How bitter becomes sweet: It's all in your head

Food has taken on a flavor that is much more than the tastes it elicits

Maria Isabel Garcia

3:0:0am September 2, 2018

8:41:11am September 1, 2018

I only eat halaya (a delicacy made mainly of ube or purple yam) when it is shaped like a big fish. Yes, a big fish. My mother is a great cook. When we, her children, were growing up, she made everything from materials that were as "original" as possible: giant fishballs from actual fish that she would steam and flake; crab omelet from crabmeat that she would tease out of crabs she bought from the market, steam and flake, and put back in their shells; and yes, halaya from ube that she would buy from people who harvested it.

(This is most probably the reason why I do not like fastfood.)

So when she would make halaya, she would layer it on her fish-shaped container and make additional dents for additional scales to make it look even more like a fish. Why anyone would mass produce fish-shaped containers for halaya is something that my research skills have not unearthed yet, but the bottomline is, my brain could really only accept halaya when it is shaped like a fish. Shaping halaya like a fish does not affect its "halaya-ness." It is still ube. But the story I have attached to ube has made it my own unique halaya, and it is this particular "swimming" halaya that mattered to me.

Food has taken on a flavor that is much more than the tastes it elicits. We all know this from experience. This is why culture is unthinkable without food. This is also why our personal histories are also written in steaming bowls of noodles, in dripping barbeques, in fresh bursts of leaves and aromas, and in indulgent sugar castles that take on every form. So knowing that there are so far 5 basic tastes that have been discovered – sweet, sour, salty, bitter, and umami (savory) – is only part of the story of why we eat what we eat.

But first, let's get on the same page about the 5 basic tastes. The 5 basic tastes are basic not because of a marketing ploy to get you to think that there is an inviolable natural law behind it. Basic taste means that each of the 5 tastes corresponds to a bunch of brain cells that when you taste a complicated dish, your brain is able to tease out any of the 5 basic tastes that make up that dish. In other words, each of the 5 tastes have a matching bunch of neurons that can identify it. So when you hear that umami is a conspiracy plot of food companies like Ajinomoto to get you to buy their product, that is fake news. It is, in fact, a myth that scientists have been trying to dispel for over 20 years. Umami is the 5th basic taste, and your brain has specialized cells that can identify it (as it can the other 4 basic tastes), whether you eat Ajinomoto products or not. No other tastes have yet been scientifically confirmed to join this gang of 5. There have been studies on neurons for identifying the taste of fat, but whether we can call this the 6th basic taste or not is still in the "waiting room" of science.

So now that we know we have brain cells that can identify tastes, and that we actually have feelings for food, science has also been figuring out how our brains reflect this experience when we eat. Do we have another matching set of brain cells that attach a "pleasure value" to the foods that we eat? Last May, a published study in Nature tested this idea.

The mind comes to be because of brain cells connecting with each other, forming networks. The kind of connections that are formed define the relationships of the things that we experience. For example, your network for daydreaming is different from your network when you are actively engaged in something. Thus, for this study, the scientists looked at the connections between the bunch of brain cells that can identify taste with the bunch of neurons for associated emotions that they suspected are activated when tastes are identified. They decided to home in on the amygdala to find these. The amygdala is like the "Emotion Highway Express" of the brain – a very good neighborhood to start when it comes to looking for "emotional cells" that are activated when we identify tastes.

The study tested these connections on the brains of mice by testing them with bitter and sweet tastes. They did this by manipulating the connections of the brain cells that can identify these tastes (in the cortex) with their corresponding emotional network (in the amygdala), and the results were fascinating.

When the connections were turned on, the mice who were drinking only water behaved as if they were tasting sweet and bitter. This shows that you can be tricked into tasting something in all its flavorful glory (taste and emotions) if the connections between those neurons in the cortex and amygdala were turned on.

But what if these specific connections were turned off? The study found that the mice were still able to identify the sweet and bitter tastes but did not behave with matching attraction or aversion. This implies that we can taste food without attaching any emotional value to them if our taste identification and emotional cells which make up our "food experience network" do not connect. We can, based on this study, "mindlessly" eat.

Even more interesting is that the study found that the brain can be tricked into judging bitter food as the attractive one and sweet food as the repulsive one by manipulating the cortex and amygdala connections. This proves again – as it has been proven countless times by our reaction to fake news – that our brains can be easily fooled. This implies that maybe there is something we could do to temper our appetite for things that we indulge in and conversely, to boost our appetites for food that we do not care for but our bodies require.

While the scientists did this study with optogenetics which makes use of light to activate embedded modified cells to be light-sensitive, this opens up other questions. Could this manipulation be done naturally, i.e., with experiences? Could we now design experiences that would modify or even radically change the way we experience food?

I think this kind of science is the deeper arena we should look into as resources dwindle and other life forms dwindle because humans eat everything. Should we start looking into ways to make us, at least, temporarily averse to eating dishes made from endangered species so we can give these creatures a break? The study I discussed here was on the quality of the experience of food, but I also think it touches on quantity. If our brains always associate pleasure with certain foods that we indulge in them en masse, you cannot help but think of humans eating the planet away. How can we make our brains recognize enough for the sake of our own personal health and the planet's?

Anthony Bourdain was right. The greatest meals of our lives are such because of context and memory. And about 100 billion of us humans who have ever lived and are living now have been eating the planet away. Could context and memory, as the cortex-amygdala pathways show, restore the planet and ourselves with it? – Rappler.com

Maria Isabel Garcia is a science writer. She has written two books, "Science Solitaire" and "Twenty One Grams of Spirit and Seven Ounces of Desire." You can reach her at sciencesolitaire@gmail.com.