The comparative reductions of the plasma lipids and lipoproteins by dietary polyunsaturated fats: salmon oil versus vegetable oils.
Level 3 - non-randomized controlled study
Controlled dietary intervention trial without reported randomization or allocation details in the abstract.
PubMed 6827988 · doi:10.1016/0026-0495(83)90226-3
What was done
Researchers compared the lipid and lipoprotein effects of three 4-week diets: a salmon oil diet rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), a vegetable oil diet rich in linoleic acid, and a control diet high in saturated fat. All diets were formulated to provide 40% of total calories from fat and 500 mg of dietary cholesterol, differing only in their fatty acid composition. Changes in plasma total cholesterol, triglycerides, LDL, VLDL, and HDL cholesterol, as well as fatty acid incorporation into plasma lipids, were measured.
What was found
In 4 weeks, the salmon oil diet significantly reduced: - Total plasma cholesterol from 188 to 162 mg/dl (p < 0.001) - Triglycerides from 77 to 48 mg/dl (p < 0.005) - LDL cholesterol from 128 to 108 mg/dl (p < 0.005) - VLDL cholesterol from 13 to 8 mg/dl (p < 0.005) HDL cholesterol did not change. Omega-3 fatty acids reached up to 30% of total fatty acids in each plasma lipid class after the salmon oil diet. The vegetable oil diet led to similar reductions in cholesterol levels but did not decrease plasma triglycerides.
Why it matters
This study provides early comparative evidence that marine omega-3 fatty acids reduce both cholesterol and triglyceride levels, whereas omega-6 vegetable oils lower cholesterol without reducing triglycerides.
Limits
The abstract does not disclose the sample size, participant characteristics, baseline health status, or whether diet assignments were randomized or structured in a crossover sequence. The intervention was short (4 weeks), and clinical cardiovascular endpoints were not assessed.
Cited by
- context In a metabolic ward feeding study of healthy volunteers consuming high-dose salmon oil for one month, average serum triglyceride levels decreased by 25%, from 100 mg/dL to 75 mg/dL.