DEAR DOCTOR K:

I know I should be eating fish regularly, but I don't like fish. Is it OK to eat shellfish instead?

DEAR READER:

Eating fish several times a week is good for your heart, and may also be good for your brain. Fish has plenty of protein and omega-3 fats ("good" fats). While this has not been absolutely proven, most nutritional scientists believe that it is the omega-3 fats in fish that make them heart-healthy.

Even if you're not a fan of fish, that still leaves plenty of options in the form of shellfish. There are crustaceans such as crab, lobster and shrimp, and bivalves such as clams, mussels, oysters and scallops.

But how do shellfish stack up nutritionally?

Shellfish are not as rich in omega-3s as most fish. Lobster contains very few omega-3s, and shrimp and clams are pretty modest contributors. Blue crab and oysters are better shellfish options.

If you're looking for protein, then you'll do all right with shellfish. With the exception of oysters, they're roughly equivalent to salmon (but not as high in protein as flounder).

If you have high total cholesterol levels, avoid a steady diet of shrimp. On the other hand, feel free to indulge in clams, crab, mussels and oysters -- they may lower your cholesterol levels a little bit.

The total calorie content of most shellfish is low. So if you're trying to lose weight, or maintain a healthy weight, shellfish are a good option.

There are a few precautions to take with shellfish. Toxins can be a problem, although getting sick from toxin-laden shellfish is rare. Still, keep an eye out for health advisories and eat accordingly.

Shellfish allergies are among the most common of food allergies. The reactions vary, but they tend to be severe.

How can you get more omega-3s in your diet if you don't like fish, and if you have allergies to shellfish? Fortunately, you have plenty of options. Lots of foods are rich in omega-3s. Flaxseed oil (especially), canola oil and soy oil are the oils with the most omega-3s. English walnuts (especially) and almonds are good, too. Brussels sprouts and kale are vegetables rich in omega-3s.

And don't forget supplements. You can get omega-3s by taking fish oil capsules. Many authorities recommend that people who don't like fish, and who have known heart disease or risk factors for heart disease, take daily fish oil capsules.

How do omega-3s help the heart? The strongest evidence is that they keep your heart from developing dangerous heart rhythms -- and sudden death. There also is evidence, though less strong, that they reduce your risk of developing atherosclerosis in the arteries of your heart. This, in turn, reduces your risk of having a heart attack.

We have a lot more information on healthy food choices in our Special Health Report "Healthy Eating: A Guide to the New Nutrition." You can find out more about it at my website.

(Dr. Komaroff is a physician and professor at Harvard Medical School. Go to his website to send questions and get additional information: www.AskDoctorK.com.)

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