Effect of combinations of fish meal and feather meal on milk fatty acid content and nitrogen utilization in dairy cows.

The effect of supplemental fishmeal in combination with feathermeal at two different proportions in the diet on milk docosahexaenoic acid (DHA) content was investigated. Recently, benefits to human health have been attributed to the consumption of this fatty acid, which is normally present in marine lipids. Six Holstein cows past peak lactation were used in a Latin square design with a 2 x 3 factorial arrangement of treatments. Fish- and feathermeals were prepared as pellets at 4:1 and 1:4 combinations and offered at 3.75, 11.75, and 27% of the diet. The supplements were top-dressed onto a basal diet based on corn silage that was progressively replaced by supplement. Nitrogen balance measures were made during the experiment because of the wide range in crude protein content of experimental diets. Milk protein content increased with level of supplementation in the diet reflecting the protein quality of the supplements used. There was overall higher milk DHA content when cows consumed the supplement containing more fishmeal than feather meal. Milk DHA content increased in a quadratic fashion, as more of either supplement was included in the diet. Apparent transfer efficiency of DHA from diet to milk declined with increasing amount of DHA in the diet. Results from this experiment suggest that transfer of docosahexaenoic acid from diet to milk may depend on diet composition and quantity present in the diet.

n-3 Fatty acids and cardiovascular disease risk factors among the Inuit of Nunavik.

BACKGROUND: Inuit traditionally consume large amounts of marine foods rich in n-3 fatty acids. Evidence exists that n-3 fatty acids have beneficial effects on key risk factors for cardiovascular disease. OBJECTIVE: Our goal was to verify the relation between plasma phospholipid concentrations of the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and various cardiovascular disease risk factors among the Inuit of Nunavik, Canada. DESIGN: The study population consisted of 426 Inuit aged 18-74 y who participated in a 1992 health survey. Data were obtained through home interviews and clinical visits. Plasma samples were analyzed for phospholipid fatty acid composition. RESULTS: Expressed as the percentage of total fatty acids, geometric mean concentrations of EPA, DHA, and their combination in plasma phospholipids were 1.99%, 4.52%, and 6.83%, respectively. n-3 Fatty acids were positively associated with HDL-cholesterol concentrations and inversely associated with triacylglycerol concentrations and the ratio of total to HDL cholesterol. In contrast, concentrations of total cholesterol, LDL cholesterol, and plasma glucose increased as n-3 fatty acid concentrations increased. There were no significant associations between n-3 fatty acids and diastolic and systolic blood pressure and plasma insulin. CONCLUSIONS: Consumption of marine products, the main source of EPA and DHA, appears to beneficially affect some cardiovascular disease risk factors. The traditional Inuit diet, which is rich in n-3 fatty acids, is probably responsible for the low mortality rate from ischemic heart disease in this population.

Effect of a fish-oil concentrate on serum lipids in postmenopausal women receiving and not receiving hormone replacement therapy in a placebo-controlled, double-blind trial.

BACKGROUND: n-3 Fatty acid supplementation lowered serum triacylglycerol concentrations in studies in which most of the subjects were male. The effects of n-3 fatty acid supplementation in postmenopausal women receiving and not receiving hormone replacement therapy (HRT) have received little attention. OBJECTIVE: We sought to determine the effects of a fish-oil-derived n-3 fatty acid concentrate on serum lipid and lipoprotein risk factors for cardiovascular disease in postmenopausal women receiving and not receiving HRT, with an emphasis on serum triacylglycerol concentrations and the ratio of triacylglycerol to HDL cholesterol. DESIGN: Postmenopausal women (n = 36) were grouped according to exogenous hormone use and were randomly allocated to receive 8 capsules/d of either placebo oil (control) or n-3 fatty acid-enriched oil (supplement). The supplement provided 2.4 g eicosapentaenoic acid (EPA) plus 1.6 g docosahexaenoic acid (DHA) daily. Serum lipids and the fatty acid composition of serum phospholipids were determined on days 0 and 28. RESULTS: Supplementation with n-3 fatty acids was associated with 26% lower serum triacylglycerol concentrations (P < 0.0001), a 28% lower overall ratio of serum triacylglycerol to HDL cholesterol (P < 0.01), and markedly greater EPA and DHA concentrations in serum phospholipids (P < 0.05). CONCLUSIONS: These results show that supplementation with a fish-oil-derived concentrate can favorably influence selected cardiovascular disease risk factors, particularly by achieving marked reductions in serum triacylglycerol concentrations and triacylglycerol:HDL cholesterol in postmenopausal women receiving and not receiving HRT. This approach could potentially reduce the risk of coronary heart disease by 27% in postmenopausal women.

Suppressive effects of fish oil on mesangial cell proliferation in vitro and in vivo.

BACKGROUND: Mesangial cell proliferation is a characteristic feature of IgA nephropathy and many other forms of glomerulonephritis. Recent clinical studies have shown that dietary fish oil supplementation retards renal disease progression in patients with IgA nephropathy. The mechanism by which this effect occurs is unknown. METHODS: The anti-Thy 1.1 (ATS) model of mesangial proliferative glomerulonephritis was employed to test the hypothesis that dietary fish oil supplementation reduces mesangial cell proliferation following acute injury. Subcultured rat mesangial cells were used to determine the in vitro effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the primary components of fish oil, on proliferation. RESULTS: Following antithymocyte serum (ATS) administration, proteinuria was significantly decreased in animals treated with fish oil compared with sesame oil-treated controls. In ATS rats given fish oil, there was less mesangial cell and matrix expansion, mesangiolysis, or basement membrane disruption (delta% = -40%). ATS rats receiving fish oil had less glomerular cell proliferation (PCNA-delta% = -50%) and a reduction of alpha-smooth muscle actin expression (delta% = -27%) by mesangial cells. In subcultured rat mesangial cells, DHA, but not EPA, significantly inhibited proliferation. CONCLUSIONS: Fish oil inhibits mesangial cell activation and proliferation in ATS glomerulonephritis, reduces proteinuria, and decreases histologic evidence of glomerular damage. In vitro, the antiproliferative effects of fish oil are more likely related to the action of DHA. We suggest that orally administered fish oil, or purified DHA, may have a suppressive effect in acute phases or relapses of glomerulopathies by inhibiting activation and proliferation of mesangial cells.

Effect of supplementation with dietary seal oil on selected cardiovascular risk factors and hemostatic variables in healthy male subjects.

The average daily consumption of seal oil by the Inuit people is approximately 8-9 g, yet there is very little information on the effect of seal oil consumption on cardiovascular disease risk factors. In this study, 19 healthy, normocholesterolemic subjects consumed 20 g of encapsulated seal oil containing eicosapentaenoic acid (EPA; 20:5n-3), docosahexaenoic acid (DHA; 22:6n-3), and docosapentaenoic acid (DPA; 22:5n-3) or 20 g of vegetable oil (control) per day for 42 days. Levels of selected cardiovascular and thrombotic risk factors as well as fatty acid profiles of serum phospholipid and nonesterified fatty acid (NEFA) were determined. EPA levels in serum phospholipid and NEFA increased by 4.3- and 2.7-fold, respectively, in the seal oil supplemented group. DHA levels rose 1.5- and 2.1-fold, respectively, and DPA levels rose 0.5- and 0.7-fold, respectively. Arachidonic acid (AA) levels dropped by 26% in both serum phospholipid and serum NEFA. There was a significant decrease in the ratio of n-6 to n-3 fatty acids in serum phospholipid from 7.2 to 2.1 and a significant increase in the ratio of EPA/AA in NEFA. Ingestion of seal oil raised the coagulant inhibitor, protein C, values by 7% and decreased plasma fibrinogen by 18%. No alterations in other hemostatic variables, including plasma activity of Factors VII, VIII, IX, and X and antithrombin, or in the concentrations of von Willebrand Factor, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride, glucose, Apo A-1, or lipoprotein(a) were observed in either group. Other risk factors for cardiovascular disease, including hematocrit, white blood cell count, plasma viscosity, systolic and diastolic blood pressures, heart rate, and platelet aggregation after stimulation with ADP or collagen did not change. Our results indicate that seal oil supplementation in healthy, normocholesterolemic subjects decreased the n-6/n-3 ratio and increased EPA, DHA, and DPA and the ratio of EPA/AA and DHA/AA in the serum phospholipid and NEFA, while exhibiting a modest beneficial effect on fibrinogen and protein C levels.

Docosahexaenoic acid and docosapentanoic acid incorporation into human platelets after 24 and 72 hours: inhibitory effects on platelet reactivity.

Short-term in vitro platelet membrane lipid enrichment studies and feeding trials of human subjects with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have shown a decreased reactivity in the platelet response to collagen. In this study, exogenous albumin-bound n-3 polyunsaturated fatty acids (PUFAs), namely EPA, DHA and docosapentanoic acid (DPA) were added to platelet suspensions and maintained at 22 degrees C for 24 and 72 hours. Subsequently, the aggregation response to agonist stimulation and the morphological appearance of the platelets were evaluated. A significant enrichment of platelet phospholipids (PL) in n-3 fatty acids occurred upon incubation with n-3 PUFAs in vitro, which was accompanied by a decrease in the aggregation response to collagen and preservation of platelet morphology compared with non-supplemented control platelet preparations. The inhibitory effect of the n-3 PUFAs appeared to be surface mediated in the case of DHA and DPA because the platelet response to agonist returned when the fatty acids were removed by washing. The platelet aggregation response after storage at 22 degrees C was also evaluated in platelet suspensions collected from healthy individuals before and after 42 days of dietary supplementation with seal oil, rich in DPA and DHA. Unlike the in vitro supplementation, in vivo modification and enrichment of platelet PLs by ingestion of seal oil did not appear to improve platelet function during storage relative to the placebo group.

Supplementation with quercetin markedly increases plasma quercetin concentration without effect on selected risk factors for heart disease in healthy subjects.

The purpose of this double-blind study was to investigate the influence of adding a quercetin-containing supplement to the diet on plasma quercetin status, serum/platelet fatty acid levels and risk factors for heart disease. Healthy men and women with cholesterol levels of 4.0-7.2 mmol/L, consumed four capsules daily of either a quercetin-containing supplement (1.0 g quercetin/d) or rice flour placebo for 28 d. Quercetin intakes were approximately 50-fold greater than the dietary intakes associated with lower coronary heart disease mortality on the basis of epidemiologic studies. Subjects consuming quercetin-containing capsules had plasma quercetin concentrations approximately 23-fold higher than those of subjects consuming the control capsules. Quercetin supplementation did not modify serum total, LDL or HDL cholesterol or triglyceride levels. There were also no alterations of other cardiovascular disease or thrombogenic risk factors, including platelet aggregation, platelet thromboxane B2 production, blood pressure or resting heart rate. Furthermore, there was no effect on the levels of (n-6) or (n-3) polyunsaturated fatty acids in serum or platelet phospholipids. In conclusion, supplementation with quercetin-containing capsules markedly enhanced the plasma quercetin concentration but had no effect on other cardiovascular or thrombogenic risk factors.

Effect of supplementation with different doses of DHA on the levels of circulating DHA as non-esterified fatty acid in subjects of Asian Indian background.

There is evidence to indicate that the high rates of coronary heart disease and myocardial infarction amongst Indians of Asian descent may be partly related to circulating nonesterified fatty acids (NEFA). As docosahexaenoic acid (DHA,22:6n-3) in NEFA form has been found to exhibit anti-platelet aggregatory and anti-arrhythmic potential in vitro, the effect of supplementary DHA was examined in healthy subjects of Asian Indian background. Furthermore, time- and dose-dependent changes in absolute levels of DHA as NEFA or phospholipid (PL) were compared. The subjects consumed 8 capsules daily of placebo (DHA-free) or low DHA (0.75 g/day)or high DHA (1.50 g/day) over 6 wks. Fasting blood samples were drawn at days 0, 21, and 42 for analysis of serum lipid/lipoprotein composition. No significant effect of DHA supplementation on the levels of serum lipid/lipoproteins (including Lp[a]) or blood pressure was found. However, the DHA level in serum phospholipid rose by 167% overall with low-dose supplementation (from 2.4-6.4 mol%) but only by an additional 23% upon doubling the dose from 0.75 g to 1.50 g/day. Furthermore, after 6 weeks of supplementation with 0.75 g or 1.5 g DHA/day, absolute concentrations of DHA as PL were not significantly different from the corresponding 3-week values. Interestingly, the absolute concentrations of serum DHA as NEFA showed a marked rise with low-dose supplementation (by 212% overall, from 2.4 to 7.5 microM) and a further 70% rise (to 12.7 microM) upon doubling the supplementation from 0.75 to 1.50 g/day. As well, the 6-week concentrations (DHA-NEFA) were significantly different than the corresponding 3-week values at both dose levels. Elevation of circulating DHA-NEFA levels via DHA supplementation, as shown herein, to concentrations that exhibit anti-thrombotic and anti-arrhythmic potential in vitro needs to be extended to trials where clinical end-points are determined.

Effects of fish meal in beef cattle diets on growth performance, carcass characteristics, and fatty acid composition of longissimus muscle.

We investigated the effects of fish meal (FM) in beef cattle diets on growth performance, carcass characteristics, and fatty acid (FA) composition of longissimus muscle in 63 yearling steers (335 +/- 23 kg). High-moisture corn and alfalfa silage diets were supplemented with either a corn gluten/blood meal mixture or FM at 10% of the diet. Fish meal contained (as-is basis) 5.87 g/kg eicosapentaenoic acid (EPA) and 9.84 g/kg docosahexaenoic acid (DHA). Seven strategies were developed to feed either a control diet (no FM) or diets containing 5 or 10% FM with FM fed for either 56, 112, or 168 d before slaughter. Average daily gain and feed efficiency were not affected (P > .10) by FM feeding but DMI decreased. Within FM diets, cattle fed 5% FM consumed more (P < .01) DM and gained more (P < .02) than cattle fed 10% FM. Carcass traits were not affected (P > .05) by feeding strategy except for fatter (P < .05) and lower (P < .06) yielding carcasses in cattle fed 5 vs 10% FM diets. Fish meal feeding increased (P < .01) concentrations of (n-3) FA, including EPA and DHA, and decreased (P < .05) concentrations of arachidonic acid. Increasing the amount of dietary FM further increased (P < .01) concentrations of EPA and DHA and decreased (P < .05) concentrations of (n-6) FA. We estimate that a 114-g steak from cattle fed 10% FM would supply 35 to 90% of the current average daily intake of EPA and DHA in North America. The results indicate that FM may have a role in niche marketing of beef provided that eating quality is not compromised.

Dietary docosahexaenoic acid as a source of eicosapentaenoic acid in vegetarians and omnivores.

The utilization of dietary docosahexaenoic acid (DHA; 22:6n-3) as a source of eicosapentaenoic acid (EPA; 20:5n-3) via retroconversion was investigated in both vegetarians and omnivores. For this purpose, an EPA-free preparation of DHA was given as a daily supplement (1.62 g DHA) over a period of 6 wk. The dietary supplement provided for a marked increase in DHA levels in both serum phospholipid (from 2.1 to 7.1 mol% in vegetarians and 2.2 to 7.6 mol% in omnivores) and platelet phospholipid (from 1.1 to 3.4 mol% in vegetarians and 1.4 to 3.9 mol% in omnivores). EPA levels rose to a significant but much lesser extent, while 20:4n-6, 22:5n-6, and 22:5n-3 all decreased. Based on the serum phospholipid data, the retroconversion of DHA to EPA in vivo was estimated to be 9.4% overall with no significant difference between omnivores and vegetarians.

Effect of garlic and fish-oil supplementation on serum lipid and lipoprotein concentrations in hypercholesterolemic men.

This study examined the effects of garlic and fish-oil supplementation (alone and in combination) on fasting serum lipids and lipoproteins in hypercholesterolemic subjects. After an initial run-in phase, 50 male subjects with moderate hypercholesterolemia were randomly assigned for 12 wk to one of four groups: 1) 900 mg garlic placebo/d + 12 g oil placebo/d; 2) 900 mg garlic/d + 12 g oil placebo/d; 3) 900 mg garlic placebo/d + 12 g fish oil/d, providing 3.6 g n-3 fatty acids/d; and 4) 900 mg garlic/d + 12 g fish oil/d. In the placebo group, mean serum total cholesterol, low-density-lipoprotein cholesterol (LDL-C), and triacylglycerols were not significantly changed in relation to baseline. Mean group total cholesterol concentrations were significantly lower with garlic+fish oil (-12.2%) and with garlic (-11.5%) after 12 wk but not with fish oil alone. Mean LDL-C concentrations were reduced with garlic+fish oil (-9.5%) and with garlic (-14.2%) but were raised with fish oil (+8.5%). Mean triacylglycerol concentrations were reduced with garlic+fish oil (-34.3%) and fish oil alone (-37.3%). The garlic groups (with and without fish oil) had significantly lower ratios of total cholesterol to high-density-lipoprotein cholesterol (HDL-C) and LDL-C to HDL-C. In summary, garlic supplementation significantly decreased both total cholesterol and LDL-C whereas fish-oil supplementation significantly decreased triacylglycerol concentrations and increased LDL-C concentrations in hypercholesterolemic men. The combination of garlic and fish oil reversed the moderate fish-oil-induced rise in LDL-C. Coadministration of garlic with fish oil was well-tolerated and had a beneficial effect on serum lipid and lipoprotein concentrations by providing a combined lowering of total cholesterol, LDL-C, and triacylglycerol concentrations as well as the ratios of total cholesterol to HDL-C and LDL-C to HDL-C.

Supplementation with an algae source of docosahexaenoic acid increases (n-3) fatty acid status and alters selected risk factors for heart disease in vegetarian subjects.

The purpose of this double-blind study was to investigate the influence of dietary supplementation with an algae source of docosahexaenoic acid [DHA; 22:6(n-3)], devoid of any eicosapentaenoic acid [EPA; 20:5(n-3)], on serum/platelet DHA status, the estimated retroconversion of DHA to EPA, and risk factors for heart disease in vegetarian subjects. Healthy vegetarians (12 male, 12 female) consumed nine capsules daily of either DHA (1.62 g/d) or corn oil for 6 wk. Consumption of DHA capsules increased DHA levels in serum phospholipid by 246% (from 2.4 to 8.3 g/100 g fatty acids) and in platelet phospholipid by 225% (from 1.2 to 3.9 g/100 g fatty acids). EPA levels increased in serum phospholipid by 117% (from 0.57 to 1.3 g/100 g fatty acids) and in platelet phospholipid by 176% (0.21 to 0.58 g/100 g fatty acids) via metabolic retroconversion; the estimated extent of DHA retroconversion to EPA was 11.3 and 12.0%, based on the serum and platelet analyses, respectively. Arachidonic acid [AA; 20:4(n-6)] levels in serum and platelet phospholipids decreased moderately during the trial period (DHA group) as did both docosapentaenoic acids [22:5(n-6) and 22:5(n-3)]. Although no significant changes were found in the total and LDL-cholesterol levels with DHA supplementation, the total cholesterol:HDL-cholesterol ratio showed a moderate decrease over time as did the LDL-cholesterol:HDL-cholesterol ratio and serum triglyceride concentrations. DHA supplementation did not alter the various thrombogenic factors measured. In conclusion, DHA supplementation markedly enhanced the DHA status (of serum and platelets), provided for the formation of substantial EPA, and lowered the total and LDL-cholesterol:HDL-cholesterol ratios.

A soy protein isolate rich in genistein and daidzein and its effects on plasma isoflavone concentrations, platelet aggregation, blood lipids and fatty acid composition of plasma phospholipid in normal men.

The effects of consuming a soy protein isolate beverage powder (60 g/d for 28 d) vs. a casein supplement was evaluated in 20 male subjects who were randomly allocated into the two groups. A dramatic rise in plasma isoflavone concentrations was observed after supplementation in the soy protein group, the levels reaching 907 +/- 245 nmol/L for genistein (a 110-fold increase) and 498 +/- 102 nmol/L for daidzein (a 150-fold increase) as measured by isotope dilution gas chromatography - mass spectrometry. These concentrations are higher than previously reported for the plasma of Japanese subjects consuming a traditional diet (276 nmol/L and 107 nmol/L, respectively). No significant differences in collagen- or 9,11-dideoxy-11alpha, 9alpha-epoxymethanoprostaglandin F2alpha (U46619)-induced platelet aggregation were observed in platelet-rich plasma from the two groups; the increase in plasma isoflavonoids from soy protein supplementation is not sufficient to significantly inhibit platelet aggregation ex vivo. Similarly, plasma total and HDL-cholesterol were not affected by protein supplementation, possibly because the men were normocholesterolemic at entry. Analysis of plasma phospholipid polyunsaturated fatty acid composition showed no differences between soy protein and casein supplementation. Previous investigations reported a significant alteration in fatty acid status in animals fed soy protein relative to those fed casein. The present studies indicate that although soy protein supplementation to a typical Western diet can increase plasma concentrations of isoflavones, this may not necessarily be sufficient to counter heart disease risk factors such as high plasma cholesterol and platelet aggregation.

Dietary alteration of dihomogamma-linolenic acid/arachidonic acid ratio in a rat 5/6-renal-ablation model. The Nutrition & Kidney Disease Research Group.

Interest in the modulation of renal diseases by polyunsaturated fatty acids (PUFA) led this group to examine the effects of borage oil (BO) and corn oil (CO) in the rat 5/6-renal-ablation model. BO is a rich source of gamma-linolenic acid (GLA; 18:3n-6), which is elongated to dihomogamma-linolenic acid (DGLA; 20:3n-6). CO is a rich source of linoleic acid (LA; 18:2n-6), a GLA and arachidonic acid (AA; 20:4n-6) precursor. The purpose of this study was to assess whether an increased DGLA:AA ratio as provided by BO would confer benefits beyond those provided by LA present in corn oil. Forty rats were used for the experiment. Seven rats were used for presurgery measurements. The remaining animals were subjected to 5/6 nephrectomy. Surviving rats (N = 30) were fed regular laboratory diet (RLD) for 7 days, at which time seven rats were used to obtain 1-wk postnephrectomy data. The remainder were then allocated to receive either RLD (N = 8), 15% BO (N = 8), or 15% CO (N = 7) diets for 20 wk. Body weight, renal phospholipid levels, renal function (proteinuria and GFR), glomerular histology, glomerular macrophage infiltration, urinary prostaglandin levels (thromboxane B2 (TxB2), 6-keto-PGF1 alpha), plasma lipid levels, and blood pressure were measured. Diets were well tolerated by all groups with a similar age-related gain in weight throughout the study. Efficacy of the PUFA diets was confirmed by alteration in renal tissue phospholipids; LA decreased in the RLD and BO groups, but not in the CO group. AA was higher in the BO and CO rats, but only the BO group showed a rise in GLA and DGLA incorporation. Proteinuria increased progressively in the RLD group but remained at 1-wk postsurgery levels in the BO and CO groups. Decline in GFR and mesangial expansion were significantly lessened by BO supplementation only. Both PUFA diets limited glomerulosclerosis and macrophage infiltration, but direct comparisons between BO and CO groups revealed significantly less glomerulosclerosis and macrophage infiltration in the BO group. Both BO and CO attenuated the rise in the TxB2 excretion rate and restored the 6-keto-PGF1 alpha:TxB2 ratio to the 1-wk postsurgery level. Plasma lipid levels rose in all groups, but the rise in cholesterol level was less in the BO and CO rats, CO being the most efficacious in this regard. BP increased progressively in RLD rats, but not in the BO and CO groups, BO providing a markedly greater hypotensive effect. In summary, both CO and BO supplemented PUFA diets limited glomerular injury in the renal-ablated rats. However, BO supplementation was more effective than CO supplementation at preserving GFR, limiting mesangial expansion and glomerulosclerosis, and reducing glomerular macrophage infiltration.

Marked enrichment of the alkenylacyl subclass of plasma ethanolamine glycerophospholipid with eicosapentaenoic acid in human subjects consuming a fish oil concentrate.

Alteration in human platelet fatty acid levels with the consumption of fish oils containing eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) have been well documented, but changes in the fatty acid composition of plasma plasmalogenic phospholipid under similar circumstances have not been delineated. In the present study, subjects consumed the fish oil concentrate (MaxEPA) for 6 wk followed immediately by a 6-wk recovery period with no fish oil ingestion. Plasma total choline glycerophospholipid (GPC) and ethanolamine glycerophospholipid (GPE) subclasses isolated from blood samples obtained at 0, 3, 6, 9 and 12 wk of the experimental period were analyzed for fatty acid composition via thin-layer and gas-liquid chromatographic techniques. Consumption of fish oil for 3 or 6 wk significantly elevated the content of n-3 fatty acids while concomitantly decreasing n-6 fatty acid levels in plasma total GPC and in diacyl and alkenylacyl (plasmalogen) GPE. Alkenylacyl GPE exhibited the greatest alteration of both n-3 and n-6 fatty acid levels. Following 6 wk of supplementation with fish oil, EPA rose by 24.6 mol% in alkenylacyl GPE compared to increases of 6.7 and 7.1 mol% in diacyl GPE and total GPC, respectively. The increase in EPA (from 5.0 to 29.6 mol%) in plasma alkenylacyl GPE represents amongst the highest enrichment of EPA in any lipid yet reported in human subjects. DHA also rose by 8.0, 4.8, and 3.1 mol% in alkenylacyl GPE, diacyl GPE, and total GPC, respectively. Alkenylacyl GPE exhibited the greatest mol% decline (by 18.7 mol%) in arachidonic acid (AA, 20:4n-6) following 6 wk of fish oil supplementation. The corresponding decreases of AA in diacyl GPE and total GPC were 8.7 and 1.8 mol%, respectively. Following the 6 wk recovery period, n-3 and n-6 fatty acid levels had returned to pre-supplementation values. The marked enrichment of alkenylacyl GPE in n-3 fatty acids, especially EPA, may be of significance with respect to a unique role for this plasma phospholipid subclass in attenuating certain lipoprotein-mediated cardiovascular effects as observed with fish/fish oil consumption.

Effects of flaxseed and flax oil diets in a rat-5/6 renal ablation model.

The objective of this study was to assess the effects of flaxseed and flax oil diets in the rat renal ablation model. Flaxseed is a rich source of alpha-linolenic acid, an 18:3n3 omega-3 fatty acid, which has anti-atherogenic and anti-inflammatory properties. Flaxseed, but not flax oil, is also rich in lignans, which are platelet-activating factor-receptor antagonists. Rats were subjected to 5/6 nephrectomy, fed a regular laboratory diet (RLD) for 1 week, then divided into three groups to receive either the RLD (n = 8), a 15% flaxseed diet (n = 8), or a 15% flax oil diet (n = 7). Blood pressure, proteinuria, glomerular filtration rate, and urinary prostaglandins (thromboxane B2 and 6-keto prostaglandin F1 alpha) were measured presurgery and at 1 week (before dietary allotment) and 20 weeks postnephrectomy when blood for plasma lipids and kidneys for histology and tissue-phospholipid analyses were obtained. Blood pressure increased progressively in the RLD group but not in the flax diet groups. Plasma triglycerides and cholesterol increased in all groups, but this increase was significantly attenuated by both flax diets. Proteinuria increased 1 week postsurgery and continued to increase in the RLD group but not in the flax diet groups. Glomerular filtration rate decreased progressively, but this decline in renal function was attenuated significantly by the flax diets. Both of the flax diets prevented glomerulosclerosis and mesangial expansion. Renal alpha-linolenic acid was increased by both the flax diets (flax oil > flaxseed), but eicosapentaenoic acid increased in the flax oil group only. The flaxseed group had greater renal-arachidonic acid levels than the flax oil and RLD groups. The total omega-3 fatty acids increased twofold to threefold in the flax oil group compared with the two other groups. The total saturated fatty acids were lower and the polyunsaturated fatty acids were increased in both flax diet groups. A progressive increase in urinary thromboxane B2 occurred in the RLD group but not in the flaxseed group; the level decreased in the flax oil group. The ratio of prostaglandin F1 alpha/thromboxane B2 was preserved in the flax oil group only. In conclusion, the dietary flax seed and flax oil attenuated the decline in renal function and reduced glomerular injury with favorable effects on blood pressure, plasma lipids, and urinary prostaglandins. While we have not proven any specific synergistic effects of the constituents of the flaxseed diet, the benefits of flax-derived alpha-linolenic acid with or without lignans in the rat-5/6 renal ablation model seem clear from this experiment.

Effects of a fish-oil and vegetable-oil formula on aggregation and ethanolamine-containing lysophospholipid generation in activated human platelets and on leukotriene production in stimulated neutrophils.

The effects of consuming a liquid formula containing either fish oil enriched in omega-3 fatty acids or vegetable oil enriched in oleic acid was evaluated in 20 male subjects randomly allocated into two groups over a 42-d period. A decrease in collagen-induced aggregation by using washed platelet suspensions was found in both groups after nutritional supplementation. A considerable rise in omega-3 and a decrease in omega-6 fatty acids occurred in the platelet phospholipid with fish-oil consumption. The degree of eicosapentaenoic acid (EPA, 20:5n-3) enrichment (fish-oil group) was dramatically greater in the ether-containing plasmenylethanolamine (13.5 mol% of fatty acids; mol% of fatty acids = moles per 100 moles of total fatty acids) than in phosphatidylethanolamine (2.8 mol%) or phosphatidylcholine (2.9 mol%). Neither treatment significantly influenced the agonist-induced accumulation of lysoplasmenylethanolamine as derived via phospholipase A2 hydrolysis of plasmenylethanolamine. HPLC measurements of eicosanoid production in A23187-stimulated neutrophils revealed a considerable decrease in the formation of arachidonic acid-derived leukotriene B4 (LTB4), by 41%, and 5-HETE (5-hydroxyeicosatetraenoic acid), by 30%, in the fish-oil group along with the appearance of the corresponding EPA-derived products [LTB5 and 5-HEPE (5-hydroxyeicosapentaenoic acid)]. No such alterations in the formation of lipoxygenase products were found with the vegetable oil treatment.