Omega-3 fatty acids and cholesterol

GUELPH, CANADA. Supplementation with fish oils (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) is highly effective in lowering the blood level of triglycerides. High triglyceride levels are a major risk factor for heart disease particularly in women. Some studies have shown that fish oil supplementation may increase the level of LDL-cholesterol (the “bad” kind), but that the ratio of HDL- cholesterol (the “good” kind) to LDL remains unchanged.

Researchers at the University of Guelph have just completed a study aimed at determining if taking gamma-linolenic acid (GLA) along with the fish oil would maintain the benefits of lowering triglyceride levels without the possible commensurate disadvantage of increasing LDL levels. Their study involved 32 women between the ages of 36 and 68 years who were assigned to one of four supplementation protocols for 28 days.

  • Group A: 4 grams of EPA + DHA daily (control group)
  • Group B: 4 grams of EPA + DHA + 1 gram of GLA
  • Group C: 4 grams of EPA + DHA + 2 grams of GLA
  • Group D: 4 grams of EPA + DHA + 4 grams of GLA

At the end of the trial period LDL concentrations were about 12% lower than at baseline in groups C and D and within plus or minus 2% of baseline values in groups A and B. Triglyceride concentrations were 40% lower at day 28 in group A, 39% lower in group B, and 35% lower in group C. There was no difference in triglyceride level in group D between day 0 and day 28 indicating that the GLA overpowered the effect of EPA and DHA on triglyceride reduction. The important LDL/HDL ratio was reduced by 6% in group B, 15% in group C, and 20% in group D. The researchers conclude that a supplementation protocol involving 4 grams of EPA + DHA plus 2 grams of GLA per day is optimum for achieving desirable cholesterol and triglyceride levels in women. They estimate that this protocol reduces the risk of having a heart attack within the next 10 years by 43%.
Laidlaw, Maggie and Holub, Bruce J. Effect of supplementation with fish oil-derived n-3 fatty acids and gamma-linolenic acid on circulating plasma lipids and fatty acid profiles in women. American Journal of Clinical Nutrition, Vol. 77, January 2003, pp. 37-42

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