Dr. Nicole Saphier's 5 foods to boost the immune system this cold and flu season

In a Sunday appearance on "Fox & Friends Weekend," Fox News medical contributor Dr. Nicole Saphier offered some power foods that can help boost the immune system.

Here are a few immune boosters that can be added to your diet, according to Saphier.

One whole, raw, red bell pepper has more than twice the daily recommended dose of vitamin C, Saphier stated.

"Vitamin C is obviously great for our immune system," she said.

"If you grill it, if you boil it, it does reduce the vitamin C a little bit, but it's still excellent, it has other nutrients in it."

Saphier shared that she slices red bell peppers and serves them to her kids "almost every morning before school."

Saphier described blueberries as a "superfood" and "nature's powerhouse."

"When it comes to all of your fruits and veggies, this has one of the highest amounts of jam-packed, antioxidant, low-calorie, low-sugar content," she said.

"Grab a handful - it's great for you."

Citrus foods like oranges and lemons provide a "high amount of vitamins," according to Saphier.

The doctor warned that citrus does have higher sugar content, so people who are diabetic should be cautious about amounts.

"Especially if you get the pre-packaged, concentrated juice from the store - that has a lot of sugar on it, [so] you have to be careful," she said.

The best way to boost citrus intake is to eat it raw or add it to a vitamin-packed juice, according to Saphier.

Although it may be surprising, garlic is "one of the best things for your immune system," according to Saphier.

The doctor shared that she takes liquid garlic and combines it with other ingredients, like turmeric and ginger, in a juice for an extra immune boost.

"People say when you look at walnuts, they look like a little mini brain," she said.

"I keep these with me in my office at the hospital," she added. "They're really good for you, so obviously you want to keep your body healthy, but your brain healthy as well."

Saphier explained that organic options are "always the way to go" to avoid exposure to pesticides, hormones and other additives, but they can be a little more expensive.

"If only we could get those prices down, so that they're more affordable and accessible," she added.