Amiodarone disrupts cholesterol biosynthesis pathway and causes accumulation of circulating desmosterol by inhibiting 24-dehydrocholesterol reductase

BACKGROUND

We have earlier reported that amiodarone, a potent and commonly used antiarrhythmic drug increases serum desmosterol, the last precursor of cholesterol, in 20 cardiac patients by an unknown mechanism.

OBJECTIVE

Here, we extended our study to a large number of cardiac patients of heterogeneous diagnoses, evaluated the effects of combining amiodarone and statins (inhibitors of cholesterol synthesis at the rate-limiting step of hydroxy-methyl-glutaryl CoA reductase) on desmosterol levels and investigated the mechanism(s) by which amiodarone interferes with the metabolism of desmosterol using in vitro studies.

METHODS AND RESULTS

We report in a clinical case-control setting of 236 cardiac patients (126 with and 110 without amiodarone treatment) that amiodarone medication is accompanied by a robust increase in serum desmosterol levels independently of gender, age, body mass index, cardiac and other diseases, and the use of statins. Lipid analyses in patient samples taken before and after initiation of amiodarone therapy showed a systematic increase of desmosterol upon drug administration, strongly arguing for a direct causal link between amiodarone and desmosterol accumulation. Mechanistically, we found that amiodarone resulted in desmosterol accumulation in cultured human cells and that the compound directly inhibited the 24-dehydrocholesterol reductase (DHCR24) enzyme activity.

CONCLUSION

These novel findings demonstrate that amiodarone blocks the cholesterol synthesis pathway by inhibiting DHCR24, causing a robust accumulation of cellular desmosterol in cells and in the sera of amiodarone-treated patients. It is conceivable that the antiarrhythmic potential and side effects of amiodarone may in part result from inhibition of the cholesterol synthesis pathway.

Desmosterol accumulation in users of amiodarone

BACKGROUND

Amiodarone is an effective and widely used antiarrhythmic drug with many possible adverse effects including hypercholesterolaemia and hepatotoxicity.

OBJECTIVE

Our aim was to evaluate how long-term amiodarone treatment affects cholesterol metabolism.

METHODS

The study population consisted of 56 cardiac patients, of whom 20 were on amiodarone (amiodarone + group) and 36 did not use the drug (amiodarone - group). We also studied a control group of 124 individuals selected randomly from the population. Cholesterol metabolism was evaluated by analysis of serum noncholesterol sterols by gas-liquid chromatography and gas chromatography-mass spectrometry.

RESULTS

Comparisons of serum lipids and noncholesterol sterols across the three groups showed increased serum triglyceride in users of amiodarone but no statistically significant group differences in total, LDL or HDL cholesterol or serum proprotein convertase subtilisin/kexin type 9 concentrations. Nor did the groups differ in the ratios of cholestanol or plant sterols to cholesterol in serum, suggesting that cholesterol absorption was unaltered. However, all users of amiodarone had very markedly elevated serum desmosterol concentrations: the desmosterol-to-cholesterol ratio (10² × μmol mmol^-1 ) averaged 1030.7 ± 115.7 (mean ± SE) in the amiodarone + group versus 82.7 ± 3.4 and 75.9 ± 1.4 in the amiodarone - and the population control groups (P < 0.001), respectively.

CONCLUSION

Use of amiodarone was associated with on average 12-fold serum desmosterol concentrations compared with the control groups. This observation is fully novel and suggests that amiodarone interferes with the conversion of desmosterol to cholesterol in the cholesterol synthesis pathway. Whether accumulation of desmosterol plays a role in amiodarone-induced hepatotoxicity deserves to be studied in the future.

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.

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.

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.

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.

The role of serum non-cholesterol sterols as surrogate markers of absolute cholesterol synthesis and absorption

AIMS

To study the whole-body cholesterol metabolism in man, cholesterol synthesis and absorption need to be measured. Because of the complicated methods of the measurements, new approaches were developed including the analysis of serum non-cholesterol sterols. In current lipidologic papers and even in intervention studies, serum non-cholesterol sterols are frequently used as surrogate markers of cholesterol metabolism without any validation to the absolute metabolic variables. The present review compares serum non-cholesterol sterols with absolute measurements of cholesterol synthesis and absorption in published papers to find out whether the serum markers are valid indicators of cholesterol metabolism in various conditions.

DATA SYNTHESIS

During statin treatment, during interventions of dietary fat, and in type 2 diabetes the relative and absolute variables of cholesterol synthesis and absorption were frequently but not constantly correlated with each other. In some occasions, especially in subjects with apolipoprotein E3/4 and E4/4 phenotypes, the relative metabolic markers were even more sensitive than the absolute ones to reflect changes in cholesterol metabolism during dietary interventions. Even in general population at very high absorption the homeostasis of cholesterol metabolism is disturbed damaging the validity of the serum markers.

CONCLUSIONS

It is worth using several instead of only one precursor and absorption sterol marker for making conclusions of altered synthesis or absorption of cholesterol, and even then the presence of at least some absolute measurement is valuable. During consumption of plant sterol-enriched diets and in situations of interfered cholesterol homeostasis the relative markers do not adequately reflect cholesterol metabolism. Accordingly, the validity of the relative markers of cholesterol metabolism should not be considered as self-evident.

Serum and lipoprotein sitostanol and non-cholesterol sterols after an acute dose of plant stanol ester on its long-term consumption

PURPOSE

Chronic inhibition of cholesterol absorption with large doses of plant stanol esters (staest) alters profoundly cholesterol metabolism, but it is unknown how an acute inhibition with a large staest dose alters the postprandial serum and lipoprotein cholesterol precursor, plant sterol, and sitostanol contents.

METHODS

Hypercholesterolemic subjects, randomly and double-blind divided into control (n = 18) and intervention groups (n = 20), consumed experimental diet without and with staest (plant stanols 8.8 g/day) for 10 weeks. Next morning after a fasting blood sample (0 h), the subjects had a breakfast without or with staest (4.5 g of plant stanols). Blood sampling was repeated 4 h later. Lipoproteins were separated with ultracentrifugation, and sterols were measured with gas-liquid chromatography.

RESULTS

In 0-h chylomicrons and VLDL, plant sterols were lower in staest than in controls. Postprandially, cholestenol (cholesterol synthesis marker) was reduced in chylomicrons in staest compared with controls (-0.13 ± 0.04 μg/dL vs. 0.01 ± 0.08 μg/dL, P < 0.05). Staest decreased postprandially avenasterol in chylomicrons (P < 0.05 from 0 h). Sitostanol was high at 0 h by chronic staest in serum and VLDL but not in chylomicrons. Postprandial sitostanol was increased by staest in VLDL only.

CONCLUSIONS

Chronic cholesterol absorption inhibition with large amount of plant stanol esters decreases plant sterols in triglyceride-rich lipoproteins. Acute plant stanol ester consumption increases sitostanol content in triglyceride-rich lipoproteins but suggests to decrease the risk of plant sterol and plant stanol accumulation into vascular wall by chylomicrons.

Association of the FTO gene variant (rs9939609) with cardiovascular disease in men with abnormal glucose metabolism--the Finnish Diabetes Prevention Study

BACKGROUND AND AIM

The common single nucleotide polymorphism (SNP) in the FTO (fat mass and obesity associated) gene has been consistently associated with an increased risk of obesity. We investigated whether the SNP rs9939609 (T/A) of the FTO is associated with risk factors of cardiovascular diseases (CVD), including serum levels of C - reactive protein (CRP), the chemokine RANTES (Regulated on Activation, Normal T Cell Expressed and Secreted; CCL5), and serum and lipoprotein lipids in the Finnish Diabetes Prevention Study (DPS). Furthermore, we examined whether the rs9939609 increased the CVD risk in the DPS and if these results could be replicated in a larger cross-sectional population-based random sample of Finnish men (the METSIM).

METHODS AND RESULTS

In the DPS, altogether 490 (BMI≥25kg/m(2)) subjects with impaired glucose tolerance were genotyped for rs9939609. Cardiovascular morbidity and mortality data were collected during the median follow-up of 10.2 years. The replication study was a population-based cross-sectional study of 6214 men. In the DPS, the AA genotype of rs9939609 was associated, independently of BMI, with increased RANTES (p=0.002) and decreased HDL cholesterol concentrations (p=0.007) in men. During the follow-up, the AA genotype was associated with an adjusted 2.09-fold risk (95% CI 1.17-3.73, p=0.013) of CVD in men. In the METSIM Study, the association with a history of myocardial infarction was replicated in the subgroup of men with type 2 diabetes.

CONCLUSION

We suggest that the variation in the FTO gene may contribute to the development of CVD in men with an abnormal glucose metabolism.

Non-cholesterol sterols in serum and endarterectomized carotid arteries after a short-term plant stanol and sterol ester challenge

BACKGROUND AND AIMS

It is not known whether dietary intake of plant stanols or sterols changes the composition of arterial sterols. Therefore, we compared serum and carotid artery cholesterol and non-cholesterol sterols after plant stanol (staest) or sterol (steest) ester feeding in endarterectomized patients.

METHODS AND RESULTS

Elderly statin-treated asymptomatic patients undergoing carotid endarterectomy were randomized double-blind to consume staest (n=11) or steest (n=11) spread (2 g of stanol or sterol/day) for four weeks preoperatively. Non-cholesterol sterols from serum and carotid artery tissue were analysed with gas-liquid chromatography. Staest spread lowered serum total (17.2%), VLDL, and LDL cholesterol and serum triglycerides, while steest spread lowered serum total (13.8%) and LDL cholesterol levels from baseline (p<0.05 for all). Serum cholestanol and avenasterol were decreased in both groups, but campesterol and sitosterol were decreased by staest and increased by steest from baseline (p<0.05 from baseline and between the groups). Serum sitostanol to cholesterol ratio was increased by staest, but in arterial tissue this ratio was similar in both groups. On staest, lathosterol, campesterol, and sitosterol, and on steest sitosterol and avenasterol correlated significantly between serum and arterial tissue. Cholesterol metabolism, eg. lathosterol/campesterol, suggested that plant sterols were reduced in serum and in arterial tissue during staest.

CONCLUSION

The novel observations were that plant stanol ester consumption, in contrast to plant sterols, tended to reduce carotid artery plant sterols in statin-treated patients. Furthermore, despite increased serum sitostanol contents during plant stanol ester consumption, their arterial levels were unchanged suggesting that sitostanol is not taken up into the arterial wall.

Dietary carbohydrate modification alters serum metabolic profiles in individuals with the metabolic syndrome

BACKGROUND AND AIMS

Whole-grain cereals and diets with a low glycemic index may protect against the development of type 2 diabetes and heart disease, but the mechanisms are poorly understood. We studied the effect of carbohydrate modification on serum metabolic profiles, including lipids and branched chain amino acids, and dependencies between these and specific gene expression pathways in adipose tissue.

METHODS AND RESULTS

Twenty subjects with metabolic syndrome were selected from the larger FUNGENUT study population, randomized either to a diet high in oat and wheat bread and potato (OWP) or rye bread and pasta (RP). Serum metabolomics analyses were performed using ultra-performance liquid chromatography coupled to electrospray ionization mass spectrometry (UPLC/MS), gas chromatography (GC) and UPLC. In the OWP group multiple proinflammatory lysophosphatidylcholines increased, while in the RP group docosahexaenoic acid (DHA 22:6n-3) increased and isoleucine decreased. mRNA expression of stress reactions- and adipose tissue differentiation-related genes were up-regulated in adipose tissue in the OWP group. In the RP group, however, pathways related to stress reactions and insulin signaling and energy metabolism were down-regulated. The lipid profiles had the strongest association with the changes in the adipose tissue differentiation pathway when using the elastic net regression model of the lipidomic profiles on selected pathways.

CONCLUSION

Our results suggest that the dietary carbohydrate modification alters the serum metabolic profile, especially in lysoPC species, and may, thus, contribute to proinflammatory processes which in turn promote adverse changes in insulin and glucose metabolism.

Cholesterol, non-cholesterol sterols and bile acids in paediatric gallstones

BACKGROUND

Depending on underlying aetiopathogenetic factors human gallstones contain various amounts of cholesterol, non-cholesterol sterols and bile acids, which have remained unexplored in paediatric gallstone patients.

AIMS

To evaluate sterol and bile acids compositions of paediatric gallstones.

PATIENTS AND METHODS

Study group included 21 consecutively cholecystectomised children. Gas-liquid chromatography was used to quantitate gallstone sterols and bile acids. Results were compared to adult gallstones (n=194).

RESULTS

Cholesterol stones (n=9) had higher proportions of cholesterol and lathosterol, but lower those of lanosterol and phytosterols than pigment stones (n=12) (p<0.05 for each). Patients with gallstone cholesterol content over 70% were female. Gallstone cholesterol positively reflected body mass index and, in cholesterol stones-group, age (r=approximately +0.700, p<0.05). Three patients on parenteral nutrition had brown pigment stones consisting of high amounts of campesterol and sitosterol ranging 483-9303 microg/100 mg of stone. Pigment stones had 13-fold higher amount of bile acids than cholesterol stones (p<0.05). Black pigment stones contained approximately 3-fold higher phytosterol proportions, and pigment stones and cholesterol stones had approximately 43% lower proportions of deoxycholic acid than adults (p<0.05).

CONCLUSION

Gallstones in patients on parenteral nutrition are rich in phytosterols. With respect to gallstone sterols, gallstone disease of adolescent girls resembles that of adults. Composition of bile acids in paediatric gallstones is different from adults.

Pandemic influenza: human rights, ethics and duty to treat

The 2009 influenza A/H1N1 pandemic seems to be only moderately severe. In the future, a pandemic influenza with high lethality, such as the Spanish influenza in 1918-1919 or even worse, may emerge. In this kind of scenario, lethality rates ranging roughly from 2% to 30% have been proposed. Legal and ethical issues should be discussed before the incident. This article aims to highlight the legal, ethical and professional aspects that might be relevant to anaesthesiologists in the case of a high-lethality infectious disease such as a severe pandemic influenza. The epidemiology, the role of anaesthesiologists and possible threats to the profession and colleagueship within medical specialties relevant to anaesthesiologists are reviewed. During historical plague epidemics, some doctors have behaved like 'deserters'. However, during the Spanish influenza, physicians remained at their jobs, although many perished. In surveys, more than half of the health-care workers have reported their willingness to work in the case of severe pandemics. Physicians have the same human rights as all citizens: they have to be effectively protected against infectious disease. However, they have a duty to treat. Fair and responsible colleagueship among the diverse medical specialties should be promoted. Until disaster threatens humanity, volunteering to work during a pandemic might be the best way to ensure that physicians and other health-care workers stay at their workplace. Broad discussion in society is needed.

Twenty-one year tracking of serum non-cholesterol sterols. The Cardiovascular Risk in Young Finns study

BACKGROUND AND AIM

To show tracking of cholesterol metabolism, the ratios to cholesterol of e.g. serum cholestenol, desmosterol, and lathosterol, reflecting cholesterol synthesis, and cholestanol, campesterol, avenasterol and sitosterol, reflecting cholesterol absorption, were measured 21 years apart.

METHODS AND RESULTS

In random population samples initially comprising 12- (n=162), 15- (n=158), and 18-year-old (n=148) males participating in the Cardiovascular Risk in Young Finns Study, serum sterols and squalene were measured with gas-liquid chromatography in 1980 and 2001. Quartiles of cholestanol, indicating low to high cholesterol absorption, were defined from the cholestanol values in 1980. Serum cholesterol increased in the oldest age group only, but synthesis markers (except desmosterol) increased in all age groups after the follow-up (e.g. lathosterol, total population +47.3+/-2.6% (SE), P<0.001). Campesterol (+69.0+/-3.0%, P<0.001) and sitosterol increased, avenasterol was unchanged, and cholestanol decreased (-6.2+/-0.7%, P<0.001), respectively. The 1980 synthesis and absorption markers were interrelated with respective values 21 years later in all age groups and quartiles (e.g. lathosterol, total population 1980 vs. 2001 r=0.460, cholestanol 1980 vs. 2001 r=0.593, P<0.001 for both). Synthesis markers were highest in the first and lowest in the fourth quartile both in 1980 and 2001 (e.g. 2001, desmosterol, quartile 1, 99+/-9, quartile 4, 83+/-2 microg/mg of cholesterol, P<0.05).

CONCLUSIONS

Cholesterol metabolism is significantly tracked in adolescent males over the follow-up of 21 years. Thus, high cholesterol synthesis and low absorption characterize subjects with the lowest cholestanol quartile, while those with the highest quartile have low synthesis and high absorption in both adolescence and later in young adult life.

Downregulation of genes involved in NFkappaB activation in peripheral blood mononuclear cells after weight loss is associated with the improvement of insulin sensitivity in individuals with the metabolic syndrome: the GENOBIN study

AIMS/HYPOTHESIS

The transcription factor nuclear factor-kappa-B (NFkappaB) is implicated in inflammatory responses, obesity and the metabolic syndrome, while immune cells appear to play a central role in mediating insulin resistance and can be used as a model to study inflammation and its relationship with insulin resistance. In peripheral blood mononuclear cells of overweight participants with the metabolic syndrome, we evaluated (1) the effect of diet-induced weight loss on the expression of genes involved in NFkappaB activation and (2) their association with insulin sensitivity. The genes studied were: TNF receptors TNFRSF1A and TNFRSF1B, and IL1R1, TLR4, TLR2, ICAM1, CCL5 and IKBKB.

METHODS

We analysed data from 34 overweight participants with abnormal glucose metabolism and the metabolic syndrome, who were randomised to a weight-reduction (n = 24) or control group (n = 10) for 33 weeks. The mRNA expression was measured using real-time PCR. Measures of insulin and glucose homeostasis were assessed by IVGTT and OGTT.

RESULTS

In general, the genes studied were downregulated after weight loss intervention. The changes in TLR4, TLR2, CCL5 and TNFRSF1A mRNA expression were associated with an increase in insulin sensitivity index independently of the change in waist circumference (p < 0.05). The change in IKBKB expression correlated with most of the changes in gene expression in the weight-reduction group.

CONCLUSIONS/INTERPRETATION

These results suggest that proteins encoded by CCL5, TLR2 and TLR4, and TNFRSF1A might contribute to insulin-resistant states that characterise obesity and the metabolic syndrome.

TRIAL REGISTRATION

ClinicalTrials.gov NCT 00621205.

Serum concentrations and expressions of serum amyloid A and leptin in adipose tissue are interrelated: the Genobin Study

OBJECTIVE

Serum amyloid A (SAA) is a novel link between increased adipose tissue mass and low-grade inflammation in obesity. Little is known about the factors regulating its serum concentration and mRNA levels. We investigated the association between SAA and leptin in obese and normal weight subjects and analyzed the effect of weight reduction on serum SAA concentration and gene expression in adipose tissue of the obese subjects.

METHODS

Seventy-five obese subjects (60+/-7 years, body mass index (BMI) 32.9+/-2.8 kg/m(2), mean+/-s.d.) with impaired fasting plasma glucose or impaired glucose tolerance and other features of metabolic syndrome, and 11 normal weight control subjects (48+/-9 years, BMI 23.7+/-1.9 kg/m(2)) were studied at the baseline. Twenty-eight obese subjects underwent a 12-week intensive weight reduction program followed by 5 months of weight maintenance. Blood samples and abdominal s.c. adipose tissue biopsies were taken at the baseline and after the follow-up. Gene expression was studied using real-time quantitative PCR.

RESULTS

The gene expressions in women and serum concentrations of leptin and SAA were interrelated independently of body fat mass in the obese subjects (r=0.54, P=0.001; r=0.24, P=0.039 respectively). In multiple linear regression analyses, leptin mRNA explained 38% of the variance in SAA mRNA (P=0.002) in the obese women. Weight loss of at least 5% increased SAA mRNA expression by 48 and 36% in men and women, but serum SAA concentrations did not change.

CONCLUSIONS

The association between SAA and leptin suggests an interaction between these two adipokines, which may have implications in inflammatory processes related to obesity and the metabolic syndrome.

SREBP-1c gene polymorphism is associated with increased inhibition of cholesterol-absorption in response to ezetimibe treatment

OBJECTIVE

Sterol regulatory binding proteins 1 and 2 (SREBPs) are transcription factors regulating lipid metabolism. A recent study has associated the CC genotype of the SREBP-1c polymorphism G952G with increased cholesterol synthesis. Further evidence suggests that SREBPs play a role in cholesterol absorption and that SREBP polymorphisms modulate the response to statin therapy. The present study examines whether the G952G polymorphism alters cholesterol synthesis and/or absorption and whether it modulates the response to widely used lipid-lowering drugs such as inhibitors of cholesterol synthesis (simvastatin) or absorption (ezetimibe).

METHODS

Seventy-two healthy male subjects with LDL cholesterol <190 mg/dL participated in the study. Twenty four subjects were treated with ezetimibe (10 mg), simvastatin (40 mg) or their combination, respectively, for two weeks. Blood was drawn before and after the 2-week treatment period.

RESULTS

Eleven CC homozygous carriers of the gene were found (15%). There were no differences in cholesterol synthesis or absorption between the CC homozygotes and the G allele-carriers, as measured by the ratios to cholesterol of serum lathosterol, desmosterol and cholestenol (synthesis markers) and cholestanol, sitosterol and campesterol (absorption markers). Ezetimibe had a significantly more potent effect in blocking cholesterol absorption in the CC homozygotes compared to the G-carriers ( P=0.002).

CONCLUSIONS

The G/C (G952G) polymorphism of the SREBP-1 gene is not associated with cholesterol synthesis or absorption in a German male population. The CC homozygotes have a significantly increased response to the effects of ezetimibe on cholesterol absorption compared to the G allele-carriers, suggesting that SREBP-1 may be implicated in ezetimibe's mechanism of action.

Weight reduction modulates expression of genes involved in extracellular matrix and cell death: the GENOBIN study

OBJECTIVE

Lifestyle and genetic factors interact in the development of obesity and the metabolic syndrome. The molecular mechanisms underlying the beneficial dietary modifications are, however, unclear. We aimed to examine the effect of the long-term moderate weight reduction on gene expression in adipose tissue (AT) and to identify genes and gene clusters responsive to treatment and thereby likely contributing to the development of the metabolic syndrome.

DESIGN

Randomized controlled and individualized weight reduction intervention.

SUBJECTS

Forty-six subjects with impaired fasting glycemia or impaired glucose tolerance and features of metabolic syndrome, aged 60+/-7 years were randomized either to a weight reduction (WR) (n=28) or a control (n=18) group lasting for 33 weeks.

MEASUREMENTS

Oral and intravenous glucose tolerance tests and subcutaneous AT biopsies were performed before and after the intervention. Gene expression of AT was studied using microarray technology in subgroups of WR (with weight reduction > or =5%, n=9) and control group (n=10). The results were confirmed using quantitative PCR.

RESULTS

In the WR group, glucose metabolism improved. Moreover, an inverse correlation between the change in S (I) and the change in body weight was found (r=-0.44, P=0.026). Downregulation of gene expression (P<0.01) involving gene ontology groups of extracellular matrix and cell death was seen. Such changes did not occur in the control group. The tenomodulin-gene was one of the most downregulated genes (-39+/-16%, P<0.0001). Moreover, its expression correlated with insulin sensitivity (r=-0.34, P=0.005) before the intervention and with body adiposity both before (r=0.42, P=0.007) and after (r=0.30, P=0.056) the intervention.

CONCLUSION

Genes regulating the extracellular matrix and cell death showed a strong downregulation after long-term weight reduction. This likely reflects a new stable state at the molecular level in AT. Further studies are warranted to elucidate the mechanisms of these genetic factors.

Moderate increase in dietary sucrose does not influence fasting or postprandial serum lipids regardless of the presence of apolipoprotein E2 allele in healthy subjects

OBJECTIVE

To investigate whether a moderate increase in dietary sucrose intake induces different serum lipid responses in normolipidemic subjects with the epsilon 2 allele compared with subjects without the epsilon 2 allele.

DESIGN

Controlled, parallel study.

SUBJECTS

There were 15 subjects with the apolipoprotein E (APOE)3/2 genotype and 19 subjects with the APOE 3/3 or 3/4 genotype, whose mean+/-s.d. age was 48+/-14 and 35+/-10 years, respectively. All subjects had normal glucose metabolism.

INTERVENTIONS

The subjects were instructed to increase their sucrose intake by 40 g/day for 8 weeks and to decrease the intake of saturated and unsaturated fat to maintain energy balance. Dietary adherence was monitored using food records and the actual increase in sucrose intake was 39.8+/-18.4 g/day. Sixteen subjects (nine with APOE 3/2 genotype, seven with APOE 3/3 or 3/4 genotypes) participated also in an 8 h oral fat tolerance test at the beginning and at the end of the intervention.

RESULTS

Body weight remained stable during the intervention. Sucrose intake did not have a significant effect on fasting concentrations of serum total and lipoprotein lipids, plasma glucose, serum insulin, squalene and non-cholesterol sterols in either genotype group. Neither were there any changes in postprandial lipid or insulin responses.

CONCLUSIONS

Moderate increase in sucrose intake does not affect fasting or postprandial serum lipid responses in healthy subjects with or without the epsilon 2 allele.

Postprandial behavior of plasma squalene and non-cholesterol sterols in men with varying cholesterol absorption

BACKGROUND

The purpose of this study was to investigate, whether low vs. high absorption of cholesterol affects the postprandial lipid clearance (squalene as the surrogate marker) and postprandial cholesterol metabolism evaluated with plasma levels of cholesterol absorption (cholestanol and plant sterols) and synthesis markers (desmosterol and lathosterol).

METHODS

Fifteen normo- or mildly hypercholesterolemic men were divided into low or high cholesterol absorbers on the basis of plasma cholestanol to cholesterol ratio and they volunteered to an oral fat load test containing fat 35 g/m(2) body surface.

RESULTS

Plasma squalene to cholesterol ratio did not differ between the groups throughout the postprandial follow-up of 8 h. The level differences in the plasma absorption and synthesis markers seen at baseline remained between the groups, so that in high absorbers the absorption markers remained high and synthesis markers low throughout the postprandial follow-up. The postprandial response curves of desmosterol (p<0.05) and lathosterol (p=0.052) to cholestanol decreased linearly in the low, but not in the high absorbers.

CONCLUSIONS

Low vs. high absorption of cholesterol does not affect the first 8-h postprandial lipid clearance. The metabolic profile of cholesterol is maintained postprandially. The postprandial decrease in cholesterol synthesis differs in low vs. high absorbers especially through the desmosterol pathway.

Plant stanol and sterol esters in prevention of cardiovascular diseases: a review

Plant sterol and stanol esters have been introduced as an additional dietary means to lower serum total and LDL cholesterol concentration. In short-term studies they lower LDL cholesterol by 10%, and according to a meta-analysis by Malcolm Law the incidence of coronary heart disease is considered to be reduced by over 20% in long-term use of these products. Plant stanol and sterol esters are not identical sterols; they have different metabolic effects and their long-term efficacy seems to be different. The present review deals with the differences of the sterols and discusses what is known of their role in preventing the cardiovascular diseases.

Cholesterol metabolism and its implications for therapeutic interventions in patients with hypercholesterolaemia

Cardiovascular diseases are the principal causes of mortality in middle-aged people and in older people. Coronary heart disease (CHD) is the most common of the cardiovascular diseases; high serum levels of cholesterol are associated with atherosclerosis and an increased risk of CHD. Cholesterol homeostasis is achieved by means of a fine balance between cholesterol intake, absorption/excretion and synthesis. All of these processes are tightly linked and a change in one of them can significantly influence the others. Results from both experimental studies and clinical trials have shown that inhibition of cholesterol synthesis with a statin increases absorption and that conversely, inhibition of cholesterol absorption increases synthesis. The tight linkage of cholesterol absorption and synthesis in maintaining cholesterol homeostasis suggests that treatment with an agent that influences only one of these two processes is likely to have distinct limits with respect to its effects on cholesterol levels. Better understanding of cholesterol homeostasis, particularly the close interrelationship between cholesterol synthesis and absorption, may result in the design of rational integrated treatment regimens that employ multiple agents with complementary actions that attack multiple mechanisms to lower cholesterol.

Synthesis and absorption markers of cholesterol in serum and lipoproteins during a large dose of statin treatment

BACKGROUND

Serum contains noncholesterol sterols, which are reliable markers of cholesterol metabolism, but their presence and importance in different lipoproteins have been insufficiently studied.

MATERIALS AND METHODS

Serum and lipoprotein cholesterol precursors squalene, cholestanol, desmosterol and lathosterol (markers of cholesterol synthesis) and cholestanol and plant sterols (markers of cholesterol absorption), and absorption efficacy and absolute synthesis of cholesterol were studied at baseline and during 6-month atorvastatin (80 mg day(-1)) treatment by the sterol balance technique in men with type 2 diabetes.

RESULTS

At baseline, approximately 14% of serum squalene was transported by VLDL, 12% by IDL, 40% by LDL and 30% by HDL. The respective values for the noncholesterol sterols were approximately 8, 4, 61 and 26%. The squalene to cholesterol ratios were highest in VLDL and IDL, those of cholestanol, desmosterol and absorption marker sterols were gradually higher, and that of lathosterol lower from VLDL to HDL. Atorvastatin reduced LDL cholesterol by approximately 50%, decreased the absolute cholesterol synthesis and turnover by approximately 40%, but increased significantly the fractional and mass absorption of cholesterol. In accordance with the fecal data, the ratios of the precursor sterols to cholesterol were reduced (-50%), but those of squalene (+48%) and the absorption sterols increased (e.g. 2.6-fold for sitosterol) similarly in each lipoprotein, but progressively from VLDL to HDL.

CONCLUSIONS

Effective lowering of LDL cholesterol by large dose of statin is associated with decreased synthesis and turnover of cholesterol and increased fractional and mass absorption of cholesterol. These changes are detectable by noncholesterol sterols in serum and in different lipoprotein fractions.

Effects of gender, apolipoprotein E phenotype and cholesterol-lowering by plant stanol esters in children: the STRIP study. Special Turku Coronary Risk Factor Intervention Project

AIM

To evaluate the effects of gender, apolipoprotein E phenotype and cholesterol absorption and synthesis (estimated as serum plant sterol and cholesterol precursor sterol concentrations) on the cholesterol-lowering effect of plant stanol esters in children.

METHODS

Eighty-one healthy, normocholesterolaemic 6-y-old children (45 boys) were recruited from the Special Turku Coronary Risk Factor Intervention Project (STRIP), a randomized prospective trial aiming at atherosclerosis prevention in childhood. This placebo-controlled, double-blind, cross-over study comprised two 3-mo study periods and a 6-wk wash-out period. During the study periods, 20 g of the children's daily dietary fat intake was replaced with plant stanol ester margarine or control margarine.

RESULTS

In boys, plant stanol esters reduced serum total and low-density lipoprotein cholesterol concentrations by 6% (0.09 to 0.42 mmol/L) and 9% (0.09 to 0.36 mmol/L), respectively (p < 0.01 for both). In girls, the decreases in concentrations were 4% (0.03 to 0.38 mmol/L) and 6% (0.02 to 0.32 mmol/l) (p < 0.05 for both). The response rate did not differ between the genders. Serum total and low-density lipoprotein cholesterol concentrations decreased by 6% and 8% (p < 0.01 for both), respectively, in both children with the apolipoprotein E 3/4 or 4/4 (apoE4+) phenotype and the apolipoprotein E 2/3 or 3/3 (apoE4-) phenotype. Cholesterol absorption decreased both in the apoE4+ children and in the apoE4- children, but cholesterol synthesis consistently increased in the apoE4+ children only.

CONCLUSION

Plant stanol esters reduce serum cholesterol concentration in healthy children irrespective of their gender or apoE4 phenotype.

LDL cholesterol lowering by bile acid malabsorption during inhibited synthesis and absorption of cholesterol in hypercholesterolemic coronary subjects

BACKGROUND AND AIMS

Recent large-scale trials have consistently documented the fact that a 25-35% reduction in low-density lipoprotein cholesterol (LDL-C) can delay the progression of atherosclerosis. This raises the question as to how much it is possible to reduce serum cholesterol using feasible therapies. The aim of this study was to investigate the cholesterol-lowering efficacy of a triple therapy combining bile acid malabsorption with the inhibition of cholesterol synthesis and absorption.

METHODS AND RESULTS

Eleven consecutive hypercholesterolemic coronary patients from Lipid Clinics on a low-fat, low-cholesterol baseline diet added simvastatin (20 mg/day) for three months, and then dietary plant stanol ester margarine (2.25 g of stanols/day) for eight weeks; finally, cholestyramine 8 g/day was added for another eight weeks. This was a before-after trial, in which the results of each period were compared with baseline and those of the previous period. Serum lipids were quantitated using commercial kits, and serum sterols by means of gas-liquid chromatography. Simvastatin lowered LDL-C by 39% (p < 0.001), and additional stanol ester margarine by a further 13% (p < 0.05). The triple treatment led to 67% reduction from baseline (p < 0.001), with all LDL-C values being < 2.6 mmol/L, and increased high-density lipoprotein cholesterol (HDL-C) by 15% (p < 0.01). It also increased the serum lathosterol/cholesterol ratio (p < 0.01), thus indicating an upregulation of cholesterol synthesis, and increased the serum sitosterol ratio (p < 0.01) despite the simultaneous consumption of plant stanols.

CONCLUSIONS

The massive reduction in LDL and increase in HDL-C obtained using our triple therapy suggests that the combination of stanol ester with only moderate doses of statin and resin makes it possible to control LDL-C levels effectively in hypercholesterolemic subjects.

Baseline intestinal absorption and synthesis of cholesterol regulate its response to hypolipidaemic treatments in coronary patients

Baseline cholesterol metabolism was hypothesized to regulate responses of cholesterol synthesis and absorption, and serum cholesterol lowering to hypolipidaemic treatment. Thus, serum cholesterol and non-cholesterol sterols were measured before and during long-term simvastatin treatment (inhibition of cholesterol synthesis) and subsequent combination of statin with plant stanol ester margarine (inhibition of cholesterol absorption) consumption in subjects with low (n=15) and high (n=15) absorption of cholesterol, defined by respective low and high baseline ratios of serum cholestanol to cholesterol. Cholesterol synthesis (defined by precursors of cholesterol) was markedly reduced by the long-term statin treatment in both groups, but more extensively in the low than high absorption group (P<0.05), yet the respective serum cholesterol reductions were similar. From among the absorption markers, sitosterol and cholestanol ratios were correspondingly increased more in the low than in the high absorption group. Plant stanol ester margarine consumption, combined with chronic statin treatment, further lowered the serum cholesterol level (P<0.001) only in the high absorption group. The sum of cholesterol absorption markers was reduced more (P<0.05) in the high than in the low absorption group, while the non-significant serum cholesterol reduction of the low absorption group was associated with relatively high increase of cholesterol synthesis. Thus, stanol ester margarine combined with chronic simvastatin treatment reduces cholesterol absorption and serum cholesterol more consistently in subjects with high than low baseline absorption of cholesterol. The profile of baseline cholesterol metabolism determines the changes in synthesis and absorption of cholesterol to hypolipidaemic treatments, but affects less differently serum cholesterol level.

Apolipoprotein E phenotype regulates cholesterol absorption in healthy 13-month-old children--The STRIP Study

High serum cholesterol concentration is one of the key risk factors in development of atherosclerosis, which may begin early in life and later progress to symptomatic coronary heart disease. In adults, apoE polymorphism strongly influences cholesterol metabolism, as subjects with apoE 3/4 or 4/4 (collectively called apoE4) phenotype absorb cholesterol effectively and thus also have higher cholesterol absorption-reflecting plant sterol concentrations in serum than subjects with other apoE phenotypes. Because of the inverse correlation of absorption and synthesis of cholesterol, concentrations of cholesterol synthesis-reflecting serum cholesterol precursor sterols are lower in subjects with apoE4 than in subjects with other phenotypes. To analyze whether apoE phenotype affects cholesterol absorption and synthesis in early childhood, we measured serum plant sterol (campesterol and sitosterol) and cholesterol precursor sterol (desmosterol and lathosterol) concentrations in healthy 13-month old children using gas-liquid chromatography. The 36 study children were participants in a randomized prospective trial (the Special Turku Coronary Risk Factor Intervention Project) aimed at decreasing exposure of the children to environmental atherosclerosis risk factors. The 16 apoE4 children had 30% to 50% higher cholesterol-adjusted campesterol and sitosterol concentrations in serum than the 20 apoE 3/3 children (p = 0.002 and p = 0.02, respectively). The concentrations of cholesterol precursor sterols in serum did not differ between the two groups of children. We conclude that the young apoE4 children may absorb cholesterol and plant sterols more effectively than the children with apoE 3/3 phenotype without compensatory reduction in endogenous synthesis of cholesterol.

Cholesterol absorption, synthesis, and fecal output in postmenopausal women with and without coronary artery disease

Hypercholesterolemia is a prominent risk factor for coronary artery disease (CAD), yet cholesterol metabolism has not been evaluated in women with CAD. The objective of this study was to determine the interrelations of CAD, serum squalene and sterols, and cholesterol metabolism with each other in postmenopausal women. For this purpose, we measured serum squalene and sterols and fecal steroids (cholesterol and bile acids) and squalene by gas-liquid chromatography and evaluated cholesterol absorption and synthesis in postmenopausal women with CAD (n=29) and age-matched controls (n=20). On similar dietary lipid intake, the cholesterol absorption efficiency and mean serum cholesterol level were comparable, but the squalene-to-cholesterol ratio was higher in cases than in controls. The presence of CAD was inversely associated with fecal total steroids (logistic regression coefficient beta/SE=-2.11, P=0.04) and cholesterol synthesis (beta/SE=-2.14, P=0.04) and turnover (beta/SE=-2.19, P=0.03) after adjustment for dietary cholesterol, family history of CAD, smoking, low and high density lipoprotein cholesterol, and serum triglyceride levels. A high serum squalene ratio was not related to cholesterol synthesis but was inversely related to fecal squalene excretion, which was lower in cases than in controls. In conclusion, the presence of CAD in postmenopausal women is independently associated with altered cholesterol metabolism, as reflected by low synthesis and inefficient elimination of cholesterol.

Dyslipidemia and a reversible decrease in insulin sensitivity induced by therapy with 13-cis-retinoic acid

BACKGROUND

13-cis-Retinoic acid (Roaccutan) treatment is associated with disturbances in lipid and sometimes also in glucose metabolism. Thus, we investigated whether 13-cis-retinoic acid treatment decreases insulin sensitivity.

METHODS

We studied 11 men [aged 24+/-2 years (mean+/-SEM), body mass index (BMI) 22.1+/-0.9 kg/m(2)] who received Roaccutan treatment for acne for a period averaging 5 months but who were otherwise healthy. The insulin sensitivity of the subjects was measured before, during and 1-3 months after the end of treatment using the euglycaemic hyperinsulinaemic clamp technique.

RESULTS

Treatment with 13-cis-retinoic acid reduced total (59+/-4 vs 55+/-4 micromol/kg/min, p<0.02), oxidative (25+/-1 vs 22+/-2 micromol/kg/min, p<0.05) and non-oxidative (36+/-3 vs 33+/-3 micromol/kg/min, p=0.05) glucose disposal rate, and there was a 4% increase in HbA(1c) (from 5.2+/-0.07 to 5.4+/-0.07%, p<0.02). After treatment cessation these values returned to baseline. 13-cis-Retinoic acid treatment also resulted in increased very low density lipoprotein (VLDL) and low density lipoprotein (LDL) cholesterol, increased VLDL triglyceride, and increased VLDL and LDL phospholipid concentrations.

CONCLUSION

Treatment of acne with 13-cis-retinoic acid reduces insulin sensitivity and induces alterations in lipid metabolism resembling those of the insulin resistance syndrome.

Familial hypercholesterolaemia in Finland: common, rare and mild mutations of the LDL receptor and their clinical consequences. Finnish FH-group

Familial hypercholesterolaemia (FH) is an autosomal co-dominantly inherited condition resulting from mutations of the low-density lipoprotein (LDL) receptor which occur in heterozygous form in approximately one in 500 individuals. Clinically, FH is characterized by 2-3-fold elevation of serum LDL cholesterol levels, accelerated development of atherosclerotic vascular disease, and, if untreated, shortened lifespan. The Finnish population, which represents a genetic isolate, offers exceptional possibilities for genetic-epidemiological studies on FH, as a handful of founder gene mutations account for the majority of FH cases in Finland. This review summarizes data from our FH studies carried out since 1985. We wish to emphasize the continuum of genotype-phenotype relationships, the importance of molecular diagnosis, the detection of novel risk factors of vascular disease, and innovations inhibiting cholesterol absorption for the modern treatment of FH.

Dietary plant sterols alter the serum plant sterol concentration but not the cholesterol precursor sterol concentrations in young children (the STRIP Study). Special Turku Coronary Risk Factor Intervention Project

Plant sterol supplementation reduces serum cholesterol concentration but may increase serum plant sterol concentrations, especially in children. We determined whether natural dietary plant sterols derived mainly from vegetable oil or margarine in early childhood affect serum concentrations of plant sterols (campesterol and sitosterol) and cholesterol precursor sterols (Delta-8 cholestenol, desmosterol, and lathosterol), reflecting endogenous cholesterol synthesis. We measured the serum sterol concentrations using gas liquid chromatography in 20 healthy 13-mo-old intervention children in a randomized, prospective study designed to decrease exposure of the children to known environmental atherosclerosis risk factors and in 20 control children. The diet of the intervention children was rich in plant sterols due to replacement of milk fat with vegetable fat, whereas the diet of the control children contained only small amounts of plant sterols. The intervention children consumed twice as much plant sterols as the control children (P < 0.001). Their serum concentrations of campesterol and sitosterol were 75% and 44% higher, respectively, than those in the control children (P < 0.001 for both), but serum cholesterol precursor sterol concentrations did not differ between the two groups. We conclude that doubling dietary plant sterol intake almost doubles serum plant sterol concentrations in 13-mo-old children, but has no effect on endogenous cholesterol synthesis. Relative intestinal absorption of natural plant sterols from the diet in early childhood is similar to that in adults.

Fate of intravenously administered squalene and plant sterols in human subjects

We have studied metabolism of plant sterols and squalene administered intravenously in the form of lipid emulsion mimicking chylomicrons (CM). The CM-like lipid emulsion was prepared by dissolving squalene in commercially available Intralipid. The emulsion was given as an intravenous bolus injection of 30 ml containing 6.3 mg of cholesterol, 1.9 mg of campesterol, 5.7 mg of sitosterol, 1.6 mg of stigmasterol, 18.1 mg of squalene, and 6 g of triglycerides in six healthy volunteers. Blood samples were drawn from the opposite arm before and serially 2.5 -180 min after the injections. The decay of CM squalene, plant sterols, and triglycerides was monoexponential. The half-life of CM squalene was 74 +/- 8 min, that of campesterol was 37 +/- 5 min (P < 0.01 from squalene), and those of sitosterol, stigmasterol, and triglycerides were 17 +/- 2, 15 +/- 1, and 17 +/- 2 min, respectively (P < 0.01 from squalene and campesterol). The CM squalene concentration still exceeded the baseline level 180 min after injection (P = 0.02), whereas plant sterols and triglycerides returned to the baseline level between 45 and 120 min after injection. The half-lives of squalene and campesterol were positively correlated with their fasting CM concentrations. In addition, VLDL squalene, campesterol, and triglyceride concentrations, VLDL, LDL, and HDL sitosterol concentrations, as well as VLDL and LDL stigmasterol concentrations were increased significantly. Cholesterol concentrations increased in VLDL (P < 0.05), but were unchanged in CM after injection. These data suggest that squalene clearance occurs more slowly than that of plant sterols and triglycerides from CM, and that squalene is more tightly associated with triglyceride-rich lipoproteins than are plant sterols in injected CM-like emulsions.

Acute effect of dietary stanyl ester dose on post-absorptive alpha-tocopherol, beta-carotene, retinol and retinyl palmitate concentrations

Stanyl esters dissolved in margarine inhibit cholesterol absorption, lower sterol absorption in general, and lower serum total cholesterol, LDL-cholesterol and plant sterol levels. To find out whether stanyl esters inhibit absorption of fat-soluble vitamins and beta-carotene in acute experiments, we performed two fat-tolerance tests fortified with vitamins (retinol 0.9-3.7 mg, alpha-tocopherol 70-581 mg), beta-carotene (25-150 mg) and squalene (0.5 g) with and without 1 g of stanyl ester added to the test meal in ten healthy men. The concentrations or areas under the curves (AUC) of cholesterol, triacylglycerols, squalene and alpha-tocopherol, beta-carotene and retinyl palmitate showed typical postprandial changes in serum, chylomicrons, VLDL and VLDL infranatant (intermediate-density lipoproteins, LDL and HDL) over 24 h after the test meal without stanyl esters, and they were not affected by the addition of stanyl esters. The post-absorptive serum campesterol concentration and campesterol : cholesterol were significantly lowered at 6-9 h by stanyl ester supplementation, reflecting reduced sterol absorption efficiency. Changes in vitamin and beta-carotene AUC did not correlate with the given doses. In conclusion, the present study shows that stanyl esters dissolved in margarine do not detectably interfere in a short-term study with the absorption of alpha-tocopherol, beta-carotene or retinol measured by a 24 h oral fat-load test.