What we eat affects how we feel, and vice versa. Why is that? What is the link between food and emotion? A study of taste perception and of interactions between the stomach and the brain has been launched to explore this link in greater detail.
Food is known to affect our mental state, for instance eating can make us happy. “Conversely, it is noticeable that, when we are stressed, we unconsciously modify our dietary pattern and eat more fast-acting carbohydrates. There is clearly an interaction between events in our stomach and in our brain. Our understanding of how this works is improving all the time”, says senior scientist Victor Kallen.
How does it work
Thus the interaction between diet and mental state operates in both directions. On the one hand, emotions such as stress, despair and euphoria affect our food choices at a subconscious level. Secondly, food has an impact on how we feel. “There is an interaction between food, the microorganisms in our intestines (microbiota) and the brain”, says microbiologist Bart Keijser.
It is not yet entirely clear exactly how the relationship between our mental state and our intestinal microbiota operates. It is based on several different interactions. “Our brain contains nerve cells (neurons) that communicate with each other via neurotransmitters. Intestinal bacteria produce certain neurotransmitter-like substances that have a direct effect on brain function. Our immune system and vagus nerve (one of the cranial nerves) play an important part in the indirect interactions between intestinal bacteria and our brain. Conversely, stress seems to have a direct effect on our intestinal microbiota. As people experience stress, there is a change in the composition of their intestinal microbiota, caused by a ‘feedback loop between the brain and the intestines’,” Dr Keijser explains.
“Food has an impact on how we feel”
Aside from interactions between the stomach and the brain, another topic that is being investigated is ‘taste experience’. Why does one person think that a particular food or drink is delicious, while someone else does not? “If you get a group of people to taste something, some of them won’t like it. Each of us experiences taste in a different way”, explains Bart Keijser.
Receptors on the tongue are just one of the factors that determine how food tastes, and this can also have a genetic background. For instance, some are better able to perceive a bitter taste than others. Moreover, bacteria in our mouth affect our perception of taste.“Taste receptors appear to be directly involved in our immune system. These receptors are not only located in the mouth, they are also found in the lungs, where they secrete substances that detect bacteria and can trigger an immune response. Who knows, the taste receptors in our mouth may also be able to do more than simply sense food, they could be directly involved in maintaining oral health.
TNO is cooperating with a number of partners in the field of taste experience. For instance, the Kikkoman company is interested in the perception of taste. “This is an important subject for us, and for other food producers. It is always difficult to know how consumers will react to new products, which is why we launched this cooperative venture. In addition to simply asking consumers for their views about a given product, we hope to use various other methods (e.g., pulse rate, brainwaves) to measure – and to better understand – their response”, says Daisuke Kaneko from Kikkoman.
The question is, how can taste preference and perception be objectively measured and, by extension, more effectively tested in future. Dr Kallen points out that “In the future, it would be interesting to take account of cultural differences as well, since the French and Germans, for example, have different preferences (sweet soy sauce and salty soy sauce, respectively).”
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