Boost your immunity with these tips and recipes
By Megan O. Steintrager, Epicurious.com
Have you noticed that people who normally shun shots are scrambling to get flu vaccines this year? And that's just the "regular" flu shot—vaccinations against H1N1, or "swine flu," aren't even widely available yet. I contacted John La Puma, M.D., the author of Chef MD's Big Book of Culinary Medicine, for advice about what to eat to boost immunity and fight the flu.
Quercetin Powerhouse Produce: Apples, Onions, Broccoli, and Tomatoes
Quercetin is one of many thousands of flavonoids—substances that are responsible for plants' colors, as well as many of their health benefits. La Puma says that in research performed on mice, stressful exercise increased flu susceptibility but quercetin canceled out the negative effects. The same illness-fighting results were found in a study on cyclists, La Puma says, citing a study from Appalachian State University in Boone, N.C. Quercetin is also believed to aid in disease prevention thanks to its anti-inflammatory properties. So load up on quercetin-packed produce, including apples, onions, broccoli, and tomatoes. Tip: When buying tomatoes, consider choosing organic, which La Puma says have higher levels of quercetin than conventionally grown ones (the same is true for lycopene in tomatoes). recipe to try Frisée and Apple Salad with Dried Cherries and Walnuts .
Chicken soup really does have healing properties, according to La Puma. A steaming bowl of soup (unappetizing language alert) "reduces mucus and facilitates coughing it up." And it seems that chicken soup is more effective at the job than hot water, according to research cited by La Puma. To get the anti-inflammatory and other health benefits of produce too, the doctor suggests making chicken soup with vegetables rather than using store-bought condensed soup or cooking with chicken alone. recipe to try: Chicken and White Bean Soup with Herb Swirl .
Add fighting the flu to the long list of green tea's health benefits, which also include fighting cancer and heart disease and possible links to "lowering cholesterol, burning fat, preventing diabetes and stroke, and staving off dementia," according to WebMD. Green tea is high in "anti-viral activity against influenza," says La Puma, citing studies involving green tea from the Dr. Rath Research Institute in Santa Clara, CA, and the Department of Biotechnology, College of Engineering, Yonsei University in Seoul, South Korea. While all kinds of tea are made from the same leaves, white and green teas contain higher levels of catechins—the flavonoids thought to be responsible for tea's antiviral properties—than oolong and black teas. Although the studies La Puma cites involved green tea, it's likely that white tea has similar flu-fighting powers. Black and oolong tea do have some catechins and are higher than green tea in other polyphenols, so while they might be the second choice for the flu, they are still good for overall health.
Vitamin D–Rich Foods: Salmon, Light Tuna, Sardines, Milk, and Cereal
Vitamin D has been a hot topic in the news recently, with stories about the sunshine vitamin's many health benefits dovetailing with reports that suggest that many of us don't get enough of it. La Puma says experiments in the 1940s showed that mice that received diets low in vitamin D were more susceptible to experimental swine flu infection than those that received adequate vitamin D. While the same has not yet been proven in humans, La Puma and many other experts believe that getting sufficient vitamin D can offer protection against swine flu—the vitamin is believed to cause the production of antimicrobial substances in the body. "In winter, too little vitamin D is made in your skin, because the angle of the sun is too low," says La Puma. "And winter is when you get flu." The good news is that food can pick up the slack. Milk (which is fortified with vitamin D in the U.S.), malted drink mixes, and fortified cereals such as Total Raisin Bran and Whole Grain Total all provide vitamin D, but La Puma says roasted sockeye salmon is the single best source, gram for gram. Roasting the fish allows it to maintain the most vitamin D. "Cooking fatty fish with oil allows the vitamin D to leak out," says La Puma. "Cooking fatty fish in water does retain a little vitamin D, at least in theory, so poaching and steaming work better than frying, deep-frying, and sautéing."
Other good fish sources of vitamin D are pink salmon, as well as light tuna and sardines packed in oil. "Packing (but not cooking) fish in oil allows retention of omega-3s and vitamin D," says La Puma. But, he warns, "pouring off the oil from canned fish pours off the vitamin D too.". If you are not a fan of the flavor or extra calories in oil-packed fish, don't worry: Water-packed varieties do have some vitamin D, just not quite as much as oil-packed. Bumble Bee Chunk Light Tuna was the top pick for oil-packed varieties in Epicurious's Canned Tuna Taste Test. recipes to try: Baked Sockeye Salmon with Bell Peppers and Capers , Penne with Tuna, Basil, and Lemon .
Yogurt and Kefir with Live Active Cultures
A recent study suggests that probiotics—the friendly bacteria found in yogurt and some other foods, as well as in pill form—may reduce cold and flu symptoms. La Puma cites the same study and says that probiotics have been shown to reduce the incidence and duration of fever, cough, and runny nose by 73, 62, and 59 percent in kids ages 3 to 5, respectively. While the study was done with supplements, La Puma says we "foodistas" may prefer to get our probiotics from what we eat. When buying yogurt and kefir, be sure to look for the "Live and Active Cultures" label and choose one with as many different strains of cultures as possible. recipes to try: Moroccan-Style Vegetable Stew with Harissa Yogurt Sauce .
Chiles Such as Serranos, Jalapeños, and Poblanos
Spicy peppers don't just help clear your sinuses, they're also a great source of vitamin C, which "has been tested in influenza A and been shown to reduce the incidence of pneumonia that comes with flu," says La Puma. The vitamin has antiviral properties and stimulates antibody production, explains La Puma. Not a chili-head? Sweet red bell peppers are also packed with vitamin C, as are guava, kiwi, oranges, green bell peppers, strawberries, Brussels sprouts, cantaloupe, and papaya, according to the USDA.
Recipes to try:
Frisée and Apple Salad with Dried Cherries and Walnuts 
Chicken and White Bean Soup with Herb Swirl 
Baked Sockeye Salmon with Bell Peppers and Capers 
Penne with Tuna, Basil, and Lemon 
Moroccan-Style Vegetable Stew with Harissa Yogurt Sauce 
All recipes courtesy of Epicurious.com