One of the best ways to ward off any flu is to build up your overall immunity. Dave Grotto, author of "101 Foods That Could Save Your Life," reveals 10 foods that provide top doses of the vitamins and nutrients you need to protect and defend against illness.

1 of 10 Mushrooms Photo: Mike Licht [CC BY 2.0] /Flickr Mushrooms used to get overlooked as a health food, but they possess two big weapons you need this flu season: selenium, which helps white blood cells produce cytokines that clear sickness, and beta glucan, an antimicrobial type of fiber, which helps activate "superhero" cells that find and destroy infections.

2 of 10 Wild-caught salmon Photo: Andrey Starostin/Shutterstock In a study published in Archives of Internal Medicine, participants with the lowest levels of vitamin D were about 40% more likely to report a recent respiratory infection than those with higher levels of vitamin D. Increase your intake with salmon. A 3.5-ounce serving provides 360 IU, and some experts recommend as much as 800 to 1000 IU each day.

3 of 10 Fresh garlic Photo: ILoveButter [CC BY 2.0] /Flickr Strong-smelling foods like garlic can stink out sickness thanks to the phytochemical allicin, an antimicrobial compound. A British study found that people taking allicin supplements suffered 46% fewer colds and recovered faster from the ones they did get. So start cooking with it daily — experts recommend two fresh cloves a day.

4 of 10 Tea Photo: voraphong/Shutterstock Researchers at Harvard University found that drinking five cups of black tea a day quadrupled the body’s immune defense system after two weeks, probably because of theanine. Tea also contains catechins, including ECGC, which act like a cleanup crew against free radicals. Grotto suggests drinking one to three cups of black, green or white tea every day.

5 of 10 Dark chocolate Photo: Africa Studio/Shutterstock Nutrition experts agree that dark chocolate deserves a place in healthy diets, and a study published in the British Journal of Nutrition says it can boost your immunity, too. High doses of cocoa support T-helper cells, which increase the immune system’s ability to defend against infection. Sweet!

6 of 10 Yogurt Photo: Ozgur Coskun/Shutterstock The digestive tract is one of your biggest immune organs, so keep disease-causing germs out with probiotics and prebiotics, found in naturally fermented foods like yogurt. One serving a day labeled with "live and active cultures" will enhance immune function according to a study from the University of Vienna in Austria.

7 of 10 Almonds Photo: Harsha K R [CC BY-SA 2.0] /Flickr Heart-healthy almonds provide the immune-boosting antioxidant vitamin E, which can reduce your chance of catching colds and developing respiratory infections, according to researchers at Tufts University. You’ll need more than a serving of almonds for your daily dose though, so try fortified cereals, sunflower seeds, turnip greens and wheat germ, too.

8 of 10 Oysters Photo: Nishihama/Shutterstock Zinc is critical for the immune system — it rallies the troops, or white blood cells, to attack bacteria and viruses like flu or cold. One medium oyster provides nearly all of the zinc you need for a day, while a portion of six gives you over five times the recommended amount.

9 of 10 Strawberries Photo: Africa Studio/Shutterstock Even though vitamin C-rich foods (hello, oranges!) are probably the first thing you think of when you feel a cold taking hold, Grotto says the illness-preventing power of that antioxidant is debatable. That said, some studies show it can reduce the intensity and duration of cold and flu, so it’s worth a try. One cup of strawberries provides 160% of your daily needs.