It's amazing that we're not sick all the time. We are attacked more than 100 million times a day by viruses, bacteria and other disease-causing organisms. Our hands alone harbor up to two million germs. The only reason we're not continually sick is that the immune system is remarkably effective at recognizing and fighting threats.

Many harmful organisms are blocked by barriers, such as skin and mucous membranes, that prevent harmful organisms from getting into the body.

Those that get past the initial barriers are spotted by antibodies and attacked by a barrage of immune cells. The antibodies "remember,, individual pathogens and attack and neutralize them during subsequent exposures.


The immune system isn't perfect, however. Immune cells aren't always effective—due to nutritional deficiencies, emotional stress and aging.

If the immune system has never been exposed to a particular vin-n or bacterium, it may not be able to mount an effective defense. Also, viruses and bacteria can develop their own defenses, which make them harder to detect and eliminate. In addition, the immune system can mistake healthy tissues for foreign invaders and launch an attack. This is what happens in autoimmune diseases, such as lupus.

Almost half of all deaths are due to infection or other immune-related problems. Even some cancers are caused by infectious organisms that break down the immune system.

Here's how to build up your immune system…


Limiting exposure to harmful organisms is one of the best preventive measures. Wash your hands after you shake hands or touch surfaces that others have touched. Avoid people who are sneezing or coughing. These measures alone can significantly cut infection from colds or flu.

Also helpful…

  • Stay social. People with active social lives and those who participate in religious or community groups are less likely to experience depression than those without social ties. Depression reduces immune response, mainly by inhibiting the activity of "attack" immune cells called T cells and B cells.

Get professional help if you're experiencing depression. The majority of depressed patients who receive medication or therapy improve within three months—and nearly all of them improve within six months.

  • Exercise daily—but don't overdo it. People who get regular exercise and take care of themselves in other ways—eating nutritious meals, not smoking, etc.—can improve immune response. Symptoms of depression also can be reduced by exercise. Thirty minutes a day is optimal for most people.

Caution: Exercising more than two hours daily actually causes immunity to decline.

  • Manage stress. Stress itself doesn't, tweaked immunity, but poor responses to stress-such as smoking, not eating healthfully and not exercising- are linked to infection. Not getting enough sleep is both a cause and a result of stress and can impair the activity of infection fighting T cells and B cells.

Stress reducers: Set aside 20 minutes to listen to music or meditate...breathe deeply for a few minutes...go for a walk or engage in other exercise.

  • Get enough omega-3s. The omega-3 fatty acids in nuts and fish have been shown to reduce depression and improve immunity. Have one-quarter cup of walnuts daily...three servings of fish weekly...or take two grams of a fish oil supplement daily.
  • Boost vitamin C. Studies indicate that vitamin C may prevent infection by boosting levels of T cells and B cells. The optimal dosage is 500 milligrams (mg) twice daily. You can get this much vitamin C with several daily servings of vitamin C-rich foods, such as tomatoes, bell peppers and citrus fruits—or you can take a supplement.
  • Favor flavonoids. These vitamin-like substances in fruits, vegetables and whole grains minimize age-related declines in immune function. You need about 31 mg of flavonoids daily.

Best sources: Cranberry juice (13 mg per eight-ounce glass)...tomato juice (7.2 mg per eight-ounce glass)...apples (4.2 mg per medium apple). . . strawberries (4.2 mg per cup). . .broccoli (4.2 mg per cup)...onions (3 mg per small onion)... red wine (3 mg per five-ounce glass).

Avoid sugar. Sugary foods, such as candy, cakes, cookies, etc., can drive blood glucose levels above 250 milli-moles per liter of blood (a normal level is between 65 and 140). Elevated blood sugar impairs the ability of immune cells to destroy bacteria.

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