Several million years ago, it is hypothesized, the first Stone Age human caught the first cold. Ever since then, doctors, nurses, herbalists, shaman and healers of every sort have been confounded by colds and flu. Over the years, these devilish pathogens have been treated with cold baths, wet feet, chili peppers, tobacco, and the application of blood-sucking leeches.

Now we understand that colds and flu are caused by viruses – but we’re still no closer to a cure. The only offense is a good defense. And as long summer days wind down, school resumes and cooler weather begins, it’s a good time to bolster your defenses before the real start of cold and flu season. You can maximize your pathogen-fighting potential, with a handful of healthy foods. Some of the best:

1. Red peppers are high in carotenoids and vitamin C, both of which enhance immune function. Other good sources: papaya, peaches, strawberries, broccoli and Brussels sprouts.

2. Ginger decreases inflammation in the body, thins mucous secretions and helps clear nasal passages. Cayenne pepper, garlic, onion and other spicy and pungent foods can also be helpful.

3. Onions are high in anti-inflammatory flavonoids called quercetin that work as natural anti-histamines. You’ll also find quercetin in tea, apples, broccoli and red wine.

4. Garlic is a potent anti-viral that’s rich in allicin and sulfides, compounds that increase immune-system activity. In one study, volunteers who took garlic supplements had significantly fewer colds than the placebo group. Those who did catch colds, recovered faster than the untreated group.

5. Almonds. Almonds contain immune-boosting vitamin E. Sunflower seeds, tomato paste, eggs, spinach, turnip greens and hazelnuts are also good sources.

6. Collard greens are rich in immune-boosting vitamins, minerals and antioxidants, as are other green leafies, like chard, spinach, kale, mustard greens and turnip greens.

7. Sardine, salmon, tuna, mackerel and herring are rich in omega-3 fatty acids, which modulate immune activity. Flax seeds, walnuts and hemp contain alpha-linolenic acid (ALA), a fatty acid that’s converted in the body to omega-3 fatty acids.

8. Green tea contains epigallocatechin gallate, a powerful immune-enhancing
compound; black and white tea have similar immune boosting effects, as does rooibos (red) tea.

9. Blueberries are rich in immune-enhancing antioxidants; you’ll find many of the same compounds in strawberries, raspberries, blackberries, cranberries and cherries.

10. Oysters are rich in zinc, which boosts the production and activity of infection-fighting white blood cells. Other sources of zinc: shrimp, crab, chickpeas and lentils.

11. Turnips are rich in sulfur-containing compounds called glucosinolates that protect against viruses; you’ll find the same compounds in cauliflower, broccoli, Brussels sprouts, cabbage and other crucifers.

12. Brazil nuts are a significant source of immune-enhancing selenium. Other sources: tuna, lobster, shrimp, egg yolks, pumpkin seeds and sunflower seeds.

13. Shiitake mushrooms contain immune-boosting compounds called lentinan and polysaccharides. In one study, HIV patients who took lentinan showed an increase in immune-activity.

14. Yogurt is rich in probiotics that activate immune cells, fight infection and stimulate the body’s resistance to pathogens.

15. Olive oil contains squalene, a compound that boosts immune function in part by increasing T-cells. Other sources: wheat germ, olives and amaranth.

Apple-Fig Chutney with Crystallized Ginger
Makes about 2 cups
1/2 cup apple juice
3/4 cup chopped dried figs
1 tablespoon olive oil
2 small red onions, quartered and thinly sliced
2 large Gala apples, chopped
1 3-inch piece fresh ginger root, peeled and finely minced
2 medium garlic cloves, finely minced
1 tablespoon honey
1/4 cup apple cider vinegar
1/4 teaspoon white pepper
2 to 3 tablespoons minced crystallized ginger
Cayenne pepper to taste

1. In a small bowl, combine apple juice and figs, and let stand at room temperature for 1 hour to soften figs.

2. In a medium pot, heat olive oil over low heat; add onions and cook, stirring occasionally, for 20 minutes until caramelized.

3. Stir in apples, ginger, garlic, honey, vinegar and white pepper; increase heat to medium-low and cook, partly covered, for 20 minutes longer, until apples are soft.

4. Add fig and juice mixture, and cook for 10 minutes longer, until most of the liquid is evaporated. Stir in crystallized ginger. Season to taste with salt and cayenne pepper, and refrigerate until ready to serve.

Lisa Turner is a chef and food writer in Boulder. She also teaches cooking and nutrition classes at Bauman College, and offers catering and nutrition consulting. Visit TheHealthyGourmet.net or InspiredEating.com for more details.