Scientists talked about the effects of coffee on the intestines and brain
Coffee can affect not only alertness, but also the functioning of the intestines and brain. Researchers from University College Cork have found that regular consumption of the drink is associated with changes in the composition of intestinal bacteria, metabolism, mood and some cognitive functions. How coffee can interact with the intestines and the brain is described in the Izvestia article.
Coffee has been linked to mood changes
The study involved 62 people who were equally divided into two groups — regular coffee drinkers and those who did not drink it at all. The researchers classified participants who drank three to five cups of a drink a day as regular consumers. The work was published in the journal Nature Communications.
At first, the participants who regularly drank coffee completely stopped drinking it for two weeks. During this period, the researchers assessed their psychological state several times, as well as took samples of biological materials. After that, coffee was returned to the diet, and the participants did not know whether they were receiving a regular caffeinated or decaffeinated drink.
After coffee was reintroduced into the diet, both groups showed lower rates of perceived stress, depression, and impulsivity compared with the period of abstaining from the drink. This indicates that some mood changes may be related not only to the effects of caffeine.
When the coffee disappeared, the intestines reacted
The researchers found particularly noticeable changes in the participants' metabolic profile after two weeks without coffee. Metabolites are small molecules that are formed or changed during metabolism. Intestinal microorganisms can also participate in their formation.
After coffee returned to the diet, scientists found differences in the composition of the intestinal microbiota. In particular, regular coffee drinkers had more Eggertella sp bacteria. and Cryptobacterium curtum. The first group of microorganisms can participate in the processes associated with the formation of acids in the gastrointestinal tract, and the second - in the exchange of bile acids. The scientists also found more representatives of the Firmicutes group.
According to the researchers, such changes may be part of a mechanism linking coffee consumption with the functioning of the intestines and brain. However, the authors do not claim that the bacteria found directly cause changes in mood or cognitive abilities.
The intestines and the brain exchanged signals
The scientists examined the results through the prism of the "gut—brain" axis, a two—way communication system between the microorganisms of the digestive tract and the nervous system.
Signals between the gut and the brain can be transmitted in several ways: through immune responses, hormones, the nervous system, and chemical compounds produced by microorganisms. Therefore, changes in the microbiota can potentially affect processes related to mood and cognitive functions.
John Cryan, Chief Researcher at the APC Microbiome Ireland Research Center at University College Cork:
Public interest in intestinal health has increased significantly. The relationship between digestion and mental health is also becoming better understood, but the mechanisms of coffee's effect on this gut—brain axis remain unclear.
Data from a new study shows that coffee can change not only the composition of intestinal bacteria, but also what substances they produce or use in metabolism. It is these changes that scientists consider as one of the possible elements of the connection between a drink and brain function.
Caffeine was not the only active ingredient.
Regular coffee and a decaffeinated drink produced different results on individual indicators. Improvements in learning and memory were observed only among participants who received decaffeinated coffee. The researchers suggest that this may indicate the role of other components of the drink. Coffee contains thousands of different chemical compounds, including polyphenols. They are able to interact with intestinal microorganisms and influence metabolic processes.
Caffeinated coffee, in turn, was associated with reduced anxiety, as well as improved alertness and attention. Thus, different components of the drink can potentially affect the body by different mechanisms.
John Cryan:
Our research shows the response of the microbiome and nervous system to coffee, as well as potential long-term benefits for microbiome health. Coffee can alter the collective activity of microbes and the metabolites they use.
However, the data obtained does not allow us to determine which component is responsible for each of the detected changes. However, the results show that it is not worth reducing the effect of coffee on the body only to caffeine.
Scientists are not yet ready to name coffee as the cause of the changes.
The authors of the study emphasize that the work does not prove a direct causal effect of coffee on mood, memory, or intestinal health. The study involved a small group of 62 people in total, so the results need to be tested on larger samples.
In addition, the work focused on short-term changes after quitting coffee and its subsequent return to the diet. Therefore, it is impossible to draw a conclusion about the long-term health effects of the drink.
John Cryan:
Coffee is not just caffeine, it is a complex nutritional factor that interacts with our gut microbes, metabolism, and even our emotional state. Our results show that coffee, both with and without caffeine, can affect health in different but complementary ways.
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