Effect of PolyGlycopleX (PGX) Consumption on Blood Lipid Profiles in Healthy, Low CVD Risk Overweight Adults.

Raised blood lipid levels are associated with a risk of a cardiovascular disease (CVD). Moderate reductions in several CVD factors such as total, low-density lipoprotein (LDL) cholesterol and non-high-density lipoprotein (non-HDL) cholesterol concentrations may be more effective in reducing overall risk than a major reduction in just one. A blind, randomised controlled trial was conducted with 120 healthy overweight (BMI 25⁻30) adults aged 25⁻70 years who were non-smokers, not diabetic and of low risk of cardiovascular disease, as assessed by the Framingham risk equation. Participants consumed 4.5 g PolyGlycopleX (PGX) as softgel capsules (PGXS) or 5 g PGX granules (PGXG) or 5 g rice flour (RF) with meals three times a day for 12 weeks. Total, LDL and non-HDL cholesterol were all significantly reduced (-6%, -5% and -3.5%, respectively) post the PGX granule treatment; however, PGX in softgel capsule form did not affect blood lipid profiles. Daily consumption of PGX granules in overweight low CVD risk adults produced lipid changes indicating a CVD preventative benefit.

Dietary fat and physiological determinants of plasma chylomicron remnant homoeostasis in normolipidaemic subjects: insight into atherogenic risk.

TAG depleted remnants of postprandial chylomicrons are a risk factor for atherosclerosis. Recent studies have demonstrated that in the fasted state, the majority of chylomicrons are small enough for transcytosis to arterial subendothelial space and accelerate atherogenesis. However, the size distribution of chylomicrons in the absorptive state is unclear. This study explored in normolipidaemic subjects the postprandial distribution of the chylomicron marker, apoB-48, in a TAG-rich lipoprotein plasma fraction (Svedberg flotation rate (Sf>400), in partially hydrolysed remnants (Sf 20-400) and in a TAG-deplete fraction (Sf<20), following ingestion of isoenergetic meals with either palm oil (PO), rice bran or coconut oil. Results from this study show that the majority of fasting chylomicrons are within the potentially pro-atherogenic Sf<20 fraction (70-75 %). Following the ingestion of test meals, chylomicronaemia was also principally distributed within the Sf<20 fraction. However, approximately 40 % of subjects demonstrated exaggerated postprandial lipaemia specifically in response to the SFA-rich PO meal, with a transient shift to more buoyant chylomicron fractions. The latter demonstrates that heterogeneity in the magnitude and duration of hyper-remnantaemia is dependent on both the nature of the meal fatty acids ingested and possible metabolic determinants that influence chylomicron metabolism. The study findings reiterate that fasting plasma TAG is a poor indicator of atherogenic chylomicron remnant homoeostasis and emphasises the merits of considering specifically, chylomicron remnant abundance and kinetics in the context of atherogenic risk. Few studies address the latter, despite the majority of life being spent in the postprandial and absorptive state.

Plasma triglyceride and high density lipoprotein cholesterol are poor surrogate markers of pro-atherogenic chylomicron remnant homeostasis in subjects with the metabolic syndrome.

BACKGROUND: Subjects with metabolic syndrome (MetS) exhibit impaired lipoprotein metabolism and have an increased risk of cardiovascular disease. Although the risk is attributed primarily to the risk associated with individual components, it is also likely affected by other associated metabolic defects. Remnants of postprandial lipoproteins show potent atherogenicity in cell and animal models of insulin resistance and in pre-diabetic subjects with postprandial dyslipidemia. However, few studies have considered regulation of chylomicron remnant homeostasis in MetS per se. This study measured the plasma concentration in Caucasian men and women of small dense chylomicrons following fasting and explored associations with metabolic and anthropometric measures. METHODS: A total of 215 Australian Caucasian participants (median age 62 years) were investigated. Of them, 40 participants were classified as having MetS. Apolipoprotein (apo) B-48, an exclusive marker of chylomicrons, metabolic markers and anthropometric measures were determined following an overnight fast. RESULTS: The fasting apo B-48 concentration was 40 % higher in subjects with MetS than those without MetS. In all subjects, triglyceride (r = 0.445, P < 0.0005), non-HDL cholesterol (r = 0.28, P < 0.0005) and HDL cholesterol concentration (r = -0.272, P < 0.0005) were weakly associated with apo B-48 concentration. In subjects with MetS, the association of apo B-48 with triglyceride and non-HDL cholesterol was enhanced, but neither were robust markers of elevated apo B-48 in MetS (r = 0.618 and r = 0.595 respectively). There was no association between apo B-48 and HDL cholesterol in subjects with MetS. CONCLUSION: This study demonstrates a substantial accumulation of pro-atherogenic remnants in subjects with MetS. We have shown that in a Caucasian cohort, the fasting plasma concentration of triglyceride or HDL/non-HDL cholesterol serves as poor surrogate markers of atherogenic chylomicron remnants. These findings suggest that subjects with MetS exhibit a chronic defect in chylomicron metabolism that is likely to contribute to their increased CV risk.

Hypertriglyceridemic subjects exhibit an accumulation of small dense chylomicron particles in the fasting state.

AIM: Normocholesterolemic subjects with elevated fasting plasma triglycerides are at increased risk of atherosclerosis through mechanisms that are not yet delineated. We hypothesized that elevated plasma triglyceride is associated with increased vascular exposure to pro-atherogenic lipoprotein remnants. To test this hypothesis, the abundance, and size distribution of chylomicron particles were determined in individuals with and without hypertriglyceridemia. METHODS: Twelve hypertriglyceridemic subjects (HTG group, triglyceride concentration ≥1.7 mmol/L) and twelve normotriglyceridemic subjects (NTG group) matched for age and gender were studied. The distribution of chylomicron particles was assessed by determining the fasting concentration of apo B-48 in serum lipoprotein fractions with Svedberg flotation rates of (Sf) > 400, Sf 20-400 and Sf < 20. RESULTS: The total concentration of apo B-48 in subjects with HTG was almost twice that observed in NTG controls with ∼80% of the increase residing in the Sf < 20 fraction (HTG: 8.7 ± 1.0 µg/mL vs NTG: 5.0 ± 0.6 µg/mL; P = 0.016). Significantly greater concentrations of apo B-48 were also observed in the less dense Sf 20-400 (HTG: 1.1 ± 0.2 µg/mL vs NTG: 0.4 ± 0.07 µg/mL; P < 0.001) and the Sf > 400 (HTG: 1.1 ± 0.3 µg/mL vs NTG: 0.3 ± 0.04 µg/mL; P < 0.001) fractions. An accumulation of triglyceride was also observed across all lipoprotein fractions in HTG subjects compared to NTG (Sf 400 & Sf 20-400: P < 0.001 and Sf < 20: P = 0.013). CONCLUSION: Normocholesterolemic, moderately hypertriglyceridemic subjects are at increased atherogenic risk due to greater apo B-48 concentration in the small, dense lipoprotein fraction.