5 Top Flu-Fighting and Cold-Crushing Foods

Come winter, your diet can determine whether you'll end up bedridden with a cold or the flu. Stave off seasonal illness with these immunity-boosting foods.

Kefir
A cultured milk product similar to yogurt, kefir is loaded with probiotics, the healthy bacteria that live in your gut—where most of your immune cells dwell—and help you absorb nutrients to keep your immune system solid. Blend one cup with fruit and drink it like a smoothie.

Red Grapefruit
Vitamin C can shorten colds while alleviating symptoms, but skip the supplements. Any more than 500 milligrams per day can cause digestive issues, and eating just one red grapefruit will satisfy your needs.

Sweet Potato
Root veggies are brimming with vitamin A, which helps the body produce white blood cells that fight bacteria and viruses. They also maintain mucosal membranes in the nose and throat to prevent infections from gaining a foothold in your body. Prick the skin with a fork and bake for 45 minutes at 400 degrees.

Cinnamon
One teaspoon has the same amount of disease-fighting antioxidants as half a cup of blueberries. And it's a versatile spice. Use it to flavor tea, cereal, smoothies, or vanilla ice cream.

Oysters
Thanks to high levels of zinc, the pneumonia and cold-proofing powers of oysters are top-notch. But the two most common ways of eating them—fried or raw in the half-shell—will raise your cholesterol and could expose you to food-borne illnesses. Instead, shuck them and broil with some minced parsley, garlic, and olive oil for about five minutes.

Recipe: Take Stock

A hot bowl of chicken broth does more than just warm you up: studies have shown that it fights respiratory infections and stems inflammation. This recipe, adapted from one tested by researchers at the University of Nebraska Medical Center, provides maximum health benefits. And it tastes good, too.

• Clean a five-to-six-pound whole chicken and put it in a large pot with ten quarts of water.
• Bring to a boil and add one pound of chicken wings, three whole onions, one sweet potato, three parsnips, two turnips, and 11 carrots. 
• Boil for an hour and a half, removing fat from the surface as it builds up.
• Add five celery stalks and one bunch of parsley and cook for another 45 minutes. 
• Remove chicken and strain out vegetables.

Makes 12 servings.