Can food with omega-3 fatty acids really prevent heart disease? It all depends.

Omega-3s are good for you. They can greatly reduce your chances of sudden cardiac arrest, which is almost always fatal.

The miracle fats are one of the hottest food additives right now. They're being used to move a lot of food products.

Maybe you've noticed. A growing number of products on the supermarket shelf now proclaim they contain omega-3s.

That's why so many things, from cereal to pancake mix, are now made with flaxseed. Flaxseed and flaxseed oil are good sources of omega 3s.

But, it turns out, not all omega-3s are the same.

There are three kinds of omega-3 fats: DHA, EPA and ALA. Both DHA and EPA, which are found in fish oil, can help your heart. ALA, the type of omega-3s found in flax seeds, soybeans and canola oil, do not prevent heart disease.

David Schardt, senior nutritionist with the Center for Science in the Public Interest, is concerned about the mega-marketing of omega-3s.

"Manufacturers who use flax, they can use soy and canola oil because they have some omega-3's. But it's not the right kind," he said. "It's a cheaper, more convenient form of omega-3's and it allows manufacturers to put omega-3's on the label. But it's deceptive, because it's not the kind that protects your heart."

Schardt says while the big omega-3 claim is usually on the front of the package, the type of omega-3 is usually indicated in smaller print, or not there at all.

One example is the Smart Balance Buttery Spread. It's loaded with omega-3s, but only a little of it is the heart-healthy DHA type.

"The labels are misleading in the sense that (it implies) you're going to get a lot of the good Omega -3. And you get some, but not as much as the label seems to imply," said Schardt.

Schardt advises consumers to be careful when reading labels and looking for omega-3s.

Find out. First, is it the right kind of Omega-3, the DHA and EPA, and are you getting a reasonable amount? You need about 500 mg per day. Most food products do not contain that amount.

So what do you do? How do you get the heart-healthy omega-3s? Eat fish at least twice a week. You want fatty fish, such as salmon, rainbow trout, sardines or mackerel. Even a tuna fish sandwich will help. A 3-ounce serving of albacore tuna has around 240 mg of the good omega-3s. That's more than half of the recommended daily intake.

What if you just can't eat that much fish?

You can take fish oil pills. These are one of the few supplements that seem to work about as well as the real thing.

In fact, the American Heart Association says people who have heart disease should take a daily fish oil supplement with 1,000 mg. That's 1 gram of DHA and EPA.