Walnut-enriched diet increases the association of LDL from hypercholesterolemic men with human HepG2 cells

In a randomized, cross-over feeding trial involving 10 men with polygenic hypercholesterolemia, a control, Mediterranean-type cholesterol-lowering diet, and a diet of similar composition in which walnuts replaced ~35% of energy from unsaturated fat, were given for 6 weeks each. Compared with the control diet, the walnut diet reduced serum total and LDL cholesterol by 4.2% (P = 0.176), and 6.0% (P = 0.087), respectively. No changes were observed in HDL cholesterol, triglycerides, and apolipoprotein A-I levels or in the relative proportion of protein, triglycerides, phospholipids, and cholesteryl esters in LDL particles. The apolipoprotein B level declined in parallel with LDL cholesterol (6.0% reduction). Whole LDL, particularly the triglyceride fraction, was enriched in polyunsaturated fatty acids from walnuts (linoleic and α-linolenic acids). In comparison with LDL obtained during the control diet, LDL obtained during the walnut diet showed a 50% increase in association rates to the LDL receptor in human hepatoma HepG2 cells. LDL uptake by HepG2 cells was correlated with α-linolenic acid content of the triglyceride plus cholesteryl ester fractions of LDL particles (r2 = 0.42, P < 0.05). Changes in the quantity and quality of LDL lipid fatty acids after a walnut-enriched diet facilitate receptor-mediated LDL clearance and may contribute to the cholesterol-lowering effect of walnut consumption.—Muñoz, S., M. Merlos, D. Zambón, C. Rodríguez, J. Sabaté, E. Ros, and J. C. Laguna. Walnut-enriched diet increases the association of LDL from hypercholesterolemic men with human HepG2 cells. J. Lipid Res. 2001. 42: 2069–2076.