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How does aging affect the immune system?

Susan S. Blum, MD
Preventive Medicine

Aging does not need to affect the immune system; diet, stress management, digestive health and the liver's ability to filter toxins are actually the main factors. Watch functional medicine expert Susan Blum, MD, explain the keys for strong immunity.

Anthony L. Komaroff, MD
Internal Medicine
Research suggests that the aging process somehow leads to a reduction of immune response, which in turn contributes to more infections, more inflammatory diseases, and more cancer. As life expectancy in developed countries has increased, so too has the incidence of age-related conditions.

While some people age healthily, the conclusion of many studies is that, compared with younger people, the elderly are far more likely to contract infectious diseases. Respiratory infections, influenza, and particularly pneumonia are a leading cause of death in people over age 65 worldwide. No one knows for sure why this happens, but some scientists have observed an age-related decrease in T cells, possibly from the thymus atrophying with age and producing fewer T cells to fight off infection. Whether this decrease in thymus function explains the drop in T cells or whether other changes play a role is not fully understood. Others are interested in whether the bone marrow becomes less efficient at producing the stem cells that give rise to the cells of the immune system.

Even vaccination seems to be less effective in older people. A reduction in immune response to infections was observed in people over age 65 who received the seasonal flu vaccine. One study showed their immune response to the flu vaccine was significantly lower than that of healthy children. Nevertheless, vaccinations for influenza and S. pneumoniae effectively lower the rates of sickness and death in older people.

Still other researchers are looking at the connection between nutrition and immunity in the elderly. A form of malnutrition that is surprisingly widespread even in affluent countries is known as "micronutrient malnutrition." Micronutrient malnutrition, in which a person is deficient in some essential vitamins and trace minerals that are obtained from or supplemented by diet, can be common in older people, who tend to eat less and often have less variety in their diets. One important question is whether dietary supplements may help older people maintain a healthier immune system. So far, there is no evidence that taking extra amounts of any vitamin will boost the immune response or protect against infection in any way. Older people should discuss this question with a physician who is well versed in geriatric nutrition, because while some dietary supplementation may be beneficial for some older people, in others it can cause metabolic problems.
Dr. Michael Roizen, MD
Internal Medicine
Our immune system begins to fail in two fundamental ways as we age. It can become negligent, allowing abnormal cells -- either infectious agents or cancer cells -- to grow unchecked. Or it can become overzealous, turning on the body and attacking normal tissues, as occurs in autoimmune diseases. Many forms of arthritis, connective tissue diseases, and allergies are autoimmune diseases.
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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.