Atherothrombogenic Risk Modulation by n-3 Fatty Acids Was not Associated with Changes in Homocysteine in Subjects with Combined Hyperlipidaemia

Do B Vitamins Enhance the Effect of Omega-3 Polyunsaturated Fatty Acids on Cardiovascular Diseases? A Systematic Review of Clinical Trials

Studies have suggested that B vitamins or omega-3 polyunsaturated fatty acids (PUFAs) may deter the development of cardiovascular disease (CVD). This systematic review aims to examine whether the combined supplementation of both B vitamins and omega-3 PUFAs could provide additional beneficial effects to prevent CVD beyond the effect of each supplement based on clinical trials published up to December 2021. The overall findings are inconsistent and inconclusive, yet the combined supplementation of these two nutrients may be more effective at reducing plasma homocysteine, triglyceride, and low-density lipoprotein-cholesterol than the individual components. The underlying mechanisms mainly include alleviating endothelial dysfunction, inhibiting atherosclerosis and lesion initiation, reducing oxidative stress, suppressing activation of pro-inflammatory cytokines, regulating endothelial nitric oxide synthase, and interfering with methylation of genes that promote atherogenesis. Although biologically plausible, the existing literature is insufficient to draw any firm conclusion regarding whether B vitamins can further enhance the potential beneficial effects of omega-3 PUFA intake on either primary or secondary prevention of CVD. The inconsistent findings may be largely explained by the methodological challenges. Therefore, well-designed high-quality trials that will use the combined supplementation of B vitamins and omega-3 PUFAs or dietary patterns rich in these two types of nutrients are warranted.

Diets and Cellular-Derived Microparticles: Weighing a Plausible Link With Cerebral Small Vessel Disease

Cerebral small vessel disease (CSVD) represents a spectrum of pathological processes of various etiologies affecting the brain microcirculation that can trigger neuroinflammation and the subsequent neurodegenerative cascade. Prevalent with aging, CSVD is a recognized risk factor for stroke, vascular dementia, Alzheimer disease, and Parkinson disease. Despite being the most common neurodegenerative condition with cerebrocardiovascular axis, understanding about it remains poor. Interestingly, modifiable risk factors such as unhealthy diet including high intake of processed food, high-fat foods, and animal by-products are known to influence the non-neural peripheral events, such as in the gastrointestinal tract and cardiovascular stress through cellular inflammation and oxidation. One key outcome from such events, among others, includes the cellular activations that lead to elevated levels of endogenous cellular-derived circulating microparticles (MPs). MPs can be produced from various cellular origins including leukocytes, platelets, endothelial cells, microbiota, and microglia. MPs could act as microthrombogenic procoagulant that served as a plausible culprit for the vulnerable end-artery microcirculation in the brain as the end-organ leading to CSVD manifestations. However, little attention has been paid on the potential role of MPs in the onset and progression of CSVD spectrum. Corroboratively, the formation of MPs is known to be influenced by diet-induced cellular stress. Thus, this review aims to appraise the body of evidence on the dietary-related impacts on circulating MPs from non-neural peripheral origins that could serve as a plausible microthrombosis in CSVD manifestation as a precursor of neurodegeneration. Here, we elaborate on the pathomechanical features of MPs in health and disease states; relevance of dietary patterns on MP release; preclinical studies pertaining to diet-based MPs contribution to disease; MP level as putative surrogates for early disease biomarkers; and lastly, the potential of MPs manipulation with diet-based approach as a novel preventive measure for CSVD in an aging society worldwide.

A combination of omega-3 fatty acids, folic acid and B-group vitamins is superior at lowering homocysteine than omega-3 alone: A meta-analysis

The aim of the study was to assess whether omega-3 polyunsaturated fatty acid supplementation alone or in combination with folic acid and B-group vitamins is effective in lowering homocysteine. The Medline Ovid, Embase and Cochrane databases were searched for randomized-controlled trial studies that intervened with omega-3 supplementation (with or without folic acid) and measured changes in homocysteine concentration. Studies were pooled using a random effects model for meta-analysis. Three different models were analyzed: all trials combined, omega-3 polyunsaturated fatty acid trials, and omega-3 polyunsaturated fatty acids with folic acid and B-group vitamin trials. Nineteen studies were included, consisting of 3267 participants completing 21 trials. Studies were heterogeneous; varying by dose, duration and participant health conditions. Across all trials, omega-3 supplementation was effective in lowering homocysteine by an average of 1.18μmol/L (95%CI: (-1.89, -0.48), P=.001). The average homocysteine-lowering effect was greater when omega-3 supplementation was combined with folic acid and B-group vitamins (-1.37μmol/L, 95%CI: (-2.38, -0.36), P<.01) compared to omega-3 supplementation alone (-1.09μmol/L 95%CI: (-2.04, -0.13), P=.03). Omega-3 polyunsaturated fatty acid supplementation was associated with a modest reduction in homocysteine. For the purposes of reducing homocysteine, a combination of omega-3s (0.2-6g/day), folic acid (150 - 2500μg/day) and vitamins B6 and B12 may be more effective than omega-3 supplementation alone.

Dietary protein and plasma total homocysteine, cysteine concentrations in coronary angiographic subjects

Background

Dietary patterns are associated with plasma total homocysteine (tHcy) concentrations in healthy populations, but the associations between dietary protein and tHcy, total cysteine (tCys) in high risk populations are unclear. We therefore examined the association between dietary protein and tHcy and tCys concentrations in coronary angiographic subjects.

Methods

We conducted a cross-sectional study of 1015 Chinese patients who underwent coronary angiography (40–85 y old). With the use of food-frequency questionnaires, we divided the total protein intakes into high animal-protein and high plant-protein diets. Circulating concentrations of tHcy and tCys were simultaneously measured by high-performance liquid chromatography with fluorescence detection.

Results

We found that high animal-protein diet was positively associated with hyperhomocysteinemia after adjustment for potential confounders, with the subjects in the highest quartile of intake having the greatest increase in risk (OR: 4.14, 95% CI: 2.67-6.43), whereas high plant-protein diet was inversely related to hyperhomocysteinemia, with a higher intake being protective. Compared with the first quartile of intake, the adjusted OR was 0.59 (95% CI: 0.38-0.91) for the fourth quartile. The total protein intake was positively associated with the risk of hypercysteinemia and the participants in highest quartile had significant OR of 1.69 (95% CI: 1.02-2.87) compared with those in lowest quartile. In multivariate linear regression analyses, high animal-protein and total-protein intakes were positively associated with plasma tHcy and tCys concentrations. The plant-protein intake was a negative determinant of plasma tHcy concentrations.

Conclusions

High animal-protein diet was positively associated with high tHcy concentrations, whereas high plant-protein diet was inversely associated with tHcy concentrations. Furthermore the total protein intake was strongly related to tCys concentrations.

Significant inverse association of marine n-3 fatty acids with plasma fibrinogen levels in Japanese in Japan but not in whites or Japanese Americans

BACKGROUND/OBJECTIVES

Numerous studies reported beneficial effects of marine n-3 fatty acids (n-3 FAs) on cardiovascular disease (CVD) and its risk factors. However, the association of marine n-3 FAs with plasma fibrinogen, a risk factor for CVD, remains uncertain.

SUBJECTS/METHODS

In a population-based, cross-sectional study of 795 men aged 40-49 without CVD (262 whites in Allegheny County, Pennsylvania, USA, 302 Japanese in Kusatsu, Japan and 229 Japanese Americans in Honolulu, Hawaii, USA), we examined the association of marine n-3 FAs with plasma fibrinogen. Serum FAs were measured by capillary gas-liquid chromatography. Marine n-3 FAs were defined as the sum of docosahexaenoic, eicosapentaenoic and docosapentaenoic acids. Plasma fibrinogen was measured by an automated clot-rate assay. Multiple linear regression analyses were performed to assess the association.

RESULTS

White, Japanese and Japanese-American men had mean marine n-3 FAs levels of 3.47%, 8.78% and 4.46%, respectively. Japanese men had a significant inverse association of marine n-3 FAs with fibrinogen (standardized regression coefficient of -0.11, P=0.049), after adjusting for age, body-mass index and current smoking. The significant inverse association remained after further adjusting for diabetes, C-reactive protein, triglycerides and other variables. White or Japanese-American men did not show a significant association.

CONCLUSIONS

We observed the significant inverse association of marine n-3 FAs with fibrinogen in Japanese, but not in whites or Japanese Americans. The observation suggests that marine n-3 FAs at very high levels, as seen in the Japanese, may decrease plasma fibrinogen levels.

High consumption of Ω-3 polyunsaturated fatty acids decrease plasma homocysteine: a meta-analysis of randomized, placebo-controlled trials

OBJECTIVE

High consumption of ω-3 polyunsaturated fatty acids (PUFAs) has been associated with lower plasma homocystine (Hcy) levels, but intervention studies in humans have been inconclusive. The objective was to systematically evaluate the effects of ω-3 PUFA supplementation on plasma Hcy levels.

METHODS

A comprehensive search of Medline, EMBASE, the Cochrane Clinical Trials Registry, and bibliographies of relevant articles published from 1966 through September 2010 was undertaken. All randomized, placebo-controlled trials that compared ω-3 PUFA supplementation with placebo were included. Two investigators performed data extraction and quality scoring independently, with discrepancies resolved by consensus.

RESULTS

Eleven trials including 702 subjects were analyzed. The outcomes studied were plasma Hcy level. Eleven randomized, placebo-controlled trials were included in this meta-analysis. Supplementation with ω-3 PUFAs was associated with a significant decrease in plasma Hcy level (weighted mean difference -1.59 μmol/L, 95% confidence interval -2.34 to -0.83) compared with control subjects.

CONCLUSION

This meta-analysis suggested that ω-3 PUFA supplementation can decrease plasma Hcy levels. The implications of these findings remain to be elucidated.

Docosahexaenoic acid decreases plasma homocysteine via regulating enzyme activity and mRNA expression involved in methionine metabolism

OBJECTIVE

The objective of this study was to investigate the regulatory effect of fish oil rich in omega-3 polyunsaturated fatty acids (PUFAs) on critical enzyme activity and mRNA expression involved in homocysteine (Hcy) metabolism.

METHODS

Thirty-six male Sprague-Dawley rats aged 3 wk, weighing 120 +/- 10 g, were randomly divided into three groups: the olive oil (OO) group, the tuna oil (TO) group, and the salmon oil (SO) group. The oil was orally administered every day using a stomach tube. Eight weeks later, plasma Hcy, phospholipids, omega-3 PUFAs, enzyme activity, and mRNA expression in tissues were determined.

RESULTS

Compared with the control group, phospholipids, total omega-3 PUFAs, and omega-3/omega-6 PUFAs in the liver and lung were significantly elevated in the TO and SO groups; 22:6omega-3 in the liver and lung was significantly increased in the TO group; and 20:5omega-3 in the two tissues was significantly elevated in the SO group. The level of plasma Hcy was significantly decreased with TO; methionine adenosyl transferase (MAT) activity was significantly increased and MAT mRNA expression was significantly upregulated with TO; cystathionine-gamma-lyase mRNA expression in TO was significantly upregulated; however, cystathionine beta-synthase and S-adenosylhomocysteine hydrolases were not significantly changed when compared with control.

CONCLUSION

TO rich in 22:6omega-3 decreases the concentration of Hcy despite increasing MAT activity and upregulating MAT mRNA expression through compensatory cystathionine-gamma-lyase mRNA expression, both of which are involved in Hcy metabolism.

Acute ingestion of long-chain (n-3) polyunsaturated fatty acids decreases fibrinolysis in men with metabolic syndrome

Individuals with metabolic syndrome (MetS) often have elevated plasma plasminogen activator inhibitor-1 (PAI-1) and tissue plasminogen activator (t-PA), contributing to an increased risk of cardiovascular disease. PAI-1 and t-PA may be affected by chronic (n-3) long-chain PUFA [(n-3)LCPUFA] supplementation; however, the acute impact of fat ingestion on these risk factors has not been established. Our objective was to investigate the acute effect of (n-3)LCPUFA on plasma PAI-1, t-PA, and platelet aggregation. We conducted a randomized crossover study in which men (n = 8, > or =45 y) with MetS consumed water or a high-saturated fat beverage (1 g fat/kg body weight) with either a high or low content of (n-3)LCPUFA. Blood samples were collected over 8 h to measure triacylglycerol (TAG), PAI-1, t-PA, and platelet aggregation. Both fat loads resulted in a significant increase in whole blood TAG concentration, plasma PAI-1 and t-PA concentrations, and PAI-1 activity, as well as a significant decrease in t-PA activity during the postprandial period. Interestingly, PAI-1 concentration and activity increased more following the high (n-3)LCPUFA compared with the low (n-3)LCPUFA beverage (P < 0.05). Furthermore, the high (n-3)LCPUFA beverage resulted in a lower t-PA activity (P < 0.05), whereas the effects of the 2 fat loads on the plasma t-PA concentration and platelet aggregation did not differ. Overall, acute intake of a high (n-3)LCPUFA beverage shifted the balance between plasma PAI-1 and t-PA, which might indicate a lower capacity for fibrinolysis.

Omega-3 fatty acids and cognitive function in women

Omega-3 fatty acids (FAs) could play an important role in maintaining cognitive function in aging individuals. The omega-3 FA docosahexaenoic acid is a major constituent of neuronal membranes and, along with the other long-chain omega-3 FAs from fish such as eicosapentaentoic acid, has been shown to have a wide variety of beneficial effects on neuronal functioning, inflammation, oxidation and cell death, as well as on the development of the characteristic pathology of Alzheimer's disease. Omega-3 FAs may prevent vascular dementia via salutary effects on lipids, inflammation, thrombosis and vascular function. Epidemiologic studies have generally supported a protective association between fish and omega-3 FA levels and cognitive decline. Some of the small, short-term, randomized trials of docosahexaenoic acid and/or eicosapentaentoic acid supplementation have found positive effects on some aspects of cognition in older adults who were cognitively intact or had mild cognitive impairment, although little effect was found in participants with Alzheimer's disease. Large, long-term trials in this area are needed.

Anticoagulant Effect of Dietary Fish Oil in Hyperlipidemia

Objective— In hyperlipidemia, dietary fish oil containing n-3 polyunsaturated fatty acids (PUFA) provokes plasma triacylglycerol lowering and hypocoagulant activity. Using APOE2 knock-in mice, the relation of these fish-oil effects with altered gene expression was investigated.

Methods and Results— Male APOE2 knock-in mice, fed regular low-fat diet, had elevated plasma levels of triacylglycerol and coagulation factors. Plasma lipids and (anti)coagulant factors reduced on feeding the mice with fish oil (n-3 PUFA) or, to a lesser degree, with sunflowerseed oil (n-6 PUFA). The fish-oil diet provoked a 40% reduction in thrombin generation. Microarray (Affymetrix) and single-gene expression analysis of mouse livers showed that fish oil induced: (1) upregulation of genes contributing to lipid degradation and oxidation; (2) downregulation of genes of γ-glutamyl carboxylase and of transcription factors implicated in lipid synthesis; (3) unchanged expression of coagulation factor genes. After fish-oil diet, vitamin K–dependent coagulation factors accumulated in periportal areas of the liver; prothrombin was partly retained in uncarboxylated form. Only part of the changes in gene expression were different from the effects of sunflowerseed oil diet.

Conclusions— The hypocoagulant effect of n-3 PUFA is not caused by reduced hepatic synthesis of coagulation factors, but rather results from retention of uncarboxylated coagulation factors. In contrast, the lipid-lowering effect of n-3 PUFA links to altered expression of genes that regulate transcription and fatty acid metabolism.

Fatty acids, lipid metabolism and Alzheimer pathology

Alzheimer's disease is the most common form of dementia in the elderly. The cause of Alzheimer's disease is still unknown and there is no cure for the disease yet despite 100 years of extensive research. Cardiovascular risk factors such as high serum cholesterol, presence of the Apolipoprotein epsilon4 (APOE epsilon4) allele and hypertension, play important roles in the development of Alzheimer's disease. We postulate that a combination of diet, lifestyle, vascular, genetic, and amyloid related factors, which enhance each other's contribution in the onset and course of Alzheimer's disease, will be more likely the cause of the disease instead of one sole mechanism. The possibility that the risk for Alzheimer's disease can be reduced by diet or lifestyle is of great importance and suggests a preventative treatment in Alzheimer's disease. Because of the great importance of lipid diets and metabolism in preventative treatment against both Alzheimer's disease and cardiovascular disease, long-chain polyunsaturated fatty acids from fish oil, ApoE genotype and cholesterol metabolism in correlation with Alzheimer's disease will be reviewed.

Dietary fat and plasma total homocysteine concentrations in 2 adult age groups: the Hordaland Homocysteine Study

BACKGROUND

The intake of n-3 (formerly called omega-3) fatty acids (FAs) may be inversely associated with plasma total homocysteine (tHcy) concentrations, but the epidemiologic data are sparse.

OBJECTIVE

We examined the association between dietary fat and tHcy in a Norwegian population.

DESIGN

A cross-sectional, population-based study of 5917 subjects in 2 age groups (47-49 and 71-74 y old) was conducted with the use of food-frequency questionnaires and measurement of plasma tHcy concentrations.

RESULTS

The intake of saturated FAs (SFAs) was positively and significantly (P for trend < 0.001) associated with tHcy concentrations; the difference in plasma tHcy concentrations between the highest and lowest quartiles of SFAs was 8.8%. The intake of marine very-long-chain n-3 FAs was inversely associated with tHcy concentrations; the difference in plasma tHcy concentrations between the lowest and the highest quartiles was -5.0% (P for trend < 0.001). Intakes of total and monounsaturated fat also were positively associated with plasma tHcy concentrations (P for trend < 0.001 and < 0.005, respectively), whereas the intake of polyunsaturated fat was positively associated with tHcy concentrations only in the younger subjects (P for trend = 0.03). The associations were weakened by additional adjustment for B vitamin intake but remained significant for SFA intake (P < 0.001). When stratified for total B vitamin intake, the inverse association between tHcy concentrations and very-long-chain n-3 FAs was significant only in the highest quartile of B vitamin intake (P for trend = 0.001), regardless of supplement use.

CONCLUSIONS

High intakes of SFAs are associated with high plasma concentrations of tHcy. The inverse association between dietary intakes of very-long-chain n-3 FAs and plasma tHcy concentrations is apparent only at high B vitamin intakes.

Platelet phospholipid n-3 PUFA negatively associated with plasma homocysteine in middle-aged and geriatric hyperlipaemia patients

Studies showed that increased dietary intake of n-3 polyunsaturated fatty acids (PUFA) has a cardiovascular beneficial effect. Increased plasma phospholipid (PL) docosahexaenoic acid (22:6n-3) is associated with decreased plasma homocysteine (Hcy). The aim of this study was to investigate the relationship between platelet PL fatty acid and plasma Hcy in middle-aged and geriatric hyperlipaemia patients (50 males, 31 females) and 65 healthy subjects (43 males, 22 females) in Hangzhou, China. Plasma Hcy demonstrated significant positive correlation with adrenic acid (22:4n-6) (r = 0.188, P = 0.018) and negative correlation with 22:6n-3 (r = -0.277, P = 0.001) and the ratio of n-3/n-6 (r = -0.231, P = 0.003) in sex-, age- and BMI-controlled partial correlation analysis. The present results suggest that increased ratio of n-3/n-6 PUFA in platelet PL is associated with decreased thrombotic risks such as plasma Hcy in middle-aged and geriatric hyperlipaemia patients in Hangzhou.

Long-chain n-3 fatty acid supplementation in men increases resistance to activated protein C

It has recently and controversially been demonstrated that fish oil supplementation may not be beneficial for everyone, but to date there have been no biological explanations. We suggest that resistance to the anticoagulant, activated protein C (APC), be considered as a potential mechanism, because it has been demonstrated that the type of fatty acids on phospholipids modulates function of the APC pathway. The APC ratio in plasma was decreased by 7% after fish oil supplementation in healthy men (P<.005; n=35). The decrease in APC ratio equates to an increase in APC resistance. Fish oil lowered the APC ratio by (1) increasing low-density lipoprotein (LDL) cholesterol (P<.01) and apolipoprotein B (P<.05) and (2) increasing platelet microparticles (P<.05). In vitro, purified LDL decreased the APC ratio and increased microparticle formation. These changes affecting the anticoagulant APC could contribute toward a prothrombotic state, potentially explaining the recent observation that fish oil supplementation may not always be of benefit. These findings will need to be repeated in different disease states.

Antiatherosclerotic and antithrombotic effects of omega-3 fatty acids

Omega-3 fatty acids from both marine and plant sources have been shown to reduce the risk of coronary artery disease death. Although their beneficial cardiovascular effects are thought to be due to their antiarrhythmic properties, omega-3 fatty acids also have been shown to have a wide range of antiatherosclerotic and antithrombotic effects in animal and human studies. Review of the findings of randomized, controlled trials published through August 2005 shows that omega-3 fatty acids of marine origin consistently lower elevated plasma triglyceride levels in a dose-dependent fashion, with greater efficacy at higher triglyceride levels. Smaller effects on lowering blood pressure, improving endothelial function, and increasing plasma levels of high-density lipoprotein cholesterol were also found. No consistent effects on other lipid, hemostatic, inflammatory, glucose tolerance, or plaque stabilization parameters were found. Epidemiologic studies show more consistent reductions in the incidence of nonfatal myocardial infarction and ischemic stroke than do the clinical trials of increased omega-3 fatty acid intake, which suggests important confounding factors in observational studies. Ongoing clinical trials may clarify the non-antiarrhythmic benefits of omega-3 fatty acid supplementation.

A significant inverse relationship between concentrations of plasma homocysteine and phospholipid docosahexaenoic acid in healthy male subjects

The aim of this study was to investigate the possibility of a relationship between plasma homocysteine (Hcy) and phospholipid FA (PUFA) in healthy Australian males. One hundred thirty six healthy male subjects aged 20-55 yr were recruited from the Melbourne metropolitan area. Each volunteer completed a semiquantitative food frequency questionnaire and gave a blood sample. Plasma Hcy concentrations were determined by an established HPLC method; the plasma phospholipid FA were determined by standard methods. Plasma Hcy concentration was significantly negatively correlated with plasma phospholipid concentration of the PUFA 20:5n-3 (r = -0.226, P = 0.009), 22:5n-3 (r= -0.182, P= 0.036), 22:6n-3 (r= -0.286, P= 0.001), total n-3 (r = -0.270, P = 0.002) and the ratio n-3/n-6 PUFA (r = -0.265, P = 0.002), and significantly positively correlated with 20:4n-6 (r= 0.180, P= 0.037). In the partial correlation analysis, after controlling for serum vitamin B12 and folate concentration, plasma Hcy was significantly negatively correlated with the plasma phospholipid concentration of 22:6n-3 (r = -0.205, P = 0.019), total n-3 (r = -0.182, P= 0.038) and the ratio n-3/n-6 PUFA (r= -0.174, P= 0.048). Evidence indicates that an increased concentration of n-3 PUFA in tissues has a beneficial effect on cardiovascular health. Our findings provide further evidence that increased consumption of dietary n-3 PUFA increases the concentration of n-3 PUFA in plasma phospholipid, which is associated with a protective effect on cardiovascular diseases and lower plasma Hcy levels. The mechanism that might explain the association between plasma 22:6n-3 and Hcy levels is not clear.

N-3 fatty acid supplementation decreases plasma homocysteine in diabetic dyslipidemia treated with statin–fibrate combination

The aim of this study was to study the effect of adding polyunsaturated fatty acid (PUFA) n-3 or placebo (containing oleic acid) to a combined statin-fibrate treatment on plasma lipoproteins, lipoperoxidation, glucose homeostasis, total homocysteine (tHcy) and microalbuminuria (MA) in patients with diabetic dyslipidemia (DDL). Twenty-four patients, who did not fulfill the recommended target lipid values with combined hypolipidemic therapy (pravastatin 20 mg+micronized fenofibrate 200 mg daily), were supplemented with 3.6 g PUFA n-3 daily for 3 months or placebo (olive oil) for the next 3 months. The concentrations of plasma lipids, fatty acid (FA) profiles of phosphatidylcholine (PC), cholesteryl esters (CE) and triglycerides (TG), tHcy levels, concentrations of conjugated dienes (CD) in low-density lipoprotein (LDL), and MA were determined in baseline state, after the PUFA n-3 and placebo treatment period. Supplementation with PUFA n-3 led to a significant decrease in plasma tHcy (-29%, P < .01) and TG (-28%, P < .05) levels, as well as to a significant decrease in MA (-24%, P < .05). The decrease in MA correlated significantly with the increase in total PUFA n-3 (r = -.509, P < or = .05) and docosahexaenoic acid (r = -.52, P < .01) in TG. The concentrations of CD in LDL increased significantly (+15%, P < .05). The supplementation with PUFA n-3 to the combined statin-fibrate treatment in patients with DDL decreased the TG and tHcy levels as well as MA. It could lead to decreased risk of atherothrombosis and delay of diabetic nephropathy onset and progression.

Effects of alpha-linolenic acid versus those of EPA/DHA on cardiovascular risk markers in healthy elderly subjects

OBJECTIVE

To compare the effects of alpha-linolenic acid (ALA, C18:3n-3) to those of eicosapentaenoic acid (EPA, C20:5n-3) plus docosahexaenoic acid (DHA, C22:6n-3) on cardiovascular risk markers in healthy elderly subjects.

DESIGN

A randomized double-blind nutritional intervention study.

SETTING

Department of Human Biology, Maastricht University, the Netherlands.

SUBJECTS

Thirty-seven mildly hypercholesterolemic subjects, 14 men and 23 women aged between 60 and 78 years.

INTERVENTIONS

During a run-in period of 3 weeks, subjects consumed an oleic acid-rich diet. The following 6 weeks, 10 subjects remained on the control diet, 13 subjects consumed an ALA-rich diet (6.8 g/day) and 14 subjects an EPA/DHA-rich diet (1.05 g EPA/day + 0.55 g DHA/day).

RESULTS

Both n-3 fatty acid diets did not change concentrations of total-cholesterol, LDL-cholesterol, HDL-cholesterol, triacylglycerol and apoA-1 when compared with the oleic acid-rich diet. However, after the EPA/DHA-rich diet, LDL-cholesterol increased by 0.39 mmol/l (P = 0.0323, 95% CI (0.030, 0.780 mmol/l)) when compared with the ALA-rich diet. Intake of EPA/DHA also increased apoB concentrations by 14 mg/dl (P = 0.0031, 95% CI (4, 23 mg/dl)) and 12 mg/dl (P = 0.005, 95% CI (3, 21 mg/dl)) versus the oleic acid and ALA-rich diet, respectively. Except for an EPA/DHA-induced increase in tissue factor pathway inhibitor (TFPI) of 14.6% (P = 0.0184 versus ALA diet, 95% CI (1.5, 18.3%)), changes in markers of hemostasis and endothelial integrity did not reach statistical significance following consumption of the two n-3 fatty acid diets.

CONCLUSIONS

In healthy elderly subjects, ALA might affect concentrations of LDL-cholesterol and apoB more favorably than EPA/DHA, whereas EPA/DHA seems to affect TFPI more beneficially.

Evidence for a protective (synergistic?) effect of B-vitamins and omega-3 fatty acids on cardiovascular diseases

The results of dietary intervention trials favor the hypothesis that higher intakes of B-vitamins (folate, vitamin B(6) and B(12)), and subsequently lower total homocysteine (tHcy) concentrations, are causally associated with a decreased risk of vascular disease in patients with cardiovascular diseases (CVD). The same is true for a higher intake of omega-3 fish fatty acids. Yet, the lack of hard end points and/or appropriate study designs precludes a definitive conclusion about causality. In the future, intervention trials with hard end points and randomized double-blind placebo-controlled designs should be able to elucidate the causality problem. There are several pathways by which B-vitamins and omega-3 fatty acids may exert their protective effect on CVD, a common pathway is a beneficial effect on the endothelial function and hemostasis. With respect to synergy between B-vitamins and omega-3 fatty acids, there is no evidence that fish oils have a tHcy-lowering effect beyond the effect of the B-vitamins. Nevertheless, animal studies clearly illustrate that vitamin B(6)- as well as folate-metabolism are linked with those of long-chain omega-3 fatty acids. Furthermore, a human study indicated synergistic effects of folic acid (synthetic form of folate) and vitamin B(6) together with omega-3 fatty acids on the atherogenic index and the fibrinogen concentration. Although these results are promising, they were produced in very small selective study populations. Thus, confirmation in large well-designed intervention trials is warranted.

Consumption of an oil composed of medium chain triacyglycerols, phytosterols, and N-3 fatty acids improves cardiovascular risk profile in overweight women

Medium chain triacylglycerols (MCT) have been suggested as efficacious in weight management because they possess greater thermogenic qualities relative to long chain triacylglycerols; however, MCT may also increase circulating lipid concentrations, possibly increasing risk of cardiovascular disease (CVD). The present objective was to examine the effect of a diet supplemented with a functional oil (FctO) composed of energy expenditure-enhancing MCT (50% of fat), cholesterol-lowering phytosterols (22 mg/kg body weight), and triacylglycerol-suppressing n-3 fatty acids (5% of fat), versus a beef tallow-based diet (BT), on plasma lipid and aminothiol concentrations. In a randomized, single-blind, crossover design, partially-inpatient trial, 17 overweight women consumed each oil as part of a controlled, supervised, targeted energy balance diet for 27 days, with 4 or 8 weeks of washout between phases. Mean plasma total cholesterol concentration was lower (P <.0001), by 9.1%, on FctO (4.37 +/- 0.20 mmol/L) versus BT (4.80 +/- 0.20 mmol/L). Mean plasma low-density lipoprotein (LDL) cholesterol was also lower (P <.0001) following FctO (2.39 +/- 0.15 mmol/L) versus BT (2.86 +/- 0.16 mmol/L), representing a 16.0% difference between diets. High-density lipoprotein (HDL) cholesterol and circulating triacylglycerol concentrations remained unaffected by treatment. Ratios of HDL:LDL and HDL:total cholesterol were higher (P <.01) by 22.0% and 11.0%, respectively, on FctO versus BT. Plasma total homocysteine remained unchanged with FctO, but decreased (P <.05) with control, hence higher (P <.05) end points were observed with FctO (6.95 +/- 0.33 micromol/L) versus BT (6.27 +/- 0.28 micromol/L). Plasma glutathione increased (P <.05) by 0.44 micromol/L with FctO supplementation. In conclusion, despite equivocal effects on homocysteine levels, consumption of a functional oil composed of MCT, phytosterols, and n-3 fatty acids for 27 days improves the overall cardiovascular risk profile of overweight women.

Serum fatty acid levels, dietary style and coronary heart disease in three neighbouring areas in Japan: the Kumihama study

CHD mortality is extremely low in Japan, particularly in rural districts, when compared with that in Western countries. This has been partly attributed to the difference in dietary lifestyle. We investigated the factors influencing CHD mortality in a rural coastal district of Japan, comprising mercantile, farming, and fishing areas with distinct dietary habits. We prospectively examined the incidence of CHD from 1994 to 1998, as well as coronary risk factors and serum fatty acid concentrations. The incidence of angina pectoris was significantly (P=0.01) lower in the fishing area than in the mercantile and farming areas. Blood pressure, physical activity, prevalence of diabetes, serum levels of uric acid and HDL-cholesterol were similar between the three areas. Total- and LDL-cholesterol levels were significantly lower but the smoking rate was markedly higher in the fishing area than in the other two areas. Serum levels of saturated fatty acids and n-6 polyunsaturated fatty acids (PUFA) were lowest in the fishing area, but n-3 PUFA did not differ significantly. The n-6:n-3 PUFA ratio was lowest and eicosapentaenoic:arachidonic acid was highest in the fishing area. Although many previous studies have emphasized the beneficial effect of n-3 PUFA in preventing CHD, the present study indicated that a lower intake of n-6 PUFA and saturated fatty acids has an additional preventive effect on CHD even when the serum level of n-3 PUFA is high because of high dietary fish consumption.

Effect of fish oil on LDL oxidation and plasma homocysteine concentrations in health

Oxidation of low-density lipoprotein (LDL) and hyperhomocysteinemia are believed to play a role in therogenesis. Whether n-3 polyunsaturated fatty acids increase LDL susceptibility to oxidation or influence homocysteine (Hcy) metabolism has long been a subject of controversy. In this study, we evaluated the effect of 8 weeks of dietary supplementation with 6 g/day of fish oil (FO; 3 g of n-3 fatty acids) on plasma lipoproteins, in vitro LDL peroxidation, antioxidant status, and plasma Hcy concentrations in 16 normolipidemic subjects. FO rapidly and significantly (P < .01) decreased plasma total and very low density lipoprotein triglyceride concentrations and had no effect on LDL or high-density-lipoprotein cholesterol. The mean lag time before onset of Cu(2+)-induced LDL oxidation, as well as plasma and LDL alpha-tocopherol and beta-carotene concentrations, was unchanged. However, changes in plasma aminothiol concentrations occurred during the study. Specifically, a progressive and significant increase in total Hcy plasma concentrations was observed (13.4% and 20% after 4 and 8 weeks, respectively; P < .01). Total glutathione concentrations were significantly higher after 8 weeks (P < .05). The tHcy increase was not associated with changes in plasma folate or vitamin B(12) concentrations. However, concentrations of plasma nitric oxide metabolites (NO(x) = NO(2) + NO(3)) were significantly higher than at baseline after 8 weeks of FO intake (74%; P < .01). Further, the changes in total Hcy and NO(x) plasma concentrations observed after 8 weeks of FO were found to be significantly correlated (r = .78, P < .001). With this study, we report for the first time the apparent interaction of n-3 fatty acids and nitric oxide on Hcy metabolism.

Dietary supplements

The amount of published information on dietary supplements mushroomed in the 1990s. In fewer than 5 years, publications increased at least 100-fold in the medical literature alone. Dietary supplements are an uncharted territory that warrants complete and accurate exploration. One should not be surprised that disease and illness may respond to dietary supplements. Nutrition is the foundation to good health, and dietary supplements may prove to be some of the most powerful medicines ever discovered. An especially exciting discovery is that dietary supplements may enhance the effects of specific drugs. This discovery may lead to more effective and safer protocols for the treatment of cancer, heart and lung disease, and a host of chronic medical conditions. Information about dietary supplements is becoming more common in the popular medical literature and is creating increased curiosity and an increased awareness. The explosion of the dietary supplement market is compelling physicians to become aware of dietary supplements. Whether or not they are used in clinical practice is a decision for the individual physician. Given the increasing number of patients who are using dietary supplements, however, it is imperative that physicians have a good understanding of this topic. Considering the increasing complexity and magnitude of this topic, physician specialization may be essential. There are many good reference books, review articles, and internet sites on specific supplements that probably should be part of every physician's reference library. The accompanying box provides a brief list of such sources.

Fats, lipids and blood coagulation

Saturated and n-3 fatty acids, postprandial lipaemia, and the combined effects of fatty acids and lipid-lowering drugs have been of principal interest in recent studies in the field of dietary fats, lipids and haemostasis. The sex-specific effect of individual saturated fatty acids on coagulation factor VII activity has been discovered, and the significant effect of factor VII R353Q polymorphism on the postprandial response has also been found. An increased intake of n-3 fatty acids or fat reduction when combined with intensive lifestyle interventions may lead to reduced thrombotic potential in type 2 diabetic patients and obese individuals. Furthermore, positive effects on haemostasis by combined treatment with long-chain n-3 fatty acids and simvastatin indicate that n-3 fatty acids may be of some relevance with lipid-lowering drugs. The possible unfavourable effect of n-3 fatty acids on plasminogen activator inhibitor-1 activity is still a matter of dispute, but recent studies suggest that n-3 fatty acids, including alpha-linolenic acid, may have antithrombotic effects by enhancing protein C activity.