Summary: Study finds no strong evidence that omega-3 fish oils containing DHA raises LDL-C in those with high triglyceride levels.
Source: Wright On Marketing and Communications
The Fatty Acid Research Institute (FARI) has published a new research paper in conjunction with The Cooper Institute on the omega-3s EPA and DHA in fish oil and low density lipoprotein cholesterol (LDL-C).
Omega-3 fatty acids have a long history of being “heart healthy,” and are well-known for lowering blood levels of triglycerides (but typically not cholesterol). 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-C, the “bad” cholesterol.
There is good evidence that people with very high serum triglyceride levels (>500 mg/dL) who are treated with high doses of omega-3, i.e., 4 g/day of EPA (eicosapentaenoic acid) and DHA commonly see a rise in LDL-C, whether this occurs in the “real world” with generally healthy people taking fish oil supplements for cardioprotection is not clear.
A recent study from the Cooper Center Longitudinal Study (CCLS) and FARI sheds new light on this question.
The investigators utilized data from 9253 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 (i.e., red blood cell (RBC) EPA+DHA levels from OmegaQuant Analytics). Questions about current use of fish oil supplements was also collected.
With this information, the researchers then asked 2 questions: 1) did people who started taking fish oil supplements between visits experience a rise in LDL-C levels, and 2) did LDL-C levels rise in people whose RBC DHA levels increased between visits?
It turns out that the answer to both of these questions was “no.” In fact, a 1-unit rise in RBC DHA levels was associated with a small (1-2 mg/dL) but statistically significant decrease in LDL-C. And this analysis took into account concurrent changes in background use of cholesterol-lowering drugs like statins. This small decrease in LDL-C is not a clinically-relevant, but this study shows that fish oil supplement use in the general population does not adversely affect LDL-C.
Dr. William Harris, President of FARI and co-inventor of the Omega-3 Index, was the lead author on this study. In his view, “these new findings from the CCLS clearly show that people who take fish oil supplements need not worry about adversely affecting their cholesterol levels as some have proposed.”
He also noted that these results also harmonize well with the conclusions 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-C in patients with high triglyceride levels.”
Commenting on this paper, Dr. Carl Lavie, a cardiologist and Medical Director of the Cardiac Rehabilitation and Prevention Program at the John Ochsner Heart and Vascular Institute in New Orleans, LA, said, “This large study from the Cooper Clinic indicates that RBC DHA levels are not associated with higher LDL-cholesterol levels (actually with lower), and adding omega-3 supplements was also not associated with increases in LDL-C.”
Dr. Lavie and colleagues recently published data from 40 studies in over 135,000 participants in the Mayo Clinic Proceedings indicating that the combined EPA and DHA dose predicted reductions in major cardiovascular outcomes2. “These new data from the Cooper Institute add to the cumulative evidence of the safety and efficacy of omega-3 from dietary sources and supplements, including the combination of EPA and DHA,” he said.
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Original Research: Closed access.
“Increases in erythrocyte DHA are not associated with increases in LDL-cholesterol: Cooper center longitudinal study” by William Harris et al. Journal of Clinical Lipidology
Abstract
Increases in erythrocyte DHA are not associated with increases in LDL-cholesterol: Cooper center longitudinal study
Background
The effects of fish oil products containing docosahexaenoic acid (DHA) on LDL-C levels are controversial.
Objective
To determine if changes in erythrocyte DHA are associated with changes in LDL-C levels.
Methods
In this prospective observational study, erythrocyte DHA levels and LDL-C levels were measured in 9253 individuals who presented for at least two examinations at a medical clinic. Changes in DHA levels and the reported use of omega-3 dietary supplements were correlated with changes in LDL-C in multi-variable adjusted models including the use of LDL-C-lowering drugs.
Results
Mean (standard deviation) age at baseline was 52.6 (10.6) years, and the time between exams averaged 1.9 (1.4) years. As a group, erythrocyte DHA increased from 5.0% (1.3) to 5.3% (1.3) (p < 0.001), and LDL-C was not significantly changed (109 (33) to 108 (33) mg/dL, p = 0.875). However, in multivariable-adjusted models of within-participant changes, a 1% increase in erythrocyte DHA was associated with a 1.9 mg/dL reduction in LDL-C (95% confidence interval (1.6, 2.2), p < 0.001). Similar relationships were seen with changes in erythrocyte EPA and EPA + DHA. In adjusted analyses, an increased use of omega-3 supplements was associated with a significant increase in erythrocyte DHA and a decrease in LDL-C in both users and non-users of lipid-lowering drugs.
Conclusions
In a predominantly male, normolipidemic, middle-aged cohort, increases in erythrocyte DHA were associated with decreases in LDL-C, and initiating fish oil supplement use did not increase LDL-C. These findings may serve to reassure individuals who, in adopting a more heart-healthy lifestyle, want to increase their omega-3 fatty acid intake.
