Essential fatty acids and cardiovascular disease: the Edinburgh Artery Study

The aim of this study was to determine whether plasma and red cell fatty acid levels were associated with cardiovascular disease, and whether any association was independent of other major risk factors. Over 1100 subjects were examined in a random sample survey of the general population (the Edinburgh Artery Study). Fatty acids were measured in three plasma fractions (triglyceride, cholesteryl ester and phospholipid) and in red cell phospholipids. Fatty acid levels in groups with cardiovascular disease (myocardial infarction (MI), angina and lower limb disease) were compared with a no disease group. In the cholesteryl ester and phospholipid fractions there were significantly lower levels of eicosapentaenoic acid in the MI group on univariate analysis (p<0.05), but not when adjusted for age, sex, smoking and systolic blood pressure using logistic regression. In the red cell fraction, alpha-linolenic acid was significantly lower in those with stroke (p<0.01) and lower limb disease (p<0.05). Linoleic acid was significantly raised in the triglyceride fraction in those with MI, probably reflecting recent dietary changes. There were significant increases in dihomo-gamma-linolenic acid in the phospholipid and red cell fractions in those with MI, and in the phospholipid fraction in the stroke group. These results do not support the hypothesis that n-6 fatty acids are protective against cardiovascular disease, although there may be some beneficial effects of the n-3 fatty acid, alpha-linolenic acid. Results from cross-sectional surveys must, however, be interpreted with caution because the presence of disease may affect dietary intake.

Omega-3 polyunsaturated fatty acid levels in the diet and in red blood cell membranes of depressed patients

BACKGROUND

There is a hypothesis that lack of n-3 polyunsaturated fatty acids (PUFAs) is of aetiological importance in depression. Docosahexaenoic acid, a member of the n-3 PUFA family, is a crucial component of synaptic cell membranes. The aim of this study was to measure RBC membrane fatty acids in a group of depressed patients relative to a well matched healthy control group.

METHOD

Red blood cell (RBC) membrane levels, and dietary PUFA intake were measured in 10 depressed patients and 14 matched healthy control subjects.

RESULTS

There was a significant depletion of RBC membrane n-3 PUFAs in the depressed subjects which was not due to reduced calorie intake. Severity of depression correlated negatively with RBC membrane levels and with dietary intake of n-3 PUFAs.

CONCLUSION

Lower RBC membrane n-3 PUFAs are associated with the severity of depression.

LIMITATIONS

Although patient numbers were small, confounding factors were well controlled for and the results were highly significant. Results of the dietary data would tend to be weakened due to the limitations associated with dietary assessment.

CLINICAL RELEVANCE

The findings raise the possibility that depressive symptoms may be alleviated by n-3 PUFA supplementation.

Depletion of omega-3 fatty acid levels in red blood cell membranes of depressive patients

BACKGROUND

It has been hypothesized that depletion of cell membrane n3 polyunsaturated fatty acids (PUFA), particularly docosahexanoic acid (DHA), may be of etiological importance in depression.

METHODS

We measured the fatty acid composition of phospholipid in cell membranes from red blood cells (RBC) of 15 depressive patients and 15 healthy control subjects.

RESULTS

Depressive patients showed significant depletions of total n3 PUFA and particularly DHA. Incubation of RBC from control subjects with hydrogen peroxide abolished all significant differences between patients and controls.

CONCLUSIONS

These findings suggest that RBC membranes in depressive patients show evidence of oxidative damage. Possible interpretations, and implications for the etiology and treatment of depression, are discussed.

Randomized controlled trial of antioxidants in intermittent claudication

Epidemiological evidence suggests that antioxidants protect against the development of atherosclerosis. To determine the effectiveness of antioxidant therapy in patients with lower limb atherosclerosis, a randomized placebo-controlled trial was performed in 120 men and women with intermittent claudication and an ankle/brachial pressure index (ABPI) < or = 0.9. The study was analysed on an intention-to-treat basis. After 2 years, there were no significant differences between antioxidant and placebo groups in plasma cholesterol, lipoproteins, haemostatic or rheological factors. However, after 6 months, low density lipoprotein cholesterol was significantly lower in those taking antioxidant (108.0 mg/dl compared with 120.1 mg/dl, p < 0.05). There were no differences in the ABPI or walking distance, although both groups improved slightly with time. The incidence of cardiovascular events and death was nonsignificantly lower in the antioxidant compared with the placebo group: event rates per year were 5.5% (95% CI 2.4-8.6) in the first year and 9.6% (95% CI 6.8-12.4) in the second year for those on antioxidants; and 7.7% (95% CI 5.1-10.3) and 13.3% (95% CI 8.9-17.7) respectively for those on placebo. Significantly fewer serious adverse events occurred in the antioxidant than the placebo group: 21.8% (95% CI 16.2-27.4) compared with 40.0% (95% CI 33.9-46.1). This study therefore suggests that although antioxidants may prevent cardiovascular events in patients with peripheral atherosclerosis, they do not improve lower limb function.

Alterations in plasma lipids, lipoproteins and high density lipoprotein subfractions in peripheral arterial disease

The concentrations of the major lipoprotein classes and of high density lipoprotein (HDL) subfractions in 63 male patients with arteriosclerosis of the lower limbs (claudication) were determined and compared with values from 63 healthy controls. The patients with peripheral arterial disease (PAD) had reduced levels of total HDL-cholesterol and HDL2b of large particle size, increased levels of small HDL3c particles and a high ratio of total plasma-cholesterol to HDL-cholesterol (coronary risk factor). The PAD patients, however, had lower levels of low density lipoprotein (LDL)-cholesterol but higher concentrations of very low density lipoprotein (VLDL)-cholesterol and plasma triglyceride than healthy subjects. This study therefore suggests that in PAD, the protective effect of HDL may be more important than the atherogenic effect of LDL. It further suggests that while HDL-cholesterol HDL2b and the ratio of total plasma-cholesterol to HDL-cholesterol may provide valid indices for identifying individuals at risk of PAD, other factors, such as LDL and total cholesterol, may not provide such an appropriate risk indicator.

In vivo and in vitro biotransformation of the lithium salt of gamma-linolenic acid by three human carcinomas

Lipid metabolism has been considered recently as a novel target for cancer therapy. In this field, lithium gamma-linolenate (LiGLA) is a promising experimental compound for use in the treatment of human tumours. In vivo and in vitro studies allowed us to assess the metabolism of radiolabelled LiGLA by tumour tissue and different organs of the host. In vitro studies demonstrated that human pancreatic (AsPC-1), prostatic (PC-3) and mammary carcinoma (ZR-75-1) cells were capable of elongating GLA from LiGLA to dihomo-gamma-linolenic acid (DGLA) and further desaturating it to arachidonic acid (AA). AsPC-1 cells showed the lowest delta5-desaturase activity on DGLA. In the in vivo studies, nude mice bearing the human carcinomas were given Li[1-(14)C]GLA (2.5 mg kg(-1)) by intravenous injection for 30 min. Mice were either sacrificed after infusion or left for up to 96 h recovery before sacrifice. In general, the organs showed a maximum uptake of radioactivity 30 min after the infusion started (t = 0). Thereafter, in major organs the percentage of injected radioactivity per g of tissue declined below 1% 96 h after infusion. In kidney, brain, testes/ovaries and all three tumour tissues, labelling remained constant throughout the experiment. The ratio of radioactivity in liver to tumour tissues ranged between 16- and 24-fold at t = 0 and between 3.1- and 3.7-fold at 96 h. All tissues showed a progressive increase in the proportion of radioactivity associated with AA with a concomitant decrease in radiolabelled GLA as the time after infusion increased. DGLA declined rapidly in liver and plasma, but at a much slower rate in brain and malignant tissue. Seventy-two hours after the infusion, GLA was only detected in plasma and tumour tissue. The sum of GLA + DGLA varied among tumour tissues, but it remained 2-4 times higher than in liver and plasma. In brain, DGLA is the major contributor to the sum of these fatty acids. Data showed that cytotoxic GLA and DGLA, the latter provided either by the host or by endogenous synthesis, remained in human tumours for at least 4 days.

Inhibition of membrane ruffling and ezrin translocation by gamma linolenic acid

Membrane ruffling of a tumour cell is correlated with its motile and metastatic behaviour. This study examined the effect of gamma linolenic acid (GLA), an anti-cancer agent, on HGF/SF induced membrane ruffling in the human cancer cell line, HT115. HGF induced a rapid appearance of membrane ruffling which was related to increased motility and the tyrosine phosphorylation and translocation of ezrin, a membrane-cytoskeleton linker protein. The presence of GLA significantly inhibited both the membrane ruffling and cell motility of the tumour cells, at sub-toxic concentrations. Western blotting revealed that the tyrosine phosphorylation of ezrin was inhibited by GLA. The translocation ezrin from cytosol and generalised areas of cell membrane to ruffled areas of the membrane induced by HGF/SF was also inhibited as shown by both indirect immunofluorescence and transmission electron microscopy. It is concluded that GLA inhibits HGF/SF induced membrane ruffling via its effect on ezrin, and this provides a further molecular explanation for the anti-tumour action of GLA.

Gamma linolenic acid inhibits tyrosine phosphorylation of focal adhesion kinase and paxillin and tumour cell matrix interaction

Gamma linolenic acid (GLA) is an anti-cancer agent recently reported to inhibit tumour cell-matrix attachment. This study examined the effects of GLA on the adhesion of two tumour cell lines, HT115 (human colon) and MDA MB 231 (human breast), to an extracellular matrix, Matrigel. The action of GLA on focal adhesion kinase(FAK) and paxillin was also investigated. Following cell adhesion to Matrigel in control experiments, both FAK and paxillin were quickly tyrosine phosphorylated and become concentrated at focal adhesion areas. Inclusion of GLA resulted in an inhibition of the tyrosine phosphorylation of both FAK and paxillin leading to a reduced attachment of both cell types to Matrigel. FAK and paxillin were also less well distributed in the focal adhesions compared with the controls. It is concluded, therefore, that GLA inhibits tumour-matrix adhesion via the inhibition of FAK and paxillin tyrosine phosphorylation.

Depleted red cell membrane essential fatty acids in drug-treated schizophrenic patients

The fatty acid composition of red blood cell membranes from 23 drug-treated schizophrenic patients was measured and compared with a healthy control group. There were substantial depletions of fatty acids from the n6 and n3 series, particularly arachidonic and docosahexanoic acid. Significant negative correlations between depleted n6 fatty acids and plasma levels of thiobarbituric acid reactive substances suggests that depletion is caused by increased breakdown of these fatty acids rather than by impaired incorporation of fatty acids into membranes. Arachidonic and docosahexanoic acids appear to show a bimodal distribution. We propose that this may be a metabolic abnormality which is of aetiological importance in schizophrenia.

Modulation of cytokine production in vivo by dietary essential fatty acids in patients with colorectal cancer

1. The effects of essential fatty acids (gamma-linolenic acid, eicosapentaenoic acid, docosahexaenoic acid), at a dose of 4.8 g/day, given in combination as dietary supplements, on cytokine production were investigated in patients with colorectal cancer. 2. Total serum cytokines--interleukin (interleukin-1 beta, 2, 4 and 6), tumour necrosis factor-alpha and interferon-gamma--were analysed using the enzyme-linked immunosorbent assay technique at different time intervals during the course of essential fatty acid supplementation. 3. Fatty acid uptake and patient compliance were confirmed by a significant increase in serum levels of gamma-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid in all three fractions: tricylglycerol, cholesterol and phospholipid. 4. There was no significant alteration in total serum cytokine concentration/levels in the first 2 months of essential fatty acid ingestion, but the levels of serum cytokines steadily declined thereafter, reaching minimum levels after 6 months of essential fatty acid supplementation. 5. Essential fatty acids, at the dose and duration (6 months) used in this study, reduced total serum interleukin-1 beta levels by 61% (P = 0.044), interleukin-2 by 63% (P = 0.05), interleukin-4 by 69% (P = 0.025), interleukin-6 by 83% (P = 0.030), tumour necrosis factor-alpha by 73% (P = 0.040) and interferon-gamma by 67% (P = 0.050). 6. Three months after cessation of essential fatty acid intake, however, these cytokine levels returned to presupplementation values. 7. This present study has shown that long-term n-3 and n-6 EFA ingestion results in a significant reduction in circulating key cytokines. The precise mechanism of this reduction is unclear.

Lithium gamma-linolenate-induced cytotoxicity against cells chronically infected with HIV-1

Lithium gamma-linolenate (Li-GLA), was evaluated for its activity in selectively killing H9 cells chronically infected with HIV-1RF. After 4 days incubation with Li-GLA approximately 90% of the H9RF cells were non-viable compared to 20% of uninfected H9 cells. The efficacy of the Li-GLA, in preferentially killing HIV infected cells also correlates with lipid peroxidation, as measured by the intracellular thiobarbituric acid-reactive material content. The addition of an antioxidant (vitamin E) to the culture medium reduced the toxicity of Li-GLA. These data indicate that this selective killing effect of cells chronically infected with HIV may be due to the enhanced extent of lipid peroxidation of the added Li-GLA.

Intracellular free Fatty-Acid release and lipid-peroxidation in cultured human breast-cancer cells in response to gamma-linolenic Acid with iron (gla + fe)

Intracellular free fatty acid (FFA) release and peroxidation of polyunsaturated fatty acid (PUFA) were studied in cultured human breast cancer cells (ZR-75-1) exposed to gamma-linolenic acid with iron (GLA + Fe). This treatment results in cell death. Increased intracellular FFA were observed in association with both the accelerated peroxidation of PUFA and the killing effect. Vitamin E reduced all three effects. The FFA were methyl esterified and analyzed by gas chromatography-mass spectrometry. The identified FFAs were 16: 0, 18: 3, 20: 3 and 20: 4 (numbers of carbons and double bonds indicated). These results suggest an association of intracellular FFA release with the peroxidation of PUFA and the cancer cell-killing by GLA in the presence of iron.

Effect of high doses of essential fatty acids on the postviral fatigue syndrome

Sixty-three adults with the diagnosis of the postviral fatigue syndrome were enrolled in a double-blind, placebo-controlled study of essential fatty acid therapy. The patients had been ill for from one to three years after an apparently viral infection, suffering from severe fatigue, myalgia and a variety of psychiatric symptoms. The preparation given contained linoleic, gamma-linolenic, eicosapentaenoic and docosahexaenoic acids and either it, or the placebo, was given as 8 x 500 mg capsules per day over a 3-month period. The trial was parallel in design and patients were evaluated at entry, one month and three months. In consultation with the patient the doctors assessed overall condition, fatigue, myalgia, dizziness, poor concentration and depression on a 3-point scale. The essential fatty acid composition of their red cell membrane phospholipids was analysed at the first and last visits. At 1 month, 74% of patients on active treatment and 23% of those on placebo assessed themselves as improved over the baseline, with the improvement being much greater in the former. At 3 months the corresponding figures were 85% and 17% (p less than 0.0001) since the placebo group had reverted towards the baseline state while those in the active group showed continued improvement. The essential fatty acid levels were abnormal at the baseline and corrected by active treatment. There were no adverse events. We conclude that essential fatty acids provide a rational, safe and effective treatment for patients with the post-viral fatigue syndrome.

Essential fatty acid supplementation during early alcohol abstinence

Interactions between ethanol, prostaglandins, and essential fatty acids (EFA) have led to the hypothesis that acute alcohol withdrawal and the sequelae of chronic alcoholism may be related to an EFA/prostaglandin deficiency. To test this hypothesis, EFA profiles in blood-lipid fractions, serum liver enzymes, cognitive function, and alcohol craving were measured in 27 acutely abstinent alcoholics before and after a 3-week double-blind trial of EFA supplementation. Upon entry into the study, alcoholics had significant differences in EFA levels as compared to normal controls, and serum levels of liver enzymes tended to correlate with these EFA levels. After 21 days, cognitive function, alcohol craving, and liver enzymes all improved in both the EFA and placebo groups; most EFA levels also approached normal values. There were no treatment effects of EFA supplementation at the dose used.

Altered arachidonic acid content in polymorphonuclear and mononuclear cells from patients with allergic rhinitis and/or asthma

We previously have found that monocytes from patients with allergic rhinitis and/or asthma produce less PGE2 than cells from normal subjects in response to a histamine-induced lymphokine. In order to investigate this observation further, we measured the fatty acid content in the total phospholipids derived from the plasma, red cells, buffy coat cells, neutrophils, monocytes and lymphocytes of 27 allergic patients and 21 normal controls. There were no substantial differences between atopics and normals in the fatty acid analyses carried out for plasma and red cells. However, linoleic acid (18:2n-6) levels were elevated significantly in the buffy coat fraction, while arachidonic acid (20:4n-6) levels were reduced. Measurement of fatty acid levels after fractionation of the buffy coat population into neutrophils and monocytes yielded similar elevations in 18:2n-6 and reduced 20:4n-6. In contrast, lymphocytes appeared to have the reverse pattern, i.e., significantly reduced 18:2n-6 and elevated 20:4n-6 levels. These data suggest that atopic leukocytes may have altered essential fatty acid metabolism.

Patients with primary Sjögren's syndrome treated for two months with evening primrose oil

Twenty-four female and 4 male patients, all fulfilling the Copenhagen criteria for primary Sjögren's syndrome (primary SS), were treated for 8 weeks with evening primrose oil (Efamol). Efamol is a seed oil which consists primarily of the n-6 essential fatty acids (EFA): cis-linoleic acid and gammalinolenic acid (GLA). The investigation was carried out as a randomized, double-blind, placebo-controlled, cross-over trial in order to determine whether long-term treatment of patients with primary SS with Efamol would improve the ocular and oral clinical status, and whether the levels of EFA in plasma and erythrocytes increase during Efamol treatment. The objective ocular status, evaluated by a combined ocular score, including the results from Schirmer-I test, break-up time and van Bijsterveld score, improved significantly during Efamol treatment when compared with Efamol start-values (p less than 0.05), but not when compared with placebo values (p less than 0.2). The GLA metabolite and prostaglandin-E1 (PGE1) precursor dihomogammalinolenic acid (20: 3n6, DGLA) increased both in plasma (p less than 0.001) and in erythrocytes (p less than 0.001) during treatment with Efamol. No correlations between objective ocular and oral status and DGLA values in plasma or erythrocytes were found.

Elevated levels of prostaglandin E2 and thromboxane B2 in depression

Plasma prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) levels were measured in 30 depressed outpatients. Plasma PGE2 was increased in all but one of these patients (p less than 0.001) and all had increased levels of TXB2 (p less than 0.001). Since monamine oxidase inhibitors inhibit brain prostaglandin synthesis, and tricyclic antidepressants may antagonize prostaglandin actions, these observations suggest new approaches to depression research.