身体出现这4个迹象，提醒你免疫力下降了！

Group 1 - The article discusses the importance of immunity as a vital physiological function of the human body and how its decline can lead to various diseases [1][2] - Immunity is categorized into two types: innate immunity, which is the body's first line of defense against pathogens, and acquired immunity, which develops over time through exposure to specific pathogens [3] Group 2 - Four signs of declining immunity are identified: frequent infections, fatigue and weakness, increased allergic reactions, and a higher likelihood of tumor growth [4][5][6][8] - The article emphasizes that aging naturally leads to a decline in immune function, and that medications are not the best way to enhance immunity [9] Group 3 - Recommendations for improving immunity include maintaining body temperature, managing stress, improving sleep quality, using probiotics, and supplementing with vitamins and minerals [10][11][12][13][14] - Specific nutrient sources are provided, such as Vitamin C from citrus fruits, Vitamin E from sunflower oil, Vitamin B6 from fish and nuts, and Vitamin D from fatty fish [17][18][19][20] Group 4 - The article advises on hydration, suggesting that individuals should establish a drinking schedule to prevent dehydration, which can lower immunity [21] - Regular physical activity is recommended, with guidelines suggesting at least 150 minutes of moderate-intensity exercise per week, or 75 minutes of high-intensity activity [22]