Effect of polyunsaturated fatty acids of the n-3 and n-6 series on lipid composition and eicosanoid synthesis of platelets and aorta and on immunological induction of atherosclerosis in rabbits

A Life in Food: A Grain of Salt and Some Humble Pie

From my senior school days, I had wanted to pursue a career in food. In quite what capacity I was not too sure. So my starting points were within the fields of animal nutrition before moving for the major part of my career to medical schools to study human nutrition and health. My career scientific achievements lie within the Kuhnian spectrum of normal science, but within that normality, I was always one to challenge conventional wisdom. An academic career is about more than just research. It is about teaching and not just the minutiae of nutrition, but about life and living, about challenges and failures. Reflecting on the experience of that career, my advice to early stage researchers is this: Be patient, determined, and resilient in the very early stages. Hold no fear of change and be courageous in challenging conventional wisdom. Always favor openness and collaboration and always seek to help others. Citation indices are important to your career, but these other avenues that I advise you to follow are what you will eventually be most proud of.

Fatty acids composition of aorta and saphenous vein tissues in patients with coronary artery diseases

Introduction: Considering importance of fatty acids in developing coronary artery disease (CAD) and lack of information about saphenous vein which is commonly used as coronary arterial bypass, in this study we investigated differences in fatty acids composition between saphenous vein and aorta tissues in patients with CAD.

Methods: Biopsy samples of aortic tissues and saphenous veins as well as blood samples were obtained form 42 patients with CAD. Fatty acids composition of the tissues was determined using gas chromatography and also serum lipid profile was evaluated by commercial kits.

Results: Levels of palmitic acid (16:0) were significantly higher in aorta in compared with saphenous (P < 0.001). Also levels of most unsaturated fatty acids (16:1, 18:1n-9, 18:1t, 18:2t, 18:3 n‐9 and 22:3n-3) were statistically higher in saphenous tissue than aorta tissue (P < 0.05). Mean levels of linoleic acid (18:2 n-6) was higher in aorta tissue in comparison with saphenous tissue (P = 0.01). We observed positive correlations between serum levels of LDL-C with elaidic acid and linoleic acid levels in saphenous. Evaluation of aorta tissue fatty acids revealed that palmitoleic acid (16:1) had positive and arachidonic and linoleic acids had negative correlations with serum HDL-C levels.

Conclusion: Our results revealed difference between fatty acids composition of aorta and saphenous vein tissues and existence of correlations between the fatty acids levels with serum lipid profile. The saphenous vein had higher poly-unsaturated fatty acids in compared to aorta tissue and thus this vein is not at risk of atherosclerosis and can be used as coronary arterial bypass.

n-3 fatty acids and lipoproteins: comparison of results from human and animal studies

The impact of n-3 fatty acids (FA) on blood lipoprotein levels has been examined in many studies over the last 15 yr in both animals and humans. Studies in humans first demonstrated the potent triglyceride-lowering effect of n-3 FA, and these were followed up with animal studies to unravel the mechanism of action. This paper reviews the reported effects of n-3 FA on blood lipoproteins in 72 placebo-controlled human trials, at least 2 wk in length and providing 7 or less g of n-3 FA/day. Trials in normolipidemic subjects (triglycerides < 2.0 mM; 177 mg/dL) were compared to those in hypertriglyceridemic patients (triglycerides > or = 2.0 mM). In the healthy subjects, mean triglyceride levels decreased by 25% (P < 0.0001), and total cholesterol (C) levels increased by 2% (P < 0.009) due to the combined increases in low density lipoprotein (LDL)-C (4%, P < 0.02) and high density lipoprotein (HDL)-C (3%, P < 0.008). In the patients, triglyceride levels decreased by 28% (P < 0.0001), LDL-C rose by 7% (P < 0.0001), but neither total C nor HDL-C changed significantly. Although the effect on triglyceride levels is also observed in rats and swine, it is rarely seen in mice, rabbits, monkeys, dogs, and hamsters. Whereas n-3 FA have only a minor impact on lipoprotein C levels in humans, they often markedly lower both total C and HDL-C levels in animals, especially monkeys. These differences are not widely appreciated and must be taken into account when studying the effects of n-3 FA on lipoprotein metabolism.

Fish oil supplementation attenuates myointimal proliferation of the abdominal aorta after balloon injury in diet-induced hypercholesterolemic rabbits

The effects of supplementing with fish oil on the myointimal proliferation of the abdominal aorta after balloon injury were studied in control and in rabbits fed a 1% cholesterol-enriched diet, with and without 10% fish oil supplementation. Twenty-one animals in each group underwent a balloon injury of the abdominal aorta and left common iliac artery after 2 weeks of feeding. The animals remained on their respective diets thereafter. In 7 balloon-injured and 7 sham-operated animals of each group, the abdominal aorta was harvested 3 days later for the analysis of prostanoids, malondialdehyde, superoxide dismutase activity, [3H]thymidine uptake, and cholesterol levels. In the other 7 balloon-injured rabbits of each group, the tissue was harvested 3 weeks later for morphometric study. The fish oil-treated rabbits had the lowest aortic production of thromboxane B2 levels and the highest 6-keto-PGF1 alpha/thromboxane B2 ratios among the three groups after balloon injury. The aortic malondialdehyde levels of the cholesterol-fed rabbits were significantly higher than the other two groups (each P < 0.001) independent of balloon injury. The myointimal proliferation of the abdominal aorta and left common iliac artery in the fish oil-treated rabbits was less severe than in the cholesterol-fed animals (both P < 0.001) and was comparable with the controls. These results suggest that a fish oil supplement changes prostanoid metabolism to a favorable pattern and reduces lipid peroxidation on the abdominal aortic wall, thus attenuating myointimal proliferation after balloon injury in diet-induced hypercholesterolemic rabbits.

Fish oil and the prevention and regression of atherosclerosis

Epidemiological studies in the seventies have put forward that dietary rather than genetic factors are responsible for the lower incidence of ischemic heart disease in Greenland Inuit and have generated a large body of both in vitro and in vivo experimental studies, exploring the putative favorable effects of fish (oil) on atherogenesis and its risk factors. The first part of this report reviews the in vivo animal studies, concentrating on the hypercholesterolemic models and the arterialized vein graft model. In the hypercholesterolemic animal studies, the results are inconclusive as the studies reporting a protective effect are matched by the number of studies showing no effect or an adverse effect. The diversity in species, dose of fish oil, duration of study, type of vessel studied and type of fish oil preparation (content of n-3 fatty acids, unesterified n-3 fatty acids, ethylesters or triglycerides) could all contribute. Furthermore, the definitions and criteria used in the literature to evaluate atherogenesis are diverse and it appears that while one parameter is affected, another is not necessarily modified in the same direction, stressing the importance of extending the analysis of the effects on atherogenesis to more than one parameter. We also believe that it is time to reach a consensus as to which animal model mimics most closely a particular human situation. Only in appropriate models, investigating more than one atherosclerosis variable, can the effects of a putative anti-atherogenic drug or diet be verified. In the veno-arterial autograft model, mimicking the patient after coronary bypass grafting, dietary fish oil has been consistently effective in preventing accelerated graft intima proliferation. It could therefore be of interest to evaluate the effects of fish oil on graft patency in patients after coronary bypass surgery after a period of years. The results from studies on restenosis after percutaneous transluminal angioplasty are also reviewed and it is concluded that the two large scale trials, that are currently underway, might reliably answer the question whether fish oil is effective as a non-pharmacological adjuvants in the prevention of restenosis. Lastly, the studies on the effects of fish oil on the regression of experimental atherosclerosis are reviewed. In view of the small number of studies (i.e., four) investigating the effects of fish oil on the regression of atherosclerosis, it is premature to draw any conclusion, and therefore further experimental work is required.

Development and regression of atherosclerosis in pigs. Effects of n-3 fatty acids, their incorporation into plasma and aortic plaque lipids, and granulocyte function

Fifty-one pigs were fed a low-cholesterol basal diet, to which either 10% (by weight) of lard fat (group INORM, n = 7), 2% cholesterol plus 8% lard fat (group II, n = 33), or 2% cholesterol plus 4% lard fat plus 4% fish oil (group IIIPREV, n = 11) was added. In all pigs, the left anterior descending coronary artery and the abdominal aorta were denuded at 1 month. In the first 24 hours thereafter, three animals in group II and two in group IIIPREV died suddenly. After 3 months, 0.5% bile acids was added to the diet in groups II and IIIPREV. After 8 months the degree of atherosclerosis was evaluated in groups INORM and IIIPREV and in 14 animals from group II (IIIND). At 4 months, one animal from Group II died of pneumonia. For the next 4 months (postinduction period), the remaining 15 animals from group II received the basal diet, to which either 10% lard fat (group IILF, n = 6) or 5% lard fat plus 5% fish oil (group IIFO, n = 9) was added. The hypercholesterolemic diet increased plasma cholesterol from 2 to 9-12 mM after 8 months. Fish oil had no major effects on plasma lipids during both induction and postinduction. Superoxide production by granulocytes in response to the membrane receptor-dependent N-formyl-methionyl-leucyl-phenylalanine (fMLP) gave a higher response in group IIIND than in group INORM. In group IIIPREV, the response to phorbol myristate acetate (PMA) and fMLP was lowered, while in groups IIFO and IILF the responses to PMA and fMLP were not affected. The response to serum-treated zymosan was similar in all groups. Abrasion caused increases in free cholesterol (40%) and phospholipids (46%) in the abdominal aortas of group INORM animals. Hypercholesterolemia increased both free and esterified cholesterol in the entire aorta. Fish oil prevented accumulation of free cholesterol in the nonabraded ascending aorta during induction and further accumulation of free cholesterol and phospholipids in the abdominal aorta during postinduction. In the nonabraded ascending aorta, triglycerides were significantly (almost five times) lower in group IIFO than in group IILF. During both induction and postinduction, a large incorporation of n-3 polyunsaturated fatty acids (up to 20%) occurred in plasma and aortic cholesterol esters and phospholipids of groups IIFO and IIIPREV.(ABSTRACT TRUNCATED AT 400 WORDS)

Aspirin inhibits platelet activity but does not attenuate experimental atherosclerosis

We evaluated the antiatherosclerotic potential of aspirin, a platelet inhibitor, in lipid-fed rabbits (0.3% cholesterol diet). Seventy-five male New Zealand white rabbits were divided into treated or control groups. The treated groups were given aspirin by daily gavage for 12 weeks (1 mg/kg, 10 mg/kg, 30 mg/kg, and 60 mg/kg) and 10 rabbits served as controls. Increased bleeding time was observed in the aspirin-treated groups (average, 58 +/- 10 seconds to 75 +/- 17 seconds; p < 0.001). Only high-dose aspirin (60 mg/kg/day) significantly inhibited platelet aggregation (1.04 +/- 0.15 vs 0.67 +/- 0.14; p < 0.05). Seventeen additional rabbits had aortic endothelial injury produced by a balloon catheter. Eight of them were given aspirin (40 mg/kg/day), and the other nine served as controls. The average percent of surface lesions and lesion thickness of the aorta and pulmonary artery were not significantly reduced by aspirin. These results show that at doses that cause antiplatelet effects, aspirin does not attenuate atherosclerosis.

The influence of fish oil supplementation on plasma lipoproteins and arterial lipids in vervet monkeys with established atherosclerosis

There is controversy about whether supplementing diets with marine fish oil can regress, promote or prevent atherosclerosis. Therefore the effects of an Atlantic pilchard oil (FO) supplement and dietary change were measured in a proven atherosclerosis model. Vervet or African Green monkeys were fed an atherogenic diet (AD) for long enough to ensure progression before treatments started. Matched groups were then treated for 20 months, either by adding FO to the AD (AD/FO), or by changing to a therapeutic diet with FO (TD/FO). Control treatments consisted of supplementing with sunflower oil (SO) instead of FO, so that treatments were AD/SO and TD/SO. The same total polyunsaturates were supplied by the FO and SO and the dose of FO was realistic (2.5% of total energy). A reference group (R) received the TD with no oil supplements. Supplementing with FO did not change the concentrations of total, low or high density lipoprotein cholesterol in plasma. After The AD/FO the intimas of aortas contained more total (p < or = 0.001), free (p < or = 0.05) and esterified (p < or = 0.05) cholesterol, total phospholipid (p < or = 0.01) and sphingomyelin (p < or = 0.05) than after the AD/SO. After FO supplementation eicosapentaenoic acid was significantly higher and arachidonic acid significantly lower in the plasma and aorta intima phosphatidylcholine. None of these changes was anti-atherogenic in terms of atherosclerosis measured in the same individuals (1). Nor did FO increase the efficacy of the TD.

The effects of acute and chronic administration of n-6 and n-3 polyunsaturated fatty acids on ethanol-induced gastric haemorrhage in rats

Female weanling rats in three equal groups (n 12) were given orally by intubation 1 ml micellar solution of taurocholic acid (10 mM) and either arachidonic acid (20:4 n-6), linoleic acid (18:2 n-6) or eicosapentaenoic acid (20:5 n-3) at a concentration of 120 mM. After 1 h the rats were given intragastrically 2 ml absolute ethanol and were killed 1 h later. Rats given oral 20:4 n-6 showed a significant reduction (P less than 0.05) in the extent (%) of gastric mucosal haemorrhage compared with either the rats given 20:5 n-3 or 18:2 n-6 (8.3 (SD 7.3), 23.2 (SD 10.4) and 21.4 (SD 10.4) respectively. In a second experiment, four equal groups (n 12) of female Wistar rats were fed for 5 weeks on either a control diet of standard laboratory rat food, or the same diet enriched with either maize oil or fish oil or butterfat at a level of 100 g/kg. Following a 24 h fast the rats received an intragastric dose of 2 ml ethanol and were killed 1 h later. Examination of the extent (%) of gastric lesion showed a significant reduction (P less than 0.05) with the feeding of either maize oil or fish oil compared with the controls (12.2 (SD 8.2), 15.3 (SD 13.2) and 29.3 (SD 14.0) respectively). The butterfat diet was not significantly different from the control diet (23.8 (SD 8.1)).

Fish oils in the prevention of atherosclerosis

The hypothesis that oils derived from the flesh of fish and marine mammals inhibit the atherosclerotic process is critically reviewed. Populations consuming a diet rich in fish have low rates of coronary heart disease. Dietary fish oil is associated with changes in serum lipids, prostaglandin and leukotriene metabolism, enhanced endothelial function and effects on growth factors released from platelets, leukocytes and endothelial cells. Dietary fish oil supplementation has been associated with inhibition of atherosclerosis experimentally induced by dietary hyperlipidemia and balloon injury. Results of studies of the use of fish oil to inhibit postangioplasty restenosis in human subjects have been inconclusive.

Dose response of fish oil versus safflower oil on graft arteriosclerosis in rabbit heterotopic cardiac allografts

With the advent of cyclosporin A, accelerated coronary arteriosclerosis has become the major impediment to the long-term survival of heart transplant recipients. Due to epidemiologic reports suggesting a salutary effect of fish oil, the dose response of fish oil on graft coronary arteriosclerosis in a rabbit heterotopic cardiac allograft model was assessed using safflower oil as a caloric control. Seven groups of New Zealand White rabbits (n = 10/group) received heterotropic heart transplants from Dutch-Belted donors and were immunosuppressed with low-dose cyclosporin A (7.5 mg/kg/day). Group 1 animals were fed a normal diet and served as control. Group 2, 3, and 4 animals received a daily supplement of low- (0.25 mL/kg/day), medium- (0.75 mL/kg/day), and high- (1.5 mL/kg/day) dose fish oil (116 mg n-3 polyunsaturated fatty acid/mL), respectively. Group 5, 6, and 7 animals were supplemented with equivalent dose of safflower oil (i.e., 0.25, 0.75, and 1.5 mL/kg/day). Oil-supplemented rabbits were pretreated for 3 weeks before transplantation and maintained on the same diet for 6 weeks after operation. The extent of graft coronary arteriosclerosis was quantified using computer-assisted, morphometric planimetry. When the animals were killed, cyclosporin A was associated with elevated plasma total cholesterol and triglyceride levels in the control group. While safflower oil prevented the increase in plasma lipids at all dosages, fish oil ameliorated the cyclosporin-induced increase in total cholesterol only with high doses. Compared to control animals, there was a trend for more graft vessel disease with increasing fish oil dose, as assessed by mean luminal occlusion and intimal thickness. A steeper trend was observed for increasing doses of safflower oil; compared to the high-dose safflower oil group, animals supplemented with low-dose safflower oil had less mean luminal occlusion (16.3% +/- 5.9% versus 41.4% +/- 7.6%, p less than 0.017) and intimal thickness (7.9 +/- 1.9 microns versus 34.0 +/- 13.0 microns, analysis of variance: p = 0.054). Low-dose safflower oil also had a slight, but nonsignificant, beneficial effect on graft vessel disease when compared to control rabbits. The same trends were observed in the degree of histologic rejection (0 = none to 3 = severe) in fish oil- and safflower oil-treated animals. Rejection score correlated weakly but significantly (p = 0.0001) with mean luminal occlusion (r = 0.52) and intimal thickness (r = 0.46). Therefore allograft coronary disease in this model appeared to exhibit an unfavorable, direct-dose response to fish oil and safflower oil, independent of effects on plasma lipids.(ABSTRACT TRUNCATED AT 400 WORDS)

Vascular protection from atherosclerosis: potential of calcium antagonists

Atherosclerosis is the result of complex, interrelated processes, many of which involve calcium. Interventions that interfere with calcium uptake by cells retard lesion development in experimental models of atherosclerosis, underscoring calcium's critical role in atherogenesis. A wide variety of calcium antagonists, including nifedipine, verapamil and diltiazem, have been shown to protect against atherosclerosis in animal models. While these drugs are quite different from each other pharmacologically, they all block intracellular calcium influx. This common property is thus the proposed mechanism for their antiatherosclerotic effects. The effectiveness of the calcium antagonists against the development of atherosclerosis in experimental models may be relevant in the selection of antihypertensive therapy--provided that their protective effects can be demonstrated in future clinical trials as well.

Incorporation and effects of dietary eicosapentaenoate (20:5(n-3)) on plasma and erythrocyte lipids of the marmoset following dietary supplementation with differing levels of linoleic acid

The effect of dietary eicosapentaenoic acid (EPA, 20:5(n-3), as the ethyl ester) on plasma lipid levels and the incorporation of EPA into erythrocyte and plasma lipids were investigated in the marmoset monkey. Marmosets were fed high mixed-fat diets (14.5% total fat) supplemented with or without 0.8% EPA for 30 weeks. Markedly elevated plasma cholesterol (16.4 mmol/l) was induced by an atherogenic-type diet but with EPA supplementation, plasma cholesterol increased to only 6.6 mmol/l. Plasma triacylglycerol levels were not elevated with an atherogenic type diet. Substantial EPA incorporation was evident for plasma phospholipid, triacylglycerol and cholesterol ester fractions. The proportion of docosapentaenoic acid (22:5(n-3)) but not docosahexaenoic acid (22:6(n-3)) was also elevated in these plasma lipid fractions. Greatest incorporation of EPA occurred when it was administered with an atherogenic type diet having a P:M:S (polyunsaturated:monounsaturated:saturated) fatty acid ratio of about 0.2:0.6:1.0 in comparison to the control diet of 1.0:1.0:1.0. Incorporation of EPA and 22:5(n-3)) into erythrocyte phospholipids was also apparent and this was at the expense of linoleic acid (18:2(n-6)). These results in the marmoset highlight both the cholesterol-lowering properties of EPA and the extent of its incorporation into plasma lipids and erythrocyte membrane phospholipids with far greater incorporation occurring when the level of dietary linoleic acid was reduced.

Effect of a high fat/cholesterol diet with or without eicosapentaenoic acid on plasma lipids, lipoproteins and lipid transfer protein activity in the marmoset

Marmosets fed a diet supplemented with 0.2% cholesterol and 10% sheep fat (by weight) developed hypercholesterolemia with a 4-fold increase in plasma cholesterol (4.28 +/- 0.57-16.38 +/- 4.22 mmol/l, mean +/- SD, P less than 0.001). This was due mainly to a 5-fold increase in the intermediate density lipoprotein (IDL) and low density lipoprotein (LDL) fraction (d = 1.006-1.063 g/ml). The proportion of plasma cholesterol in high density lipoproteins (HDL) decreased from 56% to 25% although HDL cholesterol increased from 2.40 +/- 0.42 to 4.09 +/- 0.92 mmol/l (P less than 0.001), and HDL particle radius increased from 5.10 +/- 0.18 nm to 6.06 +/- 0.73 nm (P less than 0.05). Plasma lipid transfer protein (LTP) activity increased 2.5-fold in whole plasma and 2-fold in lipoprotein-deficient plasma. The atherogenic lipoprotein profile was attenuated by adding 0.8% eicosapentaenoic acid (EPA, 20:5 n - 3, as the ethyl ester) to the atherogenic diet. Plasma cholesterol increased only 55% to 6.64 +/- 2.55 mmol/l with only an 80% increase in lipoproteins in the d = 1.006-1.063 g/ml fraction and a more favourable proportion of plasma cholesterol in HDL (44%) than without EPA. LTP activity was reduced to 1.7-fold above control in whole plasma by addition of EPA to the atherogenic diet. There was a positive correlation between plasma cholesterol and LTP activity in whole plasma (r = 0.89, P less than 0.001) and in lipoprotein-deficient plasma (r = 0.67, P less than 0.001). EPA therefore attenuated some of the adverse effects of a 0.2% cholesterol, 10% sheep fat diet on plasma lipids and lipoproteins and induced a less atherogenic profile.

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.

Regression of atherosclerosis in cholesterol-fed rabbits: effects of fish oil and verapamil

Previous studies have shown that either fish oil or verapamil can attenuate the development of atherosclerosis in the lipid-fed rabbit. The present study was designed to evaluate the individual and combined effects of these two interventions on regression. Seventy New Zealand rabbits in seven groups (10 each) were fed a 0.3% cholesterol diet for 10 weeks. Control group C10 was then killed. Control group C20 was fed a 0.3% cholesterol diet and the other five groups were fed a normal diet for an additional 10 weeks. Group F in three treated groups received 2 ml/day of fish oil (Proto-Chol, eicosapentaenoic acid, 180 mg/ml and docosahexaenoic acid, 120 mg/ml) by gavage. Group V received verapamil, 2 g/1,000 ml drinking water, and group FV received both fish oil and verapamil for an additional 10 weeks. Group CF (control for fish oil) received 2 ml/day of water by gavage and group CV (control for verapamil) received water without gavage for an additional 10 weeks. The percent of aortic and pulmonary atherosclerosis was measured by planimetry of sudanophilic lesions. The percent of aortic lesions in the four control groups (C20, C10, CF and CV) was 57 +/- 22, 40 +/- 15, 40 +/- 14 and 33 +/- 25%, respectively. The fish oil or verapamil groups (F, V, FV) showed a significant reduction in aortic lesions: 15 +/- 17%, p less than 0.05; 16 +/- 12%, p less than 0.05; and 26 +/- 24%, p = NS, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of dietary fish oil and butterfat on serum lipids and monocyte and platelet interactions with aortic endothelial cells

We studied effects of dietary lipids on some of the initial events in atherogenesis. Adult swine were fed low fat/low cholesterol diets, then challenged with a high cholesterol (1%, w/w) diet supplemented with 11.5% (w/w) butterfat (BF) or MaxEPA fish oil (FO). Serum lipids and monocyte and platelet adhesion to porcine aortic endothelial cells in vitro were measured during feeding of the low fat diet and at 1, 2, and 5 weeks after the dietary challenge. Total cholesterol increased significantly in animals fed the BF and FO diets, but there was no difference between the groups. Animals fed FO had total cholesterol/high-density lipoprotein cholesterol values twice those fed BF (P less than 0.01). After 2 weeks on the hypercholesterolemic diet, monocyte adhesion to endothelial cells increased in swine fed FO by 123% above those fed a low fat diet, and adhesion values remained elevated (56% above baseline value) after 5 weeks. Monocytes from swine fed BF showed increased adhesion by 87, 53, and 14% above those fed the low fat diet at 1, 2, and 5 weeks respectively. Platelet adhesion to endothelial cells decreased (P less than 0.05) after diet change and remained low. Adhesion of platelets from swine fed FO was significantly lower than those fed BF at 1 and cholesterol profile and greater monocyte adhesion to endothelial cells, conditions which in vivo may promote lesion initiation.

Modification of experimental and clinical atherosclerosis by dietary fish oil

A number of experimental studies have reported that dietary fish oil can attenuate the development of atherosclerosis in cholesterol-fed rats, quails, rabbits, pigs, and monkeys. Epidemiologic studies suggest that dietary fish oil can reduce the development of cardiovascular disease in humans. Data are limited but suggest that laboratory animals, normal volunteers, and patients with hyperlipidemia show similar responses to the consumption of fish oil. The major effect of dietary fish oil on serum lipoproteins is a reduction in plasma triglyceride levels, with inconsistent effects on plasma cholesterol and HDL-cholesterol. Dietary fish oil induces a significant reduction of platelet aggregation associated with a prolonged bleeding time. This antithrombotic effect may be partially related to a decreased thromboxane A2 and to an increased prostacyclin level. Dietary fish oil may also have anti-inflammatory and anti-immunologic effects through an elevation of prostaglandins and a reduction in the level of leukotriene B4. Recent experimental data suggest that either fish oil or verapamil can bring on a regression in atherosclerosis in cholesterol-fed rabbits put on a normal diet; however, there was no additive effect of the combination of these agents. Overall, data suggest that fish oil may have a role in attenuating the development of atherosclerosis.

Dietary intakes and adipose tissue levels of linoleic acid in peptic ulcer disease

Adipose tissue levels of linoleic acid were determined from biopsies of subcutaneous abdominal fat of normal healthy controls (n 40) and from two patient groups with endoscopically evaluated non-ulcer dyspepsia (n 40) or peptic ulcer disease (n 38). The level (g/100 g) of adipose tissue linoleic acid in the normal healthy controls (15.0 (SD 4.1] was significantly (P less than 0.05) greater than that in patients with non-ulcer dyspepsia (12.8 (SD 3.5] and in patients with peptic ulcer disease (11.7 (SD 2.7]. A dietary history revealed a lower intake of linoleic acid and a significantly (P less than 0.05) lower intake of dietary fibre (g/d) for both the non-ulcer dyspepsia (15.9 (SD 6.2] and peptic ulcer disease (15.2 (SD 7.8] patients compared with normal healthy controls (20.2 (SD 11.2]. Adipose tissue linoleic acid tended to increase with indices of increasing socioeconomic status, although the differences between patient and controls were not confounded by socioeconomic status. Patients with dyspepsia reported more foods causing symptoms (onion, fried foods, alcohol, citrus fruits and spices) and more foods giving relief (milk, bread) compared with control orthopaedic patients.