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About serotonin

Serotonin that controls happiness

Serotonin is a “force”

Serotonin is a tiny, tiny molecule that you can't see, but scientists call it the happy substance. Do you know the <force that is invisible but fills every corner of the universe> that appears in the movie "Star Wars"? You could say it's something like that. The Force is what gives the universe justice and order, while serotonin is what gives happiness and peace. If you fill your brain with serotonin, it may be possible to free your brain from the grip of stress and carve out your own future. And the biggest key to filling the brain with force is "food".

By the way, it is known that when the gene for the enzyme that synthesizes serotonin is knocked out to prevent the brain from producing serotonin, two things will happen.

Bone density decreases. decreased appetite;

Conversely, if you fill serotonin, you can expect two things to happen.

Increases bone density. Appetite increases.

This gives important suggestions in aiming for anti-aging. In other words, "a happy life", "preferable diet" and "athletic ability" are strongly linked by the molecule serotonin, and exist as if they were a single phenomenon. The role played by serotonin for healthy longevity is infinitely large.

Brain-Gut Interaction and Serotonin

It is known that there is a close relationship (brain-gut correlation) between the gut (intestinal bacteria) and the brain (mental activity). In other words, a good gut flora increases your chances of a happy life, and a poor gut flora decreases your chances of a happy life.


Synthesis of serotonin starts from tryptophan, but tryptophan is mostly produced by enzymatically decomposing animal proteins, after which tryptophan is hydroxylated by intestinal bacteria and changed to hydroxylated tryptophan.

In this way, about 90% of hydroxylated tryptophan is produced by intestinal bacteria, so it can be said that most of it is dependent on intestinal bacteria. Hydroxyl tryptophan is absorbed from the intestinal epithelium, enters the bloodstream, and is sent to the blood-brain barrier. You can freely pass through that narrow gate. and can reach the brain. Furthermore, it is a mechanism that changes to serotonin by an enzyme in the brain and works as a happy substance. Furthermore, it changes into melatonin in nerve cells and functions as a sleep substance. Serotonin is known to be higher during the day and melatonin is higher at night.

These two hormones create a rhythm of being active during the day and resting at night. It seems that keeping the circadian rhythm of serotonin (happiness substance) and melatonin (sleep substance) is the basis for living happily.

stress and cortisone

The biological definition of stress can be described as the body's response to external stimuli, and cortisone plays a central role in the body's response to stress. Cortisone has a strong anti-inflammatory effect, but it is also known to have strong side effects. Cortisone is also thought to be one of the causes of depression, and it is highly possible that cortisone suppresses the action of serotonin. Cortisone has a wonderful effect only temporarily, but if it continues to act for a long time (stress persists), depression-like symptoms tend to become stronger. I also think that cancer is more likely to appear as a result of sustained cortisone release disrupting the brain-gut connection. This is because cortisone strongly suppresses the three physiological functions necessary for the establishment of the brain-gut interaction.

  • Digestive function in the intestinal tract

  • immune function in blood

  • Neural function in the brain


Creating an environment in which these functions are persistently suppressed increases the likelihood of cancer. Cancer immunity by NK cells is particularly strongly affected by persistent stress. NK cells are one of the innate immunity and the most basic defense mechanisms against cancer. Since it is known that this NK cell-mediated cancer immunity is strongly suppressed by cortisone, there is a high possibility that persistent stress leads to cancer. Many researchers have also reported that the anti-cancer effects of NK cells are influenced by emotions.


Life is full of waves of emotions, but if you live with a sense of happiness, NK cells maintain a highly active state and create a state that makes it difficult for you to develop cancer. On the other hand, negative emotions such as anger inhibit the cancer prevention mechanism by NK cells. In order to enjoy the effects of serotonin through the brain-gut interaction, it is essential to appropriately control external stimuli that cause negative biological reactions and to build a stress-free living environment.

happy brain

Currently, the leading theory for the cause of depression is the so-called “serotonin theory”. According to the serotonin theory, the basic thing for feeling "happiness" in the brain is that "serotonin" works normally. On the other end of the spectrum, "depression" is thought to be caused by serotonin not working properly or lacking serotonin. Common antidepressants are compounds called specific serotonin reuptake inhibitors (SSRIs), which inhibit the breakdown of serotonin. The "serotonin theory" is also very informative for all of us. This is because the necessary condition for the brain to feel happy is that serotonin, the happiness hormone, works normally. I think this will bring the gospel to many people. In order to be happy, all you have to do is give the brain conditions to be happy. All you have to do is create an environment in your brain where serotonin works normally. In order to "activate serotonin with food", it is necessary to prepare the following three conditions for serotonin to work normally in the brain.

  • Eat "tryptophan" which is a material of serotonin (eat fish and meat)

  • Adjust the "intestinal bacteria" necessary for the synthesis of serotonin (eating vegetables and seaweed)

  • Avoid excess sugar intake (eat good fats)

Activation of serotonin by food

State the three conditions one by one.

  Eating a diet rich in tryptophan, the raw material for serotonin. Tryptophan is abundant in animal proteins and low in plant proteins. It means that humans need to eat fish and meat in order for their large brains to function properly (but be careful not to overeat). This is more than eating high-energy foods, it normalizes brain function.

  You need normal gut bacteria. Tryptophan must be hydroxylated by intestinal bacteria. This hydroxylated tryptophan is free to move into the brain and become serotonin. Brain health (happiness) is mostly brought about by “food”. So eating fermented foods, seaweed and vegetables is a great way to keep your gut bacteria healthy.

 You need to avoid excess sugar. Excess carbohydrates can lead to the release of insulin and lower blood sugar levels than normal. Among the nerve cells, there are remarkably large nerve cells. When viewed under a microscope, these neurons clearly differ in morphology from other neurons, are large, and receive input from many neurons. They act like hubs in neural networks and require large amounts of energy. Nerve cells that work with serotonin are such large-sized nerve cells, and in order to effectively transmit this energy substrate, refrain from excessive sugar intake and consider taking in good-quality fat accordingly. should

Serotonin and heart

The brain is the tissue that consumes the most energy, and it is the brain that is most affected by mitochondrial function in the body. The 24-hour rhythm of living organisms is called the circadian cycle, and normally the body secretes more serotonin in the morning and more melatonin in the evening along the time axis from morning to night. Melatonin is a sleep substance and serotonin is a happiness substance. The balance of its secretion controls the mechanism of sleep and wakefulness. How the brain and body work according to this circadian cycle is determined by how well the mitochondria in the brain work. If serotonin is secreted properly and the brain works normally, it is normal to be filled with happiness and work well from 2:00 to 3:00 in the afternoon. The serotonin pathway is an excitatory synapse, so it consumes a lot of energy. To do this, your mitochondria need adequate nutrition. The brain can be compared to a hybrid engine in a car. The fuel efficiency of a hybrid engine car is higher than that of a gasoline car because it uses both gasoline and electricity. The brain is also in the most efficient state when it is a hybrid engine of glucose and ketone bodies. Driven by this hybrid of glucose and ketone bodies, the serotonin pathway works best and gives us a sense of well-being. When you think that your brain is not working well, it is better to eat fruits (preferably in season) containing organic acids that "activate mitochondria" rather than "eating sweets".

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