Investigation of gene expressions related to cholesterol metabolism in rats fed diets enriched in n-6 or n-3 fatty acid with a cholesterol after long-term feeding using quantitative-competitive RT-PCR analysis

We have developed a method to quantitate hepatic apolipoprotein (apo) B, LDL receptor, 3-hydroxy-3-methylglutary coenzyme A reductase (HMG-CoA reductase) and cholesterol 7alpha-hydroxylase mRNA expression in rats fed a cholesterol-enriched diet after long-term feeding using competitive RT-RCR. Rats (8 wk of age) fed a conventional diet were shifted to diets containing 10% perilla oil (PEO, oleic acid+linoleic acid+alpha-linolenic acid), borage oil (BRO, oleic acid+linoleic acid+gamma-linolenic acid), evening primrose oil (EPO, linoleic acid+gamma-linolenic acid), mixed oil (MIO, oleic acid+linoleic acid+gamma-linolenic acid+alpha-linolenic acid), or palm oil (PLO, palmitic acid+oleic acid+linoleic acid) with 0.5% cholesterol for 15 wk. There were no significant differences in the food intake and body weight gain among the groups. The liver weight in the PEO and PLO groups was significantly higher than other groups. The serum total cholesterol and very low density lipoprotein (VLDL)+intermediate density lipoprotein (IDL)+low density lipoprotein (LDL)-cholesterol concentrations were consistently higher in PLO group than in the other groups. The serum high density lipoprotein cholesterol concentration was significantly lower in the PEO group than in the other groups. The liver cholesterol concentration group was significantly higher in the PEO than in the other groups. There were no significant differences in the hepatic LDL receptor mRNA level among the groups. Hepatic apo B, HMG-CoA reductase and cholesterol 7alpha-hydroxylase mRNA levels were not affected by the experimental conditions. However, hepatic cholesterol 7alpha-hydroxylase mRNA level in the PEO and MIO groups tended to be higher than in the other groups. The fecal cholesterol extraction was significantly higher in the MIO and PLO groups than in the PEO and EPO groups and the total bile acid extraction was significantly higher in the PEO and MIO groups than in the PLO group. The results of this study demonstrated that both n-6 fatty acid and n-3 fatty acids such as gamma-linolenic acid and alpha-linolenic acid lowered serum total cholesterol and VLDL+IDL+LDL-cholesterol concentrations of rats in the presence of excess cholesterol in the diet compared with dietary saturated fatty acid.     

Chemopreventive effects of dietary flaxseed oil on colon tumor development

Fatty acid composition of dietary fat, primarily the levels of omega-3 and omega-6 polyunsaturated fatty acids, has shown profound effect on colon tumor development in animal studies. Fats containing omega-6 fatty acids (for example, corn oil) enhanced and omega-3 fatty acids (for example, fish oil and mustard oil) reduced chemically induced colon tumors in rats. The purpose of this study was to investigate the effects of dietary flaxseed oil (containing alpha-linolenic acid, an omega-3 polyunsaturated fatty acid) on azoxymethane-induced colon tumor in rats and how it compared with the dietary corn oil-treated group. Male Fischer rats, separated into 2 groups of 30, were assigned to the AIN-93M diet, which was supplemented with either 15% corn oil or 15% flaxseed oil. Carcinogenesis was initiated with subcutaneous injections of azoxymethane (15 mg/kg) once a week for three consecutive weeks. Thirty-five weeks after initiation, the rats were sacrificed under ether anesthesia. Blood was collected by cardiac puncture. The gastrointestinal tract was isolated and flushed with ice-cold normal saline. The site, size, and number of tumors were recorded. The incidence and multiplicity of the tumors in the colon were determined. The fatty acid composition in the serum, colon, and tumors was estimated by using gas chromatography-flame ionization detection. Colon tumor incidence was found to be 100% and 54%, whereas multiplicity was found to be 3.1 and 0.7 tumors per rat in corn oil- and flaxseed oil-treated groups, respectively. Tumor size was significantly larger in the corn oil-treated group than in the flaxseed oil group. Colon and serum samples of the corn oil group showed an increase in the omega-6 fatty acid levels, whereas the flaxseed oil group exhibited an increase in the omega-3 fatty acid levels. The results indicate that dietary flaxseed oil, containing high levels of omega-3 fatty acids, is effective in preventing colon tumor development when compared with dietary corn oil containing omega-6 fatty acids in rats.     

Effects of perilla oil on plasma concentrations of cardioprotective (n-3) fatty acids and lipid profiles in mice

The aim of this study was to examine the effects of perilla oil as well as several vegetable oils, including flaxseed oil, canola oil, and rice bran oil on plasma levels of cardioprotective (n-3) polyunsaturated fatty acids in mice by feeding each vegetable oil for a period of eight weeks. Concentrations of docosapentaenoic acid (DHA) and eicosapentaenoic acid (EPA), fish-based (n-3) polyunsaturated fatty acids, showed an increase in the plasma of mice fed perilla and flaxseed oils compared to those of mice in the control group (P < 0.05), whereas rice bran and canola oils did not alter plasma DPA and EPA concentrations. Arachidonic acid concentration was increased by feeding rice bran oil (P < 0.05), but not canola, flaxseed, or perilla oil. In addition, oleic acid, linoleic acid, and docosahexaenoic acid concentrations were altered by feeding dietary rice bran, canola, perilla, and flaxseed oils. Findings of this study showed that perilla oil, similar to flaxseed oil, is cardioprotective and could be used as an alternative to fish oil or even flaxseed oil in animal models.     

Dietary supplementation with eicosapentaenoic acid, but not with other long-chain n-3 or n-6 polyunsaturated fatty acids, decreases natural killer cell activity in healthy subjects aged >55 y

BACKGROUND: Animal studies showed that dietary flaxseed oil [rich in the n-3 polyunsaturated fatty acid alpha-linolenic acid (ALA)], evening primrose oil [rich in the n-6 polyunsaturated fatty acid gamma-linolenic acid (GLA)], and fish oil [rich in the long-chain n-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] can decrease natural killer (NK) cell activity. There have been no studies of the effect on NK cell activity of adding these oils to the diet of humans. OBJECTIVE: Our objective was to determine the effect of dietary supplementation with oil blends rich in ALA, GLA, arachidonic acid (AA), DHA, or EPA plus DHA (fish oil) on the NK cell activity of human peripheral blood mononuclear cells. DESIGN: A randomized, placebo-controlled, double-blind, parallel study was conducted. Healthy subjects aged 55-75 y consumed 9 capsules/d for 12 wk; the capsules contained placebo oil (an 80:20 mix of palm and sunflower seed oils) or blends of placebo oil and oils rich in ALA, GLA, AA, DHA, or EPA plus DHA. Subjects in these groups consumed 2 g ALA, 770 mg GLA, 680 mg AA, 720 mg DHA, or 1 g EPA plus DHA (720 mg EPA + 280 mg DHA) daily, respectively. Total fat intake from the capsules was 4 g/d. RESULTS: The fatty acid composition of plasma phospholipids changed significantly in the GLA, AA, DHA, and fish oil groups. NK cell activity was not significantly affected by the placebo, ALA, GLA, AA, or DHA treatment. Fish oil caused a significant reduction (mean decline: 48%) in NK cell activity that was fully reversed by 4 wk after supplementation had ceased. CONCLUSION: A moderate amount of EPA but not of other n-6 or n-3 polyunsaturated fatty acids can decrease NK cell activity in healthy subjects.     

Mouse peritoneal macrophage prostaglandin E1 synthesis is altered by dietary gamma-linolenic acid.

The ability of dietary gamma-linolenic acid [18:3(n-6)] to modulate prostaglandin biosynthesis in mouse resident peritoneal macrophages was determined. Mice were fed diets containing corn oil, borage oil or evening primrose oil or a mixture of borage and fish oils. After 2 wk, resident peritoneal macrophages were isolated and stimulated with unopsonized zymosan to induce prostaglandin synthesis. Borage oil, primrose oil and fish-borage oil mixture dietary groups (containing 25.6, 11.9 and 19.5 g gamma-linolenic acid/100 g fatty acids, respectively) had significantly (P less than 0.05) enhanced prostaglandin E1 synthesis (39.7, 29.4 and 73.0 nmol prostaglandin E1/mg protein, respectively) compared with corn oil-fed (containing less than 0.1 g gamma-linolenic acid/100 g fatty acids) animals, which synthesized less than 0.1 nmol prostaglandin E1/mg protein. Borage oil- and fish-borage oil mixture-fed mice had the highest biosynthetic ratio of prostaglandin E1/prostaglandin E2 (E1/E2 approximately 0.2). Macrophages from borage oil-fed mice synthesized the lowest amount of prostacyclin (198.7 nmol 6-keto-prostaglandin F1 alpha/mg protein) compared with corn oil-, primrose oil- and fish-borage oil mixture-fed mice (379.7, 764.8 and 384.2 nmol 6-keto-prostaglandin F1 alpha/mg protein, respectively). In addition, borage oil-, primrose oil- and fish-borage oil mixture-fed mice had significantly (P less than 0.05) higher levels of dihomo-gamma-linolenic acid [20:3(n-6)] in membrane phospholipids (5.5, 3.5 and 5.7 mol/100 mol, respectively) relative to corn oil-fed mice (2.0 mol/100 mol).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of flaxseed oil supplementation on plasma adiponectin levels in dyslipidemic men

Background Dietary alpha-linolenic acid (ALA) has been associated with reduced risk of development of atherosclerosis. Adiponectin is a hormone specifically secreted by adipocytes and considered to have anti-atherogenic properties. Aim of the study We examined the effect of increased dietary intake of ALA on plasma concentration of adiponectin. Methods Thirty-five non-diabetic, dyslipidemic men, 38–71 years old, were randomly allocated to take either 15 ml of flaxseed oil rich in ALA (8.1 g/day; n = 18), or 15 ml of safflower oil per day, containing the equivalent n-6 fatty acid (11.2 g/day linoleic acid, LA; n = 17) (control group). The intervention period lasted for 12 weeks. Results Plasma levels of adiponectin did not change after the increase in dietary intake of ALA in the flaxseed oil supplementation group, compared to the control group. No changes in body mass index, serum lipid concentrations, LDL density, or plasma TNF-α were found in the flaxseed oil versus the control group. Conclusions Dietary ALA has no effect on plasma adiponectin concentration in dyslipidemic men.     

The effect of maternal supplementation with linoleic and gamma-linolenic acids on the fat composition and content of human milk: a placebo-controlled trial.

Total fat content and therefore total energy content and the content of essential fatty acids (EFAs) in milk are known to decline with prolonged breast feeding. In a placebo-controlled study a variety of evening primrose oil (Efamol) rich in linoleic and gamma-linolenic acids, or a matching placebo were given to 39 women for a period of 8 months starting between the 2nd and 6th months of lactation. Total fat and EFA contents of the milk declined in the placebo group but rose in the primrose oil supplemented group. A surprisingly high proportion of the supplemented dietary fatty acids could be accounted for by appearance in the milk. The milk composition can be readily manipulated by changing the fatty acid composition of the maternal diet.     

Differential oxidation of saturated and unsaturated fatty acids in vivo in the rat

The oxidation rates of lauric, myristic, palmitic, stearic, oleic, alpha-linolenic, linoleic, kappa-linolenic, dihomo-gamma-linolenic and arachidonic acids were studied by use of a radioisotope tracer technique in weanling rats at rest in a metabolism chamber over 24 h. Of the saturated fatty acids, lauric acid (12:0) was the most efficient energy substrate: the longer the chain length of the saturated fatty acids, the slower the rate of oxidation. Oleic acid (18:1) was oxidized at a remarkably fast rate, similar to that of lauric acid. Of the omega 6 essential fatty acids studied, linoleic acid (18:2 omega 6) was oxidized at a faster rate than any of its metabolites, with arachidonic acid (20:4 omega 6) being oxidized at the slowest rate. The rate of oxidation of gamma-linolenic acid (18:3 omega 3) was almost as fast as that of lauric and oleic acids.     

The effect of flaxseed supplementation in processed foods on serum fatty acids and enterolactone

OBJECTIVE: The purpose was to study the effects of flaxseed supplementation as a part of daily diet on serum lipids, fatty acids and plasma enterolactone. DESIGN: Eighty volunteers participated in this clinical nutrition study which was carried out in a controlled, double-blind and cross-over manner. The subjects were randomized to diet sequences AB or BA. Diet A meals contained 1.3 g/100 g ground flaxseed and 5 g/100 g flaxseed oil. Also 3-4 g/100 of inulin and wheat fiber was added. AB diet with non-supplemented foods served as control. Test subjects were on both diets for 4 weeks separated by a 4-week wash-out period. Fifteen test subjects continued an open part of the study for 4 additional months. INTERVENTIONS: The dietary intake, basic blood values, serum lipids, fatty acids and enterolactone were measured at baseline, after both intervention periods and during the open study, at baseline and after 2 and 4 months. Serum thiocyanate and blood cadmium were controlled after both intervention periods. RESULTS: The percentage of flaxseed supplemented test food out of total dietary intake was 20% of energy. The test food contained significantly higher amounts of fiber, polyunsaturated fatty acids (PUFAs) and especially alpha-linolenic acid than the control food. No significant changes were observed in the basic laboratory values or in blood lipids. There was a significant increase in serum alpha-linolenic acid, eicosapentaenoic acid and docosapentaenoic acid. Serum enterolactone concentration was doubled during flaxseed supplementation. Serum thiocyanate and blood cadmium values did not exceed reference values and there was no difference between the diets. CONCLUSIONS: In this study we were able to show that, by adding ground flaxseed and flaxseed oil to one or two daily meals, it is possible to obtain significant effects on serum levels of enterolactone and alpha-linolenic acid. SPONSORSHIP: The study was sponsored by the National Technology Agency of Finland (Tekes).     

Modification of skin composition by conjugated linoleic acid alone or with combination of other fatty acids in mice

The effects of conjugated linoleic acid (CLA), gamma-linolenic acid (GLA), linoleic acid (LA), and their combinations, on skin composition in mice were investigated. Mice (8 weeks old) were orally administered with either LA, GLA, CLA, LA + GLA, LA + CLA, or CLA + GLA for 4 weeks. Then, the skin was analysed for triacylglycerol content, fatty acid composition and collagen content. Additionally, thicknesses of the dermis layer and subcutaneous tissue layer, and the size and number of adipocytes were measured histologically. The skin fatty acid composition was modified depending upon the fatty acid composition of supplemented oils. In each oil-alone group, skin triacylglycerol content was the highest in LA, followed by GLA and CLA treatments. Combinations with CLA had a similar triacylglycerol content compared with the CLA-alone group. No significant changes in collagen content were observed among any treatments. The effects on subcutaneous thickness were similar to the results obtained in the triacylglycerol contents, where groups supplemented with CLA alone or other fatty acids had significantly thinner subcutaneous tissue compared with the LA-alone group. However, no significant difference was detected in the thickness of the dermis layers. The number of adipocytes was highest in the LA + GLA group and tended to be reduced by CLA with or without the other fatty acids. These results suggest that CLA alone or in combination with other fatty acids strongly modifies skin composition in mice.     

The effect of six different C18 fatty acids on body fat and energy metabolism in mice

We studied the effects of five high-fat semi-purified diets varying at a 4% (w/w) level in either stearic, oleic, linoleic, alpha-linolenic, or gamma-linolenic acid on body fat and energy metabolism in BALB/c mice. A diet containing caprylic, capric, lauric, and myristic acid was used as a reference diet and a diet with 4% conjugated linoleic acid (CLA) was used as a positive control as it is known to effectively lower body fat in mice. The diets were fed for 35 d. Body fat was significantly lower in the CLA group than in the other groups but was not significantly different among the non-CLA groups. Among the non-CLA groups, the linoleic acid group tended to have the highest and the alpha-linolenic acid group the lowest proportion of body fat. In energy-balance studies, the percentage of energy intake that was stored in the body was significantly lower in the CLA group compared with the other dietary groups. The percentage of energy intake eliminated in excreta was highest in the stearic acid group followed by the gamma-linolenic acid group. These results were reflected in apparent fat digestibility, which was lowest in the stearic acid group. The percentage of energy intake expended as heat was highest in the CLA-fed mice. The results of the present study suggest that body fat and energy accretion in mice fed diets containing different C18 fatty acids is by far the lowest with CLA and that linoleic acid produced the highest fat intake and energy accretion.     

Borage oil in the treatment of atopic dermatitis

Nutritional supplementation with omega-6 essential fatty acids (ω-6 EFAs) is of potential interest in the treatment of atopic dermatitis. EFAs play a vital role in skin structure and physiology. EFA deficiency replicates the symptoms of atopic dermatitis, and patients with atopic dermatitis have been reported to have imbalances in EFA levels. Although direct proof is lacking, it has been hypothesized that patients with atopic dermatitis have impaired activity of the delta-6 desaturase enzyme, affecting metabolism of linoleic acid to gamma-linolenic acid (GLA). However, to date, studies of EFA supplementation in atopic dermatitis, most commonly using evening primrose oil, have produced conflicting results. Borage oil is of interest because it contains two to three times more GLA than evening primrose oil. This review identified 12 clinical trials of oral or topical borage oil for treatment of atopic dermatitis and one preventive trial. All studies were controlled and most were randomized and double-blind, but many were small and had other methodological limitations. The results of studies of borage oil for the treatment of atopic dermatitis were highly variable, with the effect reported to be significant in five studies, insignificant in five studies, and mixed in two studies. Borage oil given to at-risk neonates did not prevent development of atopic dermatitis. However, the majority of studies showed at least a small degree of efficacy or were not able to exclude the possibility that the oil produces a small benefit. Overall, the data suggest that nutritional supplementation with borage oil is unlikely to have a major clinical effect but may be useful in some individual patients with less severe atopic dermatitis who are seeking an alternative treatment. Which patients are likely to respond cannot yet be identified. Borage oil is well tolerated in the short term but no long-term tolerability data are available.     

Flaxseed on cardiovascular disease markers in healthy menopausal women: a randomized, double-blind, placebo-controlled trial

OBJECTIVE: Due to its high content of lignans, alpha-linolenic acid and fiber, flaxseed may reduce cardiovascular disease risk in humans. The present study evaluated the effect of flaxseed on markers of cardiovascular disease risk in healthy menopausal women. METHODS: One hundred ninety-nine women were randomly assigned to consume 40 g daily of flaxseed or wheat germ placebo for 12 mo. Fatty acids, apolipoproteins A-1 and B, lipoprotein(a), low-density lipoprotein particle size, fibrinogen, C-reactive protein, insulin, and glucose were measured at baseline and at 12 mo. RESULTS: In total 179 women were available for the intention-to-treat analysis. Flaxseed increased plasma alpha-linolenic (P < 0.0001), docosapentaenoic (P = 0.001), and total omega-3 fatty (P = 0.0004) acids. Differences between flaxseed and wheat germ were observed for apolipoprotein A-1 (-0.10 +/- 0.26 g/L, P = 0.011) and apolipoprotein B (-0.05 +/- 0.16 g/L, P = 0.047). From baseline, flaxseed raised apolipoproteins A-1 and B by 4.4% (P = 0.006) and 3% (P = 0.054), whereas wheat germ increased these apolipoproteins by 11.6% (P < 0.0001) and 7% (P = 0.0001), respectively. Both treatments increased lipoprotein(a) (P < 0.0001) and decreased low-density lipoprotein peak particle size (P < 0.0001). CONCLUSION: In this large, long-term, placebo-controlled trial in healthy menopausal women, flaxseed increased some omega-3 fatty acids in plasma and had a limited effect on apolipoprotein metabolism.     

Plasma and red blood cell fatty acid composition in small for gestational age term infants fed human milk or formula

The purpose of the present study was to evaluate the effects of feeding human milk or milk formula on the fatty acid composition of plasma and red blood cell (RBC) lipids in at term small for gestational age infants (SGA) for the first 3 months of life. One group of infants received a formula with a linoleic:alpha-linolenic acid ratio of 10:1 (MF group). Another group served as control and received their own mother's milk (HM group). Blood samples were taken at birth and at 1 week, 4 weeks, and 3 months of life. Plasma and RBC fatty acid composition were analyzed by gas liquid chromatography and results of total plasma lipids were expressed as concentrations by adding an internal standard. Concentrations of saturated and monounsaturated fatty acids increased in total plasma lipids with age in all infants. In contrast, those fatty acids decreased when results were expressed as percentages of total fatty acids. Long-chain polyunsaturated fatty acids (LCP) decreased regardless of how results were expressed, but the absolute concentrations of these fatty acids in plasma available for tissue accretion were greater than suggested by the percentage results. Plasma and RBC docosahexaenoic acid (22:6n-3) decreased in the MF group in comparison to the HM group. Arachidonic acid (20:4n-6) was lower in plasma of MF-fed infant but not in RBC phospholipids. We conclude that term SGA infants fed an adapted milk formula with a linoleic:alpha-linolenic acid ratio of 10:1 but devoid of LCP may lead to a low n-3 LCP status.     

Metabolism of omega-6 polyunsaturated fatty acids in women with dysmenorrhea

Menstrual pain (dysmenorrhea) is one of the main complaints in clinics for women. The pain is often accompanied by other symptoms such as headache, nausea, constipation or diarrhea, urinary frequency, and vomiting which often leave the patients incapacitated for work or school for a few days. Dietary supplementation with polyunsaturated fatty acids (PUFA) has been shown to alleviate the menstrual pain. The purpose of the present study was to compare the effect of dietary supplementation with PUFA (sunflower seed oil, borage oil and fish oil concentrate) for three months on RBC membrane fatty acid composition in healthy and dysmenorrheica young women. Conversion of linoleic acid, via gamma-linolenic acid, to dihomo-gamma-linolenic acid (a precursor of anti-inflammatory prostaglandin E1) in dysmenorrheic subjects as compared to the controls was slower whereas the level of arachidonic acid (a precursor of pro-inflammatory PGE2) was not affected by the supplementation. Since there are no known side-effects associated with supplementation of these nutrients, management of dysmenorrhea through nutrition modulation should be an acceptable alternative to drug treatments.     

Dietary supplementation of obese children with 1000 mg alpha-linolenic acid per day: a placebo-controlled double blind study

INTRODUCTION: Enhanced dietary intake of omega-3 fatty acids may benefit persons with increased cardiovascular risk, among them obese subjects. Incorporation of omega-3 fatty acids into the plasma lipids is a prerequisite to achieve the favorable effects; however, only very few data are available on the dose of omega-3 fatty acid supplementation in children. The aim of our study was to examine the effects of the consumption of a diet supplemented with 1000 mg alpha-linolenic acid daily on plasma lipids in obese children. METHODS: In this two times six-week-long, placebo-controlled, crossover study, 9 obese children (age: 13.1 [2.5] years, body mass index: 31.2 [6.2] kg/m 2 ), median [IQR]) incorporated into their diet one egg and one meatball (50 g) per day from hens fed diets containing flaxseed oil, i.e. supplementary dietary intake of 1000 mg alpha-linolenic acid per day was provided. The fatty acid composition of plasma lipids was determined by high-resolution gas-liquid chromatography. RESULTS: Tendencies of increase were observed in the alpha-linolenic acid content of plasma lipids in the phospholipid, triacyl-glycerine and sterol-ester fractions after the supplementation with alpha-linolenic acid. In the non-esterified fatty acid fraction, the values of alpha-linolenic acid were significantly higher after the supplementation (0.11 [0.08] versus 0.14 [0.20], % weight/weight, p < 0.05), indicating the beginning of the accumulation of alpha-linolenic acid in plasma lipids. CONCLUSION: In obese children a six-week-long supplementation of the diet with 1000 mg alpha-linolenic acid per day increased significantly the contribution of omega-3 fatty acids only to the non-esterified fatty acids of plasma lipids, but had no significant effect on the esterified fractions. Increase of the dose of supplementation may be needed to influence omega-3 fatty acid status in obese children.     

Mechanisms by which botanical lipids affect inflammatory disorders

Changes in diet over the past century have markedly altered the consumption of fatty acids. The dramatic increase in the ingestion of saturated and n-6 fatty acids and concomitant decrease in n-3 fatty acids are thought to be a major driver of the increase in the incidence of inflammatory diseases such as asthma, allergy, and atherosclerosis. The central objective of the Center for Botanical Lipids at Wake Forest University School of Medicine and the Brigham and Women's Hospital is to delineate the mechanisms by which fatty acid-based dietary supplements inhibit inflammation leading to chronic human diseases such as cardiovascular disease and asthma. The key question that this center addresses is whether botanical n-6 and n-3 fatty acids directly block recognized biochemical pathways or the expression of critical genes that lead to asthma and atherosclerosis. Dietary supplementation with flaxseed oil, borage oil, and echium oil affects the biochemistry of fatty acid metabolism and thus the balance of proinflammatory mediators and atherogenic lipids. Supplementation studies have begun to identify key molecular and genetic mechanisms that regulate the production of lipid mediators involved in inflammatory and hyperlipidemic diseases. Echium oil and other oils containing stearidonic acid as well as botanical oil combinations (such as echium and borage oils) hold great promise for modulating inflammatory diseases.     

Supplementing lactating women with flaxseed oil does not increase docosahexaenoic acid in their milk

BACKGROUND: Flaxseed oil is a rich source of 18:3n-3 (alpha-linolenic acid, or ALA), which is ultimately converted to 22:6n-3 (docosahexaenoic acid, or DHA), a fatty acid important for the development of the infant brain and retina. OBJECTIVE: The objective of this study was to determine the effect of flaxseed oil supplementation on the breast-milk, plasma, and erythrocyte contents of DHA and other n-3 fatty acids in lactating women. DESIGN: Seven women took 20 g flaxseed oil (10.7 g ALA) daily for 4 wk. Breast-milk and blood samples were collected weekly before, during, and after supplementation and were analyzed for fatty acid composition. RESULTS: Breast milk, plasma, and erythrocyte ALA increased significantly over time (P < 0.001) and after 2 and 4 wk of supplementation (P < 0.05). Over time, 20:5n-3 (eicosapentaenoic acid, or EPA) increased significantly in breast milk (P = 0.004) and in plasma (P < 0.001). In addition, plasma EPA increased significantly (P < 0.05) after 2 and 4 wk of supplementation. There were significant increases over time in breast-milk 22:5n-3 (docosapentaenoic acid, or DPA) (P < 0.02), plasma DPA (P < 0.001), and erythrocyte DPA (P < 0.01). No significant changes were observed in breast-milk, plasma, or erythrocyte DHA contents after flaxseed oil supplementation. CONCLUSIONS: Dietary flaxseed oil increased the breast-milk, plasma, and erythrocyte contents of the n-3 fatty acids ALA, EPA, and DPA but had no effect on breast-milk, plasma, or erythrocyte DHA contents.     

Comparative effects of linoleic acid and gamma-linolenic acid intake on plasma lipids and platelet phospholipids in elderly people

It has been speculated that linoleic acid might be a precursor for platelet potentially anti-thrombotic polyunsaturated fatty acids like dihomo-gamma-linolenic acid. In elderly people, who are considered as a pre-thrombotic state, desaturation of linoleic acid may be diminished. To by-pass this rate limiting step, gamma-linolenic acid was given to elderly people and compared to linoleic acid with regard to the composition of plasma and platelet lipids. Sixteen old subjects took a daily supplement of lg of linoleic acid plus lg of gamma-linolenic acid (primrose oil) or 2g of linoleic acid (sunflower oil) for periods of two months in a cross over study. Increases in both dihomo-gamma-linolenic acid and arachidonic acid were noted in plasma lipids and platelet phospholipids after primrose oil supplementation. In contrast, sunflower oil did not induce such increases. Since dihomo-gamma-linolenic and arachidonic acid have opposite effects upon platelet functions, these findings could explain why primrose oil intake did not lead to any modification of platelet functions in elderly people     

Chemopreventive effects of dietary flaxseed on colon tumor development

Fatty acid composition of dietary fat plays a vital role in colon tumor development in animal models. Fats containing omega-6 fatty acids (e.g., corn oil) enhanced and omega-3 fatty acids (e.g., flaxseed oil) reduced chemically induced colon tumor development in rats. Lignans have also been shown to prevent colon tumor development in experimental animals. The objective of this investigation is to study the effects of dietary flaxseed meal, a source of both omega-3 fatty acid and lignans, on colon tumor development and compare them with the effects of dietary corn meal. Male Fischer rats, two groups of 24 each, were assigned to the AIN-93M diet supplemented with either 15% corn meal or 15% flaxseed meal, respectively. Carcinogenesis was initiated with subcutaneous injections of azoxymethane (15 mg/kg) once a week for 3 consecutive wk. After 35 wk of initiation, rats were anesthetized with ether. Blood was collected by cardiac puncture, and rats were sacrificed. The gastrointestinal tract was isolated. The site, size, and number of tumors were recorded. The fatty acid analysis of the collected serum and colon samples was performed. Expression of cyclooxygenase (COX)-1 and COX-2 was performed by Western blot method. Lignan levels in serum and colon samples were assayed. Colon tumor incidence, multiplicity, and size were found to be 82.6% and 29.4%; 1.3 and 0.3; and 44.4 and 5.3 mm(2) in corn and flaxseed meal groups, respectively. Colon and serum samples of the corn meal group showed higher levels of omega-6 fatty acid levels whereas the flaxseed meal group exhibited higher levels of omega-3 fatty acids. COX-1 and COX-2 expression in the flaxseed group was significantly lower (P < 0.05) as compared to the corn group. Dietary flaxseed meal containing high levels of omega-3 fatty acids and lignans is effective in preventing colon tumor development when compared with dietary corn meal possibly by increasing omega-3 fatty acid levels and decreasing COX-1 and COX-2 levels.