Dietary fish oils inhibit early events in the assembly of very low density lipoproteins and target apoB for degradation within the rough endoplasmic reticulum of hamster hepatocytes

Omega-3 PUFA Responders and Non-Responders and the Prevention of Lipid Dysmetabolism and Related Diseases

The long-chain omega-3 polyunsaturated fatty acids (LC-omega-3 PUFAs) eicosapentaenoic acid and docosahexaenoic acid are the most popular dietary supplements recommended for the prevention/management of lipid dysmetabolisms and related diseases. However, remarkable inconsistencies exist among the outcomes of the human intervention studies in this field, which contrast with the impressive homogeneity of positive results of most of the preclinical studies. In the present review, we will firstly examine a series of factors-such as background diet composition, gut microbiota and genetic/epigenetic variants, which may lie beneath these inconsistencies. Moreover, we will discuss the recent advance in the knowledge of possible specific biomarkers (genetic-, epigenetic- and microbiota-related) that are being investigated with the goal to apply them in a personalized supplementation with omega-3 PUFAs. We will also consider the possibility of using already available parameters (Omega-3 index, Omega-6 PUFA/Omega-3 PUFA ratio) able to predict the individual responsiveness to these fatty acids and will discuss the optimal timing for their use. Finally, we will critically examine the results of those human studies that have already adopted the distinction of the subjects into omega-3 PUFA responders and non-responders and will discuss the advantage of using such an approach.

Atorvastatin plus omega-3 fatty acid ethyl ester decreases very-low-density lipoprotein triglyceride production in insulin resistant obese men

AIM

To test the effect of atorvastatin (ATV) and ATV plus ω-3 FAEEs on VLDL-TG metabolism in obese, insulin resistant men.

METHODS

We carried out a 6-week randomized, placebo-controlled study to examine the effect of ATV (40 mg/day) and ATV plus ω-3 FAEEs (4 g/day) on VLDL-TG metabolism in 36 insulin resistant obese men. VLDL-TG kinetics were determined using d5 -glycerol, gas chromatography-mass spectrometry and compartmental modelling.

RESULTS

Compared with the placebo, ATV significantly decreased VLDL-TG concentration (-40%, p < 0.001) by increasing VLDL-TG fractional catabolic rate (FCR) (+47%, p < 0.01). ATV plus ω-3 FAEEs lowered VLDL-TG concentration to a greater degree compared with placebo (-46%, p < 0.001) or ATV monotherapy (-13%, p = 0.04). This was achieved by a reduction in VLDL-TG production rate (PR) compared with placebo (-32%, p = 0.008) or ATV (-20%, p = 0.03) as well as a reciprocal increase in VLDL-TG FCR (+42%, p < 0.05) compared with placebo.

CONCLUSION

In insulin resistant, dyslipidaemic, obese men, ATV improves VLDL-TG metabolism by increasing VLDL-TG FCR. The addition of 4 g/day ω-3 FAEE to statin therapy provides further TG-lowering by lowering VLDL-TG PR.

Docosahexaenoic acid impairs the maturation of very low density lipoproteins in rat hepatic cells

One mechanism of the lipid-lowering effects of the fish oil n-3 fatty acids [e.g., docosahexaenoic acid (DHA)] in cell and animal models is induced hepatic apolipoprotein B100 (apoB) presecretory degradation. This degradation occurs post-endoplasmic reticulum, but whether DHA induces it before or after intracellular VLDL formation remains unanswered. We found in McA-RH7777 rat hepatic cells that DHA and oleic acid (OA) treatments allowed formation of pre-VLDL particles and their transport to the Golgi, but, in contrast to OA, with DHA pre-VLDL particles failed to quantitatively assemble into fully lipidated (mature) VLDL. This failure required lipid peroxidation and was accompanied by the formation of apoB aggregates (known to be degraded by autophagy). Preventing the exit of proteins from the Golgi blocked the aggregation of apoB but did not restore VLDL maturation, indicating that failure to fully lipidate apoB preceded its aggregation. ApoB autophagic degradation did not appear to require an intermediate step of cytosolic aggresome formation. Taken with other examples in the literature, the results of this study suggest that pre-VLDL particles that are competent to escape endoplasmic reticulum quality control mechanisms but fail to mature in the Golgi remain subject to quality control surveillance late in the secretory pathway.

Dietary plant proteins and vegetable oil blends increase adiposity and plasma lipids in Atlantic salmon (Salmo salar L.)

In order to study whether lipid metabolism may be affected by maximum replacement of dietary fish oil and fish meal with vegetable oils (VO) and plant proteins (PP), Atlantic salmon (Salmo salar L.) smolts were fed a control diet containing fish oil and fish meal or one of three plant-based diets through the seawater production phase for 12 months. Diets were formulated to meet all known nutrient requirements. The whole-body lipid storage pattern was measured after 12 months, as well as post-absorptive plasma, VLDL and liver TAG. To further understand the effects on lipid metabolism, expression of genes encoding for proteins involved in VLDL assembly (apoB100), fatty acid uptake (FATP1, cd36, LPL and FABP3, FABP10 and FABP11) were measured in liver and visceral adipose tissue. Maximum dietary VO and PP increased visceral lipid stores, liver TAG, and plasma VLDL and TAG concentrations. Increased plasma TAG correlated with an increased expression of apoB100, indicating increased VLDL assembly in the liver of fish fed the high-plant protein- and VO-based diet. Atlantic salmon fed intermediate replacement levels of VO or PP did not have increased body fat or visceral mass. Overall, the present results demonstrate an interaction between dietary lipids and protein on lipid metabolism, increasing overall adiposity and TAG in the body when fish meal and fish oil are replaced concomitantly at maximised levels of VO and PP.

Eicosapentaenoic acid and docosahexaenoic acid from fish oils: differential associations with lipid responses

Fish-oil supplementation can reduce circulating triacylglycerol (TG) levels and cardiovascular risk. This study aimed to assess independent associations between changes in platelet eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and fasting and postprandial (PP) lipoprotein concentrations and LDL oxidation status, following fish-oil intervention. Fifty-five mildly hypertriacylglycerolaemic (TG 1·5–4·0 mmol/l) men completed a double-blind placebo controlled cross over study, where individuals consumed 6 g fish oil (3 g EPA+DHA) or 6 g olive oil (placebo)/d for two 6-week intervention periods, with a 12-week wash-out period in between. Fish-oil intervention resulted in a significant increase in the platelet phospholipid EPA (+491 %,P<0·001) and DHA (+44 %,P<0·001) content and a significant decrease in the arachidonic acid (-10 %,P<0·001) and γ-linolenic acid (-24 %,P<0·001) levels. A 30 % increase inex vivoLDL oxidation (P<0·001) was observed. In addition, fish oil resulted in a significant decrease in fasting and PP TG levels (P<0·001), PP non-esterified fatty acid (NEFA) levels, and in the percentage LDL as LDL-3 (P=0·040), and an increase in LDL-cholesterol (P=0·027). In multivariate analysis, changes in platelet phospholipid DHA emerged as being independently associated with the rise in LDL-cholesterol, accounting for 16 % of the variability in this outcome measure (P=0·030). In contrast, increases in platelet EPA were independently associated with the reductions in fasting (P=0·046) and PP TG (P=0·023), and PP NEFA (P=0·015), explaining 15–20 % and 25 % of the variability in response respectively. Increases in platelet EPA+DHA were independently and positively associated with the increase in LDL oxidation (P=0·011). EPA and DHA may have differential effects on plasma lipids in mildly hypertriacylglycerolaemic men.

Dietary and Nutraceutical Options for Managing the Hypertriglyceridemic Patient

Scientific evidence continues to accumulate regarding fasting serum triglycerides as an independent risk factor for coronary heart disease. In response, the National Cholesterol Education Program has revised the acceptable level of fasting triglycerides from <200 mg/dL to <150 mg/dL. A significant percentage of Americans suffer from hypertriglyceridemia, and considering the expanding numbers of individuals who are physically inactive, overweight, and suffering from the metabolic syndrome, it is expected that these numbers will continue to rise over the next decade. Fortunately, nutraceutical and lifestyle options have been shown to substantially and consistently reduce this risk factor. This review will focus on management options for the hypertriglyceridemic patient with an emphasis on nicotinic acid, pantethine, fish oils (eicosapentaenoic and docosahexaenoic acids), and modified carbohydrate diets.

Effect of docosahexaenoic acid on tissue targeting and metabolism of plasma lipoproteins

We examined the effect of the docosahexaenoic acid (DHA) content of lipoproteins on their metabolism in vivo by a radioisotope labeling and tracking method. Purified HDL and LDL were labeled with (3)H-cholesteryl oleate tracer. To mimic dietary-related changes in fatty acid composition of lipoproteins, we incorporated lipids acylated with either DHA, arachidonic (AA) or oleic (OA) acid to phosphatidylcholine (didocosahexaenoylphosphatidylcholine (di22:6-PC), diarachidonoylphosphatidylcholine (di20:4-PC) and dioleoylphosphatidylcholine (di18:0-PC), respectively) into the purified particles. The lipids, at the amount added, did not cause detectable alterations in the morphology of the lipoproteins. Levels of radiotracers in blood and in several target tissues such as brain, heart, liver, muscle and adipose were determined at 1.5, 3 and 24h after intravenous injection into C57Bl/6J mice. No statistically significant differences were detected in the tissue distribution of tracers introduced into HDL enriched in DHA, compared to particles enriched with OA. In contrast, we found a significantly higher proportion of radiolabel associated with LDL enriched in DHA in heart, brown adipose and brain tissues. The uptake of labels associated with DHA containing LDL nearly doubled for heart and brown adipose tissues at 1.5 and 3h, and it was 30% higher for brain tissues at 24h. The tissue distribution of labels from the same particles enriched in AA or OA did not show a statistically significant difference from unaltered control lipoproteins. These findings point to the possible role of DHA in the regulation of LDL metabolism and involvement of the lipoproteins in transport of n-3 PUFA to target organs.

Impairment of VLDL secretion by medium-chain fatty acids in chicken primary hepatocytes is affected by the chain length

To determine the effect of the chain length of medium-chain fatty acids (MCFAs) on VLDL secretion, the media of chicken hepatocyte cultures were supplemented with hexanoate (6:0), octanoate (8:0), decanoate (10:0), or dodecanoate (12:0). The supplementation of palmitate (16:0) or bovine serum albumin (BSA) alone in media was used as the positive control or the control, respectively. Palmitate significantly increased intracellular triacylglycerol (TG) accumulation and VLDL-TG, -cholesterol, and -apolipoprotein (apo)B secretion. On the other hand, the addition of hexanoate did not affect these variables relative to control cultures supplemented with BSA alone, whereas octanoate, decanoate, and dodecanoate decreased apoB secretion from the chicken hepatocytes. ApoB secretion from hepatocytes cultured with 1.0 mmol/L MCFA, in particular decanoate and dodecanoate, in the presence of 0.2 mmol/L palmitate was significantly lower than that obtained with 0.2 mmol/L palmitate alone. Decanoate at 0.25-1.0 mmol/L dose dependently reduced apoB mRNA expression compared with the control (BSA alone). The levels of 3-hydroxy-3-metylglutaryl-CoA reductase and apoA-I mRNA were significantly lower in cultures supplemented with hexanoate, octanoate, and decanoate than in cultures with dodecanoate and palmitate. These changes did not correspond to the reduction in VLDL-apoB secretion. We suggest that MCFAs with different chain lengths differentially affect apoB secretion and mRNA expression, with decanoate being the most effective at decreasing VLDL-apoB secretion by regulating apoB mRNA expression at the transcriptional level.

Effect of 18∶1n−9, 20∶5n−3, and 22∶6n−3 on lipid accumulation and secretion by atlantic salmon hepatocytes

We have studied the effects of dietary FA on the accumulation and secretion of [3H]glycerolipids by salmon hepatocytes in culture. Atlantic salmon were fed diets supplemented with either 100% soybean oil (SO) or 100% fish oil (FO), and grew from an initial weight of 113 +/- 5 g to a final weight of 338 +/- 19 g. Hepatocytes were isolated from both dietary groups and incubated with [3H]glycerol in an FA-free medium; a medium supplemented with 0.75 mM of one of three FA-18:1 n-9, 20:5n-3, or 22:6n-3--or a medium supplemented with 0.75 mM of the sulfur-substituted FA analog tetradecylthioacetic acid (TTA), which cannot undergo beta-oxidation. Incubations were allowed to proceed for 1, 2, 6, or 24 h. The rate of the secretion of radioactive glycerolipids with no FA added was 36% lower from hepatocytes isolated from fish fed the FO diet than it was from hepatocytes isolated from fish fed the SO diet. Hepatocytes incubated with 18:1 n-9 secreted more [3H]TAG than when incubated with no FA, whereas hepatocytes incubated with 20:5n-3 or TTA secreted less labeled TAG than when incubated with no FA. This observation was independent of the feeding group. Hepatocytes incubated with 22:6n-3 secreted the highest amounts of total [3H]glycerolipids compared with the other treatments, owing to increased secretion of phospholipids and mono- and diacylglycerols (MDG). In contrast, the same amounts of [3H]TAG were secreted from these cells as from cells incubated in an FA-free medium. The lipid-lowering effect of FO is thus independent of 22:6n-3, showing that 20:5n-3 is the FA that is responsible for the lipid-lowering effect. The ratio of TAG to MDG in lipids secreted from hepatocytes to which 20:5n-3 or TTA had been added was lower than that in lipids secreted from hepatocytes incubated with 18:1 n-9 or 22:6n-3, suggesting that the last step in TAG synthesis was inhibited. Morphometric measurements revealed that hepatocytes incubated with 20:5n-3 accumulated significantly more cellular lipid than cells treated with 18:1n-9, 22:6n-3, TTA, or no treatment. The area occupied by mitochondria was also greater in these cells. The present study shows that dietary FO reduces TAG secretion from salmon hepatocytes and that 20:5n-3 mediates this effect.

Lipid peroxidation and oxidant stress regulate hepatic apolipoprotein B degradation and VLDL production

How omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) lower plasma lipid levels is incompletely understood. We previously showed that marine omega-3 PUFAs (docosahexaenoic acid [DHA] and eicosapentaenoic acid) stimulate a novel pathway, post-ER presecretory proteolysis (PERPP), that degrades apolipoprotein B100 (ApoB100), thereby reducing lipoprotein secretion from liver cells. To identify signals stimulating PERPP, we examined known actions of omega-3 PUFA. In rat hepatoma or primary rodent hepatocytes incubated with omega-3 PUFA, cotreatment with the iron chelator desferrioxamine, an inhibitor of iron-dependent lipid peroxidation, or vitamin E, a lipid antioxidant, suppressed increases in thiobarbituric acid-reactive substances (TBARSs; a measure of lipid peroxidation products) and restored ApoB100 recovery and VLDL secretion. Moreover, omega-6 and nonmarine omega-3 PUFA, also prone to peroxidation, increased ApoB100 degradation via intracellular induction of TBARSs. Even without added fatty acids, degradation of ApoB100 in primary hepatocytes was blocked by desferrioxamine or antioxidant cotreatment. To extend these results in vivo, mice were infused with DHA, which increased hepatic TBARSs and reduced VLDL-ApoB100 secretion. These results establish a novel link between lipid peroxidation and oxidant stress with ApoB100 degradation via PERPP, and may be relevant to the hypolipidemic actions of dietary PUFAs, the basal regulation of ApoB100 secretion, and hyperlipidemias arising from ApoB100 overproduction.

Endoplasmic reticulum-associated degradation: exceptions to the rule

Quality control mechanisms in the endoplasmic reticulum (ER) ensure that misfolded proteins are recognized and targeted for degradation. According to the current view of ER-associated degradation (ERAD), the degradation does not occur in the ER itself but requires the retrotranslocation of the proteins to the cytosol where they are degraded by proteasomes. Although this model appears to be valid for many different proteins a number of exceptions from this rule suggest that additional proteasome-independent ERAD pathways may exist. In this review, we will summarize what is known about these alternative ERAD pathways.

A fish oil diet produces different degrees of suppression of apoB and triglyceride secretion in human apoB transgenic mouse strains

Human apolipoprotein B (apoB) transgenic (HuBTg) mouse strains were used to assess genetic effects on the response to fish oil (FO), a source of n-3 fatty acids. A congenic HuBTg strain of the C57BL/6 (B6) background and six F1 HuBTg strains were fed a FO for 2 weeks. Different responses of plasma lipid levels to FO were observed among these strains. In particular, plasma apoB levels changed minimally in FO-fed male B6 HuBTg mice, but increased markedly ( approximately 40%) in FO-fed male FVB/NJ (FVB) x B6 F1 HuBTg mice. These strain differences were determined mainly by hepatic apoB secretion rates and were likely regulated by posttranscriptional mechanisms. In addition, plasma triglyceride (TG) levels were reduced (14%) in FO-fed B6 mice, but not in FVB x B6 mice. These strain differences were determined mainly by TG secretion rates, but were not due to differences in hepatic lipogenesis. Hepatic mRNA levels of acyl-CoA oxidase, reflective of peroxisomal beta-oxidation rate, were increased in FO-fed B6 but not in FVB x B6 mice, which could account for the difference in TG secretion rates. In summary, differential effects of FO on plasma apoB and TG levels in B6 and FVB x B6 HuBTg mice were associated with strain differences in hepatic apoB and TG secretion and in peroxisomal beta-oxidation.

Regulatory effects of HMG CoA reductase inhibitor and fish oils on apolipoprotein B-100 kinetics in insulin-resistant obese male subjects with dyslipidemia

Hepatic accumulation of lipid substrates perturbs apolipoproteinB-100 (apoB) metabolism in insulin-resistant, obese subjects and may account for increased risk of cardiovascular disease. In a placebo-controlled trial, we examined the independent and combined effects of decreasing cholesterol synthesis with atorvastatin (40 mg/day) and triglyceride synthesis with fish oils (4 g/day) on apoB kinetics. The subjects were 48 viscerally obese, insulin-resistant men with dyslipidemia who were studied in a fasted state. We found that atorvastatin significantly decreased plasma apoB-containing lipoproteins (P < 0.001, main effect) through increases in the fractional catabolic rate (FCR) of VLDL-, IDL-, and LDL-apoB (P < 0.01). Fish oils significantly decreased plasma levels of triglycerides and VLDL-apoB (P < 0.001), decreased the VLDL-apoB secretion rate (P < 0.01), but increased the conversion of VLDL to LDL (P < 0.001). Compared with placebo, combined treatment with atorvastatin and fish oils decreased VLDL-apoB secretion (P < 0.03) and increased the FCR of apoB in each lipoprotein fraction (P < 0.03) and the percent conversion of VLDL to LDL (P < 0.05). None of the treatments altered insulin resistance. In conclusion, in visceral obesity, atorvastatin increased hepatic clearance of all apoB-containing lipoproteins, whereas fish oils decreased hepatic secretion of VLDL-apoB. The differential effects of atorvastatin and fish oils on apoB kinetics support their combined use in correcting defective apoB metabolism in obese, insulin-resistant subjects.

Octanoate inhibits very low-density lipoprotein secretion in primary cultures of chicken hepatocytes

The effects of octanoate, a medium-chain fatty acid, on very low-density lipoprotein (VLDL) secretion in primary cultures of chicken hepatocytes were compared with those of palmitate. Palmitate added to the incubation media at concentrations up to 0.36 mM increased intracellular triacylglycerol (TG) accumulation and VLDL-TG secretion in a concentration-dependent manner, whereas the addition of octanoate alone (0.21-0.6 mM) did not change these parameters. VLDL-TG secretion from hepatocytes cultured in media to which 0.6 or 1.0 mM octanoate had been added in the presence of 0.21 mM palmitate was significantly lower than that obtained under control incubation conditions (0.21 mM palmitate only). The addition of 1.0 mM octanoate to the incubation media with or without 0.21 mM palmitate decreased VLDL apolipoprotein B (apoB) secretion. These results demonstrate that the addition of octanoate to primary cultures of chicken hepatocytes reduces VLDL secretion in respect of both TG and apoB secretion. It is suggested that medium-chain fatty acids are a factor modulating VLDL secretion, which plays a key role in fat deposition in chickens.

Direct evidence for a two-step assembly of ApoB48-containing lipoproteins in the lumen of the smooth endoplasmic reticulum of rabbit enterocytes

The aim of this study was to investigate the types and characteristics of chylomicron precursors in the lumen of the secretory compartment of rabbit enterocytes. Luminal contents were separated into density subfractions in two continuous self-generating gradients of different density profiles. In enterocytes from rabbits fed a low fat diet, newly synthesized and immunodetectable apoB48 was only in the subfraction of density similar to high density lipoprotein (dense particles); the luminal triacylglycerol (TAG) content was low and only in the subfraction of density similar to that of chylomicrons/very low density lipoproteins (light particles). After feeding fat, newly synthesized, and immunodetectable apoB48 was in both dense (phospholipid-rich) and light (TAG-rich) particles. Luminal TAG mass and synthesis increased after fat feeding and was only in light particles. Pulse-chase experiments showed that the luminal-radiolabeled apoB48 lost from the dense particles was recovered in the light particles and the secreted chylomicrons. All of the light particle lipids (mass and newly synthesized) co-immunoprecipitated with apoB48. However, in the dense particles, there was a preferential co-precipitation of the preexisting rather than newly synthesized phospholipid. Assembly of apoB48-containing TAG-enriched lipoproteins is therefore a two-step process. The first step produces dense apoB48 phospholipid-rich particles, which accumulate in the smooth endoplasmic reticulum lumen. In the second step, these dense particles rapidly acquire the bulk of the TAG and additional phospholipid in a single and rapid step.

Impairment of bile salt-dependent lipase secretion in AR4-2J rat pancreatic cells induces its degradation by the proteasome

Bile salt-dependent lipase (BSDL, EC 3.1.1.13) is a lipolytic enzyme normally secreted by the pancreatic acinar cell. Co- and post-translational modifications, such as N- and O-linked glycosylation, regulate the secretion of this enzyme; therefore it was of first importance to determine the behaviour of BSDL under conditions that impaired its secretion. Using AR4-2J pancreatic cells as model, we showed, particularly when BSDL secretion is impaired, that proteasome inhibitors increased the amount of intracellular BSDL, suggesting that the proteasome is involved in the degradation of this protein. This was strengthened by the detection of ubiquitinated BSDL and of degradation product. Our results suggested that both ubiquitination and degradation of the enzyme occurred at the level of the cytosolic side of microsome membranes. ATP hydrolysis appears essential in ubiquitinated BSDL association with membranes and degradation. Furthermore, under normal secretory conditions, we have shown that a fraction of ubiquitinated BSDL is neither O-glycosylated nor N-glycosylated, suggesting that the N-glycosylation-deficient proteasome substrate does not reach the Golgi and could be degraded by the ER-associated degradation machinery. However, another fraction of ubiquitinated BSDL that is deficient in O-glycosylation, carries out endoglycosidase H-insensitive N-linked glycans, meaning that a second system, that detects abnormal BSDL molecules, could also operate at the level of the Golgi compartment. Consequently, it appears that impairment of BSDL secretion consecutive to secretion inhibition or to a deficient glycosylation leads to the proteasome-ubiquitin-dependent degradation of the protein. Therefore, this pathway is part of the quality control involved in BSDL secretion.

ApoE polymorphism and fish oil supplementation in subjects with an atherogenic lipoprotein phenotype

The study assessed the efficacy of fish oil supplementation in counteracting the classic dyslipidemia of the atherogenic lipoprotein phenotype (ALP). In addition, the impact of the common apolipoprotein E (apoE) polymorphism on the fasting and postprandial lipid profile and on responsiveness to the dietary intervention was established. Fifty-five ALP males (aged 34 to 69 years, body mass index 22 to 35 kg/m(2), triglyceride [TG] levels 1.5 to 4.0 mmol/L, high density lipoprotein cholesterol [HDL-C] <1.1 mmol/l, and percent low density lipoprotein [LDL]-3 >40% total LDL) completed a randomized placebo-controlled crossover trial of fish oil (3.0 g eicosapentaenoic acid/docosahexaenoic acid per day) and placebo (olive oil) capsules with the 6-week treatment arms separated by a 12-week washout period. In addition to fasting blood samples, at the end of each intervention arm, a postprandial assessment of lipid metabolism was carried out. Fish oil supplementation resulted in a reduction in fasting TG level of 35% (P<0.001), in postprandial TG response of 26% (TG area under the curve, P<0.001), and in percent LDL-3 of 26% (P<0.05). However, no change in HDL-C levels was evident (P=0.752). ANCOVA showed that baseline HDL-C levels were significantly lower in apoE4 carriers (P=0.035). The apoE genotype also had a striking impact on lipid responses to fish oil intervention. Individuals with an apoE2 allele displayed a marked reduction in postprandial incremental TG response (TG incremental area under the curve, P=0.023) and a trend toward an increase in lipoprotein lipase activity relative to non-E2 carriers. In apoE4 individuals, a significant increase in total cholesterol and a trend toward a reduction in HDL-C relative to the common homozygous E3/E3 profile was evident. Our data demonstrate the efficacy of fish oil fatty acids in counteracting the proatherogenic lipid profile of the ALP but also that the apoE genotype influences responsiveness to this dietary treatment.