Normal changes in the immune system occur as an individual ages. The immune system seeks out and destroys invaders that can harm the body.
The primary job of the immune system is to fight off infections. It also plays a role in helping to stop cancer in the body. The function of the immune system declines with age. As an individual gets older, his or her risk of illness generally increases.
With age, the number of immune cells may decrease slightly. More importantly, the functioning of these cells declines. The cells are often less able to control illness than in earlier years. As a person ages, the immune system produces fewer antibodies. It also responds more slowly to injury, infection, or disease.
Cells of the immune system can also lose their ability to tell the difference between normal and abnormal tissue. When this occurs, it can lead to autoimmune disorders, conditions in which the immune system attacks the person's own body. The ability to identify and fight cancer is also decreased. This is thought to be one reason that the risk of many cancers increases with age.
Other body changes allow more bacteria to enter the body. For example, aging skin provides less protection against bacteria than younger skin. If the immune system worked well, this would not be a major problem. However, because of the age-related weakness in the immune system, these other changes can also increase the risk of infections.
Other factors that contribute to how effectively the body can fight infection include: activity levelenvironmental and psychological factors, such as stress, depression, and anxietyhormonal changes within the bodynutritional statuspersonal habits, such as abusing alcohol or illegal drugssmokingdiabetes mellitus, especially if poorly controlled
To minimize the risk of infection and cancer, people should: avoid smoking and secondhand smokedrink alcohol moderately or not at alleat a well-balanced diet, following the food guide pyramidexercise dailyfollow the healthcare professional's recommendations about pneumonia vaccines, tetanus boosters, and flu shotsget enough restimplement home safety measures to reduce the chance of injurymaintain an active lifestyleobtain effective treatment for chronic diseases and conditions such as diabetes