Compared to Regular Lutein, a Lutein Nano‐Emulsion Yields a More Atherogenic Lipoprotein Profile Associated with Higher Concentrations of Cholesterol in Adipose Tissue in Guinea Pigs

Abstract

We challenged 24 guinea pigs (8/group) with a high cholesterol diet (0.25g/100g) alone (control group) or in combination with 3 mg/d of Regular lutein (R‐lutein) or 3 mg/d of lutein prepared in nano‐emulsion (NANO) (average particle diameter = 250 nm). After 6 weeks, guinea pigs were sacrificed and blood was collected to measure plasma lipids and lipoprotein size and number by Nuclear Magnetic Resonance and adipose was harvested to determine concentrations of both free and esterified cholesterol. Contrary to what we expected, guinea pigs from the NANO group had the greatest concentrations of plasma cholesterol (P<0.001). In addition, the NANO group had higher concentrations of large VLDL and total LDL particles (p<0.0001). Moreover, cholesterol concentration in the adipose tissue was highest in the NANO group (11.5 ± 2.5 mg/g), intermediate in the control group (10.2 ± 1.5 mg/g) and lowest in the R‐lutein group (9.2 ± 0.8 mg/g) (p< 0.01). In contrast hepatic cholesterol concentrations were highest in the NANO compared to the R‐lutein and control groups (P < 0.01). Further, we found a positive correlation between plasma cholesterol and free cholesterol in the adipose (r = 0.493, p = 0.014) and with large VLDL (r = 0.700, P < 0.001). These data suggest that guinea pigs fed the NANO emulsion have lower concentrations of cholesterol in the liver because they are secreting cholesterol in the large VLDL particles and possibly both lipoproteins VLDL and LDL are depositing the excess cholesterol in extra‐hepatic tissues (adipose), possibly via scavenger receptors