The best way to prevent the flu is to limit the spread of germs by washing your hands often, not touching your face and avoiding close contact with sick people, according to the Centers for Disease Control and Prevention. Certain nutrients may improve immune function, including zinc, selenium and vitamins A, C, D and E, notes Harvard Medical School.
Eat More Plant-Based Foods
Plant-based foods often contain immune-boosting nutrients and beneficial plant chemicals that act as antioxidants or have an antimicrobial effect. For example, vitamin C is an antioxidant with an antimicrobial effect that increases the activities of white blood cells that kill infected cells. Red bell peppers and broccoli are both rich in vitamin C. Foods such as garlic, ginger, green tea, oregano and turmeric contain powerful polyphenols that act as antioxidants. Pumpkin is rich in vitamin A, which also aids in immune function, according to an October 2008 ABC News article. Black-eyed peas and other legumes increase your zinc intake, tomatoes are rich in vitamin C, mushrooms provide selenium and almonds contain vitamin E, potentially improving immune function, according to the October 2013 issue of the "AARP Bulletin."
A Few Immune-Boosting Animal Foods
Milk, tuna, salmon and sardines provide vitamin D, and yogurt with live active cultures contains healthy bacteria called probiotics that may decrease the amount of unhealthy bacteria in your body and limit flu symptoms. Vitamin D may cause your body to increase the production of certain proteins that fight microbes, making you less likely to get the flu, according to the Harvard School of Public Health. Oysters are another potential immune-boosting food because of their high zinc content.
Amounts and Considerations
No one food is going to prevent the flu, but the mix of nutrients you get from following a diet rich in healthy foods may help. Don't overdose on any one food, but include a mix of nutritious foods in typical serving sizes, such as 3 ounces of oysters, a 1/2 cup of cooked broccoli and a cup of green tea.