Photo of a bowl of leafy greens

It's pretty simple: Eating a healthy diet provides important vitamins, minerals and antioxidants that can boost your immunity. Plus, taking in plenty of the good stuff means you're taking in less of the bad stuff.

Tracy Severson, a dietitian at Oregon Health & Science University, explains, "A healthy diet means you're eating less of the unhealthy foods that can weaken immunity, such as highly-processed foods full of refined grains and flours, added fats, sodium and sugar."

Read on for tips on what to put on your plate—especially during cold and flu season.

1. Get a variety of fruits and veggies

Fruits and vegetables are excellent sources of antioxidants such as vitamin C, vitamin A and vitamin E—all of which can help maintain a healthy immune system.

Severson says that vitamin C is especially important since it helps in the formation of antibodies that prevent infections. While most people associate citrus fruits with vitamin C, other good sources include strawberries, kiwis, bell peppers and broccoli.

Vitamin A keeps your digestive and respiratory systems healthy, which helps protect them during the cold and flu season. Dark leafy greens and orange fruits and vegetables such as carrots, sweet potatoes, winter squash, cantaloupe and apricots are all great sources of vitamin A.

"The best approach is to eat a variety of fruits and vegetables in a range of colors," Severson says.

2. Go nuts

When you need a quick snack, grab a handful of sunflower seeds, almonds or hazelnuts. They're all high in vitamin E, which your body needs to boost its immune system. Even a small shortage of vitamin E can make it harder for your immune system to work properly.

Nuts, as well as liquid vegetable oils, also contain healthy unsaturated fats. This makes them good substitutes for saturated and trans fats that contribute to heart disease.

3. Boost your bacteria (the good kind!)

Not all bacteria are bad for you. Live, active bacteria cultures found in fermented foods, such as yogurt, kefir and live sauerkraut, may help boost your immunity.

Good bacteria in your gut can dwindle for many reasons: changes in your lifestyle or diet, viral or bacterial infections, or use of antibiotics that wipe out the good with the bad bacteria. Severson suggests promoting good bacteria by eating fermented foods, as well as prebiotic-rich foods like high-fiber vegetables, fruits and whole grains.

4. Fortify with zinc

Zinc helps with wound-healing and keeps your immune system strong. It's found in shellfish (particularly oysters), nuts, seeds, beans, lean meats and poultry.

Already sick or on the brink of a cold? Severson says that zinc lozenges taken at the first sign of symptoms (every two waking hours for a total daily dose of at least 75 mg) have been shown to decrease the duration of colds.

Stay healthy and save money

We know it can be hard to make healthy food choices. To help, Asuris Advantages offers great savings on health-related products and services at no additional cost to you. Check out the Advantages discounts—like deals on healthy meal delivery and planning—and stay sniffle-free this season.