Inhibition of low density lipoprotein synthesis by dietary omega-3 fatty acids in humans.
Level 3 - non-randomized controlled study
Controlled metabolic crossover trial without reported randomization
PubMed 6712540 · doi:10.1161/01.atv.4.3.270
What was done
Seven healthy volunteers with normal plasma lipid levels consumed two metabolically controlled diets for 4 weeks each in a crossover study. The control diet was enriched in saturated and monounsaturated fatty acids, while the fish-oil diet provided 24 g/day of omega-3 fatty acids. Total fat and cholesterol contents were similar between the diets. Kinetic studies using 125I-labeled LDL measured the synthesis rate and fractional catabolic rate of LDL apoprotein B.
What was found
Compared to the control diet, the omega-3 diet reduced: - Total cholesterol: from 162 ± 26 mg/dl to 124 ± 26 mg/dl - LDL cholesterol: from 103 ± 27 mg/dl to 82 ± 27 mg/dl - Triglycerides: from 91 ± 34 mg/dl to 52 ± 19 mg/dl - LDL apoprotein B synthesis rate: from 13.6 ± 3.7 mg/kg/day to 9.5 ± 1.3 mg/kg/day (p < 0.05) The fractional catabolic rate of LDL was similar on both diets.
Why it matters
The study identifies the mechanism by which high-dose fish oil reduces circulating LDL in healthy individuals, showing it suppresses apoprotein B synthesis rather than increasing clearance.
Limits
The sample size is very small (n = 7), and the abstract does not specify whether treatment order was randomized. The omega-3 dose (24 g/day) is supraphysiological and far exceeds standard dietary intakes. The study only evaluated healthy normolipidemic subjects over a 4-week duration.
Cited by
- supports In early research by Dr. Bill Harris, administering 30 grams of omega-3 per day to humans produced no negative effects over a short duration.