Over the years, we've reported on numerous studies that evaluated whether eating fish or taking fish-oil supplements had an impact on heart disease. Certain fish oils contain high levels of omega-3 fatty acids, which have been linked to heart-healthy effects such as preventing blood clots, relaxing arteries and raising blood levels of HDL (good) cholesterol.
Even so, the first such study we covered back in 1995 concluded that fish eaters had no less heart disease than those who rarely or never ate fish. Then came a slew of studies pointing to apparent benefits of fish oil, such as fewer deaths from heart attacks and fewer strokes.
The most recent fish-oil study, in the April 6 Annals of Internal Medicine, looks specifically at whether omega-3-rich fish-oil capsules affect the progression of artery blockage in coronary artery disease (CAD). CAD, a major cause of heart attacks, occurs when arteries supplying the heart become clogged with fatty deposits known as plaque.
In the current study, German researchers randomly divided 223 patients with CAD into two groups. For two years, one group received daily fish-oil capsules containing a total of 1.5 grams of omega-3 fatty acids. The other group received daily placebo capsules.
To measure the change in CAD in the two groups, independent experts analyzed angiograms (dye-enhanced X-rays) of coronary artery segments at the beginning of the study and again two years later. Overall, the fish-oil group's arteries showed a smaller increase in blockage than the placebo group's arteries � and in some cases even showed regression of CAD.
In addition, the fish-oil group experienced fewer heart attacks and strokes during the two-year study, although the difference was barely enough to be statistically significant. On the downside, blood levels of LDL (bad) cholesterol were significantly higher in the fish-oil group throughout the study.
The results from this study seem to bolster the claim that omega-3 fatty acids can slow CAD's progression and may reduce the risk of further heart disease. But let's dive deeper into this chapter of the fish-oil saga. � The Editors

The Physician's Perspective
Anthony DeMaria, M.D.
Associate Editor
To its credit, the Annals study was large and well designed. However, researchers didn't track the total dietary intake of omega-3 fatty acids in either group, so we don't know for sure how much of the substance the participants really ingested. More important, measuring changes in CAD via angiograms doesn't always tell a complete clinical story.
The angiogram is certainly a valuable diagnostic tool for detecting gross abnormalities in coronary arteries, but it's not very good at measuring subtle changes in CAD. The angiogram can visualize the inner channel of an artery but not the arterial wall. This is analogous to examining a doughnut by only looking at the hole. New data indicate that acute events such as heart attacks are related more closely to the plaque within the vessel wall than to the degree of narrowing of the channel. Therefore, when studying the effects of drugs or nutrients on CAD, comparing frequency of heart attacks in two groups may be more revealing than comparing angiograms. In this study, the fish-oil group had fewer cardiovascular events than the placebo group, but statistically speaking, the difference was marginal.
Considering that even the angiographic differences between the two groups were quite modest, we have to remember that many other approaches to CAD prevention and treatment deliver more clinical "bang for the buck." Of course, correcting lifestyle risk factors, such as quitting smoking and reducing high blood pressure, should come first. The use of cholesterol-lowering drugs known as statins is another highly effective strategy against CAD. Statins change the chemical composition of plaque and have been shown to dramatically reduce the risk for heart attack and stroke in patients with CAD. Interestingly, statins often don't reduce the volume of plaque inside coronary arteries and therefore the benefits of their use may not show up on angiograms. Unless there's a near-complete blockage, cardiologists' concern with plaque in arteries has moved away from the quantity present and toward the so-called vulnerability of plaque � the properties that make some plaque prone to break off, migrate, and cause a heart attack or stroke.
On the plus side, this study suggests that benefits from omega-3s � whatever further studies determine they are � can come from supplements, not just the whole food. This finding may be meaningful for people who don't like or can't eat fish. Then again, fish is a low-fat, low-calorie source of protein and other important nutrients, so it's better to eat fish high in omega-3s (such as haddock and salmon) twice a week than to take a daily fish-oil supplement. If you rely on fish-oil supplements for your omega-3 intake, be careful about how many extra calories the supplements contain because being overweight, in and of itself, is a risk factor for heart disease. I'm also concerned about the significantly higher LDL cholesterol levels found in the fish-oil group. LDL is the type of cholesterol that leads to the formation of plaque.
While the jury's still out on whether fish and fish oil provide significant coronary benefits, there is no evidence that the dose of omega-3 fatty acids used in the Annals study causes any serious harm. Still, you should consider omega-3 supplements only as an adjunct � not as a primary treatment for CAD or as a first-line preventive measure against heart attack.

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