Cholesterol metabolism and serum non-cholesterol sterols: summary of 13 plant stanol ester interventions

Background

The efficacy and safety of plant stanols added to food products as serum cholesterol lowering agents have been demonstrated convincingly, but their effects on cholesterol metabolism and on serum non-cholesterol sterols is less evaluated. The aim of this study was to assess the validity of serum non-cholesterol sterols and squalene as bioindices of cholesterol synthesis and absorption, and to examine how the individual serum non-cholesterol sterols respond to consumption of plant stanols.

Methods

We collected all randomized, controlled plant stanol ester (STAEST) interventions in which serum cholestanol, plant sterols campesterol and sitosterol, and at least two serum cholesterol precursors had been analysed. According to these criteria, there was a total of 13 studies (total 868 subjects without lipid-lowering medication; plant stanol doses varied from 0.8 to 8.8 g/d added in esterified form; the duration of the studies varied from 4 to 52 weeks). Serum non-cholesterol sterols were assayed with gas–liquid chromatography, cholesterol synthesis with the sterol balance technique, and fractional cholesterol absorption with the dual continuous isotope feeding method.

Results

The results demonstrated that during the control and the STAEST periods, the serum plant sterol/cholesterol- and the cholestanol/cholesterol-ratios reflected fractional cholesterol absorption, and the precursor sterol/cholesterol-ratios reflected cholesterol synthesis. Plant sterol levels were dose-dependently reduced by STAEST so that 2 g of plant stanols reduced serum campesterol/cholesterol-ratio on average by 32%. Serum cholestanol/cholesterol-ratio was reduced less frequently than those of the plant sterols by STAEST, and the cholesterol precursor sterol ratios did not change consistently in the individual studies emphasizing the importance of monitoring more than one surrogate serum marker.

Conclusions

Serum non-cholesterol sterols are valid markers of cholesterol absorption and synthesis even during cholesterol absorption inhibition with STAEST. Serum plant sterol concentrations decrease dose-dependently in response to plant stanols suggesting that the higher the plant stanol dose, the more cholesterol absorption is inhibited and the greater the reduction in LDL cholesterol level is that can be achieved.

Trial registration

Clinical Trials Register # NCT00698256 [Eur J Nutr 2010, 49:111-117]

Adipose tissue INSR splicing in humans associates with fasting insulin level and is regulated by weight loss

AIMS/HYPOTHESIS

The insulin receptor (INSR) has two protein isoforms based on alternative splicing of exon 11. INSR-A promotes cell growth whereas INSR-B predominantly regulates glucose homeostasis. In this study we investigated whether weight loss regulates INSR alternative splicing and the expression of splicing factors in adipose tissue.

METHODS

To determine the relative ratio of the INSR splice variants, we implemented the PCR-capillary electrophoresis method with adipose tissue samples from two weight-loss-intervention studies, the Kuopio Obesity Surgery study (KOBS, n = 108) and a very low calorie diet (VLCD) intervention (n = 32), and from the population-based Metabolic Syndrome in Men study (METSIM, n = 49).

RESULTS

Expression of INSR-B mRNA variant increased in response to weight loss induced by both bariatric surgery (p = 1 × 10(-5)) and the VLCD (p = 1 × 10(-4)). The adipose tissue expression of INSR-B correlated negatively with fasting insulin levels in the pooled data of the three studies (p = 3 × 10(-22)). Finally, expression of several splicing factors correlated negatively with the expression of the INSR-B variant. The strongest correlation was with HNRNPA1 (p = 1 × 10(-5)), a known regulator of INSR exon 11 splicing.

CONCLUSIONS/INTERPRETATION

INSR splicing is regulated by weight loss and associates with insulin levels. The effect of weight loss on INSR splicing could be mediated by changes in the expression of splicing factors.

Hypolipidemic treatment of heterozygous familial hypercholesterolemia: a lifelong challenge

In familial hypercholesterolemia, a defect in low-density lipoprotein receptors causes lifelong two- to threefold elevations in serum low-density lipoprotein-cholesterol levels. This leads to early atherosclerotic changes in infancy. Lifelong hypolipidemic treatment that can be started at a young age is thus greatly needed. Early diagnosis of familial hypercholesterolemia is important, and improved DNA tests for low-density lipoprotein receptor mutations have made it possible to carry out diagnosis at birth. A low saturated-fat, low cholesterol diet can be safely started at 7 months of age. This can be accompanied by dietary stanol esters from 2 years of age. At the age of 10, statin treatment can be safely started. In adults, more aggressive hypolipidemic treatment is required in order to reach the treatment goal for serum low-density lipoprotein-cholesterol levels less than 2.5 mmol/l. This can be achieved by using high doses of statin, or preferably by combining a statin with resin or ezetimibe (Zeita), Merck and Shering-Plough Pharmaceuticals). Once started, treatment of familial hypercholesterolemia is lifelong.

Amyloid precursor protein α- and β-cleaved ectodomains exert opposing control of cholesterol homeostasis via SREBP2

Amyloid precursor protein (APP) is ubiquitously expressed. Studies in neuronal cells have implicated APP or its fragments as negative regulators of cholesterol metabolism. In the current study, APP acted, via its α-cleavage, as a positive regulator of sterol regulatory element-binding protein-2 (SREBP2) signaling in human astrocytic cells (U251MG), hepatic cells (HepG2), and primary fibroblasts, leading to an approximate 30% increase in SRE-dependent gene expression and, consequently, enhanced cholesterol biosynthesis and LDL receptor levels. This effect was mediated via the secretory ectodomain APPsα. The β-cleaved ectodomain, in turn, repressed SRE-dependent gene expression by up to ∼ 30%. This resulted in decreased cholesterol synthesis and LDL receptor content, establishing a physiological feedback loop in cholesterol-loaded cells, where APP undergoes preferential β-cleavage. Patients with familial Alzheimer's disease had decreased circulating lathosterol, reflecting hepatic cholesterol synthesis, and their fibroblasts had reduced LDL receptor content, which was alleviated by decreasing β-cleavage. These results show that APP regulates cholesterol metabolism in cells relevant for whole-body cholesterol balance and reveal that APP α- and β-cleavages produce opposing paracrine regulators of SREBP2 signaling.

Higher fecal bile acid hydrophobicity is associated with exacerbation of dextran sodium sulfate colitis in mice

Increased luminal bile acid hydrophobicity is associated with cytotoxicity and has been suggested to contribute to gut barrier dysfunction. The aim of this study was to compare 2 high-fat diets and a low-fat diet as to whether they modify fecal bile acid profile and hydrophobicity and/or susceptibility to dextran sodium sulfate (DSS) colitis in C57Bl/6J mice. Control and DSS-Control groups received a low-fat control diet [5.5% of total energy (E%) soy oil, 4.5 E% lard], and the DSS-Lard (5.5 E% soy oil, 54.5 E% lard) and DSS-Fish oil (5.5 E% soy oil, 27.2 E% lard and 27.2% menhaden oil) groups received high-fat diets. Feces for bile acid analysis were collected after 3-wk feeding, followed by induction of dextran DSS colitis (2 d 5% DSS in drinking water + 2 d tap water). Fecal bile acid hydrophobicity was elevated 76% in the lard group (P = 0.051) and 122% in the fish oil group (P = 0.001) compared with control, indicating potentially increased cytotoxicity. DSS caused severe colitis symptoms, evaluated as rectal bleeding, whereas all the controls were symptom free. The median symptom scores were: DSS-Control, 2.3 (IQR = 0.6, 3.0); DSS-Lard, 0.3 (IQR = 0, 2.3); and DSS-Fish oil, 2.4 (IQR = 1.9, 2.8). The only differences were DSS-Control vs. control (P < 0.001) and DSS-Fish oil vs. control (P < 0.001). Severity of symptoms in all colitic mice was positively correlated with fecal bile acid hydrophobicity (Spearman's ρ = 0.43; P = 0.028) and fecal deoxycholic acid concentration (Spearman's ρ = 0.39; P = 0.048). These results suggest that luminal bile acid modification, induced by altered dietary fat composition, may alter susceptibility to DSS colitis.

Diet and cardiovascular health in asymptomatic normo- and mildly-to-moderately hypercholesterolemic participants - baseline data from the BLOOD FLOW intervention study

BACKGROUND

For decades in Finland, intensive population strategies and preventive activities have been used to lower the risk of atherosclerotic coronary heart disease (CHD). Lifestyle changes, with the emphasis on diet, play an important role in preventive strategies. The aim of this study was to evaluate arterial stiffness and endothelial function in asymptomatic free-living adults and to relate the results to CHD risk factors and lifestyle habits with the emphasis on diet.

METHODS

Ninety-four asymptomatic participants were recruited by advertisements in four large companies and two research institutes employing mainly office workers. Arterial stiffness was assessed as the cardio-ankle vascular index in large arteries, and endothelial function as the reactive hyperemia index with peripheral arterial tonometry. The systematic Cardiovascular Risk Estimation (SCORE) was calculated.

RESULTS

The data was collected in the spring of 2011. Anthropometric, dietary, and lipid data was available from 92 participants, blood pressure from 85 and vascular measurements from 86-88 subjects (38% males; 62% females; mean age of all 51). The majority (72%) had an elevated low density lipoprotein (LDL) cholesterol concentration and over half were overweight or obese. SCORE stated that 49% of the participants had a moderate risk of cardiovascular disease. When compared to general recommendations, half of the participants had too high intake of total fat and in 66% the consumption of saturated fat was too high. In contrast, the intake of carbohydrates was too low in 90% of the participants and for fiber 73% were below recommendations. There was evidence of borderline or increased arterial stiffness in 72% of the participants and endothelial function was impaired in 8%. Arterial stiffness was associated with LDL cholesterol concentration (p = 0.024), dietary cholesterol intake (p = 0.029), and SCORE (p < 0.001).

CONCLUSIONS

In a cross-sectional study of asymptomatic middle-aged participants, the half had a moderate risk for cardiovascular diseases manifested as increased arterial stiffness, elevated LDL cholesterol concentration, and poor dietary habits. The new observation that arterial stiffness was associated with dietary cholesterol intake and SCORE emphasizes the urgency of adequate lifestyle and dietary interventions to prevent future coronary events even in asymptomatic participants.

TRIAL REGISTRATION

Clinical Trials Register # NCT01315964.

Desmosterol in human nonalcoholic steatohepatitis

Dysregulation of the cholesterol synthesis pathway and accumulation of cholesterol in the liver are linked to the pathogenesis of nonalcoholic steatohepatitis (NASH). Therefore, we investigated the association of serum and liver levels of cholesterol precursors with NASH. Liver histology was assessed in 110 obese patients (Kuopio Obesity Surgery Study [KOBS] study, age 43.7 ± 8.1 years [mean ± standard deviation, SD], body mass index [BMI] 45.0 ± 6.1 kg/m(2) ). Serum and liver levels of cholesterol precursors were measured with gas-liquid chromatography. The association between cholesterol precursors and serum alanine aminotransferase (ALT), as a marker of liver disease, was also investigated in a population cohort of 717 men (Metabolic Syndrome in Men Study [METSIM] study, age 57.6 ± 5.8 years, BMI 27.1 ± 4.0 kg/m(2) ). Serum desmosterol levels and the desmosterol-to-cholesterol ratio were higher in individuals with NASH, but not in individuals with simple steatosis, compared to obese subjects with normal liver histology (P = 0.002 and P = 0.003, respectively). Levels of serum and liver desmosterol correlated strongly (r = 0.667, P = 1 × 10(-9) ), suggesting a shared regulation. Both serum and liver desmosterol levels correlated positively with steatosis and inflammation in the liver (P < 0.05). Serum desmosterol had a higher correlation with the accumulation of cholesterol in the liver than serum cholesterol. Serum desmosterol levels (P = 2 × 10(-6) ) and the serum desmosterol-to-cholesterol ratio (P = 5 × 10(-5) ) were associated with serum ALT in the population study.

CONCLUSION

Levels of desmosterol in serum and the liver were associated with NASH. These results suggest that serum desmosterol is a marker of disturbed cholesterol metabolism in the liver. Whether desmosterol has a more specific role in the pathophysiology of NASH compared to other cholesterol precursors needs to be investigated.

Physical function and properties of quadriceps femoris muscle after bariatric surgery and subsequent weight loss

OBJECTIVES

To investigate the effects of bariatric surgery-induced weight loss on physical function, the properties of quadriceps femoris muscle (QFM), and the subjective disabilities of the subjects with excessive weight.

METHODS

Thirteen female and three male subjects were studied before and 8.8 months after Roux-en-Y gastric bypass (RYGP) operation. The health-related quality of life (RAND-36) and the self-reported disease-specific joint symptoms (WOMAC) were estimated. The objective physical function was evaluated with sock, repeated sit-to-stand, 6-minute walk, stair ascending and descending and timed up and go tests and the properties of the QFM were measured with ultrasound.

RESULTS

The average weight loss was 27.3 kg. Objectively measured physical function improved after RYGP operation. Physical functioning, physical role functioning and general health domain scores of the RAND-36 were significantly improved. The stiffness and function scores were lower after RYGP operation in knee OA subjects. The subcutaneous fat thickness and the absolute muscle thickness of QFM decreased, but the ratio of muscle cross sectional area/total body weight did not change. The fat and connective tissue proportion in the QFM muscle were significantly increased.

CONCLUSIONS

The RYPG-surgery-induced weight loss exerts a positive impact on physical function but a negative impact on a muscle structure.

The effects of plant stanol ester consumption on arterial stiffness and endothelial function in adults: a randomised controlled clinical trial

Background

The hypocholesterolemic effect of plant stanol ester consumption has been studied extensively, but its effect on cardiovascular health has been less frequently investigated. We studied the effects of plant stanol esters (staest) on arterial stiffness and endothelial function in adults without lipid medication.

Methods

Ninety-two asymptomatic subjects, 35 men and 57 women, mean age of 50.8±1.0 years (SEM) were recruited from different commercial companies. It was randomized, controlled, double-blind, parallel trial and lasted 6 months. The staest group (n=46) consumed rapeseed oil-based spread enriched with staest (3.0 g of plant stanols/d), and controls (n=46) the same spread without staest. Arterial stiffness was assessed via the cardio-ankle vascular index (CAVI) in large and as an augmentation index (AI) in peripheral arteries, and endothelial function as reactive hyperemia index (RHI). Lipids and vascular endpoints were tested using analysis of variance for repeated measurements.

Results

At baseline, 28% of subjects had a normal LDL cholesterol level (≤3.0 mmol/l) and normal arterial stiffness (<8). After the intervention, in the staest group, serum total, LDL, and non-HDL cholesterol concentrations declined by 6.6, 10.2, and 10.6% compared with controls (p<0.001 for all). CAVI was unchanged in the whole study group, but in control men, CAVI tended to increase by 3.1% (p=0.06) but was unchanged in the staest men, thus the difference in the changes between groups was statistically significant (p=0.023). AI was unchanged in staest (1.96±2.47, NS) but increased by 3.30±1.83 in controls (p=0.034) i.e. the groups differed from each other (p=0.046). The reduction in LDL and non-HDL cholesterol levels achieved by staest was related to the improvement in RHI (r=−0.452, p=0.006 and −0.436, p=0.008).

Conclusions

Lowering LDL and non-HDL cholesterol by 10% with staest for 6 months reduced arterial stiffness in small arteries. In subgroup analyses, staest also had a beneficial effect on arterial stiffness in large arteries in men and on endothelial function. Further research will be needed to confirm these results in different populations.

Trial registration

Clinical Trials Register # NCT01315964

Non-cholesterol sterol levels predict hyperglycemia and conversion to type 2 diabetes in Finnish men

We investigated the levels of non-cholesterol sterols as predictors for the development of hyperglycemia (an increase in the glucose area under the curve in an oral glucose tolerance test) and incident type 2 diabetes in a 5-year follow-up study of a population-based cohort of Finnish men (METSIM Study, N = 1,050) having non-cholesterol sterols measured at baseline. Additionally we determined the association of 538,265 single nucleotide polymorphisms (SNP) with non-cholesterol sterol levels in a cross-sectional cohort of non-diabetic offspring of type 2 diabetes (the Kuopio cohort of the EUGENE2 Study, N = 273). We found that in a cross-sectional METSIM Study the levels of sterols indicating cholesterol absorption were reduced as a function of increasing fasting glucose levels, whereas the levels of sterols indicating cholesterol synthesis were increased as a function of increasing 2-hour glucose levels. A cholesterol synthesis marker desmosterol significantly predicted an increase, and two absorption markers (campesterol and avenasterol) a decrease in the risk of hyperglycemia and incident type 2 diabetes in a 5-year follow-up of the METSIM cohort, mainly attributable to insulin sensitivity. A SNP of ABCG8 was associated with fasting plasma glucose levels in a cross-sectional study but did not predict hyperglycemia or incident type 2 diabetes. In conclusion, the levels of some, but not all non-cholesterol sterols are markers of the worsening of hyperglycemia and type 2 diabetes.

Endothelial function is well preserved in obese patients with mild obstructive sleep apnea

PURPOSE

Endothelial dysfunction is one of the early markers of cardiovascular complications in obstructive sleep apnea (OSA). The aim of our study was to evaluate whether overweight patients with mild OSA displayed endothelial dysfunction, and to assess the effect of 1-year lifestyle intervention with an early very low calorie diet in endothelial function.

METHODS

At baseline, the study population consisted of 83 overweight patients with mild OSA and 46 weight-matched non-OSA subjects. OSA patients were further randomized into a 1-year supervised lifestyle intervention group or control group which received routine lifestyle counselling. Endothelial function measured by brachial artery flow-mediated dilatation (FMD), apnea-hypopnea index (AHI), body mass index (BMI), and metabolic parameters were assessed at baseline and 12 months.

RESULTS

No correlations between endothelial function and mild OSA were detected. However, patients with impaired endothelial function had lower mean saturation and impaired endothelial function correlated significantly with glucose intolerance and dyslipidemia. After the lifestyle intervention and successful weight reduction, AHI, BMI, serum triglycerides and insulin improved significantly; however, no improvement in FMD was detected.

CONCLUSIONS

Mild OSA was not observed to be associated with endothelial dysfunction. Although in mild OSA endothelial function is still preserved, lifestyle intervention with weight reduction did achieve an improvement in other obesity-related risk factors for cardiovascular diseases, thus highlighting the importance of early intervention.

Osbpl8 deficiency in mouse causes an elevation of high-density lipoproteins and gender-specific alterations of lipid metabolism

OSBP-related protein 8 (ORP8) encoded by Osbpl8 is an endoplasmic reticulum sterol sensor implicated in cellular lipid metabolism. We generated an Osbpl8^−/− (KO) C57Bl/6 mouse strain. Wild-type and Osbpl8KO animals at the age of 13-weeks were fed for 5 weeks either chow or high-fat diet, and their plasma lipids/lipoproteins and hepatic lipids were analyzed. The chow-fed Osbpl8KO male mice showed a marked elevation of high-density lipoprotein (HDL) cholesterol (+79%) and phospholipids (+35%), while only minor increase of apolipoprotein A-I (apoA-I) was detected. In chow-fed female KO mice a less prominent increase of HDL cholesterol (+27%) was observed, while on western diet the HDL increment was prominent in both genders. The HDL increase was accompanied by an elevated level of HDL-associated apolipoprotein E in male, but not female KO animals. No differences between genotypes were observed in lecithin:cholesterol acyltransferase (LCAT) or hepatic lipase (HL) activity, or in the fractional catabolic rate of fluorescently labeled mouse HDL injected in chow-diet fed animals. The Osbpl8KO mice of both genders displayed reduced phospholipid transfer protein (PLTP) activity, but only on chow diet. These findings are consistent with a model in which Osbpl8 deficiency results in altered biosynthesis of HDL. Consistent with this hypothesis, ORP8 depleted mouse hepatocytes secreted an increased amount of nascent HDL into the culture medium. In addition to the HDL phenotype, distinct gender-specific alterations in lipid metabolism were detected: Female KO animals on chow diet showed reduced lipoprotein lipase (LPL) activity and increased plasma triglycerides, while the male KO mice displayed elevated plasma cholesterol biosynthetic markers cholestenol, desmosterol, and lathosterol. Moreover, modest gender-specific alterations in the hepatic expression of lipid homeostatic genes were observed. In conclusion, we report the first viable OsbplKO mouse model, demonstrating a HDL elevating effect of Osbpl8 knock-out and additional gender- and/or diet-dependent impacts on lipid metabolism.

Conjugated bile acids associate with altered rates of glucose and lipid oxidation after Roux-en-Y gastric bypass

BACKGROUND

Laparoscopic Roux-en-Y gastric bypass (RYGB) induces a more favorable metabolic profile than expected by weight loss alone. In this study, we investigated the effect of RYGB on serum bile acid levels and their relation to clinical outcomes.

METHODS

We included 30 obese patients who underwent RYGB (BMI = 46.1 ± 5.9 kg/m(2)). Clinical measurements and laboratory determinations were performed before surgery and 1 year after surgery. Fasting serum bile acids were measured by an enzymatic method and individual bile acids were quantified by HLPC-tandem mass spectrometry. Indirect calorimetry was performed to measure the rates of energy expenditure and substrate oxidation.

RESULTS

Fasting total serum bile acid levels increased twofold after RYGB (pre, 3.68 ± 2.03 vs. post, 7.06 ± 9.65 μmol/l, +92 %, p = 0.002). This increase in total bile acids was accompanied by a decrease in conjugated bile acids, which correlated with decreased glucose oxidation (r = 0.571, p = 0.002) and with increased lipid oxidation (r = -0.626, p = 0.0004). The change in taurine-conjugated bile acids correlated with altered DIO2 mRNA expression in adipose tissue (r = -0.498, p = 0.013) potentially linking bile acid conjugation to substrate oxidation through DIO2.

CONCLUSIONS

Fasting serum bile acid levels increase after RYGB. More specifically, changes in bile acid conjugation after RYGB associate with altered energy metabolism.

[Fatty fish modifies HDL particle size and lipid concentrations]

BACKGROUND

We investigated with 1HNMR-spectroscopy the effects of habitual fatty fish intake on serum lipiprotein profiles in persons with features of metabolic syndrome.

MATERIAL AND METHODS

The participants (n = 105) were randomized into three diet intervention groups. The groups were given different dietary instructions.

RESULTS

Increased intake of fatty fish had a significant (p < 0.05) increasing effect on the amount of large HDL-lipoprotein subclasses and their lipids.

CONCLUSIONS

Frequent intake of fatty fish may have beneficial effects on HDL-metabolism beyond that assumed to be related to its serum concentrations.

[Gastric bypass as weight loss operation: 10-year experience of one center and challenges of follow-up]

INTRODUCTION

Data about the implementation of long-term follow-up of weight loss operation patients and their nutritional status has been lacking in Finland.

PATIENTS AND METHODS

We examined the postoperative complications and long-term outcome in respect of weight control, symptoms, nutritional status and medication of 173 patients having undergone gastric bypass. The data were collected from patient records and by questionnaires.

RESULTS

Postoperative complications and weight loss were at the international level. The number of those using antidiabetic and antihypertensive drugs decreased.

CONCLUSIONS

The results are in agreement with the international level, but follow-up treatment requires attention in Finland.

Adipose tissue TCF7L2 splicing is regulated by weight loss and associates with glucose and fatty acid metabolism

We investigated the effects of obesity surgery-induced weight loss on transcription factor 7-like 2 gene (TCF7L2) alternative splicing in adipose tissue and liver. Furthermore, we determined the association of TCF7L2 splicing with the levels of plasma glucose and serum free fatty acids (FFAs) in three independent studies (n = 216). Expression of the short mRNA variant, lacking exons 12, 13, and 13a, decreased after weight loss in subcutaneous fat (n = 46) and liver (n = 11) and was more common in subcutaneous fat of subjects with type 2 diabetes than in subjects with normal glucose tolerance in obese individuals (n = 54) and a population-based sample (n = 49). Additionally, there was a positive correlation between this variant and the level of fasting glucose in nondiabetic individuals (n = 113). This association between TCF7L2 splicing and plasma glucose was independent of the TCF7L2 genotype. Finally, this variant was associated with high levels of serum FFAs during hyperinsulinemia, suggesting impaired insulin action in adipose tissue, whereas no association with insulin secretion or insulin-stimulated whole-body glucose uptake was observed. Our study shows that the short TCF7L2 mRNA variant in subcutaneous fat is regulated by weight loss and is associated with hyperglycemia and impaired insulin action in adipose tissue.

Dose-dependent LDL-cholesterol lowering effect by plant stanol ester consumption: clinical evidence

Elevated serum lipids are linked to cardiovascular diseases calling for effective therapeutic means to reduce particularly LDL-cholesterol (LDL-C) levels. Plant stanols reduce levels of LDL-C by partly blocking cholesterol absorption. Accordingly the consumption of foods with added plant stanols, typically esterified with vegetable oil fatty acids in commercial food products, are recommended for lowering serum cholesterol levels. A daily intake of 1.5 to 2.4 g of plant stanols has been scientifically evaluated to lower LDL-C by 7 to 10% in different populations, ages and with different diseases. Based on earlier studies, a general understanding is that no further reduction may be achieved in intakes in excess of approximately 2.5 g/day. Recent studies however suggest that plant stanols show a continuous dose–response effect in serum LDL-C lowering. This review discusses the evidence for a dose-effect relationship between plant stanol ester consumption and reduction of LDL-C concentrations with daily intakes of plant stanols of 4 g/day or more. We identified five such studies and the overall data demonstrate a linear dose-effect relationship with the most pertinent LDL-Cholesterol lowering outcome, 18%, achieved by a daily intake of 9 to 10 g of plant stanols. Along with reduction in LDL-C, the studies demonstrated a decrease in cholesterol absorption markers, the serum plant sterol to cholesterol ratios, by increasing the dose of plant stanol intake. None of the studies with daily intakes up to 10 g of plant stanols reported adverse clinical or biochemical effects from plant stanols. In a like manner, the magnitude of decrease in serum antioxidant vitamins was not related to the dose of plant stanols consumed and the differences between plant stanol ester consumers and controls were minor and insignificant or nonexisting. Consumption of plant stanols in high doses is feasible as a range of food products are commercially available for consumption including spreads and yoghurt type drinks. In conclusion, a dose-effect relationship of plant stanols in higher doses than currently recommended has been demonstrated by recent clinical studies and a meta-analysis. Further studies are called for to provide confirmatory evidence amenable for new health claim applications and dietary recommendations.

Effect of short-term carbohydrate overfeeding and long-term weight loss on liver fat in overweight humans

BACKGROUND

Cross-sectional studies have identified a high intake of simple sugars as an important dietary factor predicting nonalcoholic fatty liver disease (NAFLD).

OBJECTIVE

We examined whether overfeeding overweight subjects with simple sugars increases liver fat and de novo lipogenesis (DNL) and whether this is reversible by weight loss.

DESIGN

Sixteen subjects [BMI (kg/m²): 30.6 ± 1.2] were placed on a hypercaloric diet (>1000 kcal simple carbohydrates/d) for 3 wk and, thereafter, on a hypocaloric diet for 6 mo. The subjects were genotyped for rs739409 in the PNPLA3 gene. Before and after overfeeding and after hypocaloric diet, metabolic variables and liver fat (measured by proton magnetic resonance spectroscopy) were measured. The ratio of palmitate (16:0) to linoleate (18:2n-6) in serum and VLDL triglycerides was used as an index of DNL.

RESULTS

Carbohydrate overfeeding increased weight (±SEM) by 2% (1.8 ± 0.3 kg; P < 0.0001) and liver fat by 27% from 9.2 ± 1.9% to 11.7 ± 1.9% (P = 0.005). DNL increased in proportion to the increase in liver fat and serum triglycerides in subjects with PNPLA3-148IIbut not PNPLA3-148MM. During the hypocaloric diet, the subjects lost 4% of their weight (3.2 ± 0.6 kg; P < 0.0001) and 25% of their liver fat content (from 11.7 ± 1.9% to 8.8 ± 1.8%; P < 0.05).

CONCLUSIONS

Carbohydrate overfeeding for 3 wk induced a >10-fold greater relative change in liver fat (27%) than in body weight (2%). The increase in liver fat was proportional to that in DNL. Weight loss restores liver fat to normal. These data indicate that the human fatty liver avidly accumulates fat during carbohydrate overfeeding and support a role for DNL in the pathogenesis of NAFLD. This trial was registered at www.hus.fi as 235780.

Cholesterol metabolism altered and FGF21 levels high after pediatric liver transplantation despite normal serum lipids

Liver transplantation (LT) predisposes to metabolic derangements and increases the risk for cardiovascular disease. We conducted a national cross-sectional study of all pediatric recipients who underwent LT between 1987 and 2007. We measured serum levels of noncholesterol sterols (surrogate markers of cholesterol synthesis and intestinal absorption) and fibroblast growth factor 21 (FGF21) in 49 patients (74% of survivors) at a median of 10 years posttransplant and in 93 controls matched for age and gender. Although serum cholesterol levels were similar in patients and controls, patients displayed increased whole-body synthesis and decreased intestinal absorption of cholesterol compared with controls (lathosterol to cholesterol ratio 129 ± 55 vs. 96 ± 41, respectively, p < 0.001; campesterol to cholesterol ratio 233 ± 91 vs. 316 ± 107, respectively; p < 0.001). Azathioprine (r =-0.383, p = 0.007) and low-dose methylpredisolone (r =-0.492, p < 0.001) were negatively associated with lathosterol/sitosterol ratio reflecting a favorable effect on cholesterol metabolism. FGF21 levels were higher in patients than in controls (248 pg/mL vs. 77 pg/mL, p < 0.001). In healthy controls, FGF21 was associated with cholesterol metabolism, an association missing in LT recipients. Normal serum lipids are achievable in long-term survivors of pediatric LT, but changes in cholesterol metabolism and increased FGF21 levels may explicate later cardiovascular risk.

Bilberries reduce low-grade inflammation in individuals with features of metabolic syndrome

SCOPE

Low-grade inflammation is a hallmark of cardiometabolic risk. Bilberries (Vaccinium myrtillus) are rich in polyphenols with potential anti-inflammatory properties. We studied the impact of bilberries on inflammation and gene expression profile in peripheral blood mononuclear cells in subjects with metabolic syndrome.

METHODS AND RESULTS

In randomized, controlled dietary intervention, the participants consumed either a diet rich in bilberries (n = 15) or a control diet (n = 12). The bilberry group consumed daily an equivalent dose of 400 g fresh bilberries, while the control group maintained their habitual diet. No differences were found between the groups in body weight, glucose, or lipid metabolism, but bilberry supplementation tended to decrease serum high-sensitivity C-reactive protein, IL-6, IL-12, and LPS concentrations. An inflammation score was significantly different between the groups (p = 0.024). In transcriptomics analyses (three participants with improved oral glucose tolerance test in the bilberry group), Toll-like receptor signaling, cytoplasmic ribosomal proteins, and B-cell receptor signaling pathways were differently regulated. QPCR analyses (n = 13 and 11 in the bilberry and control groups, respectively) showed decreased expression of MMD and CCR2 transcripts associated with monocyte and macrophage function associated genes.

CONCLUSION

Regular bilberry consumption may reduce low-grade inflammation indicating decreased cardiometabolic risk in the long term.

Effect of weight loss on inflammation in patients with mild obstructive sleep apnea

BACKGROUND AND AIMS

Inflammation may be one mediating mechanism for cardiovascular diseases in obstructive sleep apnea (OSA). However, little is known about subclinical inflammation or the effect of lifestyle intervention on inflammation in early stages of OSA. The aim of this substudy of an existing randomized controlled trial, with post hoc analyses, was to determine the impact of lifestyle changes aimed at weight reduction on inflammatory biomarkers in overweight patients with mild OSA.

METHODS AND RESULTS

Patients were randomized to supervised intensive lifestyle intervention group (N=28) or to control group (N=31), which received routine lifestyle advices. Circulating concentrations of pro- and anti-inflammatory mediators were measured before and after the 1-year intervention. The concentrations of two pro-inflammatory mediators, high-sensitivity C-reactive protein (hsCRP) and interleukin (IL)-6, decreased significantly in both groups. Although the changes in inflammatory biomarkers favored the supervised lifestyle intervention, the only significant reduction observed between the groups was for the anti-inflammatory IL-1 receptor antagonist (IL-1RA). The change in hsCRP was associated with apnea-hypopnea index, and improving night-time oxygen saturation was related to tumor necrosis factor alpha. IL-1RA and IL-6 were associated with insulin metabolism.

CONCLUSION

Weight loss resulted in reductions in concentrations of some pro- and anti-inflammatory mediators in overweight patients with mild OSA, overall favoring the supervised lifestyle intervention. These findings suggest that more intensive treatment of obesity in OSA patients might be well-justified.

Serum interleukin 1 receptor antagonist as an independent marker of non-alcoholic steatohepatitis in humans

BACKGROUND & AIMS

Mechanisms leading to non-alcoholic steatohepatitis (NASH) have remained unclear, and non-invasive diagnosis of NASH is challenging. In this study, we investigated the benefits of measuring serum interleukin 1 receptor antagonist (IL-1RA) levels.

METHODS

Liver biopsies from 119 morbidly obese individuals (47.5 ± 9.0 years, BMI 44.9 ± 5.9 kg/m(2)) were used for histological and gene expression assessment. In a cross-sectional population-based cohort of 6447 men (58 ± 7 years, BMI 27.0 ± 3.9 kg/m(2)) the association of serum IL1-RA with serum alanine aminotransferase (ALT) levels was investigated.

RESULTS

Serum levels of IL-1RA, and liver mRNA expression of IL1RN are associated with NASH and the degree of lobular inflammation in liver (p<0.05). The decrease in serum IL-1RA level and expression of IL1RN after obesity surgery correlated with the improvement of lobular inflammation (p<0.05). We developed a novel NAFLD Liver Inflammation Score, including serum Il-1RA concentration, which performed better to diagnose NASH than did previously published scores. Results from the population study confirmed the potential of measuring serum IL-1RA level. The strongest determinants of the ALT concentration at the population level were Matsuda insulin sensitivity index (r(2)=0.130, p=7 × 10(-197)) and serum IL-1RA concentration (r(2)=0.074, p=1 × 10(-110)). IL-1RA concentrations associated significantly with ALT levels even after adjusting for BMI, alcohol consumption and insulin sensitivity (p=2 × 10(-21)).

CONCLUSIONS

IL-1RA serum levels associate with liver inflammation and serum ALT independently of obesity, alcohol consumption and insulin resistance, suggesting a potential use of IL-1RA as a non-invasive inflammatory marker for NASH.