T he quest for a healthy heart leads many Americans to the drugstore or the health food store, where the aisles are packed with vitamins, minerals, herbs and other substances that purport to help prevent or reduce the effects of heart disease. Heart disease is the leading cause of death in this country, and with the Baby Boomer generation now coming of age, heart disease is of increasing concern.

But are there nutritional supplements that are really worth your time and money? Below, cardiologist Dr. Nate Lebowitz and alternative medicine expert Dr. Samuel Benjamin offer some healthy advice on nutritional supplements for the heart.

Let's start with fish oil supplements. What do they do? NATE LEBOWITZ, MD: Fish oil has clearly entered the world of standard care. I think this was highlighted by a very large study last summer, with thousands of Italian men who had had heart attacks. Those who were put on fish oil, or omega-3 supplements from fish oil, had a dramatic drop in arrhythmias (abnormal heart rhythms), sudden death from arrhythmias, and repeat heart attack.

We've also known that it lowers triglycerides, can help with cholesterol, and can also help protect your arteries.

How much and how often should people be taking fish oil supplements? SAM BENJAMIN, MD: I think it depends on the medications you're taking. For example, if somebody is taking a blood thinner like Coumadin, or is taking aspirin, or both, they really need to discuss dosage with their physician, because fish oils will also affect the clotting mechanism, and that's an important consideration.

Also, if people are struggling with conditions in addition to their heart problems, they need to discuss these with a doctor before deciding on a dosage.

Are there other natural sources of omega-3? SAM BENJAMIN, MD: Flaxseed oil and hemp oil are both rich sources of omega-3. Hemp oil comes from the marijuana plant, but is not psychotropic in any way.

And in fact, both the flaxseed and hemp oils also contain a substantial amount of omega-6 fatty acids, which are also really good for you and your heart.

Grape skin is also said to be heart healthy. Why is this? NATE LEBOWITZ, MD: There were studies done on certain populations of the world who eat a high fat diet, but who also drink red wine every night. It turns out they have lower levels of heart disease than you would expect, relative to the amount of fat that they take in. They found that in the skin of the grape, there is a substance that has almost fifty times the antioxidant ability of even Vitamin-E, called resveratrol.

The sister compound is called pycnogenol and is made from the bark of the pine tree. It has been used as a home remedy for varicose veins in Europe for decades, and we're finding now that in basic science studies it really protects the arteries.

How can you get your resveratrol, or grape skin? NATE LEBOWITZ, MD: I would encourage people to consider either red wine in moderation, or grape juice. And certainly considering resveratrol as a supplement is definitely something that might be useful if you don't have the time to get it in your diet.

Which is more beneficial to good health: getting these substances from food or supplements? SAM BENJAMIN, MD: You want to encourage people to consider taking supplements. On the other hand, getting vitamins and minerals in your diet naturally is always the best way. One of the problems with supplements is that some of the more important but barely detectable active ingredients can be lost in the production and standardization process.

What is L-carnitine? What is it supposed to do? NATE LEBOWITZ, MD: L-carnitine is an amino acid. Within the last five years, in good scientific research and journals, L-carnitine has proven to be very useful in a number of areas. It's proven effective in the treatment of congestive heart failure, in the treatment of patients who are first presenting with a heart attack, or with symptoms suggestive of a heart attack, or in people who have had a heart attack in whom you want to protect the heart from a dangerous remodeling of the left ventricle, the pumping chamber of the heart.

There has also been much in the news about the benefits of Coenzyme-Q, or Co-Q. What are its benefits? SAM BENJAMIN, MD: Coenzyme-Q, or ubiquinone, is a naturally occurring molecule, which assists the body's enzymes in their activities. In larger doses, somewhere between 100 to 300 mg a day, there's no question that Co-Q 10 has some very positive effects in people with congestive heart failure, for example. That's the area that has been most clinically proven. It's used in Europe, not only orally, but intravenously, and its results have been very, very impressive.

Green tea extracts. Are they beneficial for heart disease? SAM BENJAMIN, MD: Green tea contains polyphenols, which lower serum cholesterol very substantially. And they are safe. I have not yet learned of any drug interactions or herb/herb interactions with polyphenols. The dosage has yet to be clearly ascertained, but the salutary effects of polyphenols are significant enough that people should consider green tea in the prevention of heart disease.

They should also tell their doctors they are taking it.

And the benefits of B-vitamins? NATE LEBOWITZ, MD: Folic acid, which is a B-vitamin, can be very helpful in the treatment of people who have elevated homocysteine, which is something that we're often testing for now in people who have early or premature coronary artery disease, or aggressive forms of coronary artery disease. If their homocysteine levels are high, taking folic acid, as long as the amount is right-say between 1 to 5 mg a day-can be extremely helpful in reducing the homocysteine level.

What role might garlic play in preventing heart conditions? Garlic works, just as aspirin does, by inhibiting platelets, which help clot the blood. And it helps lower serum cholesterol. Garlic a great day-to-day supplement, and it's cheap and safe.

And Chinese mu er? Mu er, or wood ear, is a common ingredient in sweet and sour soup-they're the little black strips. It comes from an ear-looking kind of plant that expands in water. And it is a blood thinner. But it cannot be taken with aspirin, or if you're taking Coumadin. If you eat a lot of Chinese food, it's very important that you tell your cardiologist or internist about that as well.

It seems that mistletoe is also used in disease prevention. Is that right? SAM BENJAMIN, MD: Mistletoe, or Viscum alba, is an herb used for some forms of cancer treatment here in the US at the present time, experimentally. Some people have mistakenly considered taking it for heart conditions. But it changes the rhythms of the heart, and that could be fatal. It should not be indicated for anybody with heart disease. And one wonders if that should be yanked from the shelves of stores anyway.

This raises a very good question for a lot of people. How do people decide which herbs and vitamins are not going to interfere with medications they are already on? And how do they know these natural substances are safe? SAM BENJAMIN, MD: I think it's important to ask your doctor these questions. But if your doctor does not have this background, there are a growing number of physicians in various specialties who are going into integrated medicine.

These doctors review the vitamins and herbs that you're taking, other therapies that you might be taking, to be sure that you're doing no harm. It's important to talk with a doctor who has an understanding of herb/drug and drug/drug interactions. One should never assume that because it's natural, it's safe.

From ABCNews.go.com