Effects of dietary alpha linolenic acid on cholesterol metabolism in male and female hamsters of the LPN strain

Effects of including different levels of equal mix of soybean and flaxseed oils in Japanese quail diets on the growth, carcass quality, and blood biomarkers

Corn, the primary ingredient in modern poultry feeds, contains high levels of ω-6 fatty acids but lacks sufficient ω-3 fatty acids, creating an imbalance. Maintaining a balance between ω-6 and ω-3 fatty acids in poultry diets is crucial due to their competition. This study aimed to evaluate the effects of incorporating different concentrations of an equal mix of soybean oil (SO) and flaxseed oil (FO) into quail diets on growth performance, carcass quality, and blood biochemistry. One-week-old Japanese quail birds (n = 200) were randomly assigned to four dietary groups, each comprising five replicates with 10 chicks per replicate. Four isonitrogenous/isocaloric basal diets were formulated. Group 1 (control) received a basal diet without SO or FO, while Groups 2-4 received basal diets supplemented with an equal mix of SO+FO at levels of 1.0 %, 1.5 %, and 2.0 %, respectively. The inclusion of oil mixes significantly increased body weight (BW) at five weeks and daily weight gain (DWG) during weeks 3-5 and 1-5. The feed conversion ratio (FCR) improved with the addition of oil mixes throughout the trial period. Supplementing quail diets with oil mixes resulted in reduced serum total cholesterol (TC) and LDL cholesterol, elevated serum HDL cholesterol, and no significant effect on triglycerides (TG) and VLDL cholesterol levels. Quails fed oil-supplemented diets showed lower serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and creatinine levels, while urea and uric acid were significantly affected. Birds fed diets with oil mixes also had increased serum concentrations of immunoglobulin G (IgY), immunoglobulin M (IgM), and superoxide dismutase (SOD). However, serum immunoglobulin A (IgA), malondialdehyde (MDA), and total antioxidant capacity (TAC) levels did not significantly change across experimental groups. Overall, adding up to 2 % of the SO and FO mix in growing quail feeds improved growth performance, blood lipid profile, liver and kidney function markers, immune response, and antioxidant defense. The highest level of oil mix (2 %) yielded the most beneficial effects.

The impacts of dietary inclusion of soybean oil and linseed oil on growth performance, carcass yield, and health status of growing Japanese quail

Polyunsaturated fatty acids (PUFA), including n-6 and n-3 fatty acids, are essential for enhancing the performance and health of poultry. Avian species lack desaturase enzymes for endogenous synthesis of n-6 and n-3 fatty acids. This work aimed to determine the impacts of including soybean oil (SO) and linseed oil (LO) in quail diets on growth, lipid profile, hepatic and renal functions, immunity, and antioxidant status. A total of 350 Japanese quail chicks (1-wk-old) were randomly arranged into 7 dietary treatment groups. Seven isocaloric and isonitrogenous experimental basal diets were formed based on the nutritional requirements of growing Japanese quail. Group 1, the control, received a basal with no oils, while groups 2 to 7 received a basal diet containing either 1% SO, 1.5% SO, 2% SO, 1% LO, 1.5% LO, or 2% LO, respectively. Quail groups that consumed diets containing LO at all levels showed significantly greater live body weight (LBW) at 5th wk of age than other experimental groups. The dietary incorporation of 1.5 or 2% SO or LO at all levels yielded significant improvements in body weight gain (BWG) and feed conversion ratio (FCR) through 3 to 5 and 1 to 5 wk of age. Different dietary oil sources and levels have no significant impacts on feed intake (FI) and carcass yield parameters. Lipid profile parameters were improved by adding SO and LO in quail diets, with LO having a higher effect than SO. The hepatic and renal functionality were improved by adding SO and LO in quail diets. The lowest uric acid (UA) bloodstream concentrations were recorded in the quail group fed a diet with 2% LO. Values of Gamma globulins (G-GLO) and immunoglobulins (G, M, and A) were increased by adding SO or LO to quail diets. Blood levels of MDA and TAC were improved significantly by including LO in quail diets. The activity of the superoxide dismutase (SOD) enzyme was significantly increased by adding SO or LO to quail diets. Generally, adding SO or LO to growing quail diets up to 2% could yield favorable effects on growth performance, blood lipids, hepatic and renal functions, immunity, and antioxidant status; however, LO seems to have better effects than SO.

Effects of Dietary Plant-Derived Low-Ratio Linoleic Acid/Alpha-Linolenic Acid on Blood Lipid Profiles: A Systematic Review and Meta-Analysis

This meta-analysis aimed to investigate the impact of low-ratio linoleic acid/alpha-linolenic acid (LA/ALA) supplementation on the blood lipid profiles in adults. We conducted a systematic search for relevant randomized controlled trials (RCTs) assessing the effects of low-ratio LA/ALA using databases including PubMed, Embase, Cochrane, and Web of Science, as well as screened related references up until February 2023. The intervention effects were analyzed adopting weighted mean difference (WMD) and 95% confidence interval (CI). The meta-analysis indicated that low-ratio LA/ALA supplementation decreased total cholesterol (TC, WMD: -0.09 mmol/L, 95% CI: -0.17, -0.01, p = 0.031, I2 = 33.2%), low-density lipoprotein cholesterol (LDL-C, WMD: -0.08 mmol/L, 95% CI: -0.13, -0.02, p = 0.007, I2 = 0.0%), and triglycerides (TG, WMD: -0.05 mmol/L, 95% CI: -0.09, 0.00, p = 0.049, I2 = 0.0%) concentrations. There was no significant effect on high-density lipoprotein cholesterol concentration (HDL-C, WMD: -0.00 mmol/L, 95% CI: -0.02, 0.02, p = 0.895, I2 = 0.0%). Subgroup analysis showed that low-ratio LA/ALA supplementation significantly decreased plasma TC, LDL-C, and TG concentrations when the intervention period was less than 12 weeks. In the subgroup analysis, a noteworthy decrease in both TC and LDL-C levels was observed in individuals receiving low-ratio LA/ALA supplementation in the range of 1-5. These findings suggest that this specific range could potentially be effective in reducing lipid profiles. The findings of this study provide additional evidence supporting the potential role of low-ratio LA/ALA supplementation in reducing TC, LDL-C, and TG concentrations, although no significant impact on HDL-C was observed.

Antioxidative potential and ameliorative effects of green lentil (Lens culinaris M.) sprouts against CCl4-induced oxidative stress in rats

The present study is aimed to investigate the antioxidative potential and ameliorative effects of Lens culinaris Medikus sprouts hydroalcoholic extract (LSHE) on CCl4-induced oxidative stress in rats. The research has been carried out in two successive stages. Firstly, the highest phenolic content and antioxidant activity of L. culinaris sprouts were assessed at 20 ± 1°C and 90-93% RH during sprouting. Total phenolic content (TPC), total carotenoids (TC), total flavonoids (TF), total flavonols (TFL), DPPH-RSA, and vitamin C contents of L. culinaris seeds and 6-days sprouts were determined. Subsequently, phenolics by HPLC analysis of L. culinaris seeds, 3rd and 6th-day sprouts were identified and quantified. Results indicated that 6th-day sprouts contained considerable phenolics with superior antioxidant capacity, thus selected to be examined for biological activity in a rat's module consisting of five groups. G1, normal rats orally received distilled water. G2 received 1.0 mL kg-1 of CCl4 and olive oil (1:1) intraperitoneally (i.p.) twice a week. G3 received CCl4 (i.p.) and 50 mg GAE kg-1 of LSHE daily/orally. G4 received CCl4 (i.p.) 100 mg kg-1 of LSHE orally/daily. G5 (reference group) treated by intramuscular injection (i.m.) of vit. E+Selenium (Vit. E+Se, 50 mg kg-1 twice a week). The weight gain, relative weight of organs, hypoglycemic and hypolipidemic efficiencies, liver's and kidneys' functions, and antioxidant biomarkers were examined. LSHE enhanced the weight gain recovery % and significantly reduced fasting blood glucose. The hypolipidemic effect of LSHE was dramatically reduced triglycerides (TG), total cholesterol (CHO), high- and low-density lipoproteins (HDL-c and LDL-c), and very-low-density lipoproteins (VLDL-c). Administration of 50 and 100 LSHE mg kg-1 ameliorated liver and kidney function in dose-dependent manure. Intriguingly, LSHE considerably reduced malondialdehyde (MDA) while significantly raising reduced glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) in a dose-dependent manner. In conclusion, biochemical examinations confirmed the therapeutic efficacy of LSHE as a functional product. It encouraged us to recommend L. culinaris sprout production for attenuating hepatotoxicity and nephrotoxicity, as well as being beneficial and profitable for controlling oxidative stress complications.

Beneficial Effects of Flaxseed and/or Mulberry Extracts Supplementation in Ovariectomized Wistar Rats

Low endogenous estrogen action causes several injuries. Medicinal plants, such as flaxseed and mulberry, contain substances that have been shown to be effective to the organism. The aim was to verify the effects of flaxseed and/or mulberry extracts on ovariectomized Wistar rats. The animals received supplements of extracts and estrogen or saline by gavage for 60 days and were weighed weekly. Vaginal wash, blood, pituitary, uterus, liver, and kidneys were collected. Phenolic compounds and the antioxidant activity of the extracts, lipid profile, uric acid, liver enzymes, and pituitary weight were measured. Histomorphometric for uterine wall and histopathological analyses for liver and kidney were performed. Flaxseed and mulberry extracts showed great antioxidant activity and large amounts of phenolic compounds. The treatment with extracts had less weight gain, increased pituitary weight, the predominance of vaginal epithelial cells, and reduced TC, LDL-c and lipase activity, similar to estrogen animals. Estrogen or flaxseed + mulberry animals reduced VLDL-c and TAG. HDL-c, uric acid, and liver enzymes did not differ. Estrogen or extracts demonstrated trophic action on the endometrial thickness and have not shown hepatotoxicity or nephrotoxicity. We suggested the beneficial effects of flaxseed and mulberry extract as an alternative to reduce and/or prevent the negative effects caused by low estrogenic action.

Independent factors affecting hemorrhagic and ischemic stroke in patients aged 40-69 years: a cross-sectional study

Background

Intracerebral hemorrhage (ICH) and acute ischemic stroke (AIS) have common vascular risk factors; however, ICH often occurs in adults aged < 70 years. Intracerebral hemorrhage and AIS in adults aged < 70 years should be preventable; however, it is unclear why different subtypes of ICH or AIS occur among adults aged < 70 years with vascular risk factors. This study aimed to identify independent variables for ICH or AIS onset in patients aged < 70 years.

Methods

We included patients aged 40–69 years who experienced ICH or AIS between August 2016 and July 2019. Patients aged < 40 years were excluded because other diseases, rather than vascular risk factors, are often associated with stroke etiology in this age group. Data on age, systolic blood pressure (SBP), serum lipids, and serum fatty acid levels were compared between patients with ICH and those with AIS. In addition, we conducted multivariable logistic regression analyses to identify independent factors among the variables, such as blood pressure or biomarkers, with significant differences between the two groups.

Results

Of the 1252 acute stroke patients screened, 74 patients with ICH and 149 patients with AIS met the inclusion criteria. After excluding variables with multicollinearity, SBP, glycated hemoglobin (HbA1c), and eicosapentaenoic acid (EPA) proportion (%) of total fatty acids were identified as independent factors affecting ICH and AIS. The SBP and EPA% threshold values for ICH compared to AIS were ≥ 158 mmHg and ≤ 2.3%, respectively. The HbA1c threshold value for AIS compared to ICH was ≥ 6.1%.

Conclusions

Systolic blood pressure, HbA1c, and EPA%, were independent factors between ICH and AIS. Patients aged 40–69 years with high SBP and low EPA% were at a higher risk of ICH than AIS, and those with a high HbA1c were at a higher risk of AIS than ICH.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02625-6.

Excesive consumption of unsaturated fatty acids leads to oxidative and inflammatory instability in Wistar rats

Lifestyle modifications such as increase in high-fat food consumption importantly increases the risks for cardiovascular disease. The principal objective of this study is to analyze effects of different high fat diet (HFD) sources on haemodynamic parameters, lipid and oxidative profile, myeloperoxidase activity, and markers of inflammation (IL-6/pentraxin-3). HFD containing 20% of fat, provided by lard (saturated) or soybean oil (unsaturated), as well as control diet were administering to three groups (L, SO and C). Food efficiency ratio and plasma lipids were significantly elevated in both HFD groups. However, only SO group showed an increase in systolic arterial pressure, oxidative stress index, myeloperoxidase activity, liver lipids as well as markers of inflammation: IL-6 and pentraxin-3 (PTX3). In summary, these results indicate inflammogenic potential of excessive soybean oil consumption in triggering liver damage.

Association of Serum Fatty Acids at Admission with the Age of Onset of Intracerebral Hemorrhage

Dietary triglycerides influence the serum concentrations of fatty acids (FA) and their weight percentages (wt%), which might be associated with the age of onset of intracerebral hemorrhage (ICH). We investigated the correlation between serum FA levels and proportions at admission, and the age at onset of ICH. We included patients admitted between 2016 and 2019 within 24 h of the onset of ICH, and calculated the correlation coefficients between their age, serum FA concentration, and FA wt%. We performed multiple linear regression analysis to identify individual FAs related to the age at onset of ICH. Furthermore, we estimated the threshold values of FAs that were independently associated with the age at onset of ICH <65 years, using receiver operating characteristic curves by logistic regression. Our inclusion criteria were met by 141 patients (mean age, 67 years). The concentration of dihomo-gamma-linolenic acid (DGLA) and the wt% of eicosapentaenoic acid (EPA) were significant independent variables for the age at onset of ICH. The ROC curves for the age of onset <65 years were ≥108.6 µmol/L for DGLA and ≤1.7% for EPA. Increased DGLA concentration and decreased EPA wt% were significantly associated with young-onset ICH.

Features of Serum Fatty Acids at Acute Ischemic Stroke Onset in Statin-Treated Patients with Hypercholesterolemia

In addition to diet therapy, statins are used to prevent cardiovascular disease in patients with hypercholesterolemia (HC). However, acute ischemic stroke (AIS) still occurs in statin-treated patients. How strictly statin-treated patients follow diet therapy before they experience AIS and whether they increase seafood consumption remains unknown. We investigated the serum concentrations and proportions (weight percentages: wt %) of fatty acids (FAs) at AIS onset in statin-treated patients (statin group), compared to those in non-treated patients with HC (6.465 mmol/L or higher) as controls (non-treated group). We included patients with AIS admitted between 2016 and 2019 within 24 h of AIS onset who underwent analysis of serum FAs. During the study period, 188 patients met the inclusion criteria: 133 in the statin group and 55 in the non-treated group. Interestingly, serum FA concentrations in the statin group were lower than those in the non-treated group. However, serum FA wt % in the statin group was almost identical to that in the non-treated group. In conclusion, statin-treated AIS patients had low FA concentrations and identical FA wt %, compared to non-treated AIS patients with HC.

Association of Serum Fatty Acids at Admission with the Age of Onset of Acute Ischemic Stroke

Dietary triglycerides influence fatty acid (FA) serum concentrations and weight percentages (wt %), which may be associated with the age of onset of acute ischemic stroke (AIS). We investigated the correlations between serum FA levels and proportions at admission and the age of onset of AIS. We evaluated patients with AIS admitted between 2016 and 2019 within 24 h of AIS onset and calculated the correlation coefficients between their ages, serum FA concentrations, and FA wt % values. Multiple linear regression analysis was performed to identify independent FAs indicating AIS age of onset. Furthermore, we estimated the threshold values of independent FAs for age of onset <60 years using receiver operating characteristic curves by logistic regression. A total of 525 patients (median age: 75 years) met the inclusion criteria. The concentration of dihomo-gamma-linolenic acid (DGLA) and wt % of docosahexaenoic acid (DHA) were significant independent variables for age of onset of AIS, and receiver operating characteristic curves for age of onset <60 years showed thresholds of ≥117.7 µmol/L for DGLA and ≤3.7% for DHA. An increased DGLA concentration and decreased DHA wt % were significantly associated with onset of AIS at a younger age.

Features of serum fatty acids in acute ischaemic stroke patients aged 50 years or older

Background

Serum fatty acid (s-FA) compositions and their correlation with serum lipids (s-LPs) such as total cholesterol (T-CHO) and triglycerides (TG) have been reported in healthy young subjects. However, little is known about such features in acute ischaemic stroke (AIS). The aim of our study was to investigate s-FA characteristics and their correlation with AIS in elderly patients.

Methods

We conducted a cross-sectional study of patients aged 50 years or older who were admitted between September 2015 and March 2017 within 24 h of the first AIS onset. We evaluated concentrations and compositions of s-FAs and their association with s-LPs, age, and ischaemic stroke subtypes, including large-artery atherosclerosis (LAA), small-vessel occlusion (SVO), and cardioembolism (CE) or others.

Results

One hundred ninety-one patients met our inclusion criteria. Their average age was 74.4 years, mean T-CHO and median TG were 203.4 and 94.5 mg/dl, respectively, and median or mean concentrations of palmitic acid (PA), oleic acid (OlA), linoleic acid (LiA), and docosahexaenoic acid (DHA) were 680.7, 602.5, 795.2, and 136.9 μg/ml, respectively, with mean compositions of 23.7, 21.3, 27.1, and 4.4%, respectively. PA, OlA, and LiA concentrations were weakly negatively associated with age and positively correlated with TG. In LAA or SVO (LAA_SVO) and CE or others (CE_O), mean age was 71.9 and 77.4 years (p < 0.001), mean T-CHO was 213.9 and 191.2 mg/dl (p < 0.0001), median TG was 106.5 and 88.5 mg/dl (p < 0.01), median PA was 717.2 and 648.4 μg/ml (p < 0.01), median OlA was 638.2 and 567.5 μg/ml (p < 0.01), and median LiA was 844.7 and 728.5 μg/ml (p < 0.01), respectively. DHA composition was weakly positively correlated with age. There were no differences in PA, OlA, LiA, and DHA compositions between LAA_SVO and CE_O.

Conclusions

In AIS elderly patients, concentrations, rather than compositions of PA, OlA, and LiA, correlated with age, TG, and ischaemic stroke subtypes. Patients with LAA_SVO were younger and had higher concentrations of PA, OlA, and LiA than those with CE_O. There were no differences in such compositions between LAA_SVO and CE_O.

Halophytic Grasses, a New Source of Nutraceuticals? A Review on Their Secondary Metabolites and Biological Activities

The Poaceae family, known as grasses, is distributed worldwide and is considered the most important group of monocotyledonous crops. Salt stress is multifactorial, therefore to survive, halophytes evolved a variety of adaptations, which include the biosynthesis of different primary and secondary metabolites. This trait enhances the accumulation of important families of compounds crucial to the prevention of a variety of chronic diseases. Besides, if proven edible, these species could cope with the increased soil salinity responsible for the decline of arable land due to their high nutritional/nutraceutical value. Herein, the phytochemical investigations performed in halophytes from the Poaceae family as well as their biological properties were explored. Among the 65 genera and 148 species of known halophytic grasses, only 14% of the taxa were studied phytochemically and 10% were subjected to biological evaluation. Notably, in the studied species, a variety of compound families, as well as bioactivities, were demonstrated, highlighting the potential of halophytic grasses.

On growth performance, nutrient digestibility, blood T lymphocyte subsets, and cardiac antioxidant status of broilers

Different lipid sources differ in the fatty acid profiles and differently affect growth performance as well as immune function of broilers. The influences of different dietary lipid sources on growth performance, nutrient digestibility, blood T lymphocyte population, and cardiac antioxidant status were investigated of broilers. A total of 360 one-day-old male broilers (BW = 44 ± 3 g) were randomized into 3 treatment groups, consisting of 6 replicates with 20 birds in each group. Broilers received standard diets supplemented with 5% (wt/wt) of lard (LD, as a control diet), sesame oil (SO), or flaxseed oil (FO). Broilers in both SO and FO treatment groups had lower (P < 0.05) feed conversion ratios from 22 to 42 d and during the overall phase compared to those in LD treatment group. Meanwhile, the apparent total tract nutrient digestibility of crude fat in SO and FO treatment groups was higher than that in LD treatment group. Both FO and SO treatments decreased (P < 0.05) abdominal fat percentage compared to LD treatment. Total triglycerides and total cholesterol in chicken blood were decreased (P < 0.05) by SO and FO treatments compared to LD treatment. Feeding broilers with FO and SO led to a decrease (P < 0.05) in blood CD4⁺ T lymphocyte count and in CD4⁺:CD8⁺ ratio compared to LD treatment. Sesame oil and FO treatments increased cardiac glutathione peroxidase (P < 0.05) compared to LD treatment. It is concluded that addition of 5% SO and FO to the standard corn-soybean meal diet improved feed efficiency, increased the activities of cardiac glutathione peroxidase, and affected the T lymphocytes ratio of fast growing broilers.

A Combination of Flaxseed Oil and Astaxanthin Improves Hepatic Lipid Accumulation and Reduces Oxidative Stress in High Fat-Diet Fed Rats

Hepatic lipid accumulation and oxidative stress are crucial pathophysiological mechanisms for non-alcoholic fatty liver disease (NAFLD). Thus, we examined the effect of a combination of flaxseed oil (FO) and astaxanthin (ASX) on hepatic lipid accumulation and oxidative stress in rats fed a high-fat diet. ASX was dissolved in flaxseed oil (1 g/kg; FO + ASX). Animals were fed diets containing 20% fat, where the source was lard, or 75% lard and 25% FO + ASX, or 50% lard and 50% FO + ASX, or FO + ASX, for 10 weeks. Substitution of lard with FO + ASX reduced steatosis and reduced hepatic triacylglycerol and cholesterol. The combination of FO and ASX significantly decreased hepatic sterol regulatory element-binding transcription factor 1 and 3-hydroxy-3-methylglutaryl-CoA reductase but increased peroxisome proliferator activated receptor expression. FO + ASX significantly suppressed fatty acid synthase and acetyl CoA carboxylase but induced carnitine palmitoyl transferase-1 and acyl CoA oxidase expression. FO + ASX also significantly elevated hepatic SOD, CAT and GPx activity and GSH, and markedly reduced hepatic lipid peroxidation. Thus, FO and ASX may reduce NAFLD by reversing hepatic steatosis and reducing lipid accumulation and oxidative stress.

Macronutrient intake and type 2 diabetes risk in middle-aged Australian women. Results from the Australian Longitudinal Study on Women's Health

OBJECTIVE

To investigate the association between macronutrient intake and type 2 diabetes risk in middle-aged Australian women.

DESIGN

A prospective cohort study, with 6 years (2002-2007) of follow up. Dietary intake was assessed with a validated FFQ. Relative risks with 95 % confidence intervals were used to examine risk associations.

SETTING

Australian Longitudinal Study on Women's Health, Australia.

SUBJECTS

Australian women (n 8370) from the Australian Longitudinal Study on Women's Health aged 45-50 years and free of type 2 diabetes at baseline.

RESULTS

After 6 years of follow-up, 311 women developed type 2 diabetes. After adjusting for sociodemographic, lifestyle and other dietary risk factors, MUFA, total n-3 PUFA, α-linolenic acid and total n-6 PUFA intakes were positively associated with the incidence of type 2 diabetes. The relative risks for type 2 diabetes for the highest compared with the lowest quintiles were 1·64 (95 % CI 1·06, 2·54), P = 0·04 for MUFA; 1·55 (95 % CI 1·03, 2·32), P = 0·01 for n-3 PUFA; 1·84 (95 % CI 1·25, 2·71), P < 0·01 for α-linolenic acid; and 1·60 (95 % CI 1·03, 2·48), P = 0·04 for n-6 PUFA. Other dietary macronutrients were not significantly associated with diabetes risk.

CONCLUSIONS

The data indicate that consumption of MUFA, n-3 PUFA and n-6 PUFA may influence the risk of developing type 2 diabetes in women.

Influence of Annona muricata (soursop) on biodistribution of radiopharmaceuticals in rats

PURPOSE

To evaluate the effect of hydroalcoholic extract of A. muricata on biodistribution of two radiopharmaceuticals: sodium phytate and dimercaptosuccinic acid (DMSA), both labeled with 99mtechnetium.

METHODS

Twenty four Wistar rats were divided into two treated groups and two controls groups. The controls received water and the treated received 25mg/kg/day of A. muricata by gavage for ten days. One hour after the last dose, the first treated group received 99mTc-DMSA and the second sodium 99mTc-phytate (0.66MBq each group), both via orbital plexus. Controls followed the same protocol. Forty min later, all groups were sacrificed and the blood, kidney and bladder were isolated from the first treated group and the blood, spleen and liver isolated from the second treated group. The percentage of radioactivity per gram of tissue (%ATI/g) was calculated using a gamma counter.

RESULTS

The statistical analysis showed that there was a statistically significant decrease (p<0.05) in the uptake of %ATI/g in bladder (0.11±0.01and1.60±0.08), kidney (3.52±0.51and11.84±1.57) and blood (0.15±0.01and 0.54±0.05) between the treated group and control group, respectively.

CONCLUSION

The A. muricata hydroalcoholic extract negatively influenced the uptake of 99mTc-DMSA in bladder, kidney and blood of rats.

Lipid emulsions in parenteral nutrition: current applications and future developments

INTRODUCTION

A parenteral lipid emulsion (LE), used as a key source of energy, essential fatty acids (FAs), and fat-soluble vitamins, is an integral part of a parenteral nutrition (PN) regimen. The conventional LEs, such as soybean oil (SO)-based emulsions, have caused concerns about the potential adverse effects involving oxidative stress, inflammation, and immune response probably because of undesirable FA composition.

AREAS COVERED

Recently, alternative LEs, optimizing the FA composition with partial substitution of SO with medium-chain triglyceride (MCT), olive oil (OO), and fish oil (FO), have been developed and applied in clinical practice. This review summarizes the characteristics and beneficial clinical effects of alternative parenteral LEs in critically ill, pediatric, and long-term PN patients.

EXPERT OPINION

More clinical data from sufficiently high-powered studies are required to characterize the integral biological properties of alternative LEs for further selection to fit individual needs and disease characteristics. Simultaneously, potential lipid sources with desirable FA compositions and biological properties should be selected to develop new therapeutic LEs. As supplements to current parenteral lipids, the new LEs with different therapeutic effects are expected to fit specified subpopulations of patients with different diseases. Great efforts should be devoted to the development of parenteral LEs.

Flaxseed oil and alpha-lipoic acid combination ameliorates hepatic oxidative stress and lipid accumulation in comparison to lard

BACKGROUND

Intake of high-fat diet is associated with increased non-alcoholic fatty liver disease (NAFLD). Hepatic lipid accumulation and oxidative stress are key pathophysiological mechanisms in NAFLD. Both flaxseed oil (FO) and α-lipoic acid (LA) exert potential benefit to NAFLD. The aim of this study was to determine the effect of the combination of FO and LA on hepatic lipid accumulation and oxidative stress in rats induced by high-fat diet.

METHODS

LA was dissolved in flaxseed oil to a final concentration of 8 g/kg (FO + LA). The rodent diet contained 20% fat. One-fifth of the fat was soybean oil and the others were lard (control group), or 75% lard and 25% FO + LA (L-FO + LA group), or 50% lard and 50% FO + LA (M-FO + LA group), or FO + LA (H-FO + LA group). Male Sprague-Dawley rats were fed for 10 weeks and then killed for liver collection.

RESULTS

Intake of high-fat lard caused a significant hepatic steatosis. Replacement with FO + LA was effective in reducing steatosis as well as total triglyceride and total cholesterol contents in liver. The combination of FO and LA also significantly elevated hepatic antioxidant defense capacities, as evaluated by the remarkable increase in the activities of SOD, CAT and GPx as well as the level of GSH, and the significant decline in lipid peroxidation.

CONCLUSION

The combination of FO and LA may contribute to prevent fatty livers such as NAFLD by ameliorating hepatic lipid accumulation and oxidative stress.

Sesame and flaxseed oil: nutritional quality and effects on serum lipids and glucose in rats

This study evaluated the nutritional value of sesame and flaxseed oils and their effects on the lipid and glucose profile of rats fed diets containing different fat combinations. Fatty acid composition, refractive index, and iodine and saponification values were analyzed to characterize the oils. In the biological assay, Wistar rats were fed different diets, whose fat composition consisted of varying combinations of flaxseed oil, sesame oil, and animal fat. The primary constituents of the sesame oil were oleic (28.6%), linoleic (28.4%), and lauric acid (14.6%); for the flaxseed oil they were alpha-linolenic (39.90%), oleic (17.97%) and linoleic acid (12.25%). The iodine and saponification values of the oils were within the reference range. Rats fed flaxseed oil-based diets had the lowest serum cholesterol values, whereas rats fed diets with flaxseed oil + sesame oil + animal fat had the highest glucose levels. HDL levels decreased significantly with flaxseed oil. Sesame and flaxseed oils are sources of polyunsaturated fatty acids (PUFA), and the flaxseed oil-based diet had a hypocholesterolemic effect, whereas sesame oil showed oxidative stability since it contains high levels of monounsaturated and saturated fatty acids.

Hypolipidemic effect of fruit fibers in rats fed with high dietary fat

The hypolipidemic effect of 10% fruit fibers in rats fed with high-fat diet (HFD) was evaluated. This study was conducted on a total of 50 male Albino rats divided into 10 equal groups fed with different types of dietary fruits. The feeding period lasted for 24 weeks. Fasting blood samples were collected and sera separated and subjected to lipid profile assay and atherogenic index. In addition, total antioxidant activity of different fruits was determined. The results obtained showed that pomegranate had higher content of antioxidants followed by apple, strawberry and guava compared with other fruits. Rats fed with 20% coconut oil showed a highly significant elevation in the levels of serum total cholesterol, low-density lipoprotein cholesterol and atherogenic factor while the level of high-density lipoprotein cholesterol was significantly decreased when compared with control rats. Histological examination revealed that there was a large lipid and cholesterol deposition in the livers of rats fed with HFD. The potential in lowering the levels of plasma total cholesterol and triglyceride is in the following order: pomegranate > apple > strawberry > guava > papaya > mandarin and orange. Accumulation of hepatic lipid droplets was diminished when compared with the HFD group. Also, antiatherogenic is better than the untreated groups. Accordingly these hypolipidemic effects may be due to high-fiber content and antioxidant activity of these fruits.

Efeito da linhaça (Linum usitatissimum L.) sob diferentes formas de preparo na resposta biológica em ratos

OBJETIVO: Verificar as possíveis atividades biológicas causadas pelo consumo diário de linhaça em diferentes condições de preparo, em ratos Wistar machos recém-desmamados. MÉTODOS: Os ratos recém-desmamados (n=32) foram divididos em 4 grupos de 8 animais: ração padrão; ração com 16% de grão de linhaça cru; ração com 16% de grão de linhaça assado; e ração com 7% de óleo de linhaça. Os animais foram pesados a cada três dias e, após 23 dias de período experimental, foram sacrificados por punção cardíaca, sendo os órgãos imediatamente pesados e o sangue coletado e armazenado a -18ºC para realização das análises (glicose, colesterol total, lipoproteína de alta densidade - colesterol, triglicerídios e proteínas totais). As fezes foram coletadas para a determinação de umidade, lipídeo excretado e lipídeo absorvido. RESULTADOS: Não houve diferença entre os grupos quanto ao ganho de peso total, consumo diário, coeficiente de eficácia alimentar e peso dos órgãos. A excreção diária, o teor de umidade das fezes e a quantidade de lipídeo fecal foram maiores nos grupos linhaça cru e linhaça assada em comparação aos grupos padrão e óleo de linhaça. Com exceção do lipoproteína de alta densidade-colesterol, todos os demais parâmetros bioquímicos avaliados apresentaram diferenças estatísticas entre os tratamentos. CONCLUSÃO: O consumo de linhaça, seja como grão cru, assado ou óleo, possui atividade biológica em ratos, destacando-se por reduzir os níveis de glicose, triglicerídios e colesterol. Além disso, o consumo do grão de linhaça aumentou significativamente o volume do bolo fecal e a excreção de lipídeos nas fezes.

The fat and protein fractions of freshwater clam (Corbicula fluminea) extract reduce serum cholesterol and enhance bile acid biosynthesis and sterol excretion in hypercholesterolaemic rats fed a high-cholesterol diet

We investigated whether the fat and protein fractions of freshwater clam (Corbicula fluminea) extract (FCE) could ameliorate hypercholesterolaemia in rats fed a high-cholesterol diet. We also explored the mechanism and the components that exert the hypocholesterolaemic effect of FCE. The doses of the fat and protein fractions were equivalent to those in 30 % FCE. The fat and protein fractions of FCE, two major components of FCE, significantly reduced the serum and hepatic cholesterol levels. The fat fraction more strongly reduced serum cholesterol levels than the same level of total FCE. The excretion of faecal neutral sterols increased in rats fed the total the FCE and the fat fraction of FCE. On the other hand, faecal bile acid levels were greater in rats fed the total FCE and the fat and protein fractions of FCE than in control animals. The hepatic gene expression of ATP-binding cassette transporter G5 and cholesterol 7α-hydroxylase was up-regulated by the administration of the total FCE and both the fat and protein fractions of FCE. These results showed that the fat and protein fractions of FCE had hypocholesterolaemic properties, and that these effects were greater with the fat fraction than with the protein fraction. The present study indicates that FCE exerts its hypocholesterolaemic effects through at least two different mechanisms, including enhanced excretion of neutral sterols and up-regulated biosynthesis of bile acids.

Marked variability in hepatic expression of cytochromes CYP7A1 and CYP27A1 as compared to cerebral CYP46A1. Lessons from a dietary study with omega 3 fatty acids in hamsters

Two diets simulating the recommendations of the American Heart Association to increase the intake of n-3 polyunsaturated fatty acids (n-3 PUFAs) were tested on Golden Syrian hamsters and compared to the diet simulating the current estimated consumption of fat in the United States. N-3 PUFAs were evaluated for their effects on serum and brain lipids and on the three cytochrome P450 enzymes (CYPs 7A1, 27A1, and 46A1) that play key roles in cholesterol elimination from different organs. Hamsters on the highest concentration of n-3 PUFAs had a statistically significant decrease in LDL and HDL cholesterol and no change in serum total cholesterol and triglycerides levels. CYP27A1 and CYP46A1 mRNA levels were increased in the liver and brain, respectively, whereas possible effects on CYP7A1 were obscured by a marked intergroup variability at mRNA, protein, and sterol product levels. Increased levels of CYP46A1 mRNA in the brain did not lead to significant changes in the levels of lathosterol, 24S-hydroxycholesterol or cholesterol in this organ. The data obtained are discussed in relation to inconsistent effects of n-3 PUFAs on serum lipids in human trials and reported positive effects of fish oil on cognitive function.

Hepatic lipid metabolism response to dietary fatty acids is differently modulated by PPARalpha in male and female mice

BACKGROUND

In human beings, women are at lower risk of cardiovascular diseases, and respond differently from men to dietary fatty acids.

AIM

The aim of the present study was to investigate (i) the influence of gender on the response of lipid metabolism to dietary n-3 PUFA, and (ii) the contribution of PPARalpha to this response.

METHODS

Male and female mice, wild-type (WT) and PPARalpha-null (KO), were fed on diets rich in either saturated FA (SFA) or 18:3 n-3 (ALA). Lipid composition, mRNA levels and certain activities of key enzymes and major transcription factors were determined in the liver. WT mice were slightly affected by dietary FA. However, in WT female mice, but not in males, mRNA levels of PPARalpha-dependent genes (L-FABP, ACO) were higher in the mice fed on the ALA-rich diet. When compared to WT mice, KO female mice exhibited a decreased lipogenesis capacity (40% lower FAS, ACC, and SREBP-1c mRNA level), whereas KO males showed a decrease in peroxisomal beta-oxidation (activity and expression of ACO reduced by 20 and 40%, respectively). When compared to SFA-fed KO mice, steatosis was twice lower in KO mice fed on ALA, despite the absence of dietary effect on plasma TG, CPT1 and ACO activities, or ACC and FAS expression. Besides, in mice on the SFA diet, steatosis was alleviated in females, and CPT1 expression was up-regulated to a higher extent in females than in males (2.7- and 3.6-fold, respectively, as compared to the corresponding WT groups).

CONCLUSIONS

Our data suggests estrogen to modulate the regulation of hepatic lipid metabolic pathway by dietary fatty acids. Besides, PPARalpha invalidation resulted in unexpected regulations by ALA of its known targets and was compensated partly in females, which was therefore less sensitive to the detrimental effects of a SFA-rich diet.

Carbon tetrachloride-induced liver disease in rats: the potential effect of supplement oils with vitamins E and C on the nutritional status

The aim of the present investigation was to study the effects of olive oil (OO), corn oil (CO), and flaxseed oil (FO), with or without supplementation of vitamins E and C, on food intake, body weight gain %, liver weight to body weight %, total lipids, liver functions, and liver histology in male rats intoxicated with carbon tetrachloride (CCl(4)). Forty-two rats were divided into two main groups. The first main group was fed on basal diet (BD) as a negative control group (NC). The second main group received subcutaneous injections of CCl(4) in paraffin oil (50% v/v 2 ml/kg) twice a week to induce chronic damage in the liver. The group was then divided into six subgroups, three of which were fed on 4% unsupplemented oils (CO, FO, and OO) as positive control for the three oils used. The rest of the groups were fed on 4% of the same oils supplemented with vitamins E and C. The results of the flaxseed oil rat group indicate that supplementing vitamin E and C led to a significant reduction in the mean values of total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), and liver alanine amino transferase enzyme (ALT). Moreover, it caused an increase of the mean value of high-density lipoprotein cholesterol (HDL-C) as compared to the negative control group (NC). The olive oil group supplemented with the same vitamins showed a significant decrease in the mean value of serum TC and significant (P<0.05) increase in the mean value of serum HDL-C as compared to NC. The results of the corn oil group supplemented with vitamins showed a significant increase in the mean value of serum HDL-C as compared to the negative control group. The histology results confirmed that the group hepatically injured with CCl(4) treatment and fed on supplemented FO or OO showed apparently normal hepatocytes.

CONCLUSION

The most effective treatment was observed with oils supplemented with vitamins E and C. Hierarchically FO achieved the best results compared to other additives, followed by OO and finally CO showing the least effective treatment among the observed groups.

Changes in Lipid Profile by Vegetable Oil Blends Rich in Polyunsaturated Fatty Acids in Rats with Hypercholesterolemia

The objective of this study was to investigate the effect of different blended vegetable oils having different levels and profiles of polyunsaturated fatty acids (PUFA) on hypercholesterolemia by analyzing the changes in lipid profile in high-cholesterol diet fed rats. Three vegetable oils (soy oil, sunflower oil, and the nonconventional flaxseed oil) were blended to obtain blends rich in PUFA. Thirty albino rats were used over the 2-month period. The animals were divided into five groups, wherein group 5 represents negative control, where rats were fed basal diet, while rats in group 4 received high cholesterol diet and served as positive controls. The other three groups were fed hypercholesterolemic diet (1% cholesterol + 0.25% colic acid) supplemented with blended oils. Generally, rats fed blended oils showed significantly lower levels of total cholesterol (TC), triacylglycerol (TG), and low-density lipoprotein (LDL) cholesterol as well as higher levels of high-density lipoprotein (HDL) cholesterol, in comparison with animals fed high-cholesterol diet and cholesterol-free diet. Thus, oil blends under study may be useful formulations for the treatment of hypercholesterolemia. In addition to improving the lipid profile by lowering TC, total TG, and total LDL and increasing HDL, blending of vegetable oils can result in an economic advantage of lower prices.

A comparison of the effects of fish oil and flaxseed oil on cardiac allograft chronic rejection in rats

Both fish and flaxseed oils are major sources of different n-3 fatty acids. Beneficial effects of fish oil on posttransplantation complications have been reported. The current study aimed to compare the effects of flaxseed and fish oils in a rat cardiac allograft model. Male Fischer and Lewis rats were used as donors and recipients, respectively, to generate a heterotopic cardiac allograft model. Animals were randomly assigned into three groups and fed a diet supplemented with 1) 5% (wt/wt) safflower oil (control, n = 7), 2) 5% (wt/wt) flaxseed oil ( n = 8), or 3) 2% (wt/wt) fish oil ( n = 7), and an intraperitoneal injection of cyclosporine A (CsA; 1.5 mg·kg−1·day−1) over 12 wk. Body weight, blood pressure, plasma levels of lipids, CsA, select cytokines, as well as graft function and chronic rejection features were assessed. Body weight and blood CsA levels were similar among the groups. Relative to controls, both treated groups had lower systolic and diastolic blood pressure and plasma levels of macrophage chemotactic protein-1. Treatment with fish oil significantly ( P < 0.05) lowered plasma levels of triglycerides, total cholesterol, and LDL-cholesterol. HDL-cholesterol concentrations were significantly higher ( P < 0.05) in the flaxseed oil-treated group compared with the other two groups. Both flaxseed oil and fish oil may provide similar biochemical, hemodynamic, and inflammatory benefits after heart transplantation; however, neither of the oils was able to statistically significantly impact chronic rejection or histological evidence of apparent cyclosporine-induced nephrotoxicity in this model.

Conjugated and non-conjugated octadecaenoic acids affect differently intestinal acyl coenzyme A: cholesterol acyltransferase activity

We investigated the relative hypocholesterolemic activity of linoleic acid (LA), conjugated linoleic acid (CLA), alpha-linolenic acid (LN) and conjugated linolenic acid (CLN) in hamsters. Five groups of hamsters (n=10 each) were fed either the control diet or one of the four fatty acids-supplemented diets for 6 weeks. Results demonstrated that the four octadecaenoic acids decreased plasma cholesterol differently, with CLA being the most effective. Western blotting and RT-PCR analysis demonstrated that the four octadecaenoic acids had no effect on sterol regulatory element binding protein-2 (SREBP-2), liver X receptor (LXR), 3-hydroxy-3-methylglutary-CoA reductase (HMGR), LDL receptor (LDLR), and cholesterol-7alpha-hydroxylase (CYP7A1). However, the four octadecaenoic acids increased the excretion of fecal neutral sterols with CLA being most effective followed by LN, LA and CLN, suggesting they all differentially affect cholesterol absorption. Dietary CLA was associated with the least intestinal acyl coenzyme A: cholesterol acyltransferase (ACAT) activity followed by LN, LA and CLN in a decreasing trend. Since esterification of cholesterol is catalyzed by intestinal ACAT, and is a rate-limiting step in cholesterol absorption, it was concluded that the varying effects of CLA, LN, LA and CLN on blood cholesterol were mediated, at least in part, by their inhibition on intestinal ACAT activity.

α-Linolenic acid but not conjugated linolenic acid is hypocholesterolaemic in hamsters

Conjugated linolenic acid (CLN) refers to a group of octadecatrienoic acid isomers that have three double bonds in conjugation. Both pomegranate and tung seed oils are rich in CLN but the major isomer in the former iscis9,trans11,cis13 while in the latter it iscis9,trans11,trans13. The present study examined the effects of CLN, isolated from either pomegranate seed oil or tung seed oil, and α-linolenic acid (LN), isolated from flaxseed oil, on serum cholesterol levels in male hamsters (body weight 105 g; age 10 weeks) fed a 0.1 % cholesterol and 10 % lard diet, for a period of 6 weeks. All hamsters were allowed free access to food and fluid. The blood samples were taken by bleeding from the retro-orbital sinus into a heparinized capillary tube under light ether anaesthesia after overnight fasting at weeks 0, 2, 4 and 6. It was found that supplementation of CLN at levels of 12.2–12.7 g/kg diet exhibited no significant effect on serum cholesterol level while LN at a similar level of supplementation had serum cholesterol reduced by 17–21 % compared with the control diet containing no LN and CLN. Supplementation of CLN and LN significantly decreased hepatic cholesterol but no effect was observed on heart and kidney cholesterol levels. It was concluded that LN possessed hypocholesterolaemic activity while CLN had no effect on blood cholesterol, at least in hamsters.

Gender-related response of lipid metabolism to dietary fatty acids in the hamster

Gender and dietary fatty acids are involved in the regulation of lipid metabolism, disturbances of which can lead to pathologies such as metabolic syndrome or CVD. Possible interactions between these factors were investigated in male and female hamsters fed diets rich in either saturated fatty acids (‘butter’ diet) or in α-linolenic acid (‘linseed oil’ diet). Gender effect predominated over the diet effect on cholesterol (CH) metabolism; compared to males, females exhibited lower concentrations of plasma total CH (−20%,P<0·001), LDL-CH (−40%,P<0·001) and HDL-CH (−16%,P<0·001), together with higher LDL receptor (+40%) and lower HDL receptor (−60%) hepatic content. Triacylglycerol (TG) metabolism was affected by diet above all: compared to animals fed the ‘butter’ diet, those fed the ‘linseed oil’ diet exhibited lower plasma (−23%,P=0·046) and liver TG (−20%,P=0·026) concentration which may result from both an increased β-oxidation (P<0·001), without any change in PPARα mRNA, and a decreased hepatic lipogenesis (P=0·023), without increased sterol response element binding protein 1c (SREBP1c) mRNA. The response to diet was much more pronounced in males than in females, without gender effect on the transcription level of PPARα and SREBP1c. Finally, the ‘linseed oil’ diet decreased the insulin resistance index (−80%,P<0·001) with a more marked effect in males, in relation to their higher hepatic PPARγ expression (+90%,P=0·012). In conclusion, in our model, the response of either TG or CH to dietary fatty acids is modulated differently by gender. The possible relevance of these interactions to dietary practice should be taken into account in man.

Cytochrome P450s and cholesterol homeostasis

By participating in pathways of cholesterol biosynthesis and elimination, different cytochrome P450 (P450 or CYP) enzymes play an important role in maintenance of cholesterol homeostasis. CYP51 is involved in cholesterol biosynthesis, whereas CYP 7A1, 27A1, 46A1, 7B1, 39A1, and 8B1 are the key enzymes in cholesterol catabolism to bile acids, the major route of cholesterol elimination in mammals. Cholesterol transformations to steroid hormones are also initiated by the P450 enzyme CYP11A1. Finally, one of the major drug-metabolizing P450s CYP3A4 seems to contribute to bile acid biosynthesis as well. The 9 P450s will be the focus of this review and assessed as drug targets for cholesterol lowering.

Lipid profile of rats fed high-fat diets based on flaxseed, peanut, trout, or chicken skin

OBJECTIVE

Dietary saturated fatty acids are associated with coronary disease. Conversely, dietary monounsaturated polyunsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) seem to exert a protective effect. This study evaluated the lipid profile of rats fed high-fat (HF) diets, with fat added as different sources of PUFA (flaxseed and trout), MUFA (peanut), and saturated fatty acid (chicken skin).

METHODS

Adult male Wistar rats were placed into six dietary groups (n = 10): control (normal); high fat, with 1% cholesterol, 10% soy oil, and 5% lard; and four groups fed similar HF diets, with 10% lipid as trout, flaxseed, peanut, or chicken skin. After 28 d the animals were killed. Blood, livers, and adipose tissue samples were collected.

RESULTS

A higher level (P < 0.05) of total serum cholesterol was observed in rats fed the normal diet (93.57 +/- 14.95 mg/dL) compared with those fed the HF diet (67.57 +/- 12.54 mg/dL). Total cholesterol levels in rats fed the flaxseed diet were lower (P < 0.05) than in rats fed the other fats. No difference was observed in cholesterol levels between groups fed the peanut and chicken skin diets (P > 0.05). Animals fed the peanut diet showed decreased body weight gain than did animals in the other treatment groups. There were large lipid and cholesterol depositions in livers of rats fed the HF diet. Lipid deposition in adipose tissue followed the same dietary fatty acid profile, i.e., high levels of omega-3 PUFA in the flaxseed group, high levels of MUFA in the peanut and chicken skin groups and high levels of omega-6 PUFA in the trout group.

CONCLUSIONS

These data indicate that flaxseed is promising for dietary manipulation of hyperlipidemia.

Cholesterol-metabolizing cytochromes P450

By catalyzing the first steps in different pathways of cholesterol degradation, cytochromes P450 (P450s) 7A1, 27A1, 11A1, and 46A1 play key roles in cholesterol homeostasis. CYP7A1 is a microsomal liver-specific enzyme that converts cholesterol to 7alpha-hydroxycholesterol. CYP27A1 is a ubiquitously expressed mitochondrial P450 that metabolizes cholesterol to 27-hydroxycholesterol. CYP11A1 also resides in mitochondria but is expressed mainly in steroidogenic tissues, where it catalyzes the conversion of cholesterol to pregnenolone. Finally, CYP46A1 is a brain-selective microsomal monooxygenase producing 24S-hydroxycholesterol from cholesterol. Catalytic efficiencies of cholesterol-metabolizing P450s vary significantly and probably reflect physiological requirements of different organs for the rate of cholesterol turnover. P450s 7A1, 27A1, 11A1, and 46A1 represent a unique system for elucidation of how different enzymes have adapted to fit their specific roles in cholesterol elimination. Studies of cholesterol-metabolizing P450s suggest that their activities could be modulated post-translationally and that they should also be considered as targets for regulation of cholesterol homeostasis.

Beneficial effects of alpha linolenic acid rich flaxseed oil on growth performance and hepatic cholesterol metabolism in high fat diet fed rats

The purpose of the study was to investigate the effect of flaxseed oil (FO), rich in alpha-linolenic acid (ALA) (18:3 n-3) on growth parameters and lipid metabolism of rats fed with high fat diet. High fat diet (HFD) resulted in significant alterations in hepatic lipids, increase in body weight gain and negative effect on lipoprotein metabolism. FO supplementation significantly lowered the increase in body weight gain, liver weight, plasma cholesterol, triglycerides, phospholipids, free fatty acids, high-density lipoprotein (HDL), low-density lipoprotein-cholesterol (LDL-C), very low-density lipoprotein (VLDL), LDL/HDL and TC/HDL ratio in HFD fed rats. FO significantly reduced the hepatic and plasma lipid levels indicating its hypolipidemic activity. On the other hand, oral administration of FO exhibited lower plasma lipoprotein profile as compared to HFD rats. Hepatic protection by FO is further substantiated by the normal liver histological findings in HFD fed rats. These data suggest that FO participate in the normal regulation of plasma lipid concentration and cholesterol metabolism in liver. No adverse effect of FO on growth parameters and plasma lipids in rats fed with fat-free diet. The results of the present study demonstrate that FO may be developed as a useful therapy for hyperlipidemia through reducing hepatic lipids, thereby proving its hypolipidemic activity.

Dietary linolenic acid and fasting glucose and insulin: the National Heart, Lung, and Blood Institute Family Heart Study

OBJECTIVE

To assess whether dietary linolenic acid is associated with fasting insulin and glucose.

RESEARCH METHODS AND PROCEDURES

In a cross-sectional design, we studied 3993 non-diabetic participants of the National Heart, Lung, and Blood Institute Family Heart Study 25 to 93 years of age. Linolenic acid was assessed through a food frequency questionnaire, and laboratory data were obtained after at least a 12-hour fast. We used generalized linear models to calculate adjusted means of insulin and glucose across quartiles of dietary linolenic acid.

RESULTS

From the lowest to the highest sex-specific quartile of dietary linolenic acid, means +/- standard error for logarithmic transformed fasting insulin were 4.06 +/- 0.02 (reference), 4.09 +/- 0.02, 4.13 +/- 0.02, and 4.17 +/- 0.02 pM, respectively (trend, p < 0.0001), after adjustment for age, sex, energy intake, waist-to-hip ratio, smoking, and high-density lipoprotein-cholesterol. When dietary linolenic acid was used as a continuous variable, the multivariable adjusted regression coefficient was 0.42 +/- 0.08. There was no association between dietary linolenic acid and fasting glucose (trend p = 0.82).

DISCUSSION

Our data suggest that higher consumption of dietary linolenic acid is associated with higher plasma insulin, but not glucose levels, in non-diabetic subjects. Additional studies are needed to assess whether higher intake of linolenic acid results in an increased insulin secretion and improved glucose use in vivo.

Dose effect of alpha-linolenic acid on lipid metabolism in the hamster

In order to meet dietary requirements, the consumption of alpha-linolenic acid (ALA, 18:3 n-3) must be promoted. However, its effects on triglyceride (TG) and cholesterol metabolism are still controversial, and may be dose-dependent. The effects of increasing dietary ALA intakes (1%, 10%, 20% and 40% of total FA) were investigated in male hamsters. ALA replaced oleic acid while linoleic and saturated FA were kept constant. Triglyceridemia decreased by 45% in response to 10% dietary ALA and was not affected by higher intakes. It was associated with lower hepatic total activities of acetyl-CoA-carboxylase (up to -29%) and malic enzyme (up to -42%), which were negatively correlated to ALA intake (r(2) = 0.33 and r(2) = 0.38, respectively). Adipose tissue lipogenesis was 2-6 fold lower than in the liver and was not affected by dietary treatment. Substitution of 10% ALA for oleic acid increased cholesterolemia by 15% but, as in TG, higher ALA intakes did not amplify the response. The highest ALA intake (40%) dramatically modified the hepatobiliary metabolism of sterols: cholesterol content fell by 45% in the liver and increased by 28% in the faeces. Besides, faecal bile acids decreased by 61%, and contained more hydrophobic and less secondary bile acids. Thus, replacing 10% oleic acid by ALA is sufficient to exert a beneficial hypotriglyceridemic effect, which may be counteracted by the slight increase in cholesterolemia. Higher intakes did not modify these parameters, but a very high dose resulted in adverse effects on sterol metabolism.