Omega-3 fatty acids have a long history of being heart-healthy and are well-known for lowering blood levels of blood fats called triglycerides.
Recent questions have been raised, however, about one of the two "fish oil" omega-3 fatty acids -- DHA (docosahexaenoic acid) -- and the possibility that it might actually raise levels of LDL ("bad") cholesterol.
There’s evidence that people with very high blood triglyceride levels who are treated with omega-3s (e.g., 4 g/day of EPA and DHA, the two omega-3 fatty acids in fish) commonly see a rise in LDL cholesterol. However, whether this occurs in generally healthy people taking fish oil supplements for cardio-protection is not clear.
A recent study from the Cooper Center Longitudinal Study (CCLS) and the Fatty Acid Research Institute (FARI) sheds new light on this question.
About the study
The investigators utilized data from 9,253 healthy men and women who had at least two preventive medical examinations at Cooper Clinic in Dallas over a 10-year period. These examinations routinely included both blood cholesterol testing and measurement of the Omega-3 Index, which is the amount of omega-3 fats in red blood cells. Current use of fish oil supplements was also collected.
With this information, the researchers then asked two questions:
- Did people who started taking fish oil supplements between visits experience a rise in LDL cholesterol levels?
- Did LDL cholesterol levels rise in people whose red blood cell omega-3 levels increased between visits?
The answer to both of these questions was "no." The analysis also took into account concurrent changes in background use of cholesterol-lowering drugs like statins. The findings suggest that fish oil supplement use does not increase LDL cholesterol in generally healthy adults.
The results also concur with the conclusion of a recent American Heart Association Advisory on the use of omega-3 fatty acids in the treatment of high triglyceride levels. This major review found there is "no strong evidence that DHA-containing prescription omega-3 fatty acid agents, used alone or in combination with statins, raise LDL cholesterol in patients with high triglyceride levels”.
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