Immunity, Beyond Misunderstanding To Science: Seven Habits For A Healthy Life Immunity, Beyond Misunderstanding To Science: Seven Habits For A Healthy Life

 Chapter 1: Understanding the Immune System, Our Body's Best Defenders

When we often say 'good immunity', it goes beyond simply being strong against external invasion. Immunity refers to a 'balanced' state in which one's body does not attack while effectively defending against pathogen invasion. If the immune system is overactive, autoimmune diseases such as atopy and rheumatoid arthritis can occur. The body's immune system consists of multiple levels of sophisticated defense systems, just like a well-trained army.

1.1. The immune system's step-by-step defense system

Our body's first line of defense consists of physical, chemical, and biological barriers. The skin and mucous membranes act to physically prevent pathogens from entering, and enzymes contained in stomach acids, saliva, and tears that are secreted from the stomach chemically destroy pathogens. In addition, intestinal microorganisms coexist with the host and function as a biological defense system that inhibits the reproduction of pathogens.

Pathogens that enter these primary lines of defense face the innate immune system. The system does not differentiate between specific pathogens and responds immediately by widespread attack. However, it is characterized by short duration. **NK cells, one of the major cells involved in innate immunity, have the ability to find and destroy virus-infected cells or cancer cells by themselves. Also, macrophages eat up abnormal cells or foreign substances and then pass information against them to other immune cells.

The acquired immune system, the most complex and sophisticated defense system, responds to pathogens that the innate immune system has failed to process. The core of this system is the ability to learn and remember external invaders (antigens). T cells and B cells, the main cells responsible for acquired immunity, are types of lymphocytes, which mature in the thymus and bone marrow, respectively. T cells are divided into killer T cells that directly kill infected or cancer cells, helper T cells that activate other immune cells, and inhibitory T cells that inhibit and terminate the immune response. In particular, helper T cells act as 'directors of the immune system' that assist B cells and macrophages.

The main role of B cells is to produce antibodies. When B cells first encounter a particular antigen, they differentiate into plasma cells that produce antibodies with the help of T cells, and memory B cells that store information about antigens. This process takes several days, so the primary immune response proceeds slowly. However, when the same antigen is re-invaded, memory B cells multiply immediately and produce more antibodies quickly. This secondary immune response is much faster and more effective than the primary response, and vaccination is also a key factor in action.

Chapter 2: 3 Key Habits That Build the Foundation of Immunity: Sleep, Exercise, and Stress

2.1. Habit 1: Sleep, Time for Immunity Reboot

Sleep is not just a break, but an essential time for our body's immune system to reorganize and activate. Lack of sleep is the main cause of decreased immunity, and studies have shown that a lack of sleep for two to three hours a day greatly weakens immunity. During sleep, the parasympathetic nervous system is activated to release tension in the body, which makes the immune cells, helper T cells and NK cells, more active. In addition, a large amount of melatonin, a hormone important for improving immunity, is released during a deep sleep. Therefore, experts recommend securing enough sleep of seven to eight hours a day and getting a deep sleep between 11 p.m. and 3 a.m., when immune-related hormone secretion is active.

2.2. Habit 2: Exercise, the surest way to circulate immune cells

Regular exercises help immune cells become active by facilitating blood circulation and lymphatic flow. These physiological effects are due to the release of a substance called **Myokine** from muscles during exercises, which directly stimulates immune cells. Also, low-intensity aerobic exercises such as jogging or stretching activate the parasympathetic nervous system, which is responsible for body rest, which improves immunity.

The important thing here is the proper amount of exercise. Exercise is often thought to be absolutely good, but from the perspective of the immune system, the J-curve effect appears. Light exercise increases the number of white and red blood cells, and promotes the secretion of immunoglobulins, thereby increasing immunity. However, excessive exercise can negatively affect the immune function and reduce the secretion of immunoglobulins. Also, excessive exercise can produce free oxygen, which can promote aging and strain the body. The key is to keep a steady amount of exercise that suits your condition.

2.3. Habit 3: Stress, Fatal Disorder of the Immune System

Stress is called the source of all kinds of illnesses, and has a direct adverse effect on the immune system. When the body is under stress, it activates the hypothalamus-pituitary-adrenal axis (HPA Axis), which causes excessive secretion of **Cortisol, a stress hormone. Cortisol has strong anti-inflammatory and immunosuppressive effects, and chronic stress can cause resistance to the action of these cortisol, which can worsen chronic inflammation and immune diseases.

Recent studies have found that the effect of stress on immunity goes beyond mere biochemical reactions. Studies have shown that certain immune cells (neutrophils) released from the skull bone marrow in response to chronic stress can travel to the brain and cause symptoms of depression and anxiety, showing a deep link between physical immunity and mental health. This suggests a new perspective that stress affects a complex axis where the brain, intestines, and immune systems are integrated. Therefore, finding your own stress relievers, such as meditation, exercise, laughter, and hobbies, is a fundamental way to maintain immunity beyond just relaxing your mind.

Chapter 3: Custom Fuel for Immune Cells: Secrets of Nutrition and Intestinal Health

3.1. Habits 4: Intestinal Health Care, New Criteria for Immunity

The intestine is not just a digestive system, but the largest immune system where about 70% of the body's immune cells are concentrated. The health of this organ depends on the balance of the microbiome, or microbiome, in our body. The intestinal microbiome serves as a 'teacher for life' who trains and regulates the immune system from birth. Numerous studies have demonstrated that symbiotic bacteria are essential for maintaining immune homeostasis, and intestinal microbial imbalances can cause immune dysfunction and autoimmune diseases.

For intestinal health, eating probiotics and prebiotics is helpful. Probiotics help the proliferation of beneficial bacteria in the intestine and increase immunity by increasing lymphocytes and activating phagocytosis of white blood cells. In particular, certain probiotic strains (LGG®, BB-12®) have been found to have the effect of increasing antibody production and reducing the duration of respiratory infection. Prebiotics make the intestinal environment healthier by 'feeding' these beneficial bacteria and promoting their proliferation.

3.2. Habit 5: Helpers consume key nutrients and help immune cells work

In order for immune cells to function properly, certain nutrients are needed. These nutrients are not just supplements, but act as helpers, which are essential for the growth, activation, and regulation of immune cells.

• Vitamin C: In addition to protecting cells from free oxygen by its antioxidant action, recent research has shown that it works with the TET protein essential for the functioning of **Induction-regulated T cells (iTreg)** to suppress immune responses and alleviate autoimmune diseases. It is rich in citrus fruits, strawberries, green leafy vegetables, and more.

• Vitamin D: Vitamin D, which is naturally synthesized by the body in the sun, produces immune proteins and contributes to suppressing inflammatory substances in white blood cells. Studies have reported that people with lower vitamin D levels are more vulnerable to acute respiratory infections and autoimmune diseases.

• Zinc: A mineral that is important for the normal development and function of immune cells, especially helping to activate and proliferate T cells, B cells, and NK cells. Zinc is involved in various cellular processes such as signaling and replication within cells, and has been found to be introduced into cells via specific transporters (Zip8) to regulate immune response-related pathways.

nutrient

Key roles (scientific mechanisms)

a major source of food

Vitamin C

Antioxidant, Induction Control T-Cell Function Assistance

Citrus fruits, strawberries, tomatoes, broccoli

Vitamin D

Production of immune proteins, suppression of leukocyte inflammation

blue-backed fish, fortified dairy products, mushrooms, egg yolks

Zinc

T/B/NK cell activation and proliferation support

meat, oysters, seafood, nuts, whole grains

Protein

Key components of antibodies and immune cells

lean meat, chicken, beans, tofu, seafood

Omega-3

Mitigate inflammation and enhance white blood cell activity

blue-backed fish (mackerel, salmon), nuts

beta-glucan

Promote macrophage and NK cell activation

Mushrooms, brown rice, and whole grains

3.3. Habit 6: A balanced diet, the best prescription from nature

The surest approach to immunity is to create a healthy soil with a balanced diet, rather than relying on specific ingredients or supplements. Vitamins, minerals, and fiber-rich vegetables, fruits, and whole grains are essential elements that support the functioning of the immune system. In particular, beta-carotene, which is abundant in green-yellow vegetables, is converted to vitamin A in the body to strengthen the skin's mucous membrane, which is the primary defense line against external pathogens.

The efficacy of certain foods is also noteworthy. Allicin, a spicy component of garlic, has antiviral properties, and **polygamma glutamic acid (PGA)** in fermented foods such as soybean paste and cheonggukjang has been reported to increase NK cell activity by an average of 52.3 percent. However, overconfidence in certain foods is prohibited, and eating a variety of nutrients evenly is essential for maintaining immunity in the long term.

Chapter 4: Sustainable Immunity Management Comprehensive Solution

4.1. Habits 7: The Power of Small Changes in Daily Life

Immunity management begins with small habits in daily life, not with grand efforts. Experts advise that washing your hands properly can prevent 60-70 percent of infectious diseases. In addition, drinking plenty of water helps the smooth circulation of immune cells and lymphatic fluid, and increases the body's metabolic functions, contributing to overall health.

4.2. Integrated Perspectives of Immunity Management

The key point of this blog is that immunity management cannot be a single solution. Sleep, exercise, stress management, nutrition, and intestinal health are not isolated elements from each other, but are closely linked, making up the body's complex and integrated systems. For example, stress degrades sleep quality, deteriorates intestinal health, and this causes immune cells to lose function. On the other hand, proper exercise alleviates stress, improves sleep quality, and activates intestinal exercise to indirectly support the immune system.

So, sustainable immunity depends on maintaining the 'homeostasis' of the human body by practicing all these habits in harmony. The surest way to manage immunity is to choose and consistently practice an integrated approach that matches your lifestyle and physical condition.

Finally, it is important to understand 'immunity' as an integrated state in which the body and mind's health are balanced, away from the narrow concept of simply resistance to disease. Only when we effectively manage our body's defense system through such a healthy lifestyle will we lay the foundation for preventing disease and leading a vibrant life.

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