When it comes to our kids' health, we worry about masks fitting correctly and their hand-washing skills; but what about what's on their breakfast plate?

Christina Garner, a licensed clinical nutritionist and wellness educator, with an expertise in medical nutritional counseling, at Community Health Programs, shared what foods adults and children should be eating to help boost their immune systems as we head into a cold and flu season in the middle of a pandemic.

"The immune system is an amazing machine that works for us 24 hours a day," she said in a phone interview. "I like to emphasize the word 'system'; it's not a single entity. It should be supported with balance and harmony."

She offered a few tips that people of all ages should take to support their immune system. Their goals should be:

• To get more than five servings of fruits and vegetables a day. She added one serving is roughly the size of your fist.

• Get adequate sleep. Garner said that for adults, that means 7 to 10 hours per night; teens, 9 to 10 hours per night and school-age children, 10 hours per night. "Lack of sleep makes you more susceptible to colds and the flu, and affects how you recover," she said.

• Practice stress management. Some ways Garner suggested included yoga, meditation, coloring and getting outdoors.

• Exercise. "You have to move," she said. "Moving releases stress hormones." She recommended 30 minutes of moderate exercise daily. "Walk or ride a bike after school," she suggested for children.

• Stay hydrated. Garner said the current recommendation is to consume half of your body weight, in ounces, daily. For example, a man weighing 200 pounds, would require 100 ounces per day; a 140-pound woman would ideally consume 70 ounces per day.

Foods also can play a role in boosting your immunity, Garner said. She highlighted six general categories of foods that we should be eating to help boost our immune systems this winter:

VITAMIN C-RICH FOODS

"Vitamin C is an antioxidant-rich food that can reduce the number of active days you have a cold," she said, adding three servings a day are recommended. Vitamin C-rich foods include oranges, grapefruit, bell peppers (which have more vitamin C than oranges, Garner noted), strawberries, spinach and kale.

FERMENTED FOODS

"They contain live cultures that are bacteria that feed and balance your immune system, which is housed in your gut," she said.

Examples of fermented foods include sauerkraut, yogurt, kombucha, miso, tempeh, fermented pickles and kimchi. Garner suggested making smoothies and frozen yogurt pops for kids to help them get more live cultures in their diet.

ZINC

"Foods rich in zinc have strong antioxidants that reduce your infection rate," she said. One zinc-rich food, she said, is pumpkin seeds, which can be added to trail mix for kids.

VITAMIN D-RICH FOODS

"Preliminary research has shown that those who have adequate vitamin D levels tend to have a less severe experience with COVID-19," Garner said, however, "Vitamin D-rich foods are less abundant. Get lots of sunshine to gain a good amount of vitamin D."

Some vitamin D-rich foods include mushrooms, salmon, tuna and egg yolks.

"Have hard-boiled eggs on hand to give kids as snacks or for a quick breakfast," she said.

VITAMIN D-FORTIFIED FOODS

Most dairy products; almond, oat and soy beverages, breakfast cereals and orange juice are fortified with vitamin D to support bone health and immune health.

ALLIUM VEGETABLES

"The allium family members are the smelly ones," Garner said. "Onions, shallots, leeks, chives and garlic. Garlic has the best anti-viral and anti-bacterial properties in the group."

QUERCETIN FOODS

"Quercetins are powerful antioxidants that can help support the immune system," Garner said.

Apples, red grapes, kale, spinach, capers and cherries are among the foods rich in quercetins. For kids, Garner suggested serving apple slices spread with sunflower, peanut or almond butter. She also suggested making apple crisps.

"Core golden apples, or your favorite kind of apple, and slice thin," she said. "Sprinkle them with cinnamon and sugar, and put them in the oven at 300 F for 45 to 60 minutes — you can choose the crispness. Cool and enjoy!"