaty, and sweet — everything but bitter. The problem now is that it is far too easy for us to obtain high energy foods, and we end up eating too much of the fats and sugars that our taste buds love. Our bodies are not well-suited to this Western diet abundant in fats and sugars — it is literally killing us.

So, our challenge as eaters is to rewrite languages of taste in a world of alimentary abundance. One way to do this is what Professor Morini calls “taste education” — retraining our taste buds to appreciate the sometimes bitter and pungent flavors of vegetables. We usually start developing a taste for some bitter things, like beer, coffee, and nicotine, in adolescence, so why not vegetables?

Children are even better suited to exercising their taste buds with vegetables. Introducing bitter foods early can help adjust taste preferences. Professor Morini says that parents should introduce initially disliked foods to children seven or eight times, and that it’s important to encourage children to try new or disliked foods when they are hungry. According to new research, mothers can even start writing their babies’ languages of taste in the womb, if they eat bitter foods during pregnancy. One challenge is getting the concept of taste education disseminated to the general public. I am hoping to work with some UNiSG students on a taste education initiative in Torino, where students partner with midwives to encourage women to eat bitter during their pregnancies.

[Professor Morini is a a chemist who can actually teach organic chemistry to a room full of novices. She reminded me of why I loved studying chemistry in high school, and why I chose chemistry to fulfill my natural sciences requirement in college. For more on Professor Morini, click here.]

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