Doctors warn the flu vaccine is the best defense against getting the flu, but also say building up your immune system is also extremely helpful.  That starts with sidelining the junk food and eating lots of fruits and vegetables.

"Those are just packed with vitamins and minerals and help our entire bodies function better - which helps our immune system function better and right now we need that so badly," says registered dietitian Abigail Dougherty.

Since so many grocery stores offer pre-cut packaged fresh fruits and veggies they are easy to prepare.

"It doesn't have to be in the oven, it can be in the microwave, anyway that you and our family will eat those vegetables and those fresher and healthier foods that's the best