Between 5 percent and 20 percent of Americans come down with the flu each year, and about 36,000 people die annually after being diagnosed with the flu, notes Selene Yeager, author of "The Doctors Book of Food Remedies." Washing your hands and getting a flu shot can cut your risk, but eating certain foods can also help boost your immune system so that you're less likely to succumb to the flu virus.
Boost Your Intake of Salmon and Oysters
People with low levels of vitamin D are about 40 percent more likely to come down with a respiratory infection compared to people who have higher levels of the nutrient, notes Julie Knapp, writing for Mother Nature Network. A 3.5-ounce serving of salmon provides 360 international units of vitamin D toward the minimum 600 international units that adults need each day. Along with vitamin D, getting plenty of zinc can reduce the risk of coming down with the flu because it helps boost the immune system. Three ounces of oysters supply more than the 8 to 11 milligrams of zinc adults need each day.
Eat More Avocado, Squash and Watermelon
Glutathione is a compound that encourages the immune system to boost production of macrophages, cells that target illness-causing viruses and prepare them to be destroyed. Avocados, squash and watermelon are high in glutathione and might help fend off the flu. These foods also contain vitamin C, which can strengthen your white blood cells to help fight off infection. Vitamin C, however, isn't likely to prevent the flu.
Go for Garlic and Mushrooms
Garlic contains allicin and alliin, two compounds that can destroy germs. At the same time, garlic also encourages the immune system to release natural killer cells, which can help reduce the risk of infection. Eating raw garlic is one way to ingest these compounds, but cooking it into recipes is another effective way to boost your intake. Add mushrooms to recipes, too, because they contain selenium, a mineral that helps white blood cells make cytokines, compounds that target and remove illness-causing germs. Mushrooms also contain beta glucan, a type of fiber that's anti-microbial and helps destroy infections.
Add Some Yogurt and Chocolate
Yogurt contains probiotics that can help boost the health of the immune system, according to a 2008 study published in the "Annals of Nutrition and Metabolism." Look for yogurt that contains live and active cultures to reap these benefits. Have a square of dark chocolate with your yogurt to further boost your immune system. Compounds in dark chocolate can benefit the immune system and reduce the risk of infection, according to a 2009 study published in the "British Journal of Nutrition."
Sip green tea to help keep the flu at bay. Tea contains quercetin, a compound that can help prevent viruses from multiplying, Yeager notes. Black and white tea offer similar benefits. Tea also contains theophylline, a compound that can help break up congestion. Five cups of chamomile tea each day for two weeks can raise polyphenol levels in the body, reports Yeager. Polyphenols are compounds that have anti-bacterial activity, which means they might reduce the risk of infection.