Walnuts and fatty fish influence different serum lipid fractions in normal to mildly hyperlipidemic individuals: a randomized controlled study.

BACKGROUND

Increased consumption of n-3 (omega-3) fatty acids decreases the incidence of coronary heart disease (CHD).

OBJECTIVE

The objective was to determine whether walnuts (plant n-3 fatty acid) and fatty fish (marine n-3 fatty acid) have similar effects on serum lipid markers at intakes recommended for primary prevention of CHD.

DESIGN

In a randomized crossover feeding trial, 25 normal to mildly hyperlipidemic adults consumed 3 isoenergetic diets ( approximately 30% total fat and <10% saturated fat) for 4 wk each: a control diet (no nuts or fish), a walnut diet (42.5 g walnuts/10.1 mJ), or a fish diet (113 g salmon, twice/wk). Fasting blood was drawn at baseline and at the end of each diet period and analyzed for serum lipids.

RESULTS

Serum total cholesterol and LDL cholesterol concentrations in adults who followed the walnut diet (4.87 +/- 0.18 and 2.77 +/- 0.15 mmol/L, respectively) were lower than in those who followed the control diet (5.14 +/- 0.18 and 3.06 +/- 0.15 mmol/L, respectively) and those who followed the fish diet (5.33 +/- 0.18 and 3.2 +/- 0.15 mmol/L, respectively; P < 0.0001). The fish diet resulted in decreased serum triglyceride and increased HDL-cholesterol concentrations (1.0 +/- 0.11 and 1.23 +/- 0.05 mmol/L, respectively) compared with the control diet (1.12 +/- 0.11 and 1.19 +/- 0.05 mmol/L, respectively) and the walnut diet (1.11 +/- 0.11 mmol/L, P < 0.05, and 1.18 +/- 0.05 mmol/L, P < 0.001, respectively). The ratios of total cholesterol:HDL cholesterol, LDL cholesterol:HDL cholesterol, and apolipoprotein B:apolipoprotein A-I were lower (P < 0.05) in those who followed the walnut diet compared with those who followed the control and fish diets.

CONCLUSION

Including walnuts and fatty fish in a healthy diet lowered serum cholesterol and triglyceride concentrations, respectively, which affects CHD risk favorably.