The largest immune organ in the human body, the intestine
Probiotics = lactic acid bacteria
If you translate probiotics in Korean, it means 'beneficial bacteria'. It is a general term for the bacteria in the intestines that are beneficial to health. The concept is slightly different from the commonly known lactic acid bacteria. This is because probiotics are bacteria that are beneficial to health even if they are not lactic acid bacteria.
Where does probiotics start?
Probiotics was started by Dr. Mechnikov, a Ukrainian biologist. Dr. Mechnikov, who won the 1908 Nobel Prize in Physiology or Medicine, was a yogurt lover who drank sour yogurt made from fermented milk every day. He observed that there were many good quality beneficial bacteria in the feces of long-lived Bulgarian farmers, and argued that yogurt was the reason for their longevity. The bacteria found in large quantities in yogurt are the origins of today's probiotics. If omega-3 is mackerel and calcium is milk, probiotics are yogurt.
The intestine is the body's largest immune organ.
There are many beneficial bacteria that fall into the category of probiotics, but two types of lactic acid bacteria, lactobacillus and bifidus, form the main species. This is because these two probiotics have been proven to be beneficial to health through hundreds of papers. Lactobacillus and bifidus are the most important lactic acid bacteria in yogurt and are also the main components of probiotics taken in actual nutritional form.
The intestine only makes stool...?
To understand the importance of probiotics, you first need to get to know your gut. The intestine is commonly known as the organ through which food passes and produces and excretes stool. That's right. However, this is not the only function in the intestine.
The intestine is full of immune cells of the human body!
70-80% of human immune cells, including white blood cells, are concentrated in the intestine. It can't be surprising. It's not the brain, it's not the heart, why are those important immune cells concentrated in the intestines? The reason is that food waste creates an enormous amount of bacteria through the process of digestion, fermentation, and decay. There are as many as 100 trillion bacteria in the gut. About half of the weight of the stool is made up of these bacteria. Its weight alone is approximately 1 to 1.5 kg. It means that there are bacteria weighing two and a half pounds of meat in our stomachs.
There is a reason why immune cells are concentrated in the intestine
The problem is that when there are many harmful bacteria in the intestines, these bacteria seek opportunities to penetrate the intestinal mucosa and enter the body. This is also why immune cells are concentrated in the intestines. Leukocytes are densely packed as if standing guard at the foremost guard post to block harmful bacteria trying to penetrate the mucous membrane in the large intestine and enter the human body.
Esther Lyuh, Doctor of Preventive Medicine, Seoul National University