The brain and gut are connected, why we should take probiotics

Have you ever experienced a slight pain in your stomach right before an exam or an important presentation, due to sudden tension and stress? Conversely, when you suffer from irritable bowel syndrome or chronic constipation, don't you feel depressed and irritable? Why does stress on the brain affect the gut, and why do intestinal problems adversely affect the brain?

Relationship between gut and brain

The gut is nicknamed the "second brain." This is because the gut can also make neurotransmitters such as serotonin and dopamine, which play an important role in regulating emotions. In particular, it is estimated that 90% of serotonin is secreted from the digestive tract.

On the other hand, the gut and brain can influence each other. According to the gut-brain axis, which states that the gut and brain are connected, these two organs are connected by a long vagus nerve, which allows them to exchange biochemical signals with each other.

In fact, when the brain is stressed, the gut is also affected. When our brain encounters a problem, it releases various hormones such as epinephrine, estrogen, and serotonin in a fight-or-flight response, which sends a warning signal to the gut and makes us feel sick to our stomach.

Conversely, the brain is also affected by the gut. The feeling of satiety is a prime example. Twenty minutes into the meal, the microbes in your gut produce proteins that can suppress your appetite. This is said to coincide with the time when people begin to feel full.

Brain Health and Lactobacillus

So, can we use the "gut-brain axis theory" to positively influence each other? There is a presentation by Harvard Medical School on this. Lactic acid bacteria not only have a positive effect on intestinal health, but also on our brain.

In fact, studies have shown that probiotics can help improve mood and cognition, as well as reduce stress and anxiety. Alzheimer's patients who consumed milk made from four species of lactobacillus for 12 weeks scored better on tests measuring cognitive ability compared to a control group that drank regular milk, and women who ate probiotic yogurt twice a day for four weeks were calmer when exposed to images of angry or surprised faces than the control group.

A 2018 study by the global scientific journal Science raised the possibility that gut microbes can directly affect processes in the brain. As a result of analyzing the RNA sequences of bacteria in the brains of cadavers, they were able to find three types of bacteria that are commonly present in the intestines.

Of course, it's not yet clear how gut microbes enter the brain and how much they affect brain health. However, there is evidence that the nerves that connect the gut to the brain and that a healthy balance of gut bacteria contributes to a happy person. Eating high-quality probiotics on a regular basis may have a positive effect not only on gut health, but also on improving our quality of life.