Induction of net mass lipid transfer reactions in plasma by wine consumption with dinner

The Alcohol-High-Density Lipoprotein Athero-Protective Axis

Ingestion of alcohol is associated with numerous changes in human energy metabolism, especially that of plasma lipids and lipoproteins. Regular moderate alcohol consumption is associated with reduced atherosclerotic cardiovascular disease (ASCVD), an effect that has been attributed to the concurrent elevations of plasma high-density lipoprotein-cholesterol (HDL-C) concentrations. More recent evidence has accrued against the hypothesis that raising plasma HDL concentrations prevents ASCVD so that other metabolic processes associated with alcohol consumption have been considered. This review explored the roles of other metabolites induced by alcohol consumption-triglyceride-rich lipoproteins, non-esterified free fatty acids, and acetate, the terminal alcohol metabolite in athero-protection: Current evidence suggests that acetate has a key role in athero-protection but additional studies are needed.

Dietary Alcohol and Fat Differentially Affect Plasma Cholesteryl Ester Transfer Activity and Triglycerides in Normo- and Hypertriglyceridemic Subjects

Moderate alcohol consumption is associated with increased plasma high-density lipoprotein (HDL)-cholesterol concentrations and reduced risk for cardiovascular disease. Plasma cholesteryl ester transfer activity (CETA) mediates the exchange of HDL-cholesteryl ester (CE) for the triacylglycerol (TAG) of very-low-density lipoproteins. We compared the effects of oral challenges of Alcohol, saturated fat (SAT), and (Alcohol + SAT) on plasma CETA, cholesterol, nonesterified fatty acids (NEFA), and TAG among normo-triglyceridemic (NTG) and mildly hypertriglyceridemic (HTG) volunteers having a range of plasma TAG concentrations. The major changes were (1) CETA increased more after ingestion of SAT and (Alcohol + SAT) in the HTG group versus the NTG group; (2) after all three challenges, elevation of plasma TAG concentration persisted longer in the HTG versus NTG group. Plasma cholesterol was not affected by the three dietary challenges, while Alcohol increased NEFA more in the HTG group than the NTG group. Plasma TAG best predicted plasma CETA, suggesting that intestinally derived lipoproteins are acceptors of HDL-CE. Unexpectedly, ingestion of (Alcohol + SAT) reduced the strength of the correlation between plasma TAG and CETA, that is the effects of (SAT and Alcohol) on plasma CETA are not synergistic nor additive but rather mutually suppressive. The alcohol-mediated inhibition of CE-transfer to chylomicrons maintains a higher plasma HDL-cholesterol concentration, which is athero-protective, although the suppressive metabolite underlying this correlation could be acetate, the terminal alcohol metabolite, other factors, including CETA inhibitors, are also likely important.

Effects of one single bout of low-intensity exercise on postprandial lipaemia in type 2 diabetic men

Fighting type 2 diabetes and its high risk of CVD, lifestyle intervention with diet and exercise is of uttermost importance. Epidemiological studies strongly suggest an inverse association between increased physical activity, moderate alcohol drinking and the incidence of both type 2 diabetes and CVD. However, alcohol is known to increase postprandial lipaemia, a risk marker of CVD, and exercise to reduce postprandial lipaemia in healthy individuals. The aim of the present study was to investigate how type 2 diabetic men respond, in the postprandial period, to a single exercise session feasible to perform on a daily basis for type 2 diabetic men. The twelve participants ingested a test meal containing 100 g butter, 50 g carbohydrate, together with 40 g alcohol, at each meal test, imitating a social meal situation. Two protocols included exercise sessions with 40 min at 40 % VO2max, one where they exercised 3·5 h after, and another the afternoon before the test meal. One protocol was without any exercise. No significant effect of low-intensity exercise on postprandial lipaemia following a fat-rich meal with alcohol was seen in the middle-aged type 2 diabetic men.

Alcohol

Alcohol consumption affects overall mortality. Light to moderate alcohol consumption reduces the risk of coronary heart disease; epidemiological, physiological and genetic data show a causal relationship. Light to moderate drinking is also associated with a reduced risk of other vascular diseases and probably of type 2 diabetes. Mortality and disease risk increase at higher levels of alcohol consumption. A substantial portion of the benefit of moderate drinking is connected with the alcohol component. However, small differences in effects of various alcoholic beverages on minor risk factors may occur. Proposed protective mechanisms include improved vascular elasticity, anti-thrombotic and anti-inflammatory processes and most importantly, the stimulation of high-density lipoprotein-mediated processes such as reverse cholesterol transport and antioxidative effects.

Effect of moderate alcohol consumption on parameters of reverse cholesterol transport in postmenopausal women

BACKGROUND

Alcohol consumption is associated with increased high-density lipoprotein (HDL) cholesterol levels. One of the main antiatherogenic functions of HDL is reverse cholesterol transport. Three early steps of reverse cholesterol transport are (1) cellular cholesterol efflux, (2) plasma cholesterol esterification (EST), and (3) cholesteryl ester transfer (CET) to apolipoprotein B-containing lipoproteins. Our previous study in healthy middle-aged men showed that moderate alcohol consumption increases cellular cholesterol efflux and EST. This study investigated the effect of moderate alcohol consumption on three early steps of reverse cholesterol transport in postmenopausal women.

METHODS

In a randomized crossover study, 18 postmenopausal women--all apparently healthy, non-smoking, and moderate alcohol drinkers--consumed white wine or white grape juice with evening dinner during 2 successive periods of 3 weeks. During the white wine period, alcohol intake equaled 24 g/day. At the end of each of the two experimental periods, blood samples were collected.

RESULTS

Three weeks of alcohol consumption increased serum HDL cholesterol levels (5.0%; p < 0.05), serum HDL phospholipid levels (5.8%; p < 0.05), and the ex vivo cellular cholesterol efflux capacity of plasma, measured with Fu5AH cells (3.4%; p < 0.05). Plasma EST and CET did not change.

CONCLUSIONS

Moderate alcohol intake increases serum HDL cholesterol level and stimulates cellular cholesterol efflux in postmenopausal women. Moderate alcohol consumption does not seem to affect two other early steps of reverse cholesterol transport at this level of alcohol intake. Our data suggest that the relative protection of moderate alcohol consumption against cardiovascular disease in postmenopausal women may involve the stimulation of reverse cholesterol transport through increased HDL.

Ethanol with a mixed meal decreases the incretin levels early postprandially and increases postprandial lipemia in type 2 diabetic patients

Increased postprandial lipemia is a risk marker of cardiovascular disease (CVD). While moderate alcohol drinking is associated with a reduced risk of CVD in nondiabetic and type 2 diabetic patients, it is also known that alcohol increases postprandial triacylglycerol levels. The incretins, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1), are important hormones from the gut that enhance nutrient-stimulated insulin secretion. Their responses to a moderate alcohol dose in type 2 diabetes have not previously been studied. We sought to determine how alcohol influences postprandial lipid and incretin levels in patients with type 2 diabetes when taken in combination with a fat-rich mixed meal. Eleven patients with type 2 diabetes ingested on 3 separate days in random order 3 different meals containing: 100 g butter alone or 100 g butter in combination with 40 g alcohol and 50 g carbohydrate, or 100 g butter and 120 g carbohydrate. The meal with alcohol and 50 g carbohydrate was isocaloric to that of 120 g carbohydrate. Triacylglycerol levels were measured after separation by ultracentrifugation into a chylomicron-rich fraction with Svedberg flotation unit values (Sf) > 1,000, and a chylomicron-poor fraction with Sf < 1,000. Supplementation of a fat-rich mixed meal with alcohol in type 2 diabetic subjects suppressed GLP-1 early in the postprandial phase and increased the late triacylglycerol responses compared with the 2 other meals. In the chylomicron-rich fraction, both triacylglycerol and cholesterol were increased by alcohol. No significant differences in high-density lipoprotein (HDL)-cholesterol levels were seen. Isocaloric amounts of carbohydrate and alcohol suppressed equally the postprandial free fatty acid levels, but carbohydrate increased the postprandial glucose, GIP, and insulin levels the most. Early in the postprandial phase, alcohol suppresses the incretin responses and increases the late postprandial triacylglycerol levels in type 2 diabetic patients. Whether this reflects an alcohol-induced suppression of the incretin response, which adds to the alcohol-induced impairment of triacylglycerol clearance in type 2 diabetic patients, remains to be elucidated.

Alcohol-mediated enhancement of postprandial lipemia: a contributing factor to an increase in plasma HDL and a decrease in risk of cardiovascular disease

BACKGROUND

Moderate alcohol consumption increases plasma HDL and lowers cardiovascular disease risk while transiently enhancing postprandial lipemia.

OBJECTIVE

We hypothesized that the alcohol-mediated increase in postprandial triacylglycerol-rich lipoproteins (TRLs) and their clearance elevate HDL cholesterol and reverse cholesterol transport.

DESIGN

We determined the effect in normolipidemic humans (n = 14) of postprandial lipemia produced 4 h after a test meal (M) or a test meal + 0.5 g alcohol/kg body wt (M+A) on postprandial changes in plasma lipids and on the balance of cholesterol between TRL and the cholesterol-rich LDL and HDL fractions (CRL) or red blood cells (RBCs) in fresh and incubated plasma or blood.

RESULTS

Postprandial lipemia after the M and M+A test meals caused a 56% and 89% increase in plasma triacylglycerol, a 30% and 74% increase in TRL cholesterol, and a 3.8% and 6.6% decrease in CRL cholesterol, respectively. In vitro reaction of endogenous lecithin:cholesterol acyltransferase (EC 2.3.1.43) and cholesteryl ester transfer proteins via incubation of fasting plasma samples and postprandial M and M+A plasma samples for 16 h increased TRL cholesterol by 22.8% (0.08 mmol/L), 32.6% (0.16 mmol/L), and 45.8% (0.28 mmol/L) in plasma and by 71.1% (0.27 mmol/L), 89.4% (0.45 mmol/L), and 112.5% (0.70 mmol/L) in RBC-enriched blood, respectively. After the in vitro lipolysis of TRL, the elevation of HDL cholesterol in postprandial M+A plasma, but not in postprandial M plasma, was significantly greater than in fasting plasma.

CONCLUSION

The alcohol-mediated increase in postprandial TRL flux and the hepatic removal of postprandial TRL after the acceptance of cholesterol from CRL and cell membranes contribute to increased HDL cholesterol and enhancement of reverse cholesterol transport in humans.

Rates of cholesterol esterification and esterified cholesterol net mass transfer between high-density lipoproteins and apolipoprotein B-containing lipoproteins in Type 1 diabetes

AIMS

Type 1 diabetes is associated with a high incidence of coronary heart disease (CHD) despite paradoxically normal or high high-density lipoprotein (HDL) cholesterol concentrations. Triglyceride (TG) concentrations have been shown to be important determinants of two aspects of HDL metabolism: cholesterol esterification rate and esterified cholesterol (EC) net mass transfer rate between HDL and the apolipoprotein B-containing lipoproteins. In order to try to explain the paradox, we aimed to assess the relationships between plasma TG and these two processes in Type 1 diabetic compared with non-diabetic subjects.

METHODS

Rates of cholesterol esterification and EC net mass transfer between HDL and the apolipoprotein B-containing lipoproteins were assessed by incubating whole plasma at 37 degrees C; intra-assay coefficients of variation were 6% and 30%, respectively.

RESULTS

Ten Type 1 diabetic and 10 non-diabetic subjects, with similar ages, sex distributions, body mass indices and total cholesterol and TG concentrations, were assessed. Apolipoprotein A1, HDL unesterified cholesterol, and HDL phospholipid concentrations were greater in the Type 1 diabetic subjects. There were no significant differences in the rates of cholesterol esterification or EC net mass transfer between the groups. There were strong associations between plasma TG and the rate of cholesterol esterification and between plasma TG and the rate of EC net mass transfer in Type 1 diabetic subjects (r = 0.83, P = 0.0027 and r = 0.88, P = 0.0009, respectively) and in non-diabetic subjects (r = 0.91, P = 0.0002 and r = 0.79, P = 0.0070, respectively). However, the slopes of the associations with plasma TG were significantly steeper in the Type 1 diabetic subjects (analyses of covariance P = 0.0053 and P = 0.0146, respectively).

CONCLUSIONS

Increases in TG may therefore promote more EC enrichment of atherogenic apolipoprotein B-containing lipoproteins in Type 1 diabetes while also promoting more cholesterol esterification, thereby maintaining HDL cholesterol concentrations. This could contribute to the paradox of high CHD incidence despite normal or high HDL cholesterol concentrations in Type 1 diabetes.

Alcohol: lipid metabolism and cardioprotection

The decision to consume alcohol is associated with risks and benefits that vary according to family history (genes) and environment. The risk for coronary heart disease (CHD) is reduced in populations that regularly consume moderate amounts of alcohol. The risk reduction is associated with increased plasma high-density lipoprotein (HDL) cholesterol. Predisposing factors may make some individuals more vulnerable to alcohol-related risks than others. For example, individuals with hypertriglyceridemia and a personal or family history of pancreatitis might consider the benefits of alcohol consumption not worth the health risks. The risks might be more acceptable to someone with a family history of CHD, normal plasma triglyceride levels, low HDL cholesterol, and no personal or family history of addictive behavior or pancreatitis. An understanding of the metabolic effects of alcohol and a careful study of personal and family histories should permit physicians and their patients to make informed decisions about the risks and benefits of alcohol consumption.

The health benefits of wine

Epidemiologic studies from numerous disparate populations reveal that individuals with the habit of daily moderate wine consumption enjoy significant reductions in all-cause and particularly cardiovascular mortality when compared with individuals who abstain or who drink alcohol to excess. Researchers are working to explain this observation in molecular and nutritional terms. Moderate ethanol intake from any type of beverage improves lipoprotein metabolism and lowers cardiovascular mortality risk. The question now is whether wine, particularly red wine with its abundant content of phenolic acids and polyphenols, confers additional health benefits. Discovering the nutritional properties of wine is a challenging task, which requires that the biological actions and bioavailability of the >200 individual phenolic compounds be documented and interpreted within the societal factors that stratify wine consumption and the myriad effects of alcohol alone. Further challenge arises because the health benefits of wine address the prevention of slowly developing diseases for which validated biomarkers are rare. Thus, although the benefits of the polyphenols from fruits and vegetables are increasingly accepted, consensus on wine is developing more slowly. Scientific research has demonstrated that the molecules present in grapes and in wine alter cellular metabolism and signaling, which is consistent mechanistically with reducing arterial disease. Future research must address specific mechanisms both of alcohol and of polyphenolic action and develop biomarkers of their role in disease prevention in individuals.

Moderate alcohol consumption: effects on lipids and cardiovascular disease risk

Light to moderate alcohol consumption is associated with a reduced risk of coronary heart disease, as well as ischaemic stroke and possibly type 2 diabetes. Epidemiological and physiological data are in favour of a causal relationship. Proposed protective mechanisms include the stimulation of HDL-mediated processes such as reverse cholesterol transport and antioxidative effects. More well-controlled studies are needed to provide a complete understanding of the complexity of the underlying physiological mechanisms.

Moderate alcohol consumption and changes in postprandial lipoproteins of premenopausal and postmenopausal women: a diet-controlled, randomized intervention study

Moderate alcohol consumption is associated with a reduced risk of coronary heart disease. Earlier studies in men have shown that moderate alcohol consumption affects lipoprotein metabolism and hemostasis. In this diet-controlled, randomized, crossover trial, we investigated the effect on lipoprotein metabolism of moderate consumption of red wine or red grape juice with evening dinner for 3 weeks in premenopausal women using oral contraceptives and in postmenopausal women. After 3 weeks, blood samples were collected 1 hour before dinner up to 19 hours after starting dinner at 2-hour or 4-hour intervals. Plasma triglyceride concentrations and very low density lipoprotein (VLDL) triglyceride levels peaked 3 hours after dinner with wine in both premenopausal and postmenopausal women. After wine consumption, the overall high-density lipoprotein (HDL) cholesterol level was increased in postmenopausal women (mean increase 0.17 mmol/L, or 12%, p = 0.03), and the plasma low-density lipoprotein (LDL) cholesterol level was reduced in premenopausal women (mean reduction 0.35 mmol/L, or 12%, p = 0.01) as compared with grape juice consumption. The findings suggest that postprandial lipoprotein metabolism after moderate alcohol consumption differs between oral contraceptive-using premenopausal women and postmenopausal women. The response of postmenopausal women to alcohol resembled the response found in earlier studies in men.

Ethanol with a mixed meal increases postprandial triacylglycerol but decreases postprandial non-esterified fatty acid concentrations

Plasma triacylglycerol concentrations increase after the acute ingestion of alcohol (specifically ethanol). However, the effect of ethanol when consumed with a mixed meal has not been well studied. The objective of the present study was to determine the perturbations of lipid metabolism that occur after ingestion of ethanol in combination with a mixed meal of specific fatty acid composition. Blood samples were taken from seven healthy male subjects before and after a mixed meal, with and without ethanol. The specific fatty acid composition of the test meal allowed the fatty acids to be traced into the plasma non-esterified fatty acid pool during the postprandial period. Statistical analysis by repeated measures ANOVA showed significant effects of ethanol. For example, postprandial lipaemia was enhanced after the ethanol test meal compared with the control (P < 0.05), mainly due to increases in triacylglycerol-rich lipoproteins in the flotation range Sf 60-400 (VLDL1) (P < 0.05); those in the range Sf 20-60 (VLDL2) and also Sf > 400 (chylomicrons) were not significantly affected. The later postprandial increase in plasma non-esterified fatty acid concentrations was reduced after the ingestion of ethanol (P < 0.001), but the proportions of palmitoleic acid (a marker of fatty acid content of the test meal) and of linoleic acid (a marker of endogenous lipolysis) were not affected. The results suggest a primary effect of ethanol on the stimulation of secretion of large VLDL particles, which then compete for clearance with chylomicrons by lipoprotein lipase. The results do not support an effect of ethanol on the release of non-esterified fatty acid into the plasma. The suppression of plasma non-esterified fatty acid concentrations during the postprandial period may contribute towards the beneficial effects of moderate ethanol consumption.

Daily moderate alcohol consumption increases serum paraoxonase activity; a diet-controlled, randomised intervention study in middle-aged men

Moderate alcohol consumption is associated with a reduced risk of coronary heart disease. Part of this inverse association may be explained by its effects on HDL. Paraoxonase, an HDL-associated enzyme, has been suggested to protect against LDL oxidation. We examined the effects of moderate consumption of red wine, beer and spirits in comparison with mineral water on paraoxonase activity in serum. In this diet-controlled, randomised, cross-over study 11 healthy middle-aged men consumed each of the beverages with evening dinner for 3 weeks. At the end of each 3 week period, blood samples were collected pre- and postprandially and after an overnight fast. Fasting paraoxonase activity was higher after intake of wine (P<0. 001), beer (P<0.001), and spirits (P<0.001) than after water consumption (149.4+/-111.1, 152.6+/-113.1, 152.8+/-116.5 and 143. 1+/-107.9 U/l serum), but did not differ significantly between the 3 alcoholic beverages. Similar effects were observed pre- and postprandially. The increases in paraoxonase activity were strongly correlated with coincident increases in concentrations of HDL-C and apo A-I (r=0.60, P<0.05 and r=0.70, P<0.05). These data suggest that increased serum paraoxonase may be one of the biological mechanisms underlying the reduced coronary heart disease risk in moderate alcohol consumers

Moderate alcohol consumption: the gentle face of Janus

OBJECTIVES

The regular consumption of alcohol in moderate amounts (defined in North America as up to 2 drinks per day for men and 1 drink per day for females) has been recognized in the last decade as a negative risk factor for atherosclerosis and its clinical sequelae: coronary heart disease (CHD), ischemic stroke, and peripheral vascular disease. Mortality and morbidity attributable to CHD are 40-60% lower in moderate drinkers than among abstainers. Among the mechanisms accounting for these reductions, increased circulating concentrations of HDL-cholesterol and inhibition of blood coagulation appear to be paramount. Additional benefits are, in certain beverages, conferred by the presence of constituents other than alcohol (e.g., flavonoids and hydroxystilbenes), which prevent oxidative damage, free radical formation, and elements of the inflammatory response.

CONCLUSIONS

A number of other diseases appear to be beneficially modulated by moderate alcohol consumption based on epidemiologic surveys and, in some instances, experimental evidence. These include duodenal ulcer, gallstones, enteric infections, rheumatoid arthritis, osteoporosis, and diabetes mellitus (type II). Compared with abstainers, moderate drinkers exhibit improved mental status characterized by decreased stress and depression, lower absenteeism from work, and decreased incidence of dementia (including Alzheimer's disease). Although limits of safe drinking have been conservatively defined, it is regrettable that political considerations are hampering the clinical application of this knowledge and its dissemination to the lay public.

Do known cardiovascular risk factors mediate the effect of alcohol on cardiovascular disease?

The association between alcohol intake and atherosclerotic cardiovascular disease (CVD) in epidemiological studies is consistent and shows some protection from CVD at consumption levels of one to two drinks per day, but a sharp increase in CVD associated with three or more drinks per day. Analyses of potential mediators of effects of alcohol on CVD show that it increases high density lipoprotein (HDL) cholesterol levels and favourably influences thrombotic factors, especially fibrinogen, and also fibrinolytic factors. Some evidence also suggests moderate alcohol consumption may reduce insulin resistance. However, studies also show an adverse effect of alcohol, particularly at higher doses, on blood pressure (leading to hypertension) and directly on the myocardium (leading to arrhythmias and myocardiopathy). Statistical modelling of the alcohol-CVD relationship is consistent in several studies, with a protective pathway via elevated HDL cholesterol and an adverse pathway through elevated blood pressure. Other possible mediators influenced by alcohol have not yet been examined in this type of analysis. The French Paradox has led to speculation that wine is the only protective alcoholic beverage for CVD, or at least that it has a stronger effect. Multiple non-ethanol components of wine have been studied in the laboratory and have been shown to have antioxidant or anticoagulant effects. Although wine does appear more protective in ecological studies, studies within cohorts show similar effects across alcoholic beverages, suggesting confounding in ecological studies by diet, lifestyle, or other variables. The key component of alcoholic beverages thus appears to be ethanol, consistent with the known potent effects of ethanol on HDL cholesterol and thrombotic factors. The upswing in CVD risk with three or more drinks per day is sharp and emphasizes that benefit from alcohol is limited to moderate consumption only. This upswing also cautions against any public health recommendation to drink alcohol, since many persons will not or cannot limit their intake to moderate levels.

Changes in postprandial lipoproteins of low and high density caused by moderate alcohol consumption with dinner

We measured the effects of consumption of moderate amounts of beer, wine or spirits with evening dinner on plasma LDL and HDL levels as well as composition in 11 healthy middle-aged men. Forty grams of alcohol were consumed daily with dinner for a period of 3 weeks. Mineral water was used as a negative control. Dinner was served at 6 pm and blood samples were obtained at 1 h before and 3, 5, 9, and 13 h after the start of the meal. No differences were detected between the effects of the different alcohol-containing beverages. Plasma levels of triglycerides (TG), measured 1 h before dinner were very variable and higher than fasting values (means of 2.2 and 1.5 mM, respectively). Daily consumption of 40 g of alcohol with dinner resulted in increased postprandial plasma TG levels and decreased low density lipoprotein (LDL) cholesterol concentrations. These effects were transient and observed at 11 pm (TG) and 9 pm and 11 pm (LDL). In contrast, high density lipoproteins (HDL) were raised by alcohol intake at all time points analysed. HDL composition was changed by alcohol consumption, resulting in a raised HDL-cholesterol/apo A-I ratio at 5 pm and 9 pm. The observed alcohol-dependent effects on plasma HDL and LDL during the postprandial phase are considered anti-atherogenic and may contribute to the observed protection against coronary heart disease by moderate alcohol consumption.

Alcohol and lipids

Alcoholic fatty liver and hyperlipemia result from the interaction of ethanol and its oxidation products with hepatic lipid metabolism. An early target of ethanol toxicity is mitochondrial fatty acid oxidation. Acetaldehyde and reactive oxygen species have been incriminated in the pathogenesis of the mitochondrial injury. Microsomal changes offset deleterious accumulation of fatty acids, leading to enhanced formation of triacylglycerols, which are partly secreted into the plasma and partly accumulate in the liver. However, this compensatory mechanism fades with progression of the liver injury, whereas the production of toxic metabolites increases, exacerbating the lesions and promoting fibrogenesis. The early presence of these changes confers to the fatty liver a worse prognosis than previously thought. Alcoholic hyperlipemia results primarily from increased hepatic secretion of very-low-density lipoprotein and secondarily from impairment in the removal of triacylglycerol-rich lipoproteins from the plasma. Hyperlipemia tends to disappear because of enhanced lipolytic activity and aggravation of the liver injury. With moderate alcohol consumption, the increase in high-density lipoprotein becomes the predominant feature. Its mechanism is multifactorial (increased hepatic secretion and increased extrahepatic formation as well as decreased removal) and explains part of the enhanced cholesterol transport from tissues to bile. These changes contribute to, but do not fully account for, the effects on atherosclerosis and/or coronary heart disease attributed to moderate drinking.

A controlled trial of the effects of pattern of alcohol intake on serum lipid levels in regular drinkers

To determine whether the effects of drinking pattern (predominantly weekend versus daily drinking) have differential effects on serum lipids, 55 healthy male drinkers were recruited on the basis of a regular alcohol intake, 210-500 ml absolute alcohol/week (approximately 3-6 standard drinks/day), with more than 60% consumed as beer. Fourteen subjects were categorised as predominantly weekend drinkers, while 41 subjects regularly drank on a daily basis. After maintenance of their drinking pattern during a 4-week familiarisation, subjects were randomised to either consume low alcohol beer (0.9%, v/v) only, or to maintain their usual drinking habit consuming full-strength beer (5%, v/v) for the next 4 weeks. They then switched to full-strength or low alcohol beer, respectively, for a further 4 weeks. Their drinking pattern remained constant during the study. In both weekend and daily drinkers, a reduction in alcohol intake (i.e. from 387 ml/week to 88 ml/week for weekend drinkers and from 418 ml/week to 95 ml/week for daily drinkers, respectively, P < 0.001) resulted in a similar 0.12 mmol/l fall in HDL-C (P < 0.01) with a concomitant significant fall in both apolipoproteins A-I and A-II. In daily drinkers total cholesterol fell by 0.28 mmol/l (P < 0.001) and triglyceride by 0.22 mmol/l (P < 0.01) with a reduction in alcohol intake, but no change in LDL-C was seen. In contrast, weekend drinkers total cholesterol was unchanged while triglyceride decreased by 0.26 mmol/l (P < 0.05) and LDL-C increased by 0.25 mmol/l (P < 0.01). Lp(a) increased with a reduction in alcohol intake in both daily (9.1 U/l, P < 0.05) and weekend drinkers (27.6 U/l, P = 0.07). Previous reports of a more atherogenic lipid profile with episodic versus regular daily drinking were not confirmed in this study and potentially favourable effects of alcohol to increase HDL-C and decrease Lp(a) were shown to be independent of drinking pattern in these moderate to heavy drinkers.

Delayed increase in high density lipoprotein-phospholipids after ingestion of a fat load in normolipidemic patients with coronary artery disease

We studied the effect of a single oral fat load, supplemented with retinyl palmitate (RP), on high density lipoprotein (HDL) lipids in six normolipidemic men with coronary artery disease (CAD) and in six age- and lipid-matched controls. All subjects were selected from a study group which underwent the same protocol 2 years earlier. Post-prandial total plasma lipids, plasma RP levels, and HDL lipids were evaluated at 2-h intervals up till 10 h after the meal. In most subjects the post-prandial response of plasma triglyceride (TG) and plasma RP was identical in the first and second tests. Following the fat load, control subjects showed no change in HDL total cholesterol (TC) or HDL cholesteryl ester (CE) and showed an increase in HDL-TG. CAD subjects however showed a decrease in HDL-TC and HDL-CE and an increase in HDL-TG, similar to the increase in control subjects. In control subjects an increase in HDL phospholipid (PL) was apparent between 0 and 8 h after the fat load. By contrast, in CAD subjects the increase in HDL-PL was only found after as long as 6 h. The magnitude of the post-prandial response of HDL-PL measured during the test was significantly lower in the CAD group. The effects of the fat load on HDL free cholesterol (FC) were similar to the changes in HDL-PL. These data support the hypothesis that PL and FC released during the degradation of chylomicrons as surface remnants are taken up by HDL. This process is clearly delayed in normolipidemic CAD subjects compared with controls. The data suggest that differences in the post-prandial response to an oral fat load in normolipidemic CAD patients and control subjects are not confined to the clearance of TG-rich lipoproteins, but also involve a difference in the uptake of chylomicron surface material by HDL.

Resveratrol has no effect on lipoprotein profile and does not prevent peroxidation of serum lipids in normal rats

Trans-resveratrol, one of the antioxidants found in red wine, has been the subject of controversial reports regarding its protective role against cardiovascular diseases. In this study we synthesized trans-resveratrol and injected it to rats (20 and 40 mg/kg body weight, once a day for 21 days, i.p.) to determine its effect on the serum lipid profile. Synthetic trans-resveratrol was an effective antioxidant in vitro against hydroxyl radical (I50 = 33 microM). Resveratrol treatment, however, did not have any effect on either the lipid profile or on Cu+2-dependent formation of thiobarbituric-acid-reactive substances (TBARS) from protein-associated lipids. Since the amount of resveratrol used in these experiments was orders of magnitude higher than the amounts found in wine, these results suggest that if resveratrol has any effect against coronary heart diseases, it is not related to its antioxidant role on lipids or to changes in lipoprotein profile.

Altered transfer of cholesteryl esters and phospholipids in plasma from alcohol abusers

The net mass transfer (NMT) of cholesteryl esters (CEs), triglycerides (TGs), and phospholipids (PLs) between lipoproteins was measured after incubation of fresh plasma for up to 2 hours from 18 male alcohol abusers and 17 male volunteer control subjects. In alcohol abusers the mean value of CE NMT was 3.7 nmol.mL-1.h-1 from apolipoprotein B-containing lipoproteins (apoB-containing lipoproteins) to HDL and in control subjects 8.7 nmol.mL-1.h-1 from HDL to apoB-containing lipoproteins. The NMT of PL was higher in alcohol abusers than in control subjects (35.0 vs 11.6 nmol.mL-1.h-1 from apoB-containing lipoproteins to HDL, respectively), and plasma PL transfer protein (TP) activity was 33% higher (P < .05) in alcohol abusers than in control subjects. The lack of correlation between the NMTs and CETP and PLTP activities suggests that the NMT could more closely reflect the role of lipoprotein properties in reverse cholesterol transport in vivo, whereas in vitro activities reflect the total capacity of transfer but not its direction. The rate of CE NMT from HDL to apoB-containing lipoproteins was dependent on the VLDL TG concentration. Moreover, at low VLDL TG levels, the increased HDL cholesterol concentration in alcohol abusers reversed the direction of CE NMT. This situation could be reconstructed in the plasma of control subjects by adding autologous HDL or VLDL to mimic the lipoprotein profiles of the alcohol abusers. Addition of VLDL enhanced the CE NMT from HDL to apoB-containing lipoproteins, whereas addition of HDL had an opposite effect, and at higher HDL levels, even reversed the direction of CE NMT. In conclusion, the NMT of CE and PL in alcohol abusers differs from that in control subjects. The concentrations of HDL and VLDL seem to be the major determinants of the direction of CE NMT in alcohol abusers.

Higher high density lipoprotein cholesterol associated with moderate alcohol consumption is not related to altered plasma lecithin:cholesterol acyltransferase and lipid transfer protein activity levels

Lecithin:cholesterol acyltransferase (LCAT), cholesteryl ester transfer protein (CETP) and phospholipid transfer protein (PLTP) are important factors involved in HDL metabolism. Altered plasma activity levels of these factors could play a role in the increase in high density lipoprotein (HDL) cholesterol associated with moderate alcohol consumption. We measured plasma LCAT, CETP and PLTP activities with exogenous substrate assays, as well as lipoproteins and HDL lipids in 6 alcohol-abstaining men, 18 matched men who used < or = 1 and 18 men who used > or = 1 alcohol-containing drinks per day. Plasma cholesterol and triglycerides were similar in the three groups. HDL total cholesterol, HDL cholesteryl ester, HDL free cholesterol and HDL triglycerides were higher in the alcohol drinkers compared to the abstainers (all P < 0.05). No differences in plasma LCAT, CETP and PLTP activity levels were observed between the three groups. Analysis of covariance also demonstrated that the use of alcohol was associated with higher HDL cholesterol (P < 0.04), whereas plasma LCAT, CETP and PLTP activity levels were not related to alcohol consumption. Furthermore, HDL cholesteryl ester was positively associated with LCAT activity (P < 0.001), PLTP activity (P < 0.01) and alcohol intake (P < 0.04) and negatively with plasma triglycerides (P < 0.001) and CETP activity (P < 0.03); indicating that alcohol influenced HDL cholesteryl ester independently from these biochemical parameters. The higher HDL cholesterol associated with moderate alcohol consumption is, therefore, unlikely to be caused by and effect on plasma LCAT, CETP or PLTP activity levels.