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5 Bad Habits for Adults' and Kids' Immune System Health

To stay healthy during cold and flu season, avoid these bad health habits


Updated March 02, 2011

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

5 Bad Habits for Adults' and Kids' Immune System Health

Family fighting can be stressful for everyone. Try to get along to better your health, including adults' and kids' immune system function.


Adults' and kids' immune system function is dependent on how well you take care of your body. But unhealthy habits can weaken immune system health and prevent your body from doing its job to fend off illness.

If healthy routines such as eating healthy foods and getting plenty of rest are good ways to boost your family's immune system, then these bad habits do just the opposite: They make your body more susceptible to infections such as colds flu.

Here are the top things to steer clear of if you want to avoid a weakened immune system:

1. Smoking

In animal tests, cigarette smoke was shown to worsen lung inflammation. Both active and passive smoke exposures were linked to increased occurrence and severity of respiratory virus infections. [2] Studies have also shown that cigarette smoking can inhibit the pulmonary white blood cell response to the influenza virus and tuberculosis.

2. Stress

Persistent and chronic stress can weaken the immune system and make you more vulnerable to infections. Studies have linked chronic stress to reduced white blood cell counts, which can make a body more susceptible to colds and other illnesses and make it harder to shake off infections.

Stress is also associated with triggering an inflammatory response in the immune system, which may be linked to various health problems such as heart disease. "Stress can increase inflammation," says David Katz. "Try to get along with friends and family and keep priorities in mind."

Stress and anxiety have also been linked to sleep problems, which can also play a role in suppressing the immune system.

3. Lack of Exercise

Studies have shown that moderate and regular exercise may be good for immune system function. Just walking for 30 minutes a day has been shown to increase activity of infection-fighting white blood cells and help your immune system do its job.

4. Lack of Sleep

If you’re not catching enough zzz’s, you are weakening your immune system. Not getting enough sleep can interfere with your body’s ability to fight off infections and increase inflammation in the body. Lack of sleep has also been linked to a variety of health problems including diabetes, heart disease, and obesity.

5. Poor Diet

If your diet is lacking in immune-boosting foods high in antioxidants such as fruits and vegetables, you are setting yourself up for an increased risk for infection and illness. A balanced diet helps build white blood cells and increases the body’s ability to naturally fight-off infections. Foods high in antioxidants such as vitamins A, C, and E, and beta carotene improve immune system function and help reduce the risk for colds, flu, and other infections.


1. Live interview with David Katz, MD, director of the Yale Prevention Research Center

2. Gualano RC, Hansen MJ, Vlahos R, Jones JE, Park-Jones RA, Deliyannis G, Turner SJ, Duca KA, Anderson GP., “Cigarette smoke worsens lung inflammation and impairs resolution of influenza infection in mice,” Respir Res. 2008 Jul 15;9:53, http://www.ncbi.nlm.nih.gov/pubmed/18627612

3. Feng Y, Kong Y, Barnes PF, Huang FF, Klucar P, Wang X, Samten B, Sengupta M, Machona B, Donis R, Tvinnereim AR, Shams H., “Exposure to cigarette smoke inhibits the pulmonary T-cell response to influenza virus and Mycobacterium tuberculosis,” Infect Immun. 2011 Jan;79(1):229-37. Epub 2010 Oct 25, http://www.ncbi.nlm.nih.gov/pubmed/20974820

4. Irwin MR, Wang M, Ribeiro D, Cho HJ, Olmstead R, Breen EC, Martinez-Maza O, Cole S., “Sleep loss activates cellular inflammatory signaling,” Biol Psychiatry. 2008 Sep 15;64(6):538-40. Epub 2008 Jun 17., http://www.ncbi.nlm.nih.gov/pubmed/18561896

5. “How Much Sleep Do We Really Need?” National Sleep Foundation, http://www.sleepfoundation.org/article/how-sleep-works/how-much-sleep-do-we-really-need

6. Rosa Neto JC, Lira FS, de Mello MT, Santos RV., “Importance of exercise immunology in health promotion,” Amino Acids, 2010 Oct 26, http://www.ncbi.nlm.nih.gov/pubmed/20976509

7. Nieman DC, Henson DA, Austin MD, Brown VA., “Immune response to a 30-minute walk,” Med Sci Sports Exerc. 2005 Jan;37(1):57-62, http://www.ncbi.nlm.nih.gov/pubmed/15632669

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