This flu season has many people wondering about the best ways to protect themselves. And new products are turning up on store shelves suggesting they can help people with their immune systems.

One is called ColdBuster -- an orange flavored liquid that costs about $3 a bottle.

Roman Katsman of Coldbuster says, "the claims we're allowed to make is the ingredients in coldbuster helps fight colds and flus."

The active ingredients? Vitamins C, B6 and B12, and zinc. all important for good health.

But there have been no clinical trials of its claim to be a "revolutionary immune booster".

Is it even possible to boost the immune system? This immunologist says no.

Immunologist Carl Weiss says, "there is no real known way to boost your immune system."

Increasingly products are coming on the market claiming to boost the immune system.

Usually they containing echinacea or ginseng.

And while there have been studies showing they can boost the number of immune cells in the body, no one has been able to show conclusively whether that translates into a better immune response

Weiss says, "it doesn't mean you are going to have a better outcome if you get infected by virus A or B and I think is what you have to understand and that's really the key to everything."

Depending on the ingredient the scientific evidence on whether it works or not is contradictory. Overall, the experts say, someone getting proper nutrition probably doesn't need an immune boost.