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.

The effect of orlistat on the fatty acid composition of serum lipid fractions in obese subjects.

OBJECTIVE: To determine whether there are any changes in the fatty acid composition of serum triglycerides, cholesterol esters, and phospholipids induced by administration of orlistat three times a day compared with placebo as combined with a low-fat hypocaloric diet. METHODS: After 4 weeks of placebo administration, 75 obese subjects were randomized to receive either one capsule (120 mg) of orlistat or placebo three times a day with meals for 1 year in conjunction with a nutritionally balanced hypocaloric diet. Food records were kept to estimate the nutrient intake. The fatty acid composition of serum lipids were analyzed with gas chromatograph. The molar percentage proportions of fatty acids in serum lipid fractions were calculated. RESULTS: Compared with placebo, there was a significant decrease in the proportion of linoleic acid in triglycerides, cholesterol esters, and phospholipids in the orlistat group, even after the effect of the decrease in the linoleic acid dietary intake (percent of energy), weight change, and gender were taken into account. However, the use of orlistat explained only 9% to 13% of the decrease in the proportion of linoleic acid in serum cholesterol esters, triglycerides, and phospholipids. CONCLUSION: The long-term treatment with orlistat may result in a small decline in the proportion of diet-derived fatty acids in serum lipid fractions when used in conjunction with low-fat diet.

Fatty acid composition of serum cholesterol esters, and erythrocyte and platelet membranes as indicators of long-term adherence to fat-modified diets.

Dietary adherence to four different fat-modified diets was examined in 160 subjects by determining the fatty acid composition of serum cholesterol esters (CEs) and erythrocyte (ER) and platelet (PT) membranes in addition to food records. Subjects were randomly assigned to one of the following diet groups: 1) high-sat--35/14:104 (% of energy from total/saturated:monounsaturated:polyunsaturated fatty acids in the actual diet) 2) AHA (American Heart Association) type--32/10:8:8 3) monoene-enriched--34/11:11:5, or 4) low-fat--30/12:8:3 for 6 mo. Decreases in the proportions of palmitic acid in CEs were found in the AHA-type and monoene-enriched-diet groups. An increased proportion of linoleic acid in CEs was found in the AHA-type group. The differences in the proportions of palmitic acid in CEs and linoleic and palmitoleic acids in PTs were significant in the AHA-type and monoene-enriched-diet groups compared with the high-sat group. An increase in alpha-linolenic acid in CEs was an indicator of the use of low erucic acid rapeseed oil, which was the main source of monoenes in the monoene-enriched-diet group.

Postprandial responses of individual fatty acids in subjects homozygous for the threonine- or alanine-encoding allele in codon 54 of the intestinal fatty acid binding protein 2 gene.

BACKGROUND: The affinity of intestinal fatty acid binding protein (FABP) for fatty acids is regulated by the polymorphism at codon 54 of the FABP2 gene (alanine-to-threonine shift). We found earlier that the threonine-encoding allele (Thr54) is associated with an increased postprandial lipemic response. OBJECTIVE: We studied the postprandial responses of individual fatty acids in subjects homozygous for the Thr54 or alanine-encoding allele (Ala54). DESIGN: Oral-fat-loading tests were performed in 8 subjects homozygous for Thr54 and in 7 subjects homozygous for Ala54. RESULTS: The postprandial responses of most of the 14-18-carbon fatty acids in chylomicron and VLDL triacylglycerols were significantly elevated in the Thr54 homozygotes whereas the relative increases in these fatty acids were not significantly different in both groups. The amounts of 20- and 22-carbon polyunsaturated fatty acids started to increase later than the amounts of shorter ones after the test meal, and the differences between the groups were mostly insignificant. The responses of chylomicron fatty acids correlated positively with postprandial insulin response in the Thr54 homozygotes and inversely in the Ala54 homozygotes. VLDL fatty acid responses correlated with fasting triacylglycerol concentrations in the Ala54 homozygotes but not in the Thr54 homozygotes. CONCLUSION: The threonine-encoding allele of the FABP2 gene is associated with an increased postprandial response of 14-18-carbon fatty acids but not with changes in the relative amounts of individual fatty acids introduced to chylomicron triacylglycerols.

Freshwater fish diet affects lipid composition, deformability and aggregation properties of erythrocytes.

The effect of a 12-week diet of freshwater fish on fatty acid composition of the erythrocyte membrane, RBC deformability and artificial aggregation behavior of erythrocytes was studied in 20 healthy subjects. A different quantity of meals containing fish per week (control group, 1.5 and 3.8 fish meals per week) resulted in an increased content of n - 3 polyunsaturated fatty acids. The whole cell deformability of single erythrocytes characterized by a modified micropipette technique (capillary-rigidometer) was significantly increased dependent on fish intake. The parameter of entry time for cell deformability had a negative correlation with the n - 3/n - 6 ratio of fatty acids. No change was observed in MCV and MCHC of erythrocytes after the diet. The artificial aggregation behavior of washed erythrocytes in a suspension medium of low ionic strength and reduced pH was decreased depending on the number of fish meals eaten. The present results suggest that a relatively small shift in the profile of the polyunsaturated fatty acids causes changes in the viscoelastic properties of the erythrocyte membrane and in the artificially-induced aggregation of erythrocytes.

Hemostatic factors and platelet aggregation after a fish-enriched diet or fish oil or docosahexaenoic acid supplementation.

The effects of a fish-enriched diet or dietary supplements consisting of either fish oil or a docosahexaenoic acid-rich oil (DHA-oil) on platelet aggregation and hemostatic factors were studied in healthy male students. After an experimental period of 15 weeks, the levels of tissue factor pathway inhibitor, prothrombin fragment 1+2 and fibrinogen as well as factor VII activity were not changed. Factor X activity was slightly decreased by the fish diet (P < 0.05). Collagen but not ADP-induced maximum platelet aggregation decreased in the fish diet and the fish oil groups (P < 0.05 in both). In the DHA-oil group there was a slight, statistically insignificant, increase of platelet aggregation which correlated significantly with the decrease of plasma triglycerides. Platelet aggregation measured 4 h after a standardized fat meal was lower than in the fasting state and this decrease correlated with the increase of plasma triglycerides. These results show that a fish diet and fish oil, but not DHA-oil, inhibit in vitro platelet aggregation and that hemostatic factors are not affected by moderate n-3 fatty acid supplementation.

Dose responses in platelet fatty acid composition, aggregation and prostanoid metabolism during moderate freshwater fish diet.

The dose responses in platelet fatty acid composition, aggregation and thromboxane production and in plasma prostacyclin level during moderate freshwater fish diet was studied in healthy male students (n = 100). There were four fish diet groups eating 0.9, 1.5, 2.3 or 3.8 fish-containing meals per week for 12 weeks. The meals provided about 0.25, 0.5, 0.6 or 1.1 g n-3 fatty acids per day, respectively. The increase of n-3 at the expense of n-6 fatty acids in total platelet lipids took place already with 1.5 weekly fish meals (0.5 g n-3 fatty acids/d). Most of the observed changes in platelet fatty acids were seen already after 5 weeks. ADP-and collagen-induced platelet aggregation was measured from controls and 1.5 and 3.8 fish meals per week groups. The maximum platelet aggregation values of the group with the highest fish intake were significantly lower than in the controls at the end of dietary period. A tendency towards reduced platelet aggregability was observed also in the group eating 1.5 fish meals per weeks. Thromboxane B2 and 6-keto-PGF1 alpha were determined from controls and two groups with highest fish intake. The highest intake was needed to decrease the thromboxane B2 production of clotted blood and the plasma 6-keto-PGF1 alpha concentration. A positive correlation between ADP-induced aggregation and thromboxane B2 production was found. These results show that platelet characteristics can already be modified with a very moderate freshwater fish intake.

Fish diet, fish oil and docosahexaenoic acid rich oil lower fasting and postprandial plasma lipid levels.

OBJECTIVE: The present study was carried out to clarify the effects of fish diet, fish oil and docosahexaenoic acid (DHA) rich oil on fasting and postprandial lipid levels in healthy male students. DESIGN: The study was a randomized single-blind study with a control and three study groups. SETTING: The study was carried out in the Departments of Physiology and Clinical Nutrition of University of Kuopio. SUBJECTS: Healthy male volunteers were recruited for the study from the university student population. Fifty-nine subjects entered and 55 completed the study. INTERVENTIONS: For 15 weeks the subjects in the fish diet group ate 4.3 +/- 0.5 fish containing meals per week and those in the fish oil and DHA-oil groups ate 4 g oil per day. Fish diet provided 0.38 +/- 0.04 g eicosapentaenoic acid (EPA) and 0.67 +/- 0.09 g DHA, fish oil 1.33 g EPA and 0.95 g DHA and DHA-oil (EPA-free) 1.68 g DHA per day. RESULTS: Fasting plasma triglyceride levels decreased in all test groups in 14 weeks when compared to the control group (P < 0.05). Total plasma cholesterol levels did not change but the HDL2/HDL3-cholesterol ratio increased in all test groups by over 50% (P < 0.05). The postprandial total and chylomicron triglyceride responses, measured as areas under the response curve, were lowered in 15 weeks by the fish diet and fish oil (P < 0.05), the same tendency (P < 0.1) being seen in DHA-oil group. CONCLUSIONS: These results show that both fasting and postprandial triglyceride concentrations can be decreased with moderate intakes of long-chain n-3 fatty acids either from a fish diet or fish oil and that also pure DHA has a hypotriglyceridemic effect.

The impact of the leucine 7 to proline 7 polymorphism of the neuropeptide Y gene on postprandial lipemia and on the response of serum total and lipoprotein lipids to a reduced fat diet.

OBJECTIVE: The aim of the study was to examine the impact of the leucine7 to proline7 (Leu7Pro) polymorphism of the NPY gene on postprandial (PP) lipemia, post-heparin plasma lipoprotein lipase (LPL) and hepatic lipase (HL) activities, and the response of serum lipids to a reduced fat diet. DESIGN AND SUBJECTS: Seven middle-aged obese subjects with Leu7Pro genotype were matched with seven subjects with Leu7Leu genotype for gender, age, apolipoprotein E phenotype and BMI. These 14 subjects participated in the oral 8 h fat tolerance test. Sixty-eight slightly obese middle-aged subjects (10 with the Leu7Pro genotype) had participated in intervention studies and consumed a reduced fat diet for 8 weeks. RESULTS: There were no statistically significant differences in PP areas under the curve of plasma total triglycerides (TG), chylomicron TG, VLDL-TG or insulin between the genotype groups. The TG-to-cholesterol (C) ratio in VLDL was significantly lower in the subjects with Leu7Pro genotype compared to those with the Leu7Leu genotype at time points 30 min and 1 h in the fat tolerance test. Heparin-induced activities of LPL or HL or the response of serum total or LDL-C to the reduced fat diet did not differ between the groups. CONCLUSIONS: The NPY genotype neither affects the magnitude of postprandial lipemia induced by a fat tolerance test nor the response of serum total lipids or lipids in different lipoprotein classes to the reduced fat diet. However, this preliminary study suggests that there might be compositional differences in the lipoprotein particles between the genotype groups that affect postprandial lipid metabolism. SPONSORSHIP: The Council for Health Sciences of the Academy of Finland, Kuopio University Hospital and the National Technology Agency, Finland.

Analysis of diastereomeric DAG naphthylethylurethanes by normal-phase HPLC with on-line electrospray MS.

Normal-phase HPLC resolution of sn-1,2(2,3)- and x-1,3-DAG generated by partial Grignard degradation from natural TAG was carried out with both (R)-(-) and (S)-(+)-1-(1-naphthyl)ethylurethane derivatives. The diastereomeric sn-1,2- and sn-2,3-DAG derivatives were resolved using two Supelcosil LC-Si (5 microm, 25 cm x 4.6 mm i.d.) columns in series and an isocratic elution with 0.37% isopropanol in hexane at a flow rate of 0.7 mL/min. The DAG were detected by UV absorption at 280 nm and were identified by electrospray ionization MS in the positive ion mode following postcolumn addition of chloroform/methanol/30% ammonium hydroxide (75:24.5:0.5, by vol) at 0.6 mL/min. Application of the method to a stereospecific analysis of the molecular species of TAG of rat VLDL showed that the TAG composition of VLDL circulating under basal conditions differs markedly from that of VLDL secreted by the liver during inhibition of serum lipases. The inhibition of serum lipases resulted in a significant proportional decrease in 16:0 and PUFA and an increase in 18:0 and oligoenoic FA in the sn-1-position, whereas the FA compositions in the sn-2- and sn-3-positions were much less affected.

Fatty acid composition of erythrocyte, platelet, and serum lipids in strict vegans.

The fatty acid composition of erythrocytes, platelets, and serum lipids was compared between subjects who had been eating a strict uncooked vegan diet ("living food") for years and omnivore controls. The vegan diet contains equal amounts of fat but more monounsaturated and polyunsaturated and less saturated fatty acids than the mixed diet of the control group. In vegans, the proportion of linoleic acid was greater in all lipid fractions studied. Also, the levels of other n-6 fatty acids were greater, with the exception of arachidonic acid levels, which were similar in most fractions. In erythrocytes, platelets and serum phospholipid fractions, this increase was mainly at the expense of the n-3 fatty acids. The proportions of eicosapentaenoic and docosahexaenoic acid were only 29-36% and 49-52% of those in controls, respectively. In vegans the ratio of n-3 to n-6 fatty acids was only about half that in omnivores. In addition to the lower levels of n-3 fatty acids, the proportions of palmitic and stearic acids were lower in serum cholesteryl esters, triglycerides and free fatty acids of vegans. The proportion of oleic acid was slightly lower only in serum cholesteryl esters and erythrocyte phosphatidylserine. The results show that, in the long term, the vegan diet has little effect on the proportions of oleic and arachidonic acids, whereas the levels of n-3 fatty acids are depressed to very low levels with prolonged consumption of the high linoleic and oleic acid components of this diet.

Incorporation of n-3 fatty acids into plasma lipid fractions, and erythrocyte membranes and platelets during dietary supplementation with fish, fish oil, and docosahexaenoic acid-rich oil among healthy young men.

The effects of n-3 fatty acid supplementation in the form of fresh fish, fish oil, and docosahexaenoic acid (DHA) oil on the fatty acid composition of plasma lipid fractions, and platelets and erythrocyte membranes of young healthy male students were examined. Altogether 59 subjects (aged 19-32 yr, body mass index 16.8-31.3 kg/m2) were randomized into the following diet groups: (i) control group; (ii) fish diet group eating fish meals five times per week [0.38 +/- 0.04 g elcosapentaenoic acid (EPA) and 0.67 +/- 0.09 g DHA per day]; (iii) DHA oil group taking algae-derived DHA oil capsules (1.68 g/d DHA in triglyceride form); and (iv) fish oil group (1.33 g EPA and 0.95 g DHA/d as free fatty acids) for 14 wk. The fatty acid composition of plasma lipids, platelets, and erythrocyte membranes was analyzed by gas chromatography. The subjects kept 4-d food records four times during the study to estimate the intake of nutrients. In the fish diet, in DHA oil, and in fish oil groups, the amounts of n-3 fatty acids increased and those of n-6 fatty acids decreased significantly in plasma lipid fractions and in platelets and erythrocyte membranes. A positive relationship was shown between the total n-3 polyunsaturated fatty acids (PUFA) and EPA and DHA intake and the increase in total n-3 PUFA and EPA and DHA in all lipid fractions analyzed. DHA was preferentially incorporated into phospholipid (PL) and triglyceride (TG) and there was very little uptake in cholesterol ester (CE), while EPA was preferentially incorporated into PL. and CE. The proportion of EPA in plasma lipids and platelets and erythrocyte membranes increased also by DHA supplementation, and the proportion of linoleic acid increased in platelets and erythrocyte membranes in the DHA oil group as well. These results suggest retroconversion of DHA to EPA and that DHA also interferes with linoleic acid metabolism.

Divergent incorporation of dietary trans fatty acids in different serum lipid fractions.

Trans fatty acids may be involved in atherosclerotic vascular diseases. We investigated the incorporation of dietary trans fatty acids and oleic acid into the serum triglycerides (TG), cholesterol esters (CE), and phospholipids (PL). Fourteen healthy female volunteers, aged 23.2+/-3.1 yr (mean+/-SD), body mass index 20.8+/-2.1 kg/m2 participated in this study. All subjects consumed both a trans fatty acid-enriched diet (TRANS diet) and an oleic acid-enriched diet (OLEIC diet) for 4 wk according to a randomized crossover design. Both experimental diet periods were preceded by consumption of a baseline diet for 2 wk which supplied 37% of total energy (E%) as fat: 18 E% from saturated fatty acids (SFA), 12 E% from monounsaturated fatty acids, and 6 E% from polyunsaturated fatty acids. Five E% of the SFA in the baseline diet was replaced by trans fatty acids (18:1t and 18:2c,t + 18:2t,t, where c is cis and t is trans) in the TRANS diet and by oleic acid (18:1n-9) in the OLEIC diet. After the TRANS diet, the proportions of 18:1t and 18:2t increased (P<0.001) in all serum lipid fractions analyzed. The increase of 18:1t in TG and PL (1.80+/-0.28 vs. 5.26+/-1.40; 1.07+/-0.34 vs. 3.39+/-0.76 mol% of total fatty acids, respectively) was markedly higher than that in CE (0.44+/-0.07 vs. 0.92+/-0.26), whereas that of 18:2t was nearly the same in all three fractions. The proportions of palmitic, stearic, arachidonic, and eicosapentaenoic acids in TG, CE, and PL and that of oleic acid in TG and CE were decreased when compared with the baseline value. In contrast, the proportion of palmitoleic acid in TG and PL and that of linoleic acid in PL increased on the TRANS diet. After consumption of the OLEIC diet, the proportion of oleic acid increased in all three lipid fractions analyzed, and the percentage increase was nearly the same in all fractions. In contrast, the proportions of 18:1t in TG and PL and 18:2t in TG and CE decreased when compared with the baseline value. In conclusion, a moderate increase in dietary trans fatty acids resulted in a marked incorporation into serum lipids and decreased the conversion of linoleic acid to its more unsaturated long-chain metabolites. Analysis of 18:1t from serum TG and PL seems to reflect reliably the dietary intake of this fatty acid.

Boreal freshwater fish diet modifies the plasma lipids and prostanoids and membrane fatty acids in man.

The effect of fish diet on 43 healthy male students was studied. They ate a fish-containing meal for 15 weeks on an average of 3.7 times per week. Twenty-one of them voluntarily restricted their lipid intake while the rest ate normally. Controls continued their usual eating habits (19 students). The meals consisted of Finnish freshwater fish (87%) (vendace, pike, perch and rainbow trout) and brackish water fish (13%) (Baltic herring) that provided about 1 g of omega-3 polyunsaturated fatty acids per day (0.25 g eicosapentaenoic acid and 0.55 g docosahexaenoic acid). During the diet, omega-3 fatty acids increased in erythrocyte ghosts and platelets at the expense of omega-6 fatty acids. The concentration of serum cholesterol diminished in those fish consumers who lowered their lipid intake. Apolipoprotein A1 and B were lowered in both fish-consuming groups. Triglyceride levels also showed a tendency to decrease. The formation of thromboxane B2 during incubation of whole blood decreased in both fish-consuming groups. The decrease of plasma 6-keto-PGF1 alpha was not statistically significant, if compared with the controls. The results obtained indicate that a moderate intake of fish-containing meals has some beneficial effects on the plasma lipid and prostanoid metabolism, when coronary heart disease risk factors are considered.

Associations of erythrocyte membrane fatty acids with the concentrations of C-reactive protein, interleukin 1 receptor antagonist and adiponectin in 1373 men.

Dietary and endogenous fatty acids could play a role in low-grade inflammation. In this cross-sectional study the proportions of erythrocyte membrane fatty acids (EMFA) and the concentrations of C-reactive protein (CRP), interleukin-1 receptor antagonist (IL-1Ra) and adiponectin were measured and their confounder-adjusted associations examined in 1373 randomly selected Finnish men aged 45-70 years participating in the population based Metsim study in Eastern Finland. The sum of n-6 EMFAs, without linoleic acid (LA), was positively associated with concentrations of CRP and IL-1Ra (r partial=0.139 and r partial=0.115, P<0.001). These associations were especially strong among lean men (waist circumference <94 cm; r partial=0.156 and r partial=0.189, P<0.001). Total n-3 EMFAs correlated inversely with concentrations of CRP (r partial=-0.098, P<0.001). Palmitoleic acid (16:1n-7) correlated positively with CRP (r partial=0.096, P<0.001). Cis-vaccenic acid (18:1n-7) was associated with high concentrations of adiponectin (r partial=0.139, P<0.001). In conclusion, n-6 EMFAs, except for LA, correlated positively with the inflammatory markers. Palmitoleic acid was associated with CRP, whereas, interestingly, its elongation product, cis-vaccenic acid, associated with anti-inflammatory adiponectin.

Effect of moderate freshwater fish diet on erythrocyte ghost phospholipid fatty acids.

Dose responses over 12 weeks of meals containing fish on erythrocyte phospholipids were studied in male students. In all major glycerophospholipids the proportions of long chain n-3 fatty acids increased at the expense of n-6 fatty acids with 1.5 meals a week containing fish (0.5 g n-3 fatty acids per day). The rates and magnitudes of changes varied for individual phospholipids: faster but quantitatively smaller changes occurred in phosphatidylcholine than in phosphatidylethanolamine and phosphatidylserine. Fish diet and fish oil studies have usually been made using large doses over a short time. Our results show that similar effects might result from smaller amounts given over a longer time.

Effects of moderate freshwater fish diet on lipid metabolism of Finnish students.

The effect of moderate freshwater fish intake on the lipid metabolism was studied in healthy students using a public catering system. In the first trial, male students ate an average of 3.7 fish meals per week (about 1 g of n-3 fatty acids daily) for 15 weeks. The n-3 fatty acids increased in the erythrocyte and platelet membranes at the expense of n-6 fatty acids. Serum triglyceride, apolipoprotein A1 and B levels and platelet thromboxane B2 production decreased. In the dose response study, four groups had been eating fish for 12 weeks. Similar findings were made with the highest dose as in the previous study. In addition, new measurements showed a decrease in the platelet and erythrocyte aggregability. With two lower doses (1.5 and 2.3 diet meals eaten per week), only a tendency to decreased triglyceride level and aggregability was noticed. The results obtained show that already moderate freshwater fish intake modifies, in a long-term, lipid metabolism, supporting the hypothesis of protective effect against cardiovascular diseases.

Fish diet and physical fitness in relation to membrane and serum lipids, prostanoid metabolism and platelet aggregation in female students.

The effects of a 14-week fish diet and exercise programme on lipid metabolism and platelet aggregation in healthy female students (n = 99) were studied. The subjects were divided into four groups: a control group, a fish diet group (3.5 meals containing fish per week, 0.9 g n-3 fatty acids per day), an exercise group (at least three training sessions per week) and a combined fish diet and exercise group. The proportion of n-3 fatty acids increased at the expense of n-6 fatty acids in platelets and erythrocyte ghosts in the fish diet groups. Serum triglyceride concentrations tended to decrease in the fish diet and exercise groups and a significant decrease was found in the combined fish diet and exercise group (13%, P less than 0.05). No significant changes took place in the other serum lipid and apolipoprotein concentrations. Platelet production of thromboxane B2, plasma 6-keto-PGF1 alpha concentrations and adenosine 5'-diphosphate (ADP)-induced platelet aggregation also remained unchanged in all groups during the study. However, an inverse correlation was found between physical fitness (maximal oxygen uptake and maximal exercise intensity) and serum triglycerides, total cholesterol, low density lipoprotein cholesterol and platelet aggregation. This suggests that improved physical fitness is related to beneficial changes in serum lipid concentrations and to a decreased aggregation tendency of platelets. The responses of the female subjects to a fish diet were smaller when compared to earlier studies on male subjects. This suggests that there are sex differences in the efficiency of n-3 fatty acids in modifying lipid metabolism.

Rapid separation of serum lipids for fatty acid analysis by a single aminopropyl column.

A rapid and simple method for separation of serum lipid classes for fatty acid analysis with a single aminopropyl solid phase glass column is described. The recoveries of cholesteryl esters, triglycerides, free fatty acids, and phospholipids were all at least 98%. Coefficients of variation less than 10% were obtained for absolute and relative amounts of most individual fatty acids analyzed after separation of serum lipid classes. This method provides an efficient and convenient tool to follow fatty acid patterns in serum lipid fractions.