나이 들어도 면역력 지키자…핵심은 ‘소장 내 면역 현장학교’ [건강한겨레]

As people age, their immune response weakens, causing them to feel weaker when sick and take longer to recover. This phenomenon is known as "immune decline." One reason for this is the deterioration of the thymus gland, which is responsible for teaching immune cells how to attack threats and recognize the body's own cells. The thymus is most active during childhood, but it begins to degenerate after the teenage years.

By the time a person reaches 70, the thymus produces only 10% of the T cells it once did. This reduction in T cell production means that the immune system can no longer generate new cells to combat new viruses and bacteria. However, the spleen plays a crucial role in compensating for the weakened immune system. The spleen acts as an "on-the-ground school" for immune cells, training them to respond to external threats and remember their past experiences.

In contrast to the thymus, the spleen remains relatively youthful throughout life, thanks to its rich blood supply, protective barrier, and immune surveillance capabilities. While the immune system may weaken with age, the spleen can still provide a strong foundation for maintaining immune health. To do this, it's essential to consume a variety of foods that promote gut health, such as various types of vegetables, fruits, legumes, whole grains, and nuts.

Eating a diverse range of plant-based foods ensures that the gut microbiome receives a wide array of dietary fibers, polyphenols, and metabolites that support immune function. In fact, studies have shown that individuals who consume over 30 different types of plant-based foods per week have higher gut microbiome diversity compared to those who eat fewer types.

Rather than focusing on consuming a single "good bacterium," the key to maintaining a healthy immune system lies in the diversity of gut bacteria. Therefore, the spleen, or the immune learning institution, may be unable to restore the vigor of youth, but it can still help individuals adapt to the challenges of aging by strengthening the immune system and nourishing it with a wide variety of foods.