Banish colds, flu, and H1N1, and boost your immune system this winter with these natural remedy foods.

Tall and sturdy, sunflowers seem to radiate good health -- and the seeds of these native North American flowers deliver on that promise. Two tablespoons give you more than a third of your daily requirement of vitamin E. This vitamin helps you resist the flu and upper-respiratory infections by boosting production of T-cells, a type of white blood cell that fights infection.

Pictured here, sunflower seeds are stirred into an autumn greens salad dressed with whole-grain mustard, maple syrup, and cold-pressed sunflower oil.

Other E superstars: almonds, wheat germ, hazelnuts, and peanuts.

Everything about these tender, rich-tasting nuts (pictured at top right) is larger than life, from the 150-foot trees they grow on to the amount of cold-fighting selenium they contain. (A single Brazil nut has 95 mcg -- nearly double the amount you need in a day.) Your body uses selenium to produce those infection-thwarting T-cells, which in turn destroy bacteria and viruses. Studies show that this antioxidant instigates the good bacteria in our intestines to attack bad bacteria and parasites like E. coli.

Don't go on a feeding frenzy, though. Too much selenium can be bad for your health; a small handful of nuts every few days is all you need.

These bumpy, briny bivalves inspire strong feelings: Gourmands revere them; squeamish eaters avoid them. If you're in the second camp, you may want to reconsider. High in protein, iron, and calcium, and one of the most environmentally friendly types of seafood you can buy, oysters also stand out when it comes to zinc. Six oysters provide 32 mg of this essential mineral -- four times the recommended daily amount. Zinc is so crucial that a deficiency in this mineral causes your body to function as if it's older than it really is.

Pictured here, oysters are cooked in an antioxidant-rich stew made from sweet potatoes and leeks.

Other zinc superstars: beef, crab, pork, chicken, cashews, beans, fortified cereals, and other grain products.

If you're looking for a side dish packed with flavor, you can't beat a sweet potato -- in season during the fall in most climates and winter in warmer climates -- and few foods rival it for beta-carotene content. The lining of your lungs and digestive system, the front lines of the infection war, depend on this antioxidant (which your body converts to vitamin A) to function properly. In addition, vitamin A protects the thymus gland, the body's production site for T-cells in children. Roasted, pureed, or fried (as pictured here), there's no need to hold back: For the most part, the body converts the amount of A it needs.

Cultivated for more than 1,000 years, these meaty, tender Chinese mushrooms have long served as both food and medicine. They owe their reputation as immunity boosters to a type of carbohydrate called beta-glucans. Unlike other immunity nutrients, beta-glucans don't create or regulate cells within your immune system. Instead, they act as a kind of decoy, boosting your body's immune response. When you eat shiitakes (or other beta-glucan-containing foods), your immune system reacts as if a harmful substance is present and kicks into high gear to protect you. In a 2004 animal study of swine influenza virus, the group given beta-glucans before infection developed a much milder case of the flu than those untreated. While the swine flu virus studied was not the same strain as the human H1N1 virus, the results show promise for beta-glucans' ability to prevent and treat the flu.

Pictured here, roasted shiitakes are served with garlic (a fellow superfood) and herbs atop rustic Italian bread.

Other beta-glucan superstars: yeast, maitake mushrooms, barley, and oats (particularly the bran).

Brown and fuzzy on the outside, green and luscious on the inside, kiwifruit takes the prize for vitamin C. Considered the go-to resource for staving off illness, C can help increase your resistance to disease and keeps your defenses strong. Just don't wait for the first sign of infection to start fueling up; studies show that taking large doses of C once a cold begins does not shorten its length or severity, but a regular dose of 75 to 90 mg per day might.

Pictured here, kiwis, lime juice, and chopped jalapenos make a delicious relish for this shrimp dish.

Note: Vitamin C is easily damaged by heat and water. Try to consume C-packed foods raw or barely cooked.

Regarded as one of the most potent cold and flu fighters, garlic combats a rogues' gallery of invaders, including bacteria, fungi, parasites, and viruses, thanks to the presence of polysulfides, a class of sulfur compounds. Ajoene, for instance, inhibits the growth of a broad range of microbes, including Staphylococcus aureus (a cause of staph infections) and E. coli. Garlic's most dynamic compound, allicin, blocks enzymes that help viruses spread. Allicin lies dormant in a clove until it's cut, chewed, or crushed.

Although garlic is often enjoyed roasted (as pictured in this soup), you can maximize its benefits by eating it raw -- or mince a clove and let it sit for a few minutes before cooking.