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I recently called our pediatrician's office and asked when I should bring in my 6-year-old daughter to get her vaccine. "As soon as possible. We only have five left." Needless to say, I scheduled an appointment for the next day. No one wants to get the flu or have family members get sick with it. And even though peak season for flu won't hit until the winter, there's no time like the present to get prepared.

If you've gotten your flu shot and you wash your hands religiously, you may wonder what more you can do to arm yourself against becoming sick. While there's no way to absolutely guarantee you won't get sick, eating a nutrient-rich diet can help guard against illness. Add these six foods to your routine to prevent and fight colds and flu this season:

1. Mango. This sunny fruit is packed with vitamins A and C. Vitamin A plays a role in immunity, and vitamin C is a powerful antioxidant that helps fight free radical damage caused by environmental stress. Vitamin C also helps shorten the duration of colds. One cup of sweet, juicy mango has 75 percent of your vitamin C for the day and 25 percent of your vitamin A.

Tip: Blend fresh mangos into smoothies, add it diced to oatmeal or use it in salsa to top chicken and fish.

2. Puerh tea (pronounce poo-urr). Puerh is a fermented tea that boasts more antioxidants than green tea. It has a rich, earthy flavor. Fend off colds and flu with a hot toddy made with puerh tea.

Tip: Make a puerh hot toddy. Brew the tea, then add strips of lemon zest, lemon juice, 2 teaspoons of honey and an optional splash of whiskey.

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3. Yogurt. This fermented dairy product is rich in beneficial probiotics, which studies show help keep your gut healthy. A healthy gut is a great defense against getting sick. Kefir and other cultured milk products have the same effect as yogurt.

Tip: In addition to eating yogurt by the cup and in smoothies, you can also use it plain to top chili, soup and curry dishes.

4. Chicken soup. Nearly every culture has their own version of chicken soup or some kind of broth made from a chicken carcass. Chicken broth helps break up mucous and reduces inflammation in the respiratory tract. Just make sure yours is packed with garlic. Garlic contains selenium, an essential trace mineral that helps prevent cell damage. It also helps protect your body after a vaccination, so follow up that flu shot with a bowl of chicken soup. Plus, chicken soup is great for rehydrating and might even help kill off viral cells.

Tip: If you don't have time to make it from scratch, use packaged broth and shredded rotisserie chicken, plus pre-cut vegetables to whip up a quick soup.

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5. Eggs.  The incredible egg is one of the few food sources of vitamin D, which most of us don't get enough of in the dark winter months. A vitamin D deficiency can leave you with a weakened immune system. Whip up a tasty egg dish and make sure to keep the yolks in – that's where the vitamin D is. Two eggs have 160 IU of vitamin D.

Tip: Fry up an egg, and wrap it in a corn tortilla with salsa and avocado for a tasty breakfast wrap.

6. Red meat. Beef, bison and lamb are all packed with zinc, another trace mineral that is vital for keeping your immune system strong. It also helps wounds heal. In addition to red meat, you can also get zinc in chicken, seafood, pork, fortified cereal, chickpeas, almonds and cashews.

Tip: There's no need to eat a T-bone steak! Even a smallish 3-ounce burger will deliver more than 5 mg of zinc, which gets you more than half your daily requirement. Sprinkle chopped almonds over cereal and salads, and try to get two servings of seafood weekly.

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In addition to stocking up on the foods above, here are some additional lifestyle choices you can make to stay healthy during cold and flu season.

Get shut eye. I remember cramming for exams in college and then coming home for the holidays, only to get a terrible cold or other malady. It's no secret that when we're run down we're more likely to get sick. Studies show that T cells – a type of white blood cell that attacks viruses – decrease when we're sleep deprived. Not getting enough ZZZs can also decrease the protection you get from the flu vaccine.

Stay active. Shorter, colder days cause many of us to cut back on workouts, but that's not smart for your waistline or your immune system. Regular moderate physical activity helps boost immunity. So get out there, and go for a jog. Just make sure to warm up with a bowl of hot soup afterwards.