We all want to improve our immune system to stay healthy.

So many food products now claim they can boost your immunity. But experts say many of those claims are mainly there to boost corporate profits.

Regulations of some food products are so loose that a company can make the claim they're good for your immune system without proof.

No testing and no studies have to be conducted and, in some cases, the maker doesn't even have to change the product.

Take the Fuze Vitalize Fruit Drink, for example. It's the perfect drink to quench thirst and boost immunity -- at least that's what Coca Cola wants you to think when you drink one.

And for a busy mom, Dannon's Danactive Yogurt sounds like the perfect pick-me-up. After all, the ads say it's "clinically proven to help strengthen your body's defense."

We all know vegetables are good for you, but Green Giant says its new Immunity-Boost Frozen Vegetables are even better because they were "carefully selected" to have more vitamins A and C.

These claims sure sound good. In fact, according to David Schardt, senior nutritionist at the Center for Science in the Public Interest in Washington, D.C., the claims sound good because they're too good to be true.

"These are meaningless claims designed to move products," he said.

Schardt has one advice: be skeptical of all immunity claims.

"Any product that contains any measurable amount of any nutrient, vitamin or mineral is eligible to make this claim and that's because the immune system does use virtually every nutrient.

"But it doesn't mean people who are well-nourished or eating a decent diet get any benefit from eating these food products in terms of boosting their immunity," he said.

Crystal Light recently introduced a new version of their product with an immunity boost. And Kraft added some antioxidants to its mixes and flavored water. The company claims these products, which contain vitamins A, C and E, "helps support a healthy immune system."

Not so, Schardt says.

"Drinking Crystal Light Immunity Blend drink is not going to help your immune system," he said. "They're playing with us. They know that's something we're going to be attracted to even if there's no evidence that the stuff really helps."

I received an e-mail from Dannon's PR firm, asking me to point out that the company has the results of more than 25 studies that show Danactive helps strengthen the body's defenses.

The Center for Science in the Public Interest looked at those studies and said only 11 of them were conducted with humans. It also noted that seven of the studies did not show that Dannon kept people from getting sick.

The bottom line: experts on the human immune system says it doesn't fluctuated based on what you eat for dinner or what you drink at breakfast. This is about marketing, they say, not your health.