What natural substances are known to boost immunity? Name some examples

Expert Answers
trophyhunter1 eNotes educator| Certified Educator

Probiotics which are found in yogurt are good bacteria which pass through the intestinal tract. They aid in fighting off bad bacteria, which helps to boost immunity. Adding yogurt to the diet boosts the production of white blood cells which are part of our arsenal against invading germs. Kefir, a Middle Eastern food contains different bacteria that can live in the intestinal tract along with good yeast that fights off bad strains of yeast.  Fruits and vegetables all are rich in vitamins and antioxidants and are healthy foods to help the immune system function optimally. Turmeric has cold-fighting properties and is found in foods made with curry. Garlic contains sulfur and has anti-viral, bacterial, fungal and parasitic  properties. It is also contains antioxidants. Oregano, a spice used in Italian foods prevents infections. Bell peppers contain vitamin C which fights infections and boosts immunity. Green tea is known to have antioxidant and anti--cancer properties. Ginger helps increase perspiration to remove toxins from the body. Yellow vegetables like those in the squash family contain Vitamin A another immune system booster. Blueberries have antioxidants and are loaded with vitamins A and C. Greens like collard greens and kale are excellent sources of Vitamin A.

surrestta | Student

"British researchers gave 146 people either a placebo or a garlic extract for 12 weeks; the garlic takers were two-thirds less likely to catch a cold. Other studies suggest that garlic lovers who chow more than six cloves a week have a 30% lower rate of colorectal cancer and a 50% lower rate of stomach cancer." Garlic contains antioxidants and sulfer, making is antibacterial, antiviral, and anti- parasitic.
Selenium, found in fish and shellfish, helps white blood cells produce cytokines—proteins that help clear flu viruses out of the body.
University of Nebraska researchers tested 13 brands, they found that all but one chicken noodle flavor soups "blocked the migration of inflammatory white cells—an important finding, because cold symptoms are a response to the cells' accumulation in the bronchial tubes." The amino acid, cysteine, actually resembles the bronchitis fighting drug, acetylcysteine, which could explain why this chicken noodle soup is recommended during an impending cold.
L-theanine, an amino acid found in black and green tea was proven beneficial in virus fighting in a Harvard Study. Researchers found that those who drank "5 cups a day of black tea for 2 weeks had 10 times more virus-fighting interferon in their blood than others who drank a placebo hot drink."
With your skin being a crucial organ within immunity, and the first-line defense system. For healthy skin, the Vitamin A found "in potatoes plays a plays a major role in the production of connective tissue, a key component of skin," (Prevention advisor David Katz, MD, director of the Yale-Griffin Prevention Research Center in Derby, CT).
Lactobacillus reuteri, a probiotic in yogurt, has been proven to stimulate white blood cells, making them more aggressive and able to fight toxins. 
Beta-glucan, a type of fiber with antimicrobial and antioxidant capabilities in oats and barley, defends the human body making it less likely to contract influenza, herpes, and anthrax.

acres | Student

Vitamin C mostly tops the list when it comes to boosting immunity. You can find that in most citric fruits or in Vitamin C chews. Vitamin E is a vey good antioxidant and immunity booster as well. You can get this through you average grains,seeds and vegetable oils. And of course there is a whole lot like your Zinc, Carotenoids and all that.

Basically fruits, vegetables,dairy products, green tea (VRY HIGHLY RECOMMENDED), sweet potatos, spinach etc are all very good for boosting the immunity system.

Hope that was useful! :) Take care! :D