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Nutrition

How Food Affects Your Immunity

Overview

While conclusions regarding nutrition and immunity are mixed, research in recent years has shown a link between the foods we eat, healthy and unhealthy, and our ability to fight disease. Here is an overview of how foods like garlic, fish, and tea may help you fight off everything from a common cold to cancer.

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Nutrition and Immunity by the Numbers

.6 - 1
Protein (in grams) needed daily per pound of body weight. Higher levels needed for people who exercise more, are still growing, or are dieting.

5-9
The number of fruit and vegetable servings needed daily as part of a healthy diet.

30
The percent of your daily calories that should be dedicated to fat.

0.8 – 1.2
Amount of carbs (in grams) needed per pound of body weight after a workout.

How Nutrition Boosts Immunity

An intricate network of proteins, cells, tissues, systems, and organs (like the skin, respiratory, and digestive tracts—our first line of defense) are designed to protect us from antigens, a collective term for bacteria, viruses, allergens, and other organisms that make us sick.

If disease agents get past the first line, they go up against a team of white blood cells, known as leukocytes, lymphocytes, B-cells, T-cells, Killer T-cells, macrophages, and more. Every white blood cell begins its life in bone marrow as a stem cell. For these cells to do their job effectively, we need to exercise, eat a balanced diet, and avoid foods high in saturated and trans fats.

Immune-Boosting Nutrients

Vitamins A and C

Vitamins A and C help lymphocytes reproduce properly when the body is exposed to a virus, and they enable neutrophils and macrophages to surround and kill invasive bacteria. Vitamin A is also important for strong and healthy skin. Vitamin C, which produces the protein interferon, boosts the cells that seek and destroy disease agents once they're present in the body.

Sources of vitamin A and C include colorful vegetables, fruits, whole grains, beans, and foods rich in red, orange, and/or yellow beta-carotene, like sweet potatoes, carrots, squash, cantaloupe, and pumpkin. A 2009 study published in the Journal of Agricultural and Food Chemistry showed that the skin on pumpkins could reduce the incidence of microbes that cause millions of cases of yeast infection in children and adults.

Vitamin E

Vitamin E helps the immune system by producing interleukin-2, a protein that kills bacteria, viruses, and possibly cancer cells. Interleukin-2 appears in the body as a reaction to being invaded by germs. Sources include wheat germ oil, almonds, peanut butter, spinach, broccoli, kiwi, and mango.

Tea

Researchers at Harvard found that people who drank five cups of black tea a day for two weeks produced extra-strength T-cells, which help resist cold and flu viruses. Green tea is believed to be just as effective. The interferon, or proteins, found in tea may also help protect against food poisoning, infected cuts, athletes' foot, tuberculosis, and malaria.

Zinc

Not getting enough zinc in your diet, particularly among vegetarians and people who've reduced their intake of beef, hurts immunity. A lack of zinc, which helps with the development of white bloods, can raise the risk of infections, fevers, coughs, and mucus build up. Just three ounces of lean beef provides about 30 percent of our daily zinc requirement. Other sources include oysters, fortified cereals, pork, poultry, yogurt, and milk.

Chicken Soup

The healing benefits of chicken soup aren't just an old wives' tale. Researchers at the University of Nebraska found that chicken soup, specifically an amino acid called cysteine found in it, blocked the movement of inflammatory cells. The salty broth mimics the action of cough medicines by keeping mucus thin, while garlic and onions are believed to increase the body’s immune-boosting ability.

Fish

Selenium, found in oysters, lobsters, crabs, and clams, increases the production of proteins called cytokines, according to a small study conducted in Great Britain. Cytokines may help the body fight off viruses that cause influenza. The omega-3 fats found in many seafoods, particularly salmon, have also been shown to increase the concentration of T-cells and cytokines.

Yogurt

Probiotics are live, healthy cultures found in yogurt that keep the intestinal tract free of germs that cause diseases. An Austrian study found that seven ounces of yogurt a day was enough to do the job, while a Swedish investigation found that daily supplements of Lactobacillus reuteri, a probiotic that stimulates white blood cells, resulted in 33 percent fewer sick days among workers when compared to a placebo. When buying yogurt, choose one with less than 200 calories, 4 g of fat, and 30 g of sugar per serving.

Garlic

There is limited evidence that garlic can increase cold resistance and reduce the risk of colorectal and stomach cancers. Suggested intake, though not absolutely proven, is two raw cloves a day, plus garlic added to cooked foods several times a week.

7 Tips to Improve Your Nutrition and Immunity

Here are some specific recommendations regarding foods and immunity:

  1. Eat 5-9 servings of fruits and vegetables per day.
  2. Choose lean sources of protein, about 0.6 to 1 g per pound of body weight.
  3. Limit total fat intake to 30 percent of daily calories, with 5-10 percent from saturated fats.
  4. Substitute green or black tea for coffee at least once a day.
  5. Choose a multivitamin formulated for your age and gender.
  6. Look for yogurt that contains live, active cultures.
  7. Increase your exercise periods to at least 60 minutes per day.

Take-Home Message

Your body’s immune system is dynamic. It gets stronger or weaker, depending on a variety of factors, including nutrition. While healthy eating habits aren't a guarantee that you won't get sick, being proactive with your health can help you maintain your health and wellbeing.


Tags: Health, Disease, Food

References

  1. American Journal of Clinical Nutrition
  2. CorePerformance.com
  3. David Nieman, Appalachian State University
  4. European Journal of Clinical Nutrition
  5. Georgia Tech Sports Medicine and Performance Newsletter
  6. Harvard Medical School
  7. Integrative Medicine
  8. Journal of Agricultural and Food Chemistry
  9. Medicine & Science in Sports & Exercise
  10. Medline Plus
  11. Oregon State University (Department of Nutrition and Food Management)
  12. Scripps Research Institute
  13. The New York Times
  14. Yale-Griffin Prevention Research Center

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