A Guide to Good Health reader recently asked me a question about fish oil. She wanted to know if krill oil is better for you than fish oil. Of course, the answer's never simple when it comes to your nutrition. So let's first start by discussing the ABCs of fish oil.

The catch-22 of fish oil

As you'll recall from previous issues of the Guide to Good Health, omega-3 fatty acids (found in fish or cod liver oil) are basic building blocks of good health. In fact, that's why we call them "essential" fatty acids. These vital nutrients support your immune system, heart, mood, blood sugar, joints, brain, and so much more. But they also increase free radicals in your body.

Free radicals are charged molecules that can speed up the aging process. In addition, many scientists believe that free radicals can damage your DNA. They disrupt the natural life cycle of your cells, which over time can lead to diseases like cancer.

That's why I always remind you to take plenty of antioxidants (especially vitamin E and selenium). These antioxidants neutralize free radicals.

Finding the right fish oil

Our bodies need omega-3 fatty acids for survival, but we can't produce the essential omega-3 ourselves. So we've got to get it from the foods we eat. Unfortunately, very few of us do.

In that case...

A bottle of high-quality fish oil capsules should always be a staple in your kitchen cabinet. Find a brand that you trust. Look for the bottle to say 99.99 percent purified fish oil.

But don't worry. The last .01 percent doesn't contain mercury. Just small impurities that are nearly impossible to refine away. (It's the same with gold. You'll only find 99.99 percent pure gold. There's no such thing as 100 percent pure gold.)

So if you can find good fish oil, what's the big deal about krill...?

The pros (and cons) of taking krill oil

As far as I can tell, there are four big reasons why people opt for krill instead of fish (or cod liver) oil.

First off, krill oil contains a decent dose of the antioxidant astaxanthin. So some natural medicine practitioners say you don't need the added vitamin E and selenium when you take krill. But I disagree. Even if you opt for krill oil, you should still take a natural mixed tocopherols-type vitamin E along with it.

Secondly, some people like taking krill better. There's less of a fishy aftertaste. (This isn't a huge problem in my book, especially if you take your fish oil before meals. But I know that trick doesn't work for everyone. And some people don't like to belch fish.)

Thirdly, sometimes people take krill because they want a "more pure" product. You see, fishermen catch krill in the deepest, darkest waters of Antarctica. So some people believe this pretty much guarantees that your krill oil won't contain any pollutants or heavy metals. (But as I said earlier, I wouldn't worry about it too much if you find a major brand of fish oil that says 99.99 percent pure on the bottle.)

The last benefit to taking krill has to do with the environment. You may have seen the recent TIME magazine article about fish oil. Apparently, the market for fish oil supplements has skyrocketed to $1 billion since 1996. As a result, some environmentalists say we're putting certain types of fish at risk.

Scientists have seen declining numbers of one type of fish used primarily for their oil, called menhaden. These fish eat algae in the ocean. But when menhaden levels drop off, algae grow out of control. This depletes oxygen in the ocean and—according to some environmentalists—upsets the ocean's ecosystem.

From this point of view, krill's a great option. It's a "sustainable" or "renewable" form of fish, which means even if everyone on your street starts taking krill; the fish won't disappear off the planet.

One of the biggest reasons against taking krill has to do with the cost. A 30-day supply of krill oil costs at least twice as much as regular fish oil does. Plus, research for this relatively new supplement is still pretty limited. I've yet to see overwhelming research convincing me that nutritionally it's any better for you than regular fish oil. So unless you feel strongly about one of other the reasons cited above, the benefits might not warrant the big price tag.

Decide for yourself

Look at the pros and cons and decide for yourself about krill oil. I do take it from time to time. Though, it's certainly much more expensive than regular fish oil, so I really only take it when I'm feeling extravagant!