Biological effects of fish oils in relation to chronic diseases

Lipid Peroxidation in Algae Oil: Antagonist Effects of Natural Antioxidants

Tandem mass spectrometry is proposed to check lipid oxidation, a free radical-mediated phenomenon which effects oxidative deterioration in polyunsaturated fatty acids. Antioxidants are used by the food industry to delay the oxidation process. This process can be controlled by antioxidants, which may occur as natural constituents of foods or may be intentionally added to products. Synthetic antioxidants such as BHT, BHA, and propyl gallate have been extensively used as antioxidants in the industry. The worldwide tendency to avoid or minimize the use of synthetic food additives has prompted the replacement of synthetic antioxidants with natural analogues. The entire process can be supported by the detection and characterization of the reacting species by suitable application of electrospray tandem mass spectrometry under collision-induced dissociation (ESI-CID-MS/MS). Natural antioxidants were tested in this study to check the oxidative stability of algae oil when adding the natural additive. Results were observed in algae oil in situ using electrospray mass spectrometry in tandem with collision-induced dissociation tandem mass spectrometry (ESI-CID-MS/MS) and the POBN spin trapper. The results indicate that alpha-tocopherol is a better antioxidant.

Effect of Administration of CHAGURO Made of Chayote (Sechium edule) and Tuna (Thunnus sp.) on Rats Induced with Streptozotocin-Nicotinamide and a High-Fat Diet

This study was conducted to develop Chaguro, a low-cost supplementary food made of chayote (Sechium edule (Jacq.) Swartz) and tuna fish (Thunnus sp.), for diabetes and dyslipidemia diet therapy. In order to find a formula with effective hypoglycaemic and antidyslipidemic properties, dried tuna and chayote were mixed at different ratios: F1 (75% tuna, 25% chayote), F2 (50% tuna, 50% chayote), and F3 (25% tuna, 75% chayote). Thirty male Sprague Dawley rats were assigned into healthy control group or groups induced with streptozotocin-nicotinamide and a high-fat diet. Chaguro was administered 2.7 g/ kgBW/ day using a gavage for 28 days. The administration of all Chaguro formulas improved blood markers compared to the negative control group (p < 0.001). Chaguro F2 lowered fasting blood glucose (97.07±1.18 vs 266.31±5.31), total cholesterol (113.59±2.22 vs 208.78±4.31), triglycerides (89.93±2.51 vs 142.35±2.83), LDL-c (33.87±1.87 vs 87.85±3.34) and increased HDL-c (69,08±1,85 vs 23,91±1,64) level the most compared to the negative control group (p < 0.001). Streptozotocin-induced weight loss was also prevented in all diabetic rats fed with Chaguro, with the bodyweight being similar to that of healthy controls at the end of the intervention (p < 0.001). This study found that Chaguro may be a potential food product to help lower blood glucose and improve lipid profile in diabetes and dyslipidemia.

The anti-obesity effects of a tuna peptide on 3T3-L1 adipocytes are mediated by the inhibition of the expression of lipogenic and adipogenic genes and by the activation of the Wnt/β-catenin signaling pathway

The differentiation of 3T3-L1 cells into adipocytes involves the activation of an organized system of obesity-related genes, of which those encoding CCAAT/enhancer-binding proteins (C/EBPs) and the Wnt-10b protein may play integral roles. In a previous study of ours, we found that a specific peptide found in tuna (sequence D-I-V-D-K-I-E-I; termed TP-D) inhibited 3T3-L1 cell differentiation. In the present study, we observed that the expression of expression of C/EBPs and Wnt-10b was associated with obesity. The initial step of 3T3-L1 cell differentiation involved the upregulation of C/EBP-α expression, which in turn activated various subfactors. An upstream effector of glycogen synthase kinase-3β (GSK-3β) inhibited Wnt-10b expression in 3T3-L1 adipocytes. In a previous study of ours, we sequenced the tuna peptide via sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and quadrupole time-of-flight mass spectrometry (Q-TOF MS/MS) and confirmed the anti-obesity effects thereof in 3T3-L1 adipocytes. In the present study, we demonstrate that TP-D inhibits C/EBP and promotes Wnt-10b mRNA expression, thus activating the Wnt pathway. The inhibition of lipid accumulation was measured using a glucose and triglyceride (TG) assay. Our results confirmed that TP-D altered the expression levels of C/EBP-related genes in a dose-dependent manner and activated the Wnt signaling pathway. In addition, we confirmed that total adiponectin and high-molecular weight (HMW) adiponectin levels were reduced by treatment with TP-D. These data indicate that TP-D inhibits adipocyte differentiation through the inhibition of C/EBP genes and the subsequent activation of the Wnt/β-catenin signaling pathway.

Lipid metabolism and diet: Possible mechanisms of slow aging

The ability to survive to an extremely old age is a consequence of complex interactions among genes, environment, lifestyle and luck. In the last two centuries, life expectancy in western countries has doubled, increasing from 40 to 81 years (79 for males and 82 for females). The candidate factors to determine such mortality reduction are reduced exposure to infections and the subsequent reduction in inflammatory responses, and to some extent, improvement in diet and nutrition. Among the people born at the beginning of the previous century, a small portion of individuals (1 in 10,000 born) have reached 100 years, surviving approximately 20 years more than the general population. The successful longevity of these individuals shows a familial component, possibly genetic, as underlined by the centenarian sibling's increased chance of reaching 100 years of age compared to the general population. Genetic studies on long living individuals have led to the discovery of potential genetic causes of extreme longevity. These discoveries have highlighted the role of lipid metabolism as a potential key player in the ability to survive to extreme old age. Additional studies on the longevity phenotype have confirmed the role of lipids and lipid-associated cell activities in the predisposition to longevity, from lower eukaryotes to humans. The main focus of this review is the appreciation of demographic survival data and changes in recent diet with the above mentioned genetic and phenotypic biomarkers of longevity, in order to elucidate hypotheses on mechanisms of slow aging and disease resistance.

Eicosapentaenoic fatty acid increases leptin secretion from primary cultured rat adipocytes: role of glucose metabolism

Eicosapentaenoic acid (EPA), one of the n-3 polyunsaturated fatty acids, has been shown to stimulate leptin mRNA expression and secretion in 3T3-L1 cells. However, other studies have reported inhibitory effects of EPA on leptin expression and secretion in vivo and in vitro. To determine the direct effects of EPA on basal and insulin-stimulated leptin secretion, isolated rat adipocytes were incubated with EPA in the absence and presence of insulin. EPA (10, 100, and 200 μM) increased basal leptin gene expression and secretion (+43.8%, P < 0.05; +71.1%, P < 0.01; and +73.7%, P < 0.01, respectively). EPA also increased leptin secretion in the presence of 1.6 nM insulin; however, the effect was less pronounced than in the absence of it. Because adipocyte glucose and lipid metabolism are involved in the regulation of leptin production, the metabolic effects of this fatty acid were also examined. EPA (200 μM) increased basal glucose uptake in isolated adipocytes (+50%, P < 0.05). Anaerobic metabolism of glucose, as assessed by lactate production and proportion of glucose metabolized to lactate, has been shown to be inversely correlated to leptin secretion and was decreased by EPA in both the absence and presence of insulin. EPA increased basal glucose oxidation as determined by the proportion of14C-labeled glucose metabolized to CO2. Lipogenesis (14C-labeled glucose incorporation into triglyceride) was decreased by EPA in the absence of insulin, whereas lipolysis (glycerol release) was unaffected. The EPA-induced increase of basal leptin secretion was highly correlated with increased glucose utilization ( r = +0.89, P < 0.01) and inversely related to the anaerobic glucose metabolism to lactate. EPA’s effect on insulin-stimulated leptin secretion was not related to increased glucose utilization but was inversely correlated with anaerobic glucose metabolism to lactate ( r = −0.84, P < 0.01). Together, the results suggest that EPA, like insulin, stimulates leptin production by increasing the nonanaerobic/oxidative metabolism of glucose.

Antigen-driven murine CD4+ T lymphocyte proliferation and interleukin-2 production are diminished by dietary (n-3) polyunsaturated fatty acids

This study is the first to describe the impact of consuming a diet rich in (n-3) polyunsaturated fatty acids (PUFA) from fish oil on antigen-driven activation of naive CD4+ T lymphocytes. To accomplish this, we used lymphocytes isolated from T cell receptor (TCR) transgenic mice (i.e., DO11.10). A large portion of the T lymphocytes from these mice expresses a TCR specific for a peptide within the ovalbumin (OVA) molecule (OVA(323-339)). When this antigen is presented in the context of major histocompatibility complex I-A(d) with costimulation, these naive CD4+ T cells become activated, produce interleukin (IL)-2 and clonally expand. (n-3) PUFA enrichment was accomplished by feeding DO11.10 mice one of two nutritionally complete experimental diets that differed only in the source of fat: lard or menhaden fish oil [high in (n-3) PUFA]. After 2 wk of consuming the experimental diets, lymphocytes were isolated from the spleen of each mouse, then cultured in the presence of antigen (i.e., OVA(323-339)) or concanavalin A (Con A), a nonspecific, polyclonal T cell stimulus. IL-2 production and lymphocyte proliferation were determined after 48 and 72 h, respectively. Naive CD4+ T lymphocytes from fish oil-fed mice stimulated with antigen produced less IL-2 ( approximately 33%; P < 0.001) and proliferated to a lesser extent ( approximately 50%; P < 0.0001) than the same cells from lard-fed DO11.10 mice. When stimulated with Con A, (n-3) PUFA did not affect either proliferation or IL-2 production. In summary, we report for the first time that feeding mice a diet enriched with (n-3) PUFA reduces in vitro antigen-stimulated production of IL-2 and subsequent proliferation of naive CD4+ T lymphocytes.

Oxidative stability of fish and algae oils containing long-chain polyunsaturated fatty acids in bulk and in oil-in-water emulsions

The oxidative stability of long-chain polyunsaturated fatty acid (PUFA) and docosahexaenoic acid (DHA)-containing fish and algae oils varies widely according to their fatty acid composition, the physical and colloidal states of the lipids, the contents of tocopherols and other antioxidants, and the presence and activity of transition metals. Fish and algal oils were initially much more stable to oxidation in bulk systems than in the corresponding oil-in-water emulsions. The oxidative stability of emulsions cannot, therefore, be predicted on the basis of stability data obtained with bulk long-chain PUFA-containing fish oils and DHA-containing algal oils. The relatively high oxidative stability of an algal oil containing 42% DHA was completely lost after chromatographic purification to remove tocopherols and other antioxidants. Therefore, this evidence does not support the claim that DHA-rich oils from algae are unusually stable to oxidation. Addition of ethylenediaminetetraacetic acid (EDTA) prevented oxidation of both fish and algal oil emulsions without added iron and at low iron:EDTA molar concentrations. EDTA, however, promoted the oxidation of the corresponding emulsions that contained high iron:EDTA ratios. Therefore, to be effective as a metal chelator, EDTA must be added at molar concentrations higher than that of iron to inhibit oxidation of foods containing long-chain PUFA from either fish or algae and fortified with iron.

Lipids and fatty acids in muscle, liver and skin of three edible fish from the Senegalese coast: Sardinella maderensis, Sardinella aurita and Cephalopholis taeniops

Lipid content and fatty acid composition were determined in three species of edible fish caught in Senegalese waters during the upwelling season (January, 1993). Sardinella maderensis and Sardinella aurita are fat fish containing more than 5% (fresh wt.) of lipids, whereas Cephalopholis taeniops is a lean fish with approximately 1% of lipids. Skin, liver and muscle were studied for each fish species. About 40 fatty acids were identified by GC and GC/MS as methyl esters and N-acyl pyrrolidides. Palmitic acid was the main acid in the muscle and skin of all samples studied (20-33% of total fatty acids). Oleic acid was the main fatty acid in the liver of S. maderensis (27.2%+/-0.1) and S. aurita (44.7%+/-0.1). Arachidonic acid was a minor component in all samples. The flesh (muscle) of the three fish species contained high concentrations of omega3 polyunsaturated fatty acids (PUFA), ranging from 16.0 to 29.1% and including 20:5 omega3 (eicosapentaenoic acid, EPA) and 22:6 omega3 (docosahexaenoic acid, DHA) acids as major components. These two acids together accounted for 24.7%+/-0.1 and 12.9%+/-0.1 of total acids in the skin of S. maderensis and S. aurita, respectively. The percentages of PUFA found in the fish studied were very similar to those in fish used commercially as sources of PUFA. Muscle sterols, which accounted for 9-11% of total lipids, consisted mainly of cholesterol (up to 97% of total sterols).

Concentrates of DHA from fish oil by selective esterification of cholesterol by immobilized isoforms of lipase from Candida rugosa

Two lipases (Lip A and Lip B), were purified from a commercial lipase preparation produced by Candida rugosa and partially characterized. The purified lipases were immobilized on Duolite A 568 and used in the selective esterification of cholesterol with free fatty acids from sardine fish oil. The results showed that Lip A and Lip B preferentially esterified saturated and monounsaturated fatty acids allowing a 3.4-fold (Lip B, 24 h) and 4-fold (Lip A, 10 h) enrichment of docosahexaenoic acid in the remaining free fatty acid fraction. Selectivity towards eicosapentaenoic acid was less pronounced. By this selective esterification docosahexaenoic acid was concentrated from 7.4 to 32% with a recovery of 95% of its initial content in sardine fish oil.

Antimicrobial and Biological Effects of Bomphos and Phomphos on Bacterial and Yeast Cells

In this study, the antimicrobial effects of monophosphazenes such as SM, BOMPHOS, and PHOMPHOS were examined on bacterial and yeast strains. In addition, the biological effects of these compounds were tested on the Saccharomyces cerevisiae and Candida albicans cells. The SM has an antimicrobial effect on the bacterial and yeast strains within the range of 100 and 1500 µg. When the concentration was increased, the inhibition zone expanded on the growth media (P < 0.01; P < 0.001). Like SM, BOMPHOS molecule has antimicrobial activity on the bacterial and yeast cells. The most effective concentrations of BOMPHOS on the microorganisms were observed by 1500 µg (P < 0.001). The PHOMPHOS did not effect on the bacterial and yeast cells between 100 and 1000 range, but it has an antimicrobial effect in 1500 µg. In vitro media, the biological effects of these molecules were compared with vitamin E, melatonin, and fish oil on the yeast cells. In S. cerevisiae growth media, the cell densities were increased SM, BOMPHOS, and PHOMPHOS after 20, 30, and 45 h. The highest increase in the cell density were observed in media of BOMPHOS. In C. albicans growth media, the cell density was increased by melatonin after 20, 30, and 45 h, but were decreased by other supplemental groups. Lipid level of S. cerevisiae was reduced by administered 300 and 1000 µg vitamin E and fish oil (P < 0.01). In addition, the lipid level of the same yeast cell were diminished by the 1000 µg melatonin and 300 µg PHOMPHOS (P < 0.05, P < 0.01). The lipid level of C. albicans were increased by vitamin E and BOMPHOS and fish oil, but was decreased with PHOMPHOS (P < 0.01). In conclusion, while high concentration of PHOMPHOS has antimicrobial effects on the bacterial and yeast cells, the SM and BOMPHOS have antimicrobial effects in all the concentrations. PHOMPHOS decreased the lipid level of C. albicans, but BOMPHOS increased in the the same yeast cell. In addition, the antioxidants such as vitamin E, melatonin, and fish oils have affected on the lipid synthesis of yeast cells. Copyright 2000 Academic Press.

Antimicrobial and biological effects of ipemphos and amphos on bacterial and yeast strains

In this study, the antimicrobial effects of monophosphazenes such as SM ipemphos and amphos were examined on bacterial and yeast strains. In addition, the biological effects of these compounds were tested on the lipid level of Saccharomyces cerevisiae and Candida albicans cells. The SM has an antimicrobial effect on the bacterial and yeast strains within the range of 100 and 1500 microg. When the concentration was increased, the inhibition zone expanded on the growth media ( p < 0.01; p < 0.001). The ipemphos did not affect the bacterial and yeast cells in the 100 and 600 microg range. In addition, the amphos did not show an antimicrobial effect on the bacterial cells between 100 and 300 microg or on yeast cells at any of the administered concentrations. In vitro media, the biological effects of these molecules were compared with vitamin E, melatonin and fish oil on the yeast cells. We have found that monophosphazenes have growth effects on the cells in vitro media. The lipid level of S. cerevisiae cells was decreased by 300 microg doses of vitamin E, fish oil, and ipemphos (respectively; p < 0.05, p < 0.01, and p < 0. 001). In addition, the lipid levels of the same yeast cells were depressed by 1000-microg doses in all supplemented groups. However, it was observed that the highest decrease in lipid level of S. cerevisiae cells occurred in the amphos group ( p < 0.001). The lipid levels of the C. albicans cells were significantly reduced ( p < 0.01) by 300 microg of amphos and melatonin. In contrast, the vitamin E and fish oil significantly raised ( p < 0.01; p < 0.001) the lipid level of the same yeast cell, as compared with the control. In addition, the lipid level of these cells was increased by administration of 1000 microg vitamin E, and melatonin ( p < 0.01). In conclusion, while high concentrations of ipemphos and amphos have an antimicrobial effect on bacterial and yeast cells, amphos did not affect the yeast cells. While ipemphos and amphos increased cell growth in media, they reduced the lipid level of C. albicans and S. cerevisiae. In addition, the antioxidants such as vitamin E, melatonin, and fish oils affected the lipid level of yeast cells.

Approaches for chronic disease prevention based on current understanding of underlying mechanisms

Much progress has been achieved by exploring the causes of the main human cancers and of cardiovascular and cerebrovascular diseases. Even more important has been the knowledge acquired about the mechanisms underlying the development of these diseases. In many parts of the world, particularly in the West, the major cancers associated with dietary habits involve the postmenopausal breast, distal colon, prostate, pancreas, ovary, and endometrium. Current evidence suggests that the genotoxic carcinogens for all but the last 2 of these diseases stem from the traditional intake of fried and broiled foods such as meats. The surface of these foods contains a class of powerful mutagens, heterocyclic amines, which are carcinogenic to the target organs in animal models. Fish-eating populations have lower incidences of heart disease and of many types of cancers than do other populations, which may be the result of the n-3 polyunsaturated oils found in fish. Among other dietary practices that may reduce the risk of cancer and cardiovascular disease are consuming 5-9 servings of fruits and vegetables daily, which provides antioxidants such as quercetin and isothiocyanates; having a high fiber intake, including bran cereal; and drinking 1.5-2.5 L of fluids daily. Tea polyphenols found in black and green tea may have a protective effect against heart disease and some cancers. Concentrates of such desirable products have been made available in pill form to complement health-promoting personal lifestyles. Biomedical research funded by The National Institutes of Health and organizations such as the American Cancer Society has produced sound results that could lead to prevention of chronic disease. The public must heed this information to achieve long-term health.

Serum n-3 fatty acids, fish consumption and cancer mortality in six Japanese populations in Japan and Brazil

Japanese people consume significant amounts of long chain n-3 polyunsaturated fatty acids (PUFAs) derived from fish, but the association of PUFAs with cancer mortality has not been fully investigated. To study geographic differences in n-3 PUFAs intake, we compared serum fatty acid and dietary fish intake among various Japanese populations having different rates of cancer mortality. The subjects were 50 men from each of five regions in Japan and 47 Japanese men from Sao Paulo, Brazil. All were randomly selected and aged 40 to 49 years. Serum fatty acids were measured by gas chromatography and the frequency of fish intake was obtained by a food frequency questionnaire. Significant geographic differences in serum fatty acid levels (% of total fatty acids) and fish intake (days/4 weeks) were observed. The percentages of serum total PUFA were similar in the six regions, though there was an almost three-fold difference in n-3 PUFAs content between Brazil (3.9%) and Akita (10.9%). The frequency of total fish intake corresponded to serum n-3 PUFAs composition. The relationship between cancer mortality and serum n-3 PUFAs levels was not clear, though an inverse association between prostate cancer and serum n-3 PUFAs levels appeared to exist. The results suggest that although serum n-3 PUFAs varied significantly, the observed geographic difference did not account for the different cancer risks at the population level.

Comparison of fatty acid profiles in the serum of patients with prostate cancer and benign prostatic hyperplasia

OBJECTIVE

The role of dietary fatty acids (FAs) in benign and malignant prostatic diseases was investigated by comparing the composition value of serum fatty acids in the normal controls, and patients with prostate cancer (PC) and benign prostatic hyperplasia (BPH). Also, to estimate a possible association between PC risk and PUFAs, omega-3, omega-6 and omega-3/omega-6 FA composition ratios were compared among these groups.

METHODS

Serum samples were obtained from 24 BPH and 19 PC patients, and from 21 age-matched normal male subjects. The serum concentration of 21 fatty acids was determined using gas chromatography/mass spectrometry.

RESULT

The proportional values of saturated fatty acids (SFAs) groups demonstrated no specific difference between the control subjects and the patients. In the polyunsaturated fatty acids (PUFAs), we found that the omega-3 PUFAs level was significantly decreased in patient with BPH and PC and that the omega-6 PUFAs level was increased in PC only. The ratio of omega-3/omega-6 PUFAs decreased in the following order of normal, BPH, and PC.

CONCLUSION

It was proposed that the changed composition level of PUFAs including omega-3 and omega-6 PUFAs have certain relationship with both prostatic diseases. Therefore, the ratio of omega-3/omega-6 PUFAs also may have an important association with the benign and malignant status of prostatic disease.

Hydrolysis of menhaden oil by a Candida cylindracea lipase immobilized in a hollow-fiber reactor

A lipase from Candida cylindracea immobilized by adsorption on microporous polypropylene fibers was used to selectively hydrolyze the saturated and monounsaturated fatty acid residues of menhaden oil at 40 degrees C and pH 7.0. At a space time of 3.5 h, the shell and tube reactor containing these hollow fibers gives a fractional release of each of the saturated and monounsaturated fatty acid residues (i.e., C14, C16, C16:1, C18:1) of ca. 88% of the corresponding possible asymptotic value. The corresponding coproduct glycerides retained over 90% of the initial residues of both eicosapentaenoic (EPA; C20:5) and docosahexaenoic (DHA; C22:6) acids. The half-life of the immobilized lipase was 170 h when the reactor was operated at the indicated (optimum) conditions. Rate expressions associated with a generic ping-pong bi-bi mechanism were used to fit the experimental data for the lipase catalyzed reaction. Both uni- and multiresponse nonlinear regression methods were employed to determine the kinetic parameters associated with these rate expressions. The best statistical fit of the uniresponse data was obtained for a rate expression, which is formally equivalent to a general Michaelis-Menten mechanism. After reparameterization, this rate expression reduced to a pseudo-first-order model. For the multiresponse analysis, a model that employed a normal distribution of the ratio of Vmax/Km with respect to the chain length of the fatty acid residues provided the best statistical fit of the experimental data.

Worldwide prevention of cancer and other chronic diseases based on knowledge of mechanisms

International research, particularly as part of US/Japan programs, has led to major advances in knowledge of causes of heart disease, stroke, many types of cancer and diabetes, showing that individual lifestyle is associated with these diseases. In Japan, a major health problem is high blood pressure and stroke, and cancer of the stomach, from excessive use of salt and salted, pickled foods, and the relative low intake of protective fruits and vegetables. We identified a likely gastric carcinogen, 2-chloro-4-methylthiobutanoate, in salted, pickled fish. In the Western world, heart disease and cancer of the breast, colon, rectum, prostate, pancreas, ovary and endometrium relate to a nutritional tradition too high in total fat and fried or broiled meats, and too low in fiber, vegetables and fruits. The cooked meats contain genotoxic chemicals, heterocyclic amines, causative elements in heart disease and the nutritionally linked cancers. Decreasing total fat intake, from 40 to 20% of calories and a greater use of starches such as rice, pasta, potatoes and whole grain bread, as well as daily intake of five to nine vegetables and fruits would be beneficial. Adults should consume 2.5 l of fluids per day. Green or black tea and fruit juices have health promoting properties. Regular exercise contributes to good health, and to the avoidance of obesity, a major problem in the USA and of increasing importance in Japan. Avoidance of a risky lifestyle would likely prevent diseases important not only for the individual and his family, but with major impact in lowering medical care costs. Tobacco and cigarette use, particularly on a Western diet, involve a high risk of heart attacks, and cancers of the lung, pancreas, kidney, urinary bladder, and cervix, accounting for 35% of medical care expenditures.

Prediagnostic level of fatty acids in serum phospholipids: omega-3 and omega-6 fatty acids and the risk of prostate cancer

Ecological and case-control studies have demonstrated a positive correlation between consumption of fat and the risk of prostate cancer. Two recent human studies have focused on alpha-linolenic acid as a risk factor for prostate cancer. Animal experiments have shown that dietary omega-6 polyunsaturated fatty acids have generally stimulated tumour development, whereas omega-3 polyunsaturated fatty acids have diminished it. The aim of our study was to investigate the association between these fatty acids and the subsequent risk of prostate cancer. Blood donors to the Janus serum data bank in Norway, who later developed prostate cancer, were matched to blood donors without prostate cancer (141 matched sets); the proportional level of fatty acids measured before diagnosis in the donors' serum was examined. The risk of later prostate cancer was analysed by conditional logistic regression. Increasing risk for prostate cancer was found with increasing quartiles of palmitoleic, palmitic and alpha-linolenic acid. An inverse risk association was found with increasing levels of tetracosanoic acid, for the ratios of linoleic to alpha-linolenic acid and arachidonic to eicosapentaenoic acid. There was no clear association between the risk effect of total omega-3 and total omega-6 fatty acids. There were no indications of a relationship between fatty acids and more aggressive cancers. Our results verify recent findings of a positive association between alpha-linolenic acid and a negative association between the ratio of linoleic to alpha-linolenic acid and the risk of prostate cancer.

Reduced breast cancer mortality among fishermen's wives in Norway

International comparisons show that populations having a high consumption of fish experience low incidence of breast cancer. We compared death rates from breast cancer among socioeconomic groups in a prospective study of 533,276 Norwegian women aged 35-54 years who were followed from 1970 through 1985. Compared with the reference group (wives of unskilled workers) the fishermen's wives had a decreased risk of breast cancer with a relative risk (RR) of 0.67 (95% confidence interval [CI] = 0.47-0.94) adjusted for age and the number of children. Among fishermen's wives who were parous, adjustment for age at first birth gave an RR of 0.62 (CI = 0.43-0.91). This study supports the hypothesis that certain aspects of diet, i.e., fish consumption, may be associated with lower breast-cancer mortality.

Stability of a commercially prepared fish oil (omega-3 fatty acid) laboratory rodent diet

There is evidence that highly unsaturated omega-3 fatty acids present in fish oils can provide a cancer-protective effect; however, when added to laboratory rodent formulations, these fatty acids are subject to rapid and/or extensive oxidation and other chemical changes by exposure to air, light, or heat during processing of pellets or when stored for various lengths of time. An animal diet with 16% refined fish oil and 4% corn oil was commercially prepared with antioxidants (butylated hydroxytoluene and butylated hydroxyquinone in addition to alpha-tocopherol) present, and precautions were taken to prevent oxidation at all stages of production and handling. Fatty acid composition of dried powdered diet as well as freshly processed dried pellets was analyzed from four lots at the beginning and end of a 45-day feeding period. Additionally, fatty acid analyses were carried out on pellets dried by both vacuum and air techniques, and pellets were left exposed to air at room temperature for 96 hours. No statistical difference in overall fatty acid composition was observed among lots due to pelletization or drying procedures. Moreover, 4 days of exposure of pellets to air at ambient temperatures and 45 days of freezer storage had no significant effect on their fatty acid composition. It would appear that rodent diets containing omega-3 fatty acids can be reliably prepared commercially and safely substituted for diets prepared manually and in bulk on a weekly basis.

Modulation of phorbol ester-elicited events in mouse epidermis by dietary n-3 and n-6 fatty acids

Because arachidonic acid-derived eicosanoids are potent modulators of hyperproliferation and inflammation during skin tumor promotion with the phorbol ester, 12-0-tetradecanoylphorbol-13-acetate (TPA) (17, 18), it was hypothesized that dietary modification of epidermal fatty acids might modulate TPA-induced biochemical events in mouse skin. Semipurified diets containing 10% total fat composed of corn oil (CO) or a combination of CO and menhaden oil (MO) or coconut oil (CT) were fed to SENCAR mice for 4 weeks. Fatty acid composition of epidermal phospholipids generally reflected fatty acid composition of dietary oils fed to the mice. Since fatty acid-derived eicosanoids are thought to be essential in tumorigenesis, we compared the effects of dietary fats on prostaglandin E (PGE) production in epidermis treated with a single dose of TPA. TPA-induced PGE production in mouse epidermis from mice fed the MO diet was significantly reduced compared to PGE production in epidermal homogenates from mice fed the CO or CT diets. Type of dietary fats did not appear to modulate TPA-induced vascular permeability, however hyperplasia was slightly elevated in skins of mice fed MO. The subcellular distribution of protein kinase C, the plasma membrane receptor for TPA predominantly located in the cytosol (80%), was altered in epidermis from mice fed the MO diet compared to preparations from mice fed CO or CT diets which exhibited normal protein kinase C distribution. Our results suggest that n-3 rich dietary lipids modulate TPA-elicited events in mouse skin to a greater extent than diets containing higher proportions of saturated or n-6 fatty acids.

Effect of dietary fat on the lipid composition and utilization of short-chain fatty acids by rat colonocytes

The objective of the present studies was to examine the effect of dietary fat on the lipid composition of rat colonocytes and their utilization of short-chain fatty acids (SCFA). Rats were fed 14% beef fat, fish oil or safflower oil plus 2% corn oil in a semi-synthetic base diet for 4 wk. Colonocytes were isolated and their lipid composition was examined. Feeding beef fat and fish oil resulted in an increase in monounsaturated fatty acids and a reduction in omega-6 fatty acids. Feeding fish oil resulted in an enrichment with omega-3 fatty acids. There was no dietary influence on the amount of either cholesterol or phospholipids of colonocytes. Fish oil feeding resulted in significant increase in colonocyte free fatty acids (FFA) as compared to other diets. Dietary fat was found to have no effect on SCFA utilization by colonocytes. Colonocytes were found to utilize SCFA in the order of butyrate greater than or equal to acetate greater than or equal to propionate. The presence of acetate and propionate in the medium had no effect on the rate of butyrate utilization.

Influence of fatty acid composition of diet on cholesterol content of eel liver and muscle

The influence of different diets on cholesterol content of liver and muscle of European eel (Anguilla anguilla) was studied for the first time. In control eel, cholesterol constituted near 7.5% of total lipids in liver and about 1% in muscle. Feeding herring meal-55% diet produced a drastic increase in hepatic cholesterol after a 30 d period. In muscle, cholesterol content also increased after any dietary treatment. Free cholesterol represented about 34% of total cholesterol in liver and about 50% in muscle. In both tissues, these percentages increased after any experimental condition assayed. The n-3/n-6 ratio in the fatty acid composition was manifestly low in herring meal-55% diet, mainly due to the minimal amount of total n-3 fatty acids. This fact may account for the increase in liver cholesterol, bearing in mind the hypocholesterolemic effect of the polyunsaturated n-3 fatty acids.

Lipid peroxidation in rat tissue slices: effect of dietary vitamin E, corn oil-lard and menhaden oil

Rats were fed for 5 weeks either 10% (w/w) menhaden oil (MO) or a 10% corn oil-lard (COL) mixture (1:1) in diets with less than or equal to 5 IU or less than or equal to 2 IU/kg vitamin E, respectively, or the same diets supplemented with d-alpha-tocopheryl succinate to a total of 35 and 180 IU vitamin E/kg, respectively. Slices of liver and heart from these rats were used to study lipid peroxidation in vitro. Thiobarbituric acid-reactive substances (TBARS) were measured in the medium after incubation of the slices at 37 degrees C for 1 hr in the absence (uninduced) and presence of 0.5 mM tert-butyl hydroperoxide (induced). The release of TBARS from slices of heart and liver from rats fed either lipid decreased with increasing levels of dietary vitamin E. At the same level of dietary vitamin E, TBARS release was greater for slices of liver and heart from the MO-fed rats than from the COL-fed rats. Application of the TBARS data to a model simulating the experimental conditions showed a good correlation (r = 0.95, p less than 0.001) between experimental and simulated values. Of the 16:0-22:6 fatty acids measured in liver from MO-fed rats, 15.4% was n-6 fatty acids and 29.9% was n-3 fatty acids; in liver from COL-fed rats, the respective values were 37.4% and 3.7%. Liver and kidney vitamin E levels were unaffected by the dietary lipid.(ABSTRACT TRUNCATED AT 250 WORDS)

Omega-3 fatty acids increase the arachidonic acid content of liver cholesterol ester and plasma triacylglycerol fractions in the rat

Recent studies have demonstrated that dietary fish oils rich in eicosapentaenoic acid (C20:5,omega 3) lower the content of arachidonic acid and its metabolites in plasma and tissue phospholipids. The present study examined the fatty acid composition of cholesterol ester and triacylglycerol fractions from plasma and livers of rats fed diets enriched with saturated fatty acids (beef tallow), alpha-linolenic acid (linseed oil) or eicosapentaenoic acid (fish oil). Feeding diets containing linseed oil or fish oil for 28 days increased arachidonic acid (C20:4,omega 6) levels in the cholesterol ester fraction of liver and in the triacylglycerol fraction of the plasma lipids. Plasma cholesterol esters were depleted of C20:4,omega 6 after feeding of the diet containing either linseed oil or fish oil. The changes in C20:4,omega 6 content cannot be explained by alterations in cholesterol ester or triacylglycerol pools of plasma and liver. These results suggest that the decrease in phospholipid C20:4,omega 6 content generally observed after fish oil consumption may be partly due to a shift of C20:4,omega 6 from phospholipid to the triacylglycerol and/or cholesterol ester pools in the same tissue. Triacylglycerols and cholesterol esters may therefore play a buffering role in the homeostatic maintenance of tissue phospholipid levels of arachidonic acid.

Analytical-scale high-performance liquid chromatography of omega-3 fatty acid esters derived from fish oils

Fish oil triglycerides were transesterified to their corresponding methyl and ethyl esters. The esters were separated by reversed-phase high-performance liquid chromatography on a 10-cm column of 5-microns octadecylsilyl silica, using a ternary mobile phase of acetonitrile-tetrahydrofuran-water (9:5:11). The separation of principal saturated and unsaturated C14-C22 fatty acid esters was accomplished in 60 min. For the polyenoic acid esters, detection limits of ca. 26 micrograms were observed, and baseline resolution of the important critical pair of esters of the omega 3 fatty acids, eicosapentaenoic acid (C20:5 omega 3) and docosahexaenoic acid (C22:6 omega 3) was achieved. However, to obtain baseline resolution of the esters from minor fatty acid esters, a urea crystallization procedure was required prior to chromatographic analysis. The influence on the reversed-phase chromatographic retention of four different ester moieties on the fatty acids were also studied. The n-alkyl esters exhibited an increase in ln k' with increasing chain length and with increasing lipophilic character of the alkyl ester moieties; however, with the aromatic benzyl derivatives there was a decrease in ln k' compared with the alkyl esters.

Preparative-scale high-performance liquid chromatography of omega-3 polyunsaturated fatty acid esters derived from fish oil

Marine triglyceride-derived omega-3 polyunsaturated fatty acid ethyl esters were separated by preparative high-performance liquid chromatography on a 25-microns octadecyl stationary phase using a ternary isocratic mobile phase of acetonitrile-tetrahydrofuran-water (466:233:300, v/v/v). The highest purity first-run fractions obtained were ethyl esters of the major marine polyunsaturates eicosapentaenoic acid (20:5 omega 3, 97.7%) and docosahexaenoic acid (22:6 omega 3, 93.7%), and the minor polyunsaturate octadecatetraenoic acid (18:4 omega 3, 98.1%).

Phospholipid profile and production of prostanoids by murine colonic epithelium: effect of dietary fat

Dietary fat and abnormal production of various prostanoids have been linked to various disease states of the large bowel, including cancer of the colon. Studies were conducted to determine the effect of dietary fat (beef tallow or corn oil) on the lipid composition and prostanoid production of the murine colon. Female C57BL/6J mice were fed high-fat (HF) diets (47% of calories as fat) or low-fat (LF) diets (10% of calories as fat). After four wk of dietary treatment, the mucosa was scraped, and lipids were extracted from the mucosal and muscle layers. The fat content of the diets did not significantly alter the amount of phospholipid (PL) or neutral lipid in the colonic tissue. However, the HF affected the PL profile of the colonic mucosa. For example, the ratio of phosphatidylcholine (PC) to phosphatidylethanolamine (PE) was significantly higher for both the HF groups compared with that of the two LF groups (0.76 +/- 0.15 and 0.80 +/- 0.13 vs 0.31 +/- 0.20 and 0.34 +/- 0.18). Production of 13,14-dihydro-15-keto-PGE2 (measured as bicyclic PGE2) and TXB2 (a stable metabolite of TXA2) and PGF1 alpha (a stable metabolite of PGI2) was unaffected by the dietary treatments. The muscle had a different PL profile (PC:PE is 2.6 +/- 0.1) than the mucosa and contributed a larger proportion of the prostanoids formed. This study demonstrates that the phospholipid polar head group composition of normal colonic mucosa is altered by dietary fat, but the ability of the mucosa to synthesize metabolites of PGE2, TXA2 and PGI2 is not affected.

Interaction of (n-3) and (n-6) fatty acids in desaturation and chain elongation of essential fatty acids in cultured glioma cells

Recent research in various biological systems has revived interest in interactions between the (n-6) and (n-3) essential fatty acids. We have utilized cultured glioma cells to show that linolenic acid, 18:3(n-3), is rapidly desaturated and chain elongated; 20:5(n-3) is the major product and accumulates almost exclusively in phospholipids. We examined effects of various (n-6), (n-3), (n-9) and (n-7) fatty acids at 40 microM concentration on desaturation and chain elongation processes using [1-14C]18:3(n-3) as substrate. In general, monoenoic fatty acids were without effect. The (n-6) fatty acids (18:2, 18:3, 20:3, 20:4 and 22:4) had little effect on total product formed. There was a shift of labeled product to triacylglycerol, and in phospholipids, slightly enhanced conversion of 20:5 to 22:5 was evident. In contrast, 22:6(n-3) was inhibitory, whereas 20:3(n-3) and 20:5(n-3) had much less effect. At concentrations less than 75 microM, all acids were inhibitory. Most products were esterified to phosphatidylcholine, but phosphatidylethanolamine also contained a major portion of 20:5 and 22:5. We provide a condensed overview of how the (n-6) and (n-3) fatty acids interact to modify relative rates of desaturation and chain elongation, depending on the essential fatty acid precursor. Thus, the balance between these dietary acids can markedly influence enzymes providing crucial membrane components and substrates for biologically active oxygenated derivatives.