Introduction:
Epidemiological and clinical evidence demonstrate benefits of walnuts on cardiometabolic risk factors.
Hypothesis:
Previously, we conducted a study that evaluated the acute, postprandial effects of walnut components [separated nut skins (5.6 g), de-fatted nutmeat (34 g), and nut oil (51 g)] versus whole walnuts (85 g) on lipid/lipoprotein responses and other measures of CVD risk. The results reported herein are from an ancillary study that compared postprandial whole walnut values to fasting values, to test the hypothesis that the whole walnut treatment would improve reverse cholesterol transport.
Methods:
A randomized 4-period crossover design was conducted with healthy overweight and obese adults (n=15; 9 women and 6 men) with moderate hypercholesterolemia. Plasma lipids were measured at 0 (fasting), 30, 60, 120, 240, and 360 min post meal consumption; serum for
ex vivo
cholesterol efflux analysis was collected at 0 and 240 min. The mean fractional efflux of radiolabeled cholesterol was conducted in J774 macrophage cells cultured with 2.5% human serum.
Results:
A mixed linear model demonstrated an increase in TG postprandially (P < 0.01). TG levels were significantly increased at 120, 240, and 360 min compared to baseline (30.1 ± 5.1 mg/dl, 42.7 ± 5.2 mg/dl, 21.1 ± 5.1 mg/dl, respectively; P < 0.01 for all). HDL-C and the total cholesterol:HDL-C (TC:HDL) ratio also increased postprandially (P = 0.04 and P < 0.01, respectively). HDL-C increased at 60 min (1.8 ± 0.7 mg/dl; P = 0.01) and TC:HDL increased at 120, 240, and 360 min (0.2 ± 0.1, 0.3 ± 0.1, 0.3 ± 0.1, respectively; P < 0.01 for all) compared to baseline. Cholesterol efflux was increased by 3.3 % in cells cultured with postprandial serum relative to fasting baseline (baseline: 18.6 ± 0.3 %, 240 min: 19.2 ± 0.3 %; P = 0.02). Cholesterol efflux correlated positively with plasma HDL-C concentrations (r = 0.43; P = 0.02).
Conclusion:
Acute consumption of walnuts increased
ex vivo
cholesterol efflux, suggesting a novel mechanism by which walnut consumption may reduce cardiovascular risk.
Membrane lipid response to clathrin coat protein determined by infrared spectroscopy. Possible involvement in coated vesicle formation.
