Monounsaturated fatty acid-enriched diet decreases plasma plasminogen activator inhibitor type 1

Diet and hemostatic factors

The coagulation, fibrinolytic, and platelet activating systems are complex and interact extensively, and with other systems such as inflammation. Key reactions often require biomembranes, suggesting that dietary lipids, to the extent that they influence membrane composition, may have important regulatory roles. Also, recent evidence suggests that both postprandial and fasting lipoproteins may be associated with either factor levels or activation state or both. This issue has added importance because several hemostatic and fibrinolytic factors are known CVD risk factors. Although there are associations between fasting lipid levels and several coagulation and fibrinolytic factors, the mechanisms are unclear, as are the implications for intervention. In general, postprandial lipids are at least somewhat procoagulant because they activate factor VII. It remains to be demonstrated, however, that this postprandial activation has important clinical correlates. Dietary supplementation with marine omega-3 fatty acids does prolong the bleeding time and may decrease thrombotic potential; however, other than this, little is known about the direct effects of dietary fatty acids on hemostatic and fibrinolytic activities. Much work is needed in carefully controlled studies to expand our knowledge in this important area.

Interaction of physical activity and diet: implications for haemostatic factors

Regular moderate intensity physical activity and habitual diet providing no more than one third of energy from fats have been recommended for the prevention of atherosclerotic diseases. The background for these guidelines is the key role of plasma lipids. However, the importance of thrombogenesis in acute myocardial infarction has become obvious during the last decade. Hyperlipidaemia and excess of adipose tissue increase platelet aggregability and blood coagulation, and decrease fibrinolysis. Both regular physical activity and dietary fat reduction decrease blood lipids and body fat thereby diminishing the risk of thrombosis. Currently, data on interactions between physical activity and diet on haemostasis are scarce, and the few studies available have not demonstrated additional effects when these two lifestyle modifications have been combined. This paper is restricted only to studies using controlled randomized design. Regular moderate intensity physical activity as well as diet rich in omega-3 fatty acids decrease platelet aggregability. The effects of regular physical activity on plasma fibrinogen remain contradictory, while the impact of diet is even less clear. Plasminogen activator inhibitor-1, a possible link between insulin resistance syndrome and coronary heart disease, may decrease due to physical training or low fat diet. It can be hypothesized that moderation in physical activity and diet carries a more powerful impact on blood coagulation and fibrinolysis than either lifestyle modification alone. Studies focusing on the interactions of regular moderate physical activity and fat-modified diet are needed in efforts to optimize the preventive actions by lifestyle changes.

Circulating levels of endothelial function are modulated by dietary monounsaturated fat

BACKGROUND

For the most part, the benefits of monounsaturated-rich diets (MUFA-diet) have been related to their action on plasma lipid levels. However other non-lipidic effects could also be involved in their protective effects. One of these involves the decrease in plasma levels of plasminogen activator inhibitor type 1 (PAI-1), the main inhibitor of fibrinolysis. Given that the PAI-1 is of endothelial origin, one hypothesis is that the MUFA-diet could protect against CHD by modulating some endothelial components.

METHODS AND RESULTS

Healthy male subjects (n = 25) received three different consecutive diets, each lasting 28 days: a low fat NCEP-I-diet, with 28% calories as fat, 10% saturated fat (SAT), 12% monounsaturated (MUFA) and 6% polyunsaturated (PUFA); a MUFA-diet, with 38% calories as fat, 10% SAT, 22% MUFA and 6% PUFA; and a SAT rich-diet (SAT-diet), with 38% calories as fat, 20% SAT, 12% MUFA and 6% PUFA. After each dietary period, the plasma lipid profile was determined, including total cholesterol, HDL cholesterol, LDL cholesterol, total triglyceride, apo A1, apo B plasma levels and conjugated diene formation, after incubation of LDL particles with Cu 5 microM/l. Endothelial products measured in plasma were von Willebrand factor (vWF), E-selectin, Thrombomodulin and Tissue Factor Pathway Inhibitor (TFPI) levels. We observed a decrease in vWF, PAI-1 and TFPI plasma levels and an increase in lag time of conjugated diene formation after the MUFA-diet. There was a positive correlation between the decreases in TFPI and vWF and the changes in total cholesterol, LDL-C, apo B plasma levels. The decrease in TFPI was negatively correlated with the increase in lag time of conjugated diene formation. PAI-1 plasma levels were positively correlated with total cholesterol, LDL-C and triglycerides and negatively correlated with HDL-C.

CONCLUSIONS

Consumption of a Mediterranean-type MUFA-diet produces a decrease in plasma levels of vWF, TFPI and PAI-1 plasma levels in young healthy males. Given that these substances are of endothelial origin, one could suggest that the MUFA of the diet has a beneficial effect on endothelial function resulting in protective changes against thrombogenesis.

The effects of structurally defined triglycerides of differing fatty acid composition on postprandial haemostasis in young, healthy men

The aim of this study was to investigate whether a number of key haemostatic factors were altered when healthy young individuals were challenged with a fat load of physiological size contained within a meal composed of normal ingredients and whether this response was modified when the fatty acid composition of the meal was altered radically. Eight healthy male volunteers each randomly consumed four meals which were identical in terms of gross nutritional content (41% of energy provided as fat, 17% as protein and 42% as carbohydrate) but which differed in fatty acid composition. To reduce the possible influence of fatty acid position within the triglyceride molecule on lipid absorption and subsequent metabolic effects, the structural integrity of 91% of fat (test triglycerides such as 1,3 distearoyl-2-oleoyl glycerol (S-O-S), trioleine (O-O-O), and 1,3 dilinoleoyl-2-oleoyl glycerol, (L-O-L)) in the meals was controlled so that the principal fatty acid in the sn-2 position was oleic acid (18:1n-9). Meals rich in either a test triglyceride or a control oil provided 44+/-6 g of fat. No significant alterations from fasted values of elevated plasma factor VII coagulant activity (FVIIc) or F1 + 2 were observed. FVIIA varied significantly over the postprandial time course; however, when expressed as a percentage of the fasting value, the FVIIa responses to O-O-O and L-O-L differed significantly but this was not evident when the absolute values were analysed. Similarly, no difference in plasma fibrinopeptide A (FPA) concentrations were evident. After all four meals, chylomicron contained proportionately more palmitic acid and generally less oleic acid than the ingested lipids. This study clearly demonstrates that postprandial haemostatic responses of young healthy individuals to a physiological fat load are minimal, (irrespective of triglyceride structure).

The role of dietary fatty acids in lipoprotein oxidation and atherosclerosis

Although it is well established that dietary saturated fatty acid intake is an important risk factor for coronary heart disease, there remains substantial controversy regarding whether these dietary fatty acids should be replaced with either carbohydrates, monounsaturated fatty acids, polyunsaturated fatty acids or a combination of these. This review highlights recent studies evaluating the role of dietary fatty acids in atherosclerosis, with a particular emphasis on their roles in lipoprotein oxidation and other potential proatherogenic processes.

Functional food science and the cardiovascular system

Cardiovascular disease has a multifactorial aetiology, as is illustrated by the existence of numerous risk indicators, many of which can be influenced by dietary means. It should be recalled, however, that only after a cause-and-effect relationship has been established between the disease and a given risk indicator (called a risk factor in that case), can modifying this factor be expected to affect disease morbidity and mortality. In this paper, effects of diet on cardiovascular risk are reviewed, with special emphasis on modification of the plasma lipoprotein profile and of hypertension. In addition, dietary influences on arterial thrombotic processes, immunological interactions, insulin resistance and hyperhomocysteinaemia are discussed. Dietary lipids are able to affect lipoprotein metabolism in a significant way, thereby modifying the risk of cardiovascular disease. However, more research is required concerning the possible interactions between the various dietary fatty acids, and between fatty acids and dietary cholesterol. In addition, more studies are needed with respect to the possible importance of the postprandial state. Although in the aetiology of hypertension the genetic component is definitely stronger than environmental factors, some benefit in terms of the development and coronary complications of atherosclerosis in hypertensive patients can be expected from fatty acids such as alpha-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid. This particularly holds for those subjects where the hypertensive mechanism involves the formation of thromboxane A2 and/or alpha 1-adrenergic activities. However, large-scale trials are required to test this contention. Certain aspects of blood platelet function, blood coagulability, and fibrinolytic activity are associated with cardiovascular risk, but causality has been insufficiently proven. Nonetheless, well-designed intervention studies should be initiated to further evaluate such promising dietary components as the various n-3 and n-6 fatty acids and their combination, antioxidants, fibre, etc. for their effect on processes participating in arterial thrombus formation. Long-chain polyenes of the n-3 family and antioxidants can modify the activity of immunocompetent cells, but we are at an early stage of examining the role of immune function on the development of atherosclerotic plaques. Actually, there is little, if any, evidence that dietary modulation of immune system responses of cells participating in atherogenesis exerts beneficial effects. Although it seems feasible to modulate insulin sensitivity and subsequent cardiovascular risk factors by decreasing the total amount of dietary fat and increasing the proportion of polyunsaturated fatty acids, additional studies on the efficacy of specific fatty acids, dietary fibre, and low-energy diets, as well as on the mechanisms involved are required to understand the real function of these dietary components. Finally, dietary supplements containing folate and vitamins B6 and/or B12 should be tested for their potential to reduce cardiovascular risk by lowering the plasma level of homocysteine.

Comparison of bezafibrate versus lovastatin for lowering plasma insulin, fibrinogen, and plasminogen activator inhibitor-1 concentrations in hyperlipemic heart transplant patients

Accelerated coronary artery disease is the most serious obstacle to long-term survival in heart transplant recipients. Hyperlipemia, hyperinsulinism, and changes in endothelial cell hemostatic function have been implicated in cardiac allograft vascular disease. Both lovastatin and bezafibrate are safe, effective, and well tolerated therapies for hyperlipidemia. Our study compares the effect of these lipid-lowering drugs in 21 patients with post-heart transplantation hyperlipidemia on different risk factors related to insulin resistance syndrome. Patients were given the same diet for 3 months, then randomized to lovastatin or bezafibrate for a period of 8 weeks, and crossed over to an additional 8 weeks of either bezafibrate or lovastatin. Baseline parameters were also compared with those of a control group of healthy subjects and after both periods of pharmacologic treatment. Transplant patients had higher insulin (35 +/- 3 vs 24 +/- 3 microIU/L), fibrinogen (298 +/- 15 vs 261 +/- 14 mg/dl), and plasminogen activator inhibitor-1 (PAI-1) (17 +/- 2 vs 11.7 +/- 2 arbitrary units/ml) plasma levels than controls. Significant decreases in insulin (-37 +/- 3%), fibrinogen (-12 +/- 4%), and PAI-1 plasma levels (-18 +/- 12%) were only observed after bezafibrate treatment. In conclusion, bezafibrate decreases plasma insulin, fibrinogen, and PAI-1 in hyperlipidemic heart transplant recipients.

Diet and haemostasis: time for nutrition science to get more involved

Abnormal haemostasis, and specifically a pre-thrombotic state characterized by hypercoagulability, increased platelet aggregation and impaired fibrinolysis, is associated with increased atheroma and thrombosis. The recent literature clearly indicates that diet may prevent or be used to treat some abnormal haemostatic states. There are reports on effects of energy intake and expenditure, alcohol consumption, intakes of total fat, different fatty acids, fish oil, NSP and vitamins on markers of coagulation, platelet function and fibrinolysis. Some of the confusion and controversy in this field has arisen because the wrong markers of haemostasis have been measured in dietary trials. Moreover, many of the studies have lacked good dietary control. It is suggested that more sensitive, functional markers of the balance between the different facets of the haemostatic system should be measured. It is also important to test hypotheses developed from known observations and to propose mechanisms of action of the various dietary factors, based on our improved understanding of the haemostatic system.