In this blog post, we will take an easy and interesting look at the role and importance of intestinal bacteria, which affect digestion, immunity, constitution, and even emotions.
Raise your right hand. Now raise your left hand. It’s not difficult at all. As the owners of our bodies, we can consciously control all of our actions. But what about controlling what happens inside our bodies? We eat when we are hungry and sleep when we are sleepy. If there are foods that we cannot digest well, we are careful not to eat them, and if we tend to gain weight easily, we exercise to lose weight. Just listening to this, it seems that we are doing enough to maintain our health as masters of our own bodies. However, there is another fundamental cause that makes my body unable to digest certain foods and gain weight easily. It is the other master of my body: intestinal bacteria. Intestinal bacteria are, literally, bacteria that live in our intestines.
There are about 500 trillion living organisms in the human body. Among them, there are about 4,000 species of intestinal bacteria, amounting to about 100 trillion. This is more than the total number of cells in our body, and weighs 1.3 to 2.3 kg. And from this small amount, they excrete 50% of the waste we produce!
When did such a huge number of bacteria enter our bodies? Intestinal bacteria begin to help form our bodies in the womb and are our lifelong companions. Breast milk even contains about 600 species of bacteria and oligosaccharides, which are food for the intestinal bacteria in infants. This alone shows that intestinal bacteria have been symbiotic partners throughout human history. And we have maintained this long symbiotic relationship by suppressing the ‘antibacterial proteins’ in our intestines that kill bacteria so that our immune system does not kill intestinal bacteria. With a constant temperature of 39 degrees Celsius, a constant supply of food, and protection, the intestines are a paradise for bacteria.
However, these bacteria do not just live and eat. Intestinal bacteria perform very important tasks, just like an organ. First, they have a tremendous impact on human nutrition. Intestinal bacteria break down sugars, proteins, and fibres that humans cannot digest, thereby aiding digestion. They also produce various vitamins that support our vital functions.
And the acid they produce makes the inside of the intestines acidic, which helps digestion. Since they have such a huge impact on nutrition, they ultimately determine a person’s constitution. Intestinal bacteria are broadly divided into the phyla Firmicutes and Bacteroidetes. According to animal experiments conducted by a research team at the University of Washington in 2006, the more obese a person is, the higher the percentage of Firmicutes bacteria.
These bacteria convert nutrients into easily digestible sugars and fatty acids, which are absorbed as energy sources, making it easier to gain weight. When the ratio of these two bacteria in the gut was adjusted, there was a possibility of improving body constitution, so if you are having trouble dieting, maybe you should blame your gut bacteria.
In addition, gut bacteria also play a significant role in the immune system. Intestinal bacteria live in the intestines, maintaining their own territories, and when other bacteria invade from outside, they kill them with various antibacterial substances, including bacteriocins, to maintain intestinal health. They also activate the immune system, which consists of T cells and B cells, to help eliminate invading bacteria.
The role of intestinal bacteria does not end there. Recent studies have revealed that intestinal bacteria also play an important role in the brain. This relationship, known as the ‘gut-brain axis,’ suggests that intestinal bacteria can affect our emotions, behaviour, and even our mental health. The fact that people often experience indigestion in stressful situations is an example of how closely the intestines and the brain are connected. Research on the gut-brain axis has the potential to bring about major changes in medicine and healthcare in the future.
Normally, intestinal bacteria of the same species gather in their own areas, maintaining a balance between each other and forming a single ecosystem within the intestines. However, factors such as an unbalanced diet, excessive use of antibiotics, ageing, and stress can disrupt this ecosystem. This leads to an increase in the proportion of harmful bacteria, preventing the vital activities mentioned above from functioning properly. In addition, problems such as intestinal decay, carcinogen production, and diarrhoea may occur. To prevent this, it is helpful to reduce the above negative factors and consume lactic acid bacteria. The efforts we make for the intestinal bacteria, the other masters of our bodies who are working silently even now, are well worth it, if only for ourselves.
