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Can a Diet Affect the Immune System?

Jun 4, 2011 | By Christa Miller
Can a Diet Affect the Immune System?
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Healthy habits such as washing your hands, exercising daily, avoiding cigarettes and getting medical checkups can help you bolster your immune system. What you eat can also influence your health. In fact, a diet that's rich in fruits, whole grains, vegetables, healthy fats and lean proteins may offer your immune system ideal fuel for defense, according to Harvard Health Publications.

Antioxidants

Free radicals are toxic byproducts that appear after cell metabolism or after you ingest toxins such as pesticides and cigarette smoke. Over time, free radicals can damage once-healthy cells in your body through a process known as oxidation, according to the Mayo Clinic website. Substances called antioxidants may help boost your immunity and fight off diseases such as cancer by neutralizing those free radicals. Nutrients such as vitamin C, vitamin E, beta-carotene, lutein, lycopene and polyphenols are antioxidants.

Major Sources of Antioxidants

A variety of fruits, vegetables, herbs, grains, healthy proteins and even beverages and desserts are rich in antioxidants. Berries, apples, avocados, cherries, tomatoes, plums and kiwis are among the top fruit sources of antioxidants. Artichokes, red cabbage, sweet potatoes, broccoli and spinach are some of the top vegetable sources, according to the Mayo Clinic website. Herbs such as ginger, turmeric powder, cinnamon and ground cloves may also help ward off free-radical damage. Healthy sources of protein such as kidney beans, black beans, walnuts, hazelnuts, pistachios and almonds can supply you with many antioxidants. Even coffee, red wine, pomegranate juice and dark chocolate have antioxidants.

Preliminary Research

Some preliminary evidence links a healthy diet to improved immunity. For instance, study participants eating a tomato-rich diet for three weeks had 38 percent less white blood cell damage from free radicals than they had when they ate no tomatoes for three weeks, according to research published in a 1999 issue of the "American Journal of Clinical Nutrition." Study authors suggest that the lycopene in the tomatoes helped fight off free-radical damage by acting as an antioxidant. Other research conducted in 2005 at London's Imperial College found that study participants who drank five cups of chamomile tea daily for two weeks had increased body levels of the antioxidants polyphenols and continued to have them for two weeks after. This suggested to the study author, Dr. Elaine Holmes, that the participants would have increased resistance to infections.

Deficiency Risks

Some evidence suggests that being low in various micronutrients can alter your body's ability to fight off infections. For instance, a vitamin A deficiency has been linked to increased risk of infectious diseases, and a selenium deficiency has been linked to increased risk of many types of cancer. A zinc deficiency could impair your immune system's T cells as well as other immune cells. Even being marginally low in certain nutrients can cause negative symptoms such as impaired mental abilities, slowed recovery from surgery and reduced resistance to infection and disease. Many Americans are deficient in nutrients such as vitamin A and vitamin C, according to the Cleveland Clinic website.

Considerations

Research linking nutrition to immunity is still in its infancy. Some research suggests that populations that are malnourished are more likely to develop infectious diseases, and some evidence suggests that eating nutritious foods can make a difference in your level of white blood cells and other disease-fighting aspects of your immune system. However, as of 2011 little research has been able to directly link diet to the body's success in fighting off specific ailments.

References

Article reviewed by Alison Gaynor Last updated on: Jun 4, 2011

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