Avoid excess sun exposure. "People get fever blisters around the mouth from too much sun, which suggests that excessive sun may impair our ability to contain infection," says Ardis Dee Hoven, M.D., an infectious-disease specialist at the University of Kentucky College of Medicine. Wear protective clothing and sunscreen if you expect to spend more than 20 minutes in the midday sun.
Quit smoking. Abstaining for a month increases the activity of natural killer cells. And "smokers damage protective cells in the mouth and bronchial tubes, increasing their ability to get bacterial and viral infections," Hoven says.
Avoid excess alcohol. Chronic alcohol abuse and even episodes of heavy drinking can suppress immune function. Alcohol impedes the ability of white-blood cells to travel to infected sites, gobble up and destroy foreign invaders, and identify malignant cells. As a result, alcoholics are more susceptible to bacterial diseases such as pneumonia and tuberculosis, and have an increased risk of developing cancer. So limit your intake to no more than two drinks per day for men and one drink per day for women.
