Your immune system is responsible for helping fight off everything from the common cold to cancer. A tall order!

Send in some reinforcements so it doesn't get battle fatigue. Here are four foods your immune system loves.

Sweet, Creamy, Steamy, Crunchy . . .
Oranges, yogurt, tea, and pumpkin seeds are the order of the day when it comes to giving your immune system a treat, according to RealAge experts Michael Roizen, MD, and Mehmet Oz, MD, authors of the best-selling (and now newly expanded and updated) YOU: The Owner's Manual. Here's how these four superfoods help:

1. Oranges are chock-full of vitamin C, an antioxidant vitamin that helps your immune system fend off disease-causing invaders. Other good C options: bell peppers, strawberries, cantaloupe, and broccoli. Or take 400 milligrams of vitamin C three times daily. (Look up more C sources.)
2. Yogurt (unpasteurized) contains Lactobacillus acidophilus -- a healthy bacterium that helps thwart fungus-related infections. Or take a 20-milligram acidophilus supplement twice daily. (Here's another great natural fungicide.)
3. Tea is full of flavonoids, powerful vitamin-like substances that reduce immune-system aging. You'll also find them in oats, onions, broccoli, tomatoes, apples, and berries. (Boost your berry intake with this Triple Berry Blender Blaster.)
4. Pumpkin seeds are great year round, not just at Halloween, because they contain zinc -- a nutrient that's been shown to help reduce the average length of the common cold. (Find out how zinc can make exercise easier, too.)

Are your immunizations current? Get a checklist with this vaccine assessment.