Immunity

Immunity is the body’s own defense mechanism, responsible for identifying and eliminating any foreign invaders (such as viruses and bacteria), dealing with aging, damaged, dead, or mutated cells, and recognizing and handling virus-infected cells.[1][2][3] It is the physiological response of the human body to identify and exclude “non-self” entities.

The term “immunity” (免疫, mian yi) first appeared in the Chinese medical book “Immunity Formulas” (免疫类方) during the Ming Dynasty, where it meant “to be exempt from pestilence,” or to prevent and control infectious diseases. The term can also refer to the body’s ability to resist viruses and harsh external environments, as well as mental resilience.

How the Immune System Works

The immune system is a complex network of organs, cells, and proteins that work together to protect the body.[4] It has two main components:

• Innate Immunity: This is the body’s first line of defense, which you are born with.[3][4][5] It provides a general, non-specific protection against pathogens. For example, the skin acts as a physical barrier, and certain white blood cells can immediately recognize and attack foreign invaders.[3][4]

• Adaptive (Acquired) Immunity: This type of immunity develops throughout your life as you are exposed to diseases or receive vaccinations.[3][6] The adaptive immune system has a “memory” and can recognize specific pathogens, allowing for a stronger and faster response upon re-exposure. This is why you typically don’t get sick from the same virus twice.[3]

Immunity and Aging

Modern medical science has established a close link between immunity and aging. A decline in immune function, known as immunosenescence, is one of the most significant causes of aging.[7][8][9] As we age, our immune system’s ability to fight off infections and diseases diminishes.[7][8][10] This decline typically begins around the age of 30 and progresses slowly and continuously. The aging immune system becomes less effective at protecting against infections and cancer and is also associated with an increased risk of autoimmune disorders and chronic inflammation.[7][9][10]

How to Boost Your Immunity

The World Health Organization (WHO) has outlined a healthy lifestyle with four key pillars to improve overall health and, by extension, immunity: a balanced diet, regular physical activity, quitting smoking and limiting alcohol, and psychological balance.[11][12] Research indicates that adopting these habits can significantly reduce the risk of chronic diseases like hypertension, stroke, diabetes, and cancer, and can extend one’s lifespan by more than 10 years.

Here’s a closer look at these recommendations:

• Balanced Diet: A healthy diet is crucial for a strong immune system.[4][13] This includes a variety of fruits, vegetables, lean proteins, and whole grains.[4][13][14] A popular dietary guideline in some health circles is summarized as “one, two, three, four, five; red, yellow, green, white, black.” This refers to incorporating a variety of colorful foods into your diet. For example, this might include having one portion of dairy, two of protein, three of grains, four of vegetables, and five of fruits. It’s also important to consume foods that are not too sweet or salty and to eat until you are about 70-80% full. Limiting cold, raw, and frozen foods is also recommended.

• Moderate Exercise: Regular physical activity can help boost your immune system.[13][15] Walking and Tai Chi are excellent forms of moderate exercise. The WHO recommends at least 150–300 minutes of moderate-intensity aerobic physical activity per week for adults.[16]

• Quit Smoking and Limit Alcohol: Smoking weakens the immune system.[4][10] If quitting entirely is not possible, it is advised to smoke no more than five cigarettes a day. Alcohol consumption should also be limited, with a recommendation of no more than 15 grams of alcohol per meal.

• Psychological Balance: Maintaining a positive mental state can have a more significant impact on your health than all other preventive measures combined. Being open-minded, easygoing, and kind-hearted are essential for a strong immune system.