The Effect of N-6 and N-3 Polyunsaturated Fatty Acids on Hemostasis, Blood Lipids and Blood Pressure

Diverging results from studies of marine oil supplementation to western diets initiated the undertaking of a double-blind crossover study, with administration to healthy volunteers for 4 weeks of either 10 g of fish oil or 10 g of vegetable oil. Each oil containing approx. 40% of n-3 and n-6 polyunsaturated fatty acids (PUFA) respectively. During the n-3 PUFA period, systolic blood pressure, plasma total lipids, triglycerides and VLDL concentrations fell significantly whereas plasma antithrombin-III (AT-III) rose. Cutaneous bleeding time increased significantly. In contrast only AT-III rose during the n-6 PUFA feeding, however, more marked than during the n-3 oil period. It is concluded that a n-3 PUFA oil supplement to the western diet exerts an effect that generally is considered as beneficial in terms of the risk of developing cardiovascular diseases. It is in this respect superior to that of n-6 PUFA, stressing the necessity of a more differentiated approach to advices on dietary PUFA enrichment than presently is exerted.

Dose-Response Studies on the Effect of n-3 Polyunsaturated Fatty Acids on Lipids and Haemostasis

We have studied the dose-response effects of dietary supplementation with n-3 polyunsaturated fatty acids (n-3 PUFA’s) on lipids and haemostasis. Ten healthy males were each given 1.3 g,4 g or 9 g of n-3 PUFA’s daily for 6-week periods. Bleeding time, HDL-cholesterol and plasminogen activator inhibitor increased with the dose of n-3 PUFA. Plasma fibrinogen and triglyceride levels were reduced in a dose-dependent fashion.

After ingestion of 1.3 g of n-3 PUFA’s plasma fibrinogen decreased from 9 to 7 μmol/l and HDL-cholesterol increased from 1.2 to 1.3 mmol/l. The bleeding time was prolonged from 5 to 6.5 min while triglyceride levels decreased from 1.2 to 0.9 mmol/l after ingestion of 4 g of n-3 PUFA’s. Dietary supplementation with the highest daily dose (9 g) reduced plasma levels of triglycerides, fibrinogen and von Willebrand factor, while bleeding time, plasminogen activator antigen, plasminogen activator inhibitor and the ratio of HDL-cholesterol to total cholesterol increased.

The Effect of n-3 Fatty Acids on Lipids and Haemostasis in Patients with Type lla and Type IV Hyperlipidaemia

Plasma lipids and haemostasis were investigated in 17 patients with hyperlipidaemia before and after 6 weeks supplementation with 6 g n-3 fatty acids. Nine of the patients had type IIa and 8 had type IV hyperlipidaemia. No effect on plasma cholesterol, LDL- or HDL-cholesterol were seen, but plasma triglycerides decreased after n-3 supplementation. Apolipoprotein B increased and apolipoprotein A1 decreased after the oil supplement. The bleeding time was prolonged, but platelet aggregation was unaltered by n-3 fatty acids. Protein C activity increased in type II a and decreased in type IV after the supplement. Fibrinolysis was markedly depressed while von Willebrand factor antigen was reduced after intake of n-3 fatty acids.

Effect of trans fatty acid intake on abdominal and liver fat deposition and blood lipids: a randomized trial in overweight postmenopausal women

Background:

Intake of industrially produced trans fatty acids (TFAs) is, according to observational studies, associated with an increased risk of cardiovascular disease, but the causal mechanisms have not been fully elucidated. Besides inducing dyslipidemia, TFA intake is suspected to promote abdominal and liver fat deposition.

Objective:

We examined the effect of a high intake of TFA as part of an isocaloric diet on whole-body, abdominal and hepatic fat deposition, and blood lipids in postmenopausal women.

Methods:

In a 16-week double-blind parallel intervention study, 52 healthy overweight postmenopausal women were randomized to receive either partially hydrogenated soybean oil providing 15.7 g day⁻¹ of TFA or a control oil with mainly oleic and palmitic acid. Before and after the intervention, body composition was assessed by dual-energy X-ray absorptiometry, abdominal fat by magnetic resonance (MR) imaging, and liver fat by ¹H MR spectroscopy.

Results:

Compared with the control fat, TFA intake decreased plasma high-density lipoprotein (HDL)-cholesterol by 10%, increased low-density lipoprotein (LDL)-cholesterol by 18% and resulted in an increased LDL/HDL-cholesterol ratio (baseline adjusted mean (95% CI) difference between diet groups 0.41 (0.22; 0.60); P<0.001). TFA tended to increase the body fat (0.46 (−0.20; 1.17) kg; P=0.16) and waist circumference (1.1 (−0.1; 2.4) cm; P=0.08) more than the control fat, whereas neither abdominal nor liver fat deposition was affected by TFA.

Conclusion:

The adverse effect of dietary TFA on cardiovascular disease risk involves induction of dyslipidemia, and perhaps body fat, whereas weight gain-independent accumulation of ectopic fat could not be identified as a contributory factor during short-term intake.

Bioavailability of marine n-3 fatty acid formulations

The use of marine n-3 polyunsaturated fatty acids (n-3 PUFA) as supplements has prompted the development of concentrated formulations to overcome compliance problems. The present study compares three concentrated preparations - ethyl esters, free fatty acids and re-esterified triglycerides - with placebo oil in a double-blinded design, and with fish body oil and cod liver oil in single-blinded arms. Seventy-two volunteers were given approximately 3.3g of eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) daily for 2 weeks. Increases in absolute amounts of EPA and DHA in fasting serum triglycerides, cholesterol esters and phospholipids were examined. Bioavailability of EPA+DHA from re-esterified triglycerides was superior (124%) compared with natural fish oil, whereas the bioavailability from ethyl esters was inferior (73%). Free fatty acid bioavailability (91%) did not differ significantly from natural triglycerides. The stereochemistry of fatty acid in acylglycerols did not influence the bioavailability of EPA and DHA.

Hemostatic factors and renin in Greenland Eskimos on a high eicosapentaenoic acid intake. Results of the Fifth UmanaK Expedition

The Fifth UmanaK expedition compared the fatty acid composition of platelets, bleeding times before and after ingestion of acetylsalicylic acid, 24-hour urinary tetranorprostanedioate, creatinine and Na output, as well as plasma renin, serum electrolytes and antithrombin III in 20 Greenland Eskimos and 20 Danes. The results indicate that the prostaglandin production was not inhibited in the Eskimos, and that the antiaggregatory prostanoids predominate in Eskimos compared to Danes. Although blood pressure and 24-hour urinary Na output were similar, the plasma renin level was significantly higher in the Eskimos on a high eicosapentaenoic acid intake.

Personal reflections on the incidence of ischaemic heart disease in Oslo during the Second World War

The dietary changes in Norway and especially in Oslo during the Second World War, with reduced fat intake and increased consumption of fish and fish products, was paralleled by a reduced incidence of and mortality from IHD. This was probably caused to a high degree by reduced platelet aggregability leading to a reduced tendency to thrombosis. We suggest that the mechanism behind this reduction was a changed balance between pro- and anti-aggregatory prostaglandins towards the anti-aggregatory side, caused by eicosapentaenoic acid from fish lipids. Furthermore, hypocholesterolaemia due to reduced fat intake and increased consumption of polyunsaturated fatty acids certainly contributed to this effect by reducing platelet aggregability.

Protein C in acute renal failure

In 16 patients with acute renal failure we studied protein C activity, both coagulant and amidolytic, as well as protein C antigen level. Protein C coagulant activity was markedly decreased in acute renal failure. Furthermore, changes in kidney function were paralleled by alterations in protein C coagulant activity. The amidolytic activity and antigen level of protein C were normal in most cases, and the changes observed in a few patients seem clearly related to changes in liver function. This defective protein C could contribute to the thrombotic tendency reported in patients with acute renal failure.

The composition of food consumed by Greenland Eskimos

Food specimens have been collected, by means of the double-portion technique, from Greenland Eskimo hunters and their wives, in all seven persons, on seven consecutive days. Their food was found to contain more protein and less carbohydrates than average Danish food and an almost equal amount of fat. Compared with Danish food, the fatty acid pattern of the consumed lipids--essentially of mammalian marine origin--showed a higher content of long chain polyunsaturated fatty acids (especially C20:5) and lower contents of linoleic and linolenic acids. However, the sum of the polyunsaturated fatty acids was smaller than in Danish food. Using Keys' formula, describing the serum cholesterol level as a function of the nutritional fatty acids, the essentially lower serum choelsterol level found in Greenland Eskimos was not explained by our findings. It is suggested instead to be a special metabolic effect of the long chain polyunsaturated fatty acids from marine mammals. There might be a similar effect on the plasma triglyceride and very low density lipoprotein concentrations, explaining the much lower plasma concentrations of these components in Eskimos than in Western populations. Our findings might have an essential bearing on the difference in morbidity from coronary atherosclerotic disease between these populations.

Fast food: unfriendly and unhealthy

Although nutrition experts might be able to navigate the menus of fast-food restaurant chains, and based on the nutritional information, compose apparently 'healthy' meals, there are still many reasons why frequent fast-food consumption at most chains is unhealthy and contributes to weight gain, obesity, type 2 diabetes and coronary artery disease. Fast food generally has a high-energy density, which, together with large portion sizes, induces over consumption of calories. In addition, we have found it to be a myth that the typical fast-food meal is the same worldwide. Chemical analyses of 74 samples of fast-food menus consisting of French fries and fried chicken (nuggets/hot wings) bought in McDonalds and KFC outlets in 35 countries in 2005-2006 showed that the total fat content of the same menu varies from 41 to 65 g at McDonalds and from 42 to 74 g at KFC. In addition, fast food from major chains in most countries still contains unacceptably high levels of industrially produced trans-fatty acids (IP-TFA). IP-TFA have powerful biological effects and may contribute to increased weight gain, abdominal obesity, type 2 diabetes and coronary artery disease. The food quality and portion size need to be improved before it is safe to eat frequently at most fast-food chains.

Intake of ruminant trans fatty acids in the Danish population aged 1–80 years

OBJECTIVE

To estimate the intake of ruminant trans fatty acids (TFA) in the Danish population aged 1-80 years.

DESIGN

Descriptive study.

SUBJECTS

A sex- and age-stratified random sample drawn from the Danish Civil Registration System. A total of 3098 participants (51% female) aged 1-80 years were included. The participation was 66%. DIETARY INFORMATION: A 7-day dietary record.

RESULTS

The estimated median intake of ruminant TFA was 1.4 g/day with the 80% central range being from 0.9 to 2.1 among children aged 1-6 years and 1.6 g/day (1.0-2.4) among children aged 7-14 years. The median TFA intake was 1.8 g/day (0.9-2.9) among adults aged 15-29 years and among adults aged 30-80 years. The intake expressed as percentage of energy intake was 0.8, 0.6, 0.7, and 0.7, respectively. Dairy products were the main source of ruminant TFA.

CONCLUSIONS

The median intake of ruminant TFA in the Danish population aged 1-80 years is estimated to be 1.7 g/day (0.9-2.7), corresponding to 0.7% of energy intake (0.5-1.0), with dairy products being the main source of ruminant TFA.

SPONSORSHIP

The Danish Heart Foundation (Grants 02-2-9-8-22010 and 03-2-9-4-22087) and the Female Researchers in Joint Action (FREJA) programme from the Danish Medical Research Council.

No effect of taurine on platelet aggregation in men with a predisposition to type 2 diabetes mellitus

Any diet therapy that potentially could affect platelet function would also influence the initiation of atherosclerotic plaque formation which is an important complication of diabetes mellitus eventually resulting in myocardial infarction and stroke. Blood platelets are rich in taurine, and it has been shown that taurine inhibits platelet aggregation in healthy subjects. The purpose was to examine the effect of taurine supplementation on platelet aggregation in high-risk subjects with a positive family history of T2DM. Twenty healthy men were included in a double-blinded, randomized, crossover study, receiving daily supplementation of 1.5 g taurine or placebo for two 8-week periods. Subjects were overweight and first-degree relatives of T2DM patients. At the end of each treatment, fasting blood samples for assessment of platelet aggregation was drawn. Platelet aggregation was induced by ADP. Plasma taurine concentration was significantly greater after taurine intervention compared to placebo (131.4+/-61.7 vs. 38.9+/-6.7 micromol/l, P<0.0001). There was no difference in the threshold level for complete platelet aggregation induced by ADP in vivo between placebo and taurine intervention (placebo 3.86+/-2.21 vs. taurine 3.86+/-3.25 micromol/l). Supplementation with 1.5 g of taurine for 8 weeks had no effect on platelet aggregation in overweight prediabetic men.

Effects of trans- and n-3 unsaturated fatty acids on cardiovascular risk markers in healthy males. An 8 weeks dietary intervention study

BACKGROUND

Studies of long-term intake of industrially produced trans fatty acids (TFA) and n-3 polyunsaturated fatty acids (PUFA) suggest opposite effects on cardiovascular disease risk. Common mechanisms of action are probable.

OBJECTIVE

To examine the effects on cardiovascular risk markers of dietary enrichment with TFA or n-3 PUFA.

DESIGN

Randomized, double-blind, parallel intervention trial.

SETTING

Department of Human Nutrition, The Royal Veterinary and Agricultural University.

SUBJECTS

In all, 87 healthy males included, 79 completed.

INTERVENTION

Subjects were randomly assigned to 8 weeks of a daily intake of 33 g of experimental fats from either partially hydrogenated soy oil containing 20 g of TFA, 12 g of fish oil with approximately 4 g of n-3 PUFA and 21 g of control fat, or 33 g of control fat. The experimental fats were incorporated into bakery products. Plasma lipids, blood pressure, heart rate variability (HRV), arterial dilatory capacity, compliance, and distensibility were recorded before and after intervention and at follow-up 12 weeks after the intervention.

RESULTS

High-density lipoprotein cholesterol (HDL-C) decreased in the TFA group and triglycerides and mean arterial blood pressure decreased in the n-3 PUFA group compared to the control group. HRV, arterial dilatory capacity, compliance, and distensibility were unchanged.

CONCLUSION

The results indicate that the association between coronary heart disease risk and intake of TFA and n-3 PUFA relates only modestly to changes in traditional risk markers.

SPONSORSHIP

Danish Medical Research Council (Grant no. 22-01-0390), Center of Advanced Food Research (Copenhagen, Denmark) (Grant no. KVL-R-2001-107), the Danish Heart Association (Grant no. 99-2-3-45-22748), Novozymes (Bagsvaerd, Denmark), Aarhus Olie (Aarhus, Denmark), and from private sources. The experimental fats were provided by Pronova Biocare (Aalesund, Norway) and Aarhus Olie (Aarhus, Denmark).

Effect of taurine treatment on insulin secretion and action, and on serum lipid levels in overweight men with a genetic predisposition for type II diabetes mellitus

BACKGROUND

The prevalence of type 2 diabetes mellitus (T2DM) is increasing with an epidemic growth rate. Animal studies with taurine supplementation have shown increased insulin secretion and action, suggesting that taurine supplementation may have a potential to prevent T2DM.

OBJECTIVE

To assess the effect of taurine treatment on insulin secretion and action, and on plasma lipid levels in overweight men with a positive history of T2DM.

DESIGN

20 nondiabetic subjects were included in a double-blinded, randomized, crossover study, receiving a daily supplementation of 1.5 g taurine or placebo for two periods of 8 weeks. The subjects were overweight first-degree relatives of T2DM patients. An intravenous glucose tolerance test (IVGTT) was used to measure first-phase insulin secretory response, and a euglycemic hyperinsulinemic clamp was used to determine peripheral insulin action.

RESULTS

Mean plasma taurine concentration was 39 +/- 7 (s.d.) micromol/l after placebo and 131 +/- 62 micromol/l after taurine intervention (P < 0.0001). There was no significant difference after taurine intervention compared to placebo in incremental insulin response (Insincr.) neither during the IVGTT, nor in insulin-stimulated glucose disposal during the clamp. Insulin secretion, adjusted for insulin sensitivity, was also unchanged. There was no significant effect of taurine supplementation on blood lipid levels as well.

CONCLUSION

Daily supplementation with 1.5 g taurine for 8 weeks had no effect on insulin secretion or sensitivity, or on blood lipid levels. These findings in persons with an increased risk of T2DM are in contrast to those from animal studies, and do not support the assumption that dietary supplementation with taurine can be used to prevent the development of T2DM.

N-3 fatty acids and cardiac function after myocardial infarction in Denmark

In order to evaluate the effect of marine n-3 polyunsaturated fatty acids (n-3 PUFA) on systolic left ventricular function, we investigated the effect of daily supplementation with 5.2 g n-3 PUFA for 12 weeks in 55 patients with a recent myocardial infarction in a double blind placebo-controlled design. Left ventricular function was assessed by transthoracal echo-cardiography and plasma concentration of proANP and N-terminal proANP. No effect of n-3 PUFA could be demonstrated on these indices of left ventricular function.

[The importance of trans-fatty acids for health. Update 2001]

The contribution of a high intake of trans fatty acids to the risk of coronary heart disease has gained further support since the report from the Danish Nutrition Council in 1994. Any deleterious effect of trans fatty acids on the human fetus and newborn infants has not been negated. Their possible effect on cancer is still unsettled. The daily intake of trans fatty acids from partially hydrogenated oils in Denmark was in 1994 about 2.5 grams (recommended 2.0 grams) and has since decreased, mainly due to a reduction of the trans fatty acid content in Danish margarines. Population groups with eating habits that include frequent intake of French fries, micro-oven popcorn, chocolate bars, fast food, etc., may consume trans fatty acids in amounts far exceeding the recommended maximum levels. The Danish Nutrition Council recommends that the addition of industrially produced trans fatty acids to food stuffs ceases before 2005 and until then that declaration of the content in foodstuffs becomes mandatory.

[Homocysteine and cardiovascular disease]

Treatment of highly increased plasma concentrations of homocysteine in patients with rare inborn errors of metabolism reduces their risk of vascular thromboses. Many, but not all, epidemiological studies show a relation between slightly increased plasma homocysteine and ischaemic cardiovascular disease. Folic acid supplements reduce plasma homocysteine. The results of ongoing studies of the effect of folic acid and other vitamins on the incidence of cardiovascular disease are expected within the next five years. The available data support the measurement of plasma homocysteine as a part of screening of patients with early and/or frequent vascular thromboses and a disparity between established risk factors and symptoms. Plasma homocysteine > 30 mumol/l in such patients should prompt a search for an inborn error of metabolism.

Marine n-3 fatty acids, wine intake, and heart rate variability in patients referred for coronary angiography

BACKGROUND

Dietary n-3 polyunsaturated fatty acids (PUFAs) derived from fish may reduce the incidence of sudden cardiac death (SCD). In addition, wine drinking is suggested to have a protective effect against cardiovascular death.

METHODS AND RESULTS

We included 291 patients referred for coronary angiography in whom ischemic heart disease was suspected and all of whom completed a food questionnaire regarding fish and wine intake. The n-3 PUFA composition of granulocyte membranes and of adipose tissue was measured. In addition, 24-hour heart rate variability (HRV) was analyzed. Fish intake was positively associated with the level of n-3 PUFAs in adipose tissue. Significant positive correlation coefficients were found between HRV indices and the levels of n-3 PUFAs in granulocytes. Wine intake was also significantly positively related to HRV, but the patients with the highest wine intake also had the highest intake of fish, as documented by a high n-3 PUFA content in adipose tissue. Multiple linear regression analysis revealed that traditional factors such as treatment with ss-blockers, smoking, age, and previous myocardial infarction were independently related to HRV, and furthermore that n-3 PUFAs (but not wine intake) were significantly independently associated with HRV.

CONCLUSIONS

The close positive association between n-3 PUFAs and HRV in patients suspected of having ischemic heart disease may indicate a protective effect of n-3 PUFAs against SCD. This may partly explain the reduction in SCD observed in humans with a modest intake of n-3 PUFA. Wine intake was also positively correlated with HRV, but this correlation was no longer significant after controlling for the cellular level of n-3 PUFA.

[Proper advice on nutrition. Recommendations concerning the conduct of the nutritional news]

The Committee on Proper Conduct in Public Advice on Nutrition, set up by the Danish Nutrition Council, has produced recommendations to persons involved in communicating results of nutrition research. The guidelines are targeted on scientists, industry, journalists and publishers as well as consumers to facilitate proper conduct in communication of own or other scientists' research results, which might influence consumers' choice and intake of food. The results are presented as recommendations and checklists providing the necessary requirements to bring people in a position to make the best possible evaluation of the new scientific results and to put the results into their proper perspective. The aim of this report is to improve the process so that the communicator focuses on the background information necessary for the reader/listener/viewer in the current situation to achieve a balanced view and benefit from the new scientific result.

Alpha-linolenic acid and heart rate variability

BACKGROUND AND AIM

The marine long-chained n-3 polyunsaturated fatty acids seem to have antiarrhythmic effects in humans. Similar effect has also been postulated for alpha-linolenic acid, a plant-derived polyunsaturated fatty acid--from the n-3 family. The purpose of the study was to examine the relation between the content of alpha-linolenic acid in cell membranes and the risk of malignant arrhythmias as assessed by determination of heart rate variability (HRV).

METHODS AND RESULTS

Patients at high risk of sudden cardiac death (52 with a previous myocardial infarction and 29 with chronic renal failure on dialysis) were enrolled as well as 64 healthy volunteers. The cell membrane content of alpha-linolenic acid was analyzed by gas chromatography and related to 24-hour HRV, which was measured in all subjects. No correlations were found between levels of alpha-linolenic acid and 24-hour HRV.

CONCLUSION

The present study was unable to demonstrate a positive correlation between cell membrane levels of alpha-linolenic acid and HRV. Our results suggest that alpha-linolenic acid per se is devoid of an antiarrhythmic effect, though this effect could arise from its conversion to the longer chained n-3 PUFA, usually derived from fish.

N-3 fatty acids from fish and coronary artery disease: implications for public health

OBJECTIVE

To review and discuss the effect of n-3 polyunsaturated fatty acids (PUFA) from fish in the prevention and, primarily, in the treatment of coronary artery disease (CAD).

DESIGN

Overview of the literature.

SETTING

Denmark.

RESULTS

There is good evidence that fish consumption may reduce the risk of CAD.

CONCLUSIONS

Fish can be recommended to reduce the risk of CAD both in healthy subjects and in patients with a high risk of CAD or with documented CAD. The use of fish oil concentrates can not be recommended in general, but may be considered in patients after a myocardial infarction or in patients with hypertriglyceridaemia. An increased intake of n-3 polyunsaturated fatty acids from fish may have substantial implications for public health and health economy by decreasing the risk of coronary events and sudden cardiac death.

Heart rate variability and fatty acid content of blood cell membranes: a dose-response study with n-3 fatty acids

BACKGROUND

Dietary intake of long-chain n-3 polyunsaturated fatty acids (PUFA) may protect against sudden cardiac death, an event that may be predicted by measurement of heart rate variability (HRV).

OBJECTIVE

The objectives of this study were to 1) examine the correlations between the content of fatty acids in blood cell membranes (platelets and granulocytes) and HRV in healthy subjects, and 2) assess the effect on HRV of dietary intervention with n-3 PUFA in different doses.

DESIGN

Sixty healthy volunteers (25 women and 35 men) were randomly assigned to 3 treatment groups in a double-blind design. Subjects received a daily supplement of either 6.6 g n-3 PUFA, 2.0 g n-3 PUFA, or placebo (olive oil). A 24-h Holter recording was obtained for each subject before supplementation and after 12 wk of supplementation; the 24-h HRV was then related to the content of fatty acids in granulocytes and platelets.

RESULTS

Before supplementation, positive correlations were observed in men between the content of docosahexaenoic acid in cell membranes and HRV indexes (r = 0.50, P < 0.01), whereas such correlations were not found in women. Dietary intervention revealed a dose-dependent effect of n-3 PUFA on HRV in men, whereas no effect was found in women.

CONCLUSION

The study showed a beneficial effect of n-3 PUFA on HRV in healthy men, suggesting an antiarrhythmic effect of n-3 PUFA. No such effect was observed in healthy women.

Heart rate variability and n-3 fatty acids in patients with chronic renal failure--a pilot study

Patients with chronic renal failure (CRF) often have autonomic cardiac dysfunction, which can be assessed by measuring heart rate variability (HRV). This dysfunction prediposes the patients to sudden cardiac death. This study describes 24-hour HRV in patients with CRF compared to HRV in patients with a previous myocardial infarction (MI). Furthermore, associations between HRV in patients with CRF and the content of n-3 polyunsaturated fatty acids (PUFA) in cell membranes were examined, because n-3 PUFA may improve HRV. Twenty-nine patients with CRF treated with dialysis were enrolled. A 24-hour Holter recording was obtained at baseline and the HRV variables, RR (= mean of all normal RR intervals during the 24-hour recording) and SDNN (= standard deviation of all normal RR intervals in the entire 24-hour recording) were analyzed. Also, granulocyte fatty acid composition was determined. The patients were allocated to dietary supplementation with either 5.2 g of n-3 PUFA or a placebo oil (olive oil) daily for 12 weeks in a double-blind design. At the end of the supplementation period the Holter recording and blood sampling were repeated. At baseline the CRF patients' mean SDNN ws 86 ms compared to 118 ms (p < 0.01) in patients with a previous MI. After supplementation with either n-3 PUFA or placebo a highly significant correlation was observed between the content of n-3 PUFA in cell membranes and HRV (r = 0.71, p < 0.01). Furthermore, when the patients were dichotomized according to their mean SDNN, it was found, that those with the highest SDNN had a higher content of n-3 PUFA in cell membranes compared to those with the lowest SDNN (7.8% vs 4.2%, p < 0.05). In conclusion, HRV was decreased in CRF patients indicating a cardiovascular autonomic dysfunction. The positive correlation between the n-3 PUFA content in cell membranes and HRV suggests that the effects of an increased intake of n-3 PUFA in CRF patients should be further studied.

n-3 fatty acids do not decrease plasma endothelin levels in healthy individuals

The effect of three different doses of n-3 polyunsaturated fatty acids (PUFA) on endothelin-1 (ET-1) was studied. Study 1 included 40 healthy volunteers randomized to a single supplement of 20 g of n-3 or n-6 PUFA. Plasma ET-1 was measured 14 h after ingestion, and no changes in plasma ET-1 after intake of n-3 PUFA were observed, compared to baseline values. In study 2, 32 subjects had 0.65 g of n-3 PUFA or a fat mixture per day for 12 weeks. No changes in plasma ET-1 were found after the oil supplements. Finally, 22 persons had 4 g of n-3 PUFA for 6 weeks. A significant increase in plasma ET-1 was seen in this group after the supplement. Thus, n-3 PUFAs do not lower plasma levels of ET-1, the most potent vasoconstrictor known.

[n-3 polyunsaturated fatty acids, heart rate variability and ventricular arrhythmias in post-AMI-patients. A clinical controlled trial]

There is evidence for an antiarrhythmic effect of n-3 polyunsaturated fatty acids (n-3 PUFA) in animals. The aim of the present study was to investigate the effect of dietary n-3 PUFA on ventricular arrhythmias and heart rate variability (HRV) in patients with a previous myocardial infarction. Fifty-five patients were randomized to receive either 5.2 g of n-3 PUFA daily for 12 weeks or placebo in a double blind, placebo-controlled study. Prior to randomization a 24-hour Holter recording was obtained, and this was repeated at the end of the study. The major end-points were the number of ventricular extrasystoles (VE)/24 hours and the 24-hour HRV. A non-significant decrease in VE/24 hours was found in both the n-3 PUFA group and among controls after dietary supplementation, whereas HRV significantly increased after n-3 PUFA compared to both baseline values (p = 0.04) and to controls (p = 0.01). The present study therefore supports the hypothesis that n-3 PUFA may have an anti-arrhythmic effect in humans.

Fish consumption, n-3 fatty acids in cell membranes, and heart rate variability in survivors of myocardial infarction with left ventricular dysfunction

To elucidate a possible antiarrhythmic effect of long-chained n-3 polyunsaturated fatty acids, heart rate variability was assessed in 52 patients with a previous myocardial infarction and left ventricular dysfunction. The content of n-3 polyunsaturated fatty acids in platelets was closely associated with the patient's fish-consuming habits, and a significant positive correlation was observed between the n-3 fatty acid docosahexaenoic acid and heart rate variability.

Homocysteine in Greenland Inuits

Patients with homozygous homocystinuria are at greatly increased risk for development of atherosclerosis and thrombosis (1). Elevated plasma levels of homocysteine (HCY) are caused by reduced enzymatic catabolism or reduced enzymatic remethylation of HCY, due to either hereditary enzyme defects or to nutritional deficiencies of vitamins functioning as cofactors. However, several recent studies have suggested that persons with mildly elevated plasma levels of HCY also are at increased risk for coronary heart disease. (2-4). There are some indications that dietary n-3 polyunsaturated fatty acids (PUFAs) may offer protection against coronary heart disease (5-6). Several mechanisms may be involved, including beneficial effects of n-3 PUFAs on plasma lipids, platelet and leukocyte reactivity, blood pressure and vasoreactivity (7). Interestingly, Olszewski el al. recently found HCY-levels to be lowered 36% in 15 type IIa or IIb hyperlipemic men by n-3 PUFA supplementation. A possible beneficial effect of n-3 PUFA on the incidence of coronary heart disease was initially suggested from studies in Greenland Inuits by our group (8). We therefore investigated plasma levels of homocysteine in a group of traditionally living Greenland Inuits with a diet consisting mainly of marine food and with a very high content of n-3 PUFAs.

Increased plasma apolipoprotein (a) levels in IDDM patients with diabetic nephropathy

OBJECTIVE

The relative mortality from cardiovascular disease (CVD) is increased 40-fold in IDDM patients suffering from diabetic nephropathy as compared with nondiabetic subjects on average. We assessed the potential contribution of dyslipidemia in general and elevated serum apolipoprotein (a) [apo(a)] in particular to CVD in nephropathic patients with IDDM.

RESEARCH DESIGN AND METHODS

We investigated 199 IDDM patients with diabetic nephropathy and 192 normoalbuminuric IDDM patients matched for sex, age, diabetes duration, and BMI.

RESULTS

The prevalence of CVD was 30 and 12% in patients with and without nephropathy, respectively (P < 0.001). The level of apo(a) was significantly higher in patients with nephropathy, 189 (20-2,350) U/l as compared with the normoalbuminuric group, 103 (20-1,940) U/l (P < 0.005). The prevalence of plasma apo(a) > 300 U/l (at-risk level for cardiovascular pathogenicity) was 38% (31-45) vs. 22% (16-28) in patients with and without nephropathy, respectively (P < 0.0005). In nephropathic patients, the prevalence of plasma apo(a) > 300 U/l was raised in patients with CVD (48%, 36-61%) as compared with patients without (34%, 26-42%) (P = 0.05). Furthermore, the serum concentrations of the following apolipoproteins and lipids were higher in patients with nephropathy as compared with normoalbuminuric patients: apoB 1.33 +/- 0.37 vs. 1.06 +/- 0.26 g/l; total cholesterol 5.6 +/- 1.2 vs. 4.8 +/- 0.9 mmol/l; and triglycerides 1.22 (0.31-9.87) vs. 0.77 (0.28-3.05) mmol/l, P < 0.0001. Multiple logistic regression analysis of cardiovascular risk factors revealed that plasma apo(a) concentration > 300 U/l is an independent risk factor for coronary heart disease, odds ratio 1.86 (1.03-3.36) (P < 0.05).

CONCLUSIONS

Dyslipidemia and raised plasma concentrations of apo(a), particularly > 300 U/l, may contribute to the enhanced morbidity and mortality from CVD characteristically observed in IDDM patients with diabetic nephropathy.

The apolipoprotein E polymorphism in Greenland Inuit in its global perspective

Apolipoprotein E (apoE) genotypes were determined in Inuit population samples from Nuuk on the south-west coast of Greenland (n = 100) and from the Ammassalik region on the south-east coast (n = 78). The epsilon 2 allele was absent in the latter sample, and the epsilon 4 allele frequency was relatively high, about 23%. As in most other populations, mean plasma lipoprotein-related variables, except high-density lipoprotein (HDL) cholesterol, were higher in both Inuit men and women with epsilon 4 than in epsilon 3 epsilon 3 genotypes (P < 0.05 for triglycerides in men, and for non-HDL cholesterol and apolipoprotein B in women). The estimated apoE allele frequencies were combined with data from other studies of aboriginal peoples to outline a world map of apoE allele frequencies. A recent study of non-human primates suggests that epsilon 4, and not epsilon 3, is the ancestral allele in humans and we have used the map to generate additional hypotheses regarding the history of the apoE polymorphism in humans.

No effect of a very low dose of n-3 fatty acids on monocyte function in healthy humans

There is some evidence that intake of sea food rich in n-3 polyunsaturated fatty acids (PUFA) may protect against coronary heart disease (CHD). Thus, even very low daily amounts of n-3 PUFA below 0.5 g have been reported to reduce the incidence of CHD, although it is unknown by what mechanisms this may occur. Monocytes are of major importance in atherogenesis, and we therefore studied the effect of a daily supplement with 0.65 g of n-3 PUFA for 12 weeks on monocyte function in a randomized placebo-controlled trial of 32 healthy subjects. No effect of dietary n-3 PUFA could be demonstrated on monocyte chemotaxis, on chemiluminescence, or on formation of cytokines and leukotriene B4 from activated monocytes.

The influence of trans fatty acids on health: a report from the Danish Nutrition Council

Trans fatty acids constitute 0-30% of the fat in Danish margarines, most in industry and bakery margarines and usually less in table margarine. The trans fatty acids make margarines more solid at room temperature and therefore provide an economical storage advantage. In British and U.S. reports from 1984-1989, the trans fatty acids were more or less acquitted of unhealthy effects. During the last 5-6 years, however, a series of new studies has been published regarding both the connection between the consumption of trans fatty acids and the occurrence of coronary heart disease and the impact on the lipoprotein level in plasma. Studies suggest that the consumption of trans fatty acids from margarine is equally, or perhaps more, responsible for the development of arteriosclerosis than saturated fatty acids. In addition, it is now clear that both the fetus and the breast-fed baby are exposed to trans fatty acids in relation to the mother's consumption. A couple of recent studies suggest a possible restrictive influence of the trans fatty acids on the weight of the fetus. The average consumption of trans fatty acids from margarine in Denmark in 1991 was approximately 2.5 g/day per person. For about 150,000 adult Danes, the consumption is assumed to be more than 5 g/day per person. On this basis, the Danish Nutrition Council recommend that the consumption of trans fatty acids is reduced as much as possible. This can be done by reducing the fat content in food and by reducing the trans fatty acid content in all Danish margarine products to 5% or less. Thereafter, the group of adult Danes, including pregnant and breast-feeding women, with a large consumption of margarine and margarine-containing products, will on average only consume 2 g of vegetable trans fatty acids/day. This corresponds to the consumption in the low-risk groups in the above-mentioned epidemiological studies. In addition, the Danish Nutrition Council encourage the producers of margarines to make products that can be marketed as 'free of trans fatty acids'.

The effect of n-3 fatty acids on neutrophil chemiluminescence

The effect of dietary supplementation with n-3 polyunsaturated fatty acids (PUFAs) on the production of free oxygen radicals from activated neutrophils was investigated in healthy subjects, using chemiluminescence. In the first study 22 persons were give 4 g n-3 PUFAs daily for 6 weeks. There was a median reduction of chemiluminescence from neutrophils stimulated with opsonized zymosan of 37% (p < 0.001). The median content of eicosapentaenoic acid in platelets, used as an indicator for cellular fatty acid profile, increased from 0.70 to 2.80% (p < 0.001), and there was a significant negative correlation between the chemiluminescence signal and the content of eicosapentaenoic acid in platelets (p < 0.001). In a second, low-dose study 24 persons were allocated to daily supplementation with either 0.65 g n-3 PUFAs or with a control oil for 6 weeks. Compared to the control group there was a median reduction of 38 and 44% in chemiluminescence from neutrophils stimulated with opsonized zymosan and phorbol,12-myristate,13-acetate (PMA), respectively. Neither of these differences, however, was statistically significant. These findings lend support for a possible role of n-3 PUFAs in the management of inflammatory disorders.

[The effect on health of dietary antioxidants and antioxidant supplements]

Reactive free oxygen radicals are formed in the reactions involved in normal cell metabolism. This formation is closely regulated e.g. by dietary antioxidants. Present knowledge suggests that an imbalance, with surplus of free radicals, can play a role in the pathogenesis of certain types of cancer, atherosclerosis, and cataract. A number of epidemiological studies have demonstrated a reduced risk of developing these diseases in persons who consume a diet with a high content of vegetables and fruit, which contains large quantities of the antioxidants: beta-carotene, vitamins C and E. Intervention studies, using supplements of these antioxidants, have so far not been able to show a beneficial effect. The apparently protective effect of fruit and vegetables may be due to other active ingredients. In Denmark the average intake of vegetables and fruit is low, and it is estimated that an increased consumption of these foods could reduce the occurrence of certain cancer types and atherosclerosis. In contrast, there is no evidence that antioxidant supplements would provide protection against disease, and their safety remains to be established.

[Significance of trans-fatty acids for health]

Trans fatty acids make up 0-30% of the fatty acids in Danish margarines. The intake of trans fatty acids from margarine in Denmark was in 1991 on average about 2.5 gram/person/day, and for about 150,000 Danes more than 5 gram/person/day. Several recent case-control studies and a large cohort study as well as clinical ward studies suggest that the intake of trans fatty acids enhances atherogenesis to the same extent or possibly even more than saturated fatty acids. In addition a few studies suggest that the intake of trans fatty acids by the pregnant mother impairs growth of the human foetus. On this background it seems reasonable to reduce the intake of trans fatty acids as much as possible. This could be implemented by a reduction in the fat content of the diet together with a reduction of trans fatty acid content to less than 5% in all margarines. This would ensure that Danes--including pregnant and nursing women--with a high intake of margarine on average consume less than 2 gram of trans fatty acids of vegetables origin per day. This amount corresponds to intake in low risk groups in several studies.