Are you doing everything you can do to keep your immune system up to par? Check out these top nutrition tips to stay healthy this cold and flu season:
Vitamin C tops the list of immune boosters. There has been more research about the immune boosting effects of Vitamin C than perhaps any other nutrient. Vitamin C is available naturally in many fruits and vegetables. Unlike most animals that produce their own Vitamin C, the human body does not synthesize any. Vitamin C has substantial antiviral and antibacterial benefits though it's known for its protective aspects in creating host resistance. The most abundant vitamin C foods are guava, papaya, strawberries, kiwi, cantaloupe, orange, and grapefruit (1).
The live cultures found in yogurt, particularly Lactobaccilus and Bifidobacteria, may be beneficial in enhancing immunity. Having a healthy supply of gut flora increases a person's white blood cell production and activity. They may also boost the immunity while taking antibiotics, and they supply added protection to those who may have a compromised immune system. In a recent Swedish study, those who drank a daily supplement of Lactobacillus reuteri (a specific probiotic that appears to stimulate white blood cells) took 33% fewer sick days than those given a placebo. Probiotic rich foods include yogurt, kefir, select cheeses and milk, sauerkraut, kim chi and tempeh (2).
Mushrooms are antioxidant rich and very high in selenium. Selenium has been studied to reduce the risk of developing a severe flu. Mushrooms are also recognized for their antiviral, antibacterial, and anti-tumor effects. White button mushrooms in particular have noticeably greater immune boosting effects than other mushrooms such as, oyster and shiitake (3, 4).
High Fiber Grains
Oats and barley in particular contain beta-glucan, a type of fiber with antimicrobial and antioxidant capabilities. They enhance resistance to various fungal, bacterial and viral diseases. Beta-glucan is also found in protective amounts in shiitake and maitake mushrooms. Beta-glucan enhances immunity, similarly to echinacea and astragalus root. Beta-glucan binds to macrophages and other white blood cells and activates anti-infection activity by increasing the production of free radicals (5).
Vitamin E has been studied for its production of natural killer and B-cells, the cells that produce antibodies that destroy bacteria. The highest vitamin E foods are green leafy vegetables, sunflower seeds, almonds and blueberries (6).
Carrots and Sweet Potato
The antioxidant beta carotene has been studied to increase the number natural killer T-cells in our immune system. Beta carotene is a powerful antioxidant that mops up excess free radicals that can accelerate illness (7).
Zinc is a mineral which increases the production of white blood cells. As little as 15 to 25 milligrams a day will help to support immune function. Some of the top zinc foods are oyster, crab, grass fed beef and beans (8).
Garlic is known for its antibacterial, antiviral, antifungal and immune boosting effects. Garlic stimulates the production of white blood cells and increases the efficiency of antibody production. The immune-boosting properties of garlic seem to be due to its sulfur-containing compounds. Garlic can also act as an antioxidant that reduces the build-up of free radicals in the bloodstream (9).
Omega-3 Fatty Acids
Omega-3 fats reduce inflammation, increasing airflow and protect the lungs from colds and respiratory infections. The omega-3 fatty acids in ground flaxseed and fish such as, salmon, tuna, sole, flounder, sardines, herring and mackerel, act as immune boosters by increasing the activity of phagocytes, the white blood cells that destroy bacteria. Other omega-3 rich foods are tofu, edamame and walnuts (10).
The amino acid responsible for immune boosting components in tea is, L-theanine. It is abundant in both black and green tea. Many already know to drink green tea to help fight disease, new research is also including white tea, for its strong ability to destroy the organisms that cause disease (11, 12).
In Health and Happiness,
Kelly Harrington, MS, RDN
Registered Dietitian Nutritionist for Healthy Goods
1. US National Library of Medicine National Institute of Health (NIH). Dietary Supplement Fact Sheet: Vitamin C.
2. National Products Foundation Vitamins and Herbs A-Z: Probiotics.
3. US National Library of Medicine National Institute of Health (NIH). Dietary Supplement Fact Sheet: Selenium.
4. National Products Foundation Vitamins and Herbs A-Z: Selenium.
5. National Products Foundation Vitamins and Herbs A-Z: Beta-Glucan.
6. US National Library of Medicine National Institute of Health (NIH). Dietary Supplement Fact Sheet: Vitamin E.
7. National Products Foundation Vitamins and Herbs A-Z: Beta-Carotene.
8. US National Library of Medicine National Institute of Health (NIH). Dietary Supplement Fact Sheet: Zinc.
9. National Products Foundation Vitamins and Herbs A-Z: Garlic.
10. National Products Foundation Vitamins and Herbs A-Z: Fish Oil & Cod Liver Oil (EPA & DHA). \
11. Rowe C A, et-al. Specific formulation of Camella sinensis prevents cold and flu symptoms and enhances gamma delta T cell function: A randomized, double-blind, placebo controlled study. J Am Coll Nutrition, 2007, 26: 445-452.
12. J Bukowski et-al. L-theanine intervention enhances human gamma delta T lymphocyte function. Nutr Rev, 2008, 66: 96-102.