A comprehensive review of the health benefits of flaxseed oil in relation to its chemical composition and comparison with other omega-3-rich oils

Flaxseed (Linum usitatissimum L) is an ancient perennial plant species regarded as a multipurpose plant owing to its richness in omega-3 polyunsaturated fatty acids (PUFA) including α-linolenic acid (ALA). The extensive biochemical analysis of flaxseed resulted in the identification of its bioactive, i.e., lignans with potential application in the improvement of human health. Flaxseed oil, fibers, and lignans exert potential health benefits including reduction of cardiovascular disease, atherosclerosis, diabetes, cancer, arthritis, osteoporosis, and autoimmune and neurological disorders that have led to the diversification of flaxseed plant applications. This comprehensive review focuses on flaxseed oil as the major product of flaxseed with emphasis on the interrelationship between its chemical composition and biological effects. Effects reviewed include antioxidant, anti-inflammatory, antimicrobial, anticancer, antiulcer, anti-osteoporotic, cardioprotective, metabolic, and neuroprotective. This study provides an overview of flaxseed oil effects with the reported action mechanisms related to its phytochemical composition and in comparison, to other PUFA-rich oils. This study presents the most updated and comprehensive review summarizing flaxseed oil's health benefits for the treatment of various diseases.

Flaxseed supplementation significantly reduces hemoglobin A1c in patients with type 2 diabetes mellitus: A systematic review and meta-analysis

Flaxseed is a functional food because of its high content of alpha-linolenic acid, lignans, and dietary fiber. We hypothesized that flaxseed supplementation would improve cardiometabolic parameters in patients with type 2 diabetes mellitus (T2DM); however, clinical trials have shown conflicting results. Therefore, this systematic review and meta-analysis was conducted to determine the impact of flaxseed supplementation in patients with T2DM. Randomized controlled trials were systematically searched in PubMed, Web of Science, Scopus, Cochrane Library, and Embase until 25 March 2022. A total of 13 studies were included, and the results showed that flaxseed supplementation significantly reduced hemoglobin A1c (HbA1c) in participants with T2DM compared with the control group. In contrast, it had no effects on body weight, body mass index, blood pressure, fasting blood glucose (FBG), homeostatic model assessment for insulin resistance, quantitative insulin sensitivity check index, and lipid parameters. In the subgroup analyses, FBG was significantly reduced with supplementation of flaxseed in participants with baseline FBG ≥8.0 mmol/L or baseline HbA1c ≥7.0%. And a significant decrease in HbA1c in participants with baseline HbA1c ≥7.0% after flaxseed supplementation. In addition, subgroup analyses indicated that whole flaxseed supplementation significantly increased high-density lipoprotein cholesterol and reduced total cholesterol or low-density lipoprotein cholesterol in participants with T2DM. In conclusion, flaxseed supplementation significantly reduced HbA1c in participants with T2DM, especially those with poorly controlled blood sugar levels. However, larger scale studies with better designs are needed to confirm insignificant and/or ambiguous findings.

Therapeutic and Nutraceutical Effects of Polyphenolics from Natural Sources

The prevalence of cardiovascular disease, oxidative stress-related complications, and chronic age-related illnesses is gradually increasing worldwide. Several causes include the ineffectiveness of medicinal treatment therapies, their toxicity, their inability to provide radical solutions in some diseases, and the necessity of multiple drug therapy in certain chronic diseases. It is therefore necessary for alternative treatment methods to be sought. In this review, polyphenols were identified and classified according to their chemical structure, and the sources of these polyphenol molecules are indicated. The cardioprotective, ROS scavenging, anti-aging, anticancer properties of polyphenolic compounds have been demonstrated by the results of many studies, and these natural antioxidant molecules are potential alternative therapeutic agents.

Integrated omics approaches for flax improvement under abiotic and biotic stress: Current status and future prospects

Flax (Linum usitatissimum L.) or linseed is one of the important industrial crops grown all over the world for seed oil and fiber. Besides oil and fiber, flax offers a wide range of nutritional and therapeutic applications as a feed and food source owing to high amount of α-linolenic acid (omega-3 fatty acid), lignans, protein, minerals, and vitamins. Periodic losses caused by unpredictable environmental stresses such as drought, heat, salinity-alkalinity, and diseases pose a threat to meet the rising market demand. Furthermore, these abiotic and biotic stressors have a negative impact on biological diversity and quality of oil/fiber. Therefore, understanding the interaction of genetic and environmental factors in stress tolerance mechanism and identification of underlying genes for economically important traits is critical for flax improvement and sustainability. In recent technological era, numerous omics techniques such as genomics, transcriptomics, metabolomics, proteomics, phenomics, and ionomics have evolved. The advancements in sequencing technologies accelerated development of genomic resources which facilitated finer genetic mapping, quantitative trait loci (QTL) mapping, genome-wide association studies (GWAS), and genomic selection in major cereal and oilseed crops including flax. Extensive studies in the area of genomics and transcriptomics have been conducted post flax genome sequencing. Interestingly, research has been focused more for abiotic stresses tolerance compared to disease resistance in flax through transcriptomics, while the other areas of omics such as metabolomics, proteomics, ionomics, and phenomics are in the initial stages in flax and several key questions remain unanswered. Little has been explored in the integration of omic-scale data to explain complex genetic, physiological and biochemical basis of stress tolerance in flax. In this review, the current status of various omics approaches for elucidation of molecular pathways underlying abiotic and biotic stress tolerance in flax have been presented and the importance of integrated omics technologies in future research and breeding have been emphasized to ensure sustainable yield in challenging environments.

Identification of QTNs Associated With Flowering Time, Maturity, and Plant Height Traits in Linum usitatissimum L. Using Genome-Wide Association Study

Early flowering, maturity, and plant height are important traits for linseed to fit in rice fallows, for rainfed agriculture, and for economically viable cultivation. Here, Multi-Locus Genome-Wide Association Study (ML-GWAS) was undertaken in an association mapping panel of 131 accessions, genotyped using 68,925 SNPs identified by genotyping by sequencing approach. Phenotypic evaluation data of five environments comprising 3 years and two locations were used. GWAS was performed for three flowering time traits including days to 5%, 50%, and 95% flowering, days to maturity, and plant height by employing five ML-GWAS methods: FASTmrEMMA, FASTmrMLM, ISIS EM-BLASSO, mrMLM, and pLARmEB. A total of 335 unique QTNs have been identified for five traits across five environments. 109 QTNs were stable as observed in ≥2 methods and/or environments, explaining up to 36.6% phenotypic variance. For three flowering time traits, days to maturity, and plant height, 53, 30, and 27 stable QTNs, respectively, were identified. Candidate genes having roles in flower, pollen, embryo, seed and fruit development, and xylem/phloem histogenesis have been identified. Gene expression of candidate genes for flowering and plant height were studied using transcriptome of an early maturing variety Sharda (IC0523807). The present study unravels QTNs/candidate genes underlying complex flowering, days to maturity, and plant height traits in linseed.

Antioxidant Content and Antioxidant Capacity of the Protein-Rich Powdered Beverages Enriched with Flax Seeds Gum

Powdered beverages produced from dried fruit and vegetables are new products whose properties may be tailored by adding efficient nutrients and functional ingredients. The analyses of low-molecular antioxidants and antioxidant properties as well as nutrient content and digestibility were tested in beverages enriched with lentil proteins (AGF) and flaxseed gum (FSG). A replacement of sprouted lentil flour with the AGF deteriorated the phenolic content. As a main source of phenolics and vitamin C, lyophilized parsley leaves and broccoli sprouts were recognized. (There was no clear effect of the FGS.) The highest content of phenolics was determined in the beverages with these additives without the AGS (c.a. 125 μg/g). The AGF significantly improved the ability to quench ABTS radicals and reduce power. The best results were for the beverages without the FSG. (The effect was enhanced by lyophilized fruit and green vegetables.) The lowest chelating power and ability to quench hydroxyl radicals were in the beverages based on the AGF (improvement by the FSG and green vegetables). The tailoring of beverages' recipes significantly increased protein content and did not affect nutrient digestibility. The modifications allow obtaining the beverages exhibiting multidirectional antioxidant properties, being a source of easily bioaccessible starch and proteins.

Flaxseed Oil and Heated Flaxseed Supplements Have Different Effects on Lipid Deposition and Ileal Microbiota in Albas Cashmere Goats

Simple Summary

With the grassland desertification intensified, pasture carrying capacity decreased, and grass seasonal changed, stall-feeding fattening has become an effective means to protect the natural environment. The stall-feeding fattening increased the cashmere goats’ weight but reduced the meat quality and increased the saturated fatty acids content in muscle and fat tissue of cashmere goats. Supplementing flaxseed and flaxseed oil rich-in linolenic acid (ALA) to diet to improve meat quality is an effective nutritional regulation means. Previous research results of our team showed that compared to diet supplemented with flaxseed oil, added flaxseed increased linoleic acid biohydrogenation by reducing the Ruminobacter relative abundance and increasing the relative abundance of Prevotellaceae_UCG-001 and Fretibacterium in rumen, protected ALA away from biohydrogenation, and more n-3 polyunsaturated fatty acids entered the post-intestinal tract. Based on the previous research, this study explored whether the ALA flowing into the posterior intestine can reduce fat deposition and blood lipid by affecting intestinal microbiota. The results showed that adding flaxseed grain to diet decreased the growth performance, lipid deposition, and blood lipid content of goats by regulating the blood lipid-related enzyme activity, which positively associated with [Eubacterium]_coprostanoligenes_group, but negatively associated with unclassified_f_Peptostreptococcaceae, Intestinibacter, and Ruminococcus_2.

Abstract

The present study investigated the effect of flaxseed grain or flaxseed oil on ileal microbiota and lipid deposition of cashmere goats. Sixty kid goats (average body weight 18.6 ± 0.1 kg) were allocated to three treatments, fed for 90 days, with control treatment: basal diet (CON, total-mixed ration), experimental treatment: basal diet with added flaxseed oil (LNO), experimental treatment: basal diet with added heated flaxseed grain (HLS). The final body weight, body weight gain, the weight of kidney fat, omental fat, tail fat, and fat tissue, the activity of fatty acid synthetase, acetyl-coa carboxylase, and malic dehydrogenase, and the relative abundance (RA) of unclassified_f_Peptostreptococcaceae and Intestinibacter were remarkably higher in the LNO treatment than in the HLS treatment, but the [Eubacterium]_coprostanoligenes_group RA showed the opposite result. The content of triglyceride, cholesterol, and low-density lipoprotein cholesterol were significantly higher in the CON and LNO treatments than in the HLS treatment, while the hormone-sensitive lipase activity and the non-esterified fatty acid content showed the opposite result. In conclusion, the flaxseed grain is more efficient than flaxseed oil in ameliorating the blood lipid profiles and it is a potential product for decreasing the lipid deposition of cashmere goats.

Synergistic Effect of Omega-3 Fatty Acids and Oral-Hypoglycemic Drug on Lipid Normalization through Modulation of Hepatic Gene Expression in High Fat Diet with Low Streptozotocin-Induced Diabetic Rats

Type 2 diabetes mellitus, which an outcome of impaired insulin action and its secretion, is concomitantly associated with lipid abnormalities. The study was designed to evaluate the combinational effect of omega-3 fatty acids (flax and fish oil) and glibenclamide on abnormal lipid profiles, increased blood glucose, and impaired liver and kidney functions in a high fat diet with low streptozotocin (STZ)-induced diabetic rats, including its probable mechanism of action. The male Wistar rats (n = 48) were distributed into eight groups. All animal groups except the healthy received a high fat diet (HFD) for 90 days. Further, diabetes was developed by low dose STZ (35 mg/kg). Diabetic animals received, omega-3 fatty acids (500 mg/kg), along with glibenclamide (0.25 mg/kg). Both flax and fish oil intervention decreased (p ≤ 0.001) serum triglycerides and very low density lipoprotein and elevated (p ≤ 0.001) high density lipoprotein levels in diabetic rats. Total cholesterol and low-density lipoprotein level was decreased (p ≤ 0.001) in fish oil-treated rats. However, it remained unaffected in the flax oil treatment group. Both flax and fish oil intervention downregulate the expression of fatty acid metabolism genes, transcription factors (sterol regulatory element-binding proteins-1c and nuclear factor-κβ), and their regulatory genes i.e., acetyl-coA carboxylase alpha, fatty acid synthase, and tumor necrosis factors-α. The peroxisome proliferator-activated receptor gamma gene expression was upregulated (p ≤ 0.001) in the fish oil treatment group. Whereas, carnitine palmitoyltransferase 1 and fatty acid binding protein gene expression were upregulated (p ≤ 0.001) in both flax and fish oil intervention group.

Healthcare Cost Implications of Utilizing a Dietary Intervention to Lower LDL Cholesterol: Proof of Concept Actuarial Analysis and Recommendations

PURPOSE OF REVIEW

To determine if subsidizing the cost of a food-based intervention for managing hyperlipidemia could be cost-effective under commercial insurance and/or Medicare coverage scenarios.

RECENT FINDINGS

A large number of patients eligible for pharmaceutical treatment of hyperlipidemia either cannot or will not use lipid lowering drugs, leaving them at increased cardiovascular risk. Lipid levels can be modified by diet, but food has never enjoyed covered benefit status. We evaluated the financial implications of providing insurance coverage for a specifically formulated suite of food products previously documented to yield statistically significant lipid reductions, using multiple product uptake and lipid impact scenarios in both commercially covered and Medicare-covered populations. Even after controlling for multiple confounders, we noted positive payback on subsidizing the cost of lipid-lowering foods under all scenarios. Addressing a root cause of hyperlipidemia by directly encouraging dietary modification provides a cost-effective alternative for cholesterol management, especially for statin intolerant or statin unwilling patients.

Protective Effect of Flaxseed on the Health of Experimental Animals Exposed to Xylene

Xylene is mainly used as a solvent in the printing, tire and leather industries. It is also used as: a facility cleaner, paint and varnish thinner, component of fuel, and chemical for the laboratory processing of histological preparations. For these reasons people are frequently exposed to xylene and the risk of intoxication is high. This study focused on the protective effect of flaxseed on mice experimentally intoxicated with xylene. The experiment lasted 14 days. The mice used in this study (n = 60) were allocated to 3 groups: the control group (C) received only the standard diet; the xylene group (X) was fed a standard diet and was administered xylene p. o. (10 µl daily); and the xylene + flaxseed group (XF) received the standard feed, crushed flaxseed and xylene at the same dose as group X. The observations involved changes in: body weight, liver enzyme levels, and caspase activity in the liver of the mice. The administration of additives resulted in significant changes in the body weight of the mice on day 7 of the experiment (P < 0.05). The highest weight gain was observed in mice from the XF group. In contrast, the body weight of the mice from group X exposed only to xylene was the lowest. The biochemical analysis of the liver cells of the xylene intoxicated mice showed elevated levels of: aspartate aminotransferase (AST), De Ritis ratio (AST/ALT ratio), and lactate dehydrogenase isoenzymes LDH-3 and LDH-5. Caspase-3, the marker of apoptosis, was increased in the XF group. Thus, the administration of flaxseed in our experiment had a beneficial effect on the clinical and metabolic parameters of mice intoxicated with xylene. Our results indicated that the administration of flaxseed, may act as a preventative measure with respect to xylene intoxication of animals; however, further analyses are needed to confirm this assumption.

Flaxseed (Linum Usitatissimum L.) Supplementation in Patients Undergoing Lipoprotein Apheresis for Severe Hyperlipidemia-A Pilot Study

Being rich in polyunsaturated fatty acids, flaxseed (Linum usitatissimum L.) is thought to be able to decrease lipid levels and dampen inflammation. In this pilot study, we aimed to determine whether flaxseed supplementation could improve the profiles of lipids and inflammatory mediators in patients with severe hyperlipidemia resistant to conventional lipid-lowering pharmacotherapy and requiring lipoprotein apheresis. To this end, six patients received, blindly—in addition to their normal lipoprotein apheresis regimen—a 10-week dietary supplementation with flaxseed (28 g/d) administered in biscuits. This was followed by a 10-week washed out-period and a 10-week supplementation phase with whole wheat placebo. Blood samples were collected at the end of each phase, before the lipoprotein apheresis session. The primary endpoint was the lipid profile and the secondary endpoints were the concentrations of inflammatory mediators and tolerability. Flaxseed supplementation was well-tolerated and resulted in a consistent and significant decrease in total cholesterol and low-density lipoprotein (LDL) levels. The median (and range) percentage decrease was 11.5% (0–18.8) and 7.3% (4.4–26.6), for cholesterol (p = 0.015) and LDL-C (p = 0.003), respectively. On the other hand, there was no significant effect of flaxseed on lipoprotein(a) (Lp(a)), C-reactive protein (CRP), and interleukin 6 (IL-6) concentrations. These observations indicate that flaxseed can produce a cholesterol- and LDL-lowering effect in patients treated with lipoprotein apheresis. Thus, flaxseed supplementation may help to control cholesterol in this patient population. The flaxseed supplementation protocol applied may be of use for further adequately-powered studies to validate and extend our findings.

Overcoming the Bitter Taste of Oils Enriched in Fatty Acids to Obtain Their Effects on the Heart in Health and Disease

Fatty acids come in a variety of structures and, because of this, create a variety of functions for these lipids. Some fatty acids have a role to play in energy metabolism, some help in lipid storage, cell structure, the physical state of the lipid, and even in food stability. Fatty acid metabolism plays a particularly important role in meeting the energy demands of the heart. It is the primary source of myocardial energy in control conditions. Its role changes dramatically in disease states in the heart, but the pathologic role these fatty acids play depends upon the type of cardiovascular disease and the type of fatty acid. However, no matter how good a food is for one's health, its taste will ultimately become a deciding factor in its influence on human health. No food will provide health benefits if it is not ingested. This review discusses the taste characteristics of culinary oils that contain fatty acids and how these fatty acids affect the performance of the heart during healthy and diseased conditions. The contrasting contributions that different fatty acid molecules have in either promoting cardiac pathologies or protecting the heart from cardiovascular disease is also highlighted in this article.

Flaxseed Lignans as Important Dietary Polyphenols for Cancer Prevention and Treatment: Chemistry, Pharmacokinetics, and Molecular Targets

Cancer causes considerable morbidity and mortality across the world. Socioeconomic, environmental, and lifestyle factors contribute to the increasing cancer prevalence, bespeaking a need for effective prevention and treatment strategies. Phytochemicals like plant polyphenols are generally considered to have anticancer, anti-inflammatory, antiviral, antimicrobial, and immunomodulatory effects, which explain their promotion for human health. The past several decades have contributed to a growing evidence base in the literature that demonstrate ability of polyphenols to modulate multiple targets of carcinogenesis linking models of cancer characteristics (i.e., hallmarks and nutraceutical-based targeting of cancer) via direct or indirect interaction or modulation of cellular and molecular targets. This evidence is particularly relevant for the lignans, an ubiquitous, important class of dietary polyphenols present in high levels in food sources such as flaxseed. Literature evidence on lignans suggests potential benefit in cancer prevention and treatment. This review summarizes the relevant chemical and pharmacokinetic properties of dietary polyphenols and specifically focuses on the biological targets of flaxseed lignans. The consolidation of the considerable body of data on the diverse targets of the lignans will aid continued research into their potential for use in combination with other cancer chemotherapies, utilizing flaxseed lignan-enriched natural products.

Effect ofα-linolenic acid on 24-h ambulatory blood pressure in untreated high-normal and stage I hypertensive subjects

Results of intervention studies on the effects ofα-linolenic acid (ALA; C18 : 3n-3) on blood pressure (BP) are conflicting. Discrepancies between studies may be due to differences in study population, as subjects with increased baseline BP levels may be more responsive. Therefore, we examined specifically the effects of ALA on 24-h ambulatory blood pressure (ABP) in (pre-)hypertensive subjects. In a double-blind, randomised, placebo-controlled parallel study, fifty-nine overweight and obese adults (forty males and nineteen females) with (pre-)hypertension (mean age of 60 (sd8) years) received daily 10 g refined cold-pressed flaxseed oil, providing 4·7 g (approximately 2 % of energy) ALA (n29) or 10 g of high-oleic sunflower oil as control (n30) for 12 weeks. Compliance was excellent as indicated by vial count and plasma phospholipid fatty-acid composition. Compared with control, the changes of –1·4 mmHg in mean arterial pressure (MAP; 24 h ABP) after flaxseed oil intake (95 % CI –4·8, 2·0 mmHg,P=0·40) of –1·5 mmHg in systolic BP (95 % CI –6·0, 3·0 mmHg,P=0·51) and of –1·4 mmHg in diastolic BP (95 % CI –4·2, 1·4 mmHg,P=0·31) were not statistically significant. Also, no effects were found for office BP and for MAP, systolic BP, and diastolic BP when daytime and night-time BP were analysed separately and for night-time dipping. In conclusion, high intake of ALA, about 3–5 times recommended daily intakes, for 12 weeks does not significantly affect BP in subjects with (pre-)hypertension.

The effect of Lactobacillus acidophilus and Lactobacillus casei on the in vitro bioaccessibility of flaxseed lignans (Linum usitatissimum L.)

Secoisolariciresinol (SECO) is present in flaxseeds as a glucoside, secoisolariciresinol diglucoside (SDG), which can be metabolized to enterodiol (ED) and enterolactone (EL) by the human intestinal microbiota. The aim of this study was to evaluate the effect of Lactobacillus casei and Lactobacillus acidophilus on the bioaccessibility of flaxseed lignans from a complete in vitro digestion of whole flaxseeds (WFs) and flaxseed flour (FF). Lignans are only detected in the large intestine. The bioaccessibility of SDG for FF digestion can be ordered as follows: control (without probiotics) > L. casei > L. acidophilus; and for WF digestion, only in the presence of L. casei SDG was detected. For SECO and EL, the presence of both probiotics had no effect on FF and WF digestion. However, in the digestion of WF both L. casei and L. acidophilus increased ED bioaccessibility in the first 12 h; but both probiotics had no significant effect on FF digestion.

Nutrition Questionnaires plus (NQplus) study, a prospective study on dietary determinants and cardiometabolic health in Dutch adults

PURPOSE

During the past decades, the number of people with cardiometabolic conditions substantially increased. To identify dietary factors that may be responsible for this increase in cardiometabolic conditions, the Nutrition Questionnaires plus (NQplus) study was initiated. The aim of this article is to provide an overview of the study design and baseline characteristics of the NQplus population.

PARTICIPANTS

The NQplus study is a prospective cohort study among 2048 Dutch men (52%) and women (48%) aged 20-70 years.

FINDINGS TO DATE

At baseline, we assessed habitual dietary intake, conducted physical examinations (measuring, eg, anthropometrics, body composition, blood pressure, pulse wave velocity, advanced glycation end product accumulation, cognitive performance), collected blood and 24-hour urine and administered a variety of validated demographic, health and lifestyle questionnaires. Participants had a mean BMI of 26.0±4.2 kg/m², were mostly highly educated (63%), married or having a registered partnership (72%) and having a paid job (72%). Estimated daily energy and macronutrient intakes (mean±SD) were 8581±2531 kJ, 15±2energy (en%) of protein, 43±6 en% of carbohydrates, 36±5 en% of fat and 11±13 g of alcohol. Mean systolic blood pressure was 126±15 mm Hg, total cholesterol 5.3±1.1 mmol/L and haemoglobin A1c 36±5 mmol/mol. A total of 24% of the participants reported to be diagnosed with hypertension, 18% with hypercholesterolaemia and 4% with diabetes mellitus. All measurements were repeated after 1 and 2 years of follow-up.

FUTURE PLANS

We endeavour to continue measurements on the long-term. Moreover, dietary assessment methods used in the NQplus study will be extensively validated, that is, Food Frequency Questionnaires, 24-hour recalls and urinary and blood biomarkers of exposure. As such, the NQplus study will provide a unique opportunity to study many cross-sectional and longitudinal associations between diet and cardiometabolic health outcomes using the best dietary assessment methods available so far.

Flaxseed: its bioactive components and their cardiovascular benefits

Cardiovascular disease remains the leading cause of mortality and morbidity worldwide. The inclusion of functional foods and natural health products in the diet are gaining increasing recognition as integral components of lifestyle changes in the fight against cardiovascular disease. Several preclinical and clinical studies have shown the beneficial cardiovascular effects of dietary supplementation with flaxseed. The cardiovascular effects of dietary flaxseed have included an antihypertensive action, antiatherogenic effects, a lowering of cholesterol, an anti-inflammatory action, and an inhibition of arrhythmias. Its enrichment in the ω-3 fatty acid α-linolenic acid and the antioxidant lignan secoisolariciresinol diglucoside as well as its high fiber content have been implicated primarily in these beneficial cardiovascular actions. Although not as well recognized, flaxseed is also composed of other potential bioactive compounds such as proteins, cyclolinopeptides, and cyanogenic glycosides, which may also produce biological actions. These compounds could also be responsible for the cardiovascular effects of flaxseed. This article will not only summarize the cardiovascular effects of dietary supplementation with flaxseed but also review its bioactive compounds in terms of their properties, biological effects, and proposed mechanisms of action. It will also discuss promising research directions for the future to identify additional health-related benefits of dietary flaxseed.

The effect of flaxseed supplementation on body weight and body composition: a systematic review and meta-analysis of 45 randomized placebo-controlled trials

Flaxseed consumption may be inversely associated with obesity; however, findings of available randomized controlled trials (RCTs) are conflicting. The present study aimed to systematically review and analyse RCTs assessing the effects of flaxseed consumption on body weight and body composition. PubMed, Medline via Ovid, SCOPUS, EMBASE and ISI Web of Sciences databases were searched up to November 2016. Mean changes in body composition indices including body weight, body mass index (BMI) and waist circumference were extracted. Effect sizes were expressed as weighted mean difference (WMD) and 95% confidence intervals (CI). Heterogeneity between studies was assessed with the I² test. Publication bias and subgroup analyses were also performed. The quality of articles was assessed via the Jadad scale. A total of 45 RCTs were included. Meta-analyses suggested a significant reduction in body weight (WMD: -0.99 kg, 95% CI: -1.67, -0.31, p = 0.004), BMI (WMD: -0.30 kg m^-2 , 95% CI: -0.53, -0.08, p = 0.008) and waist circumference (WMD: -0.80 cm, 95% CI: -1.40, -0.20, p = 0.008) following flaxseed supplementation. Subgroup analyses showed that using whole flaxseed in doses ≥30 g d^-1 , longer-term interventions (≥12 weeks) and studies including participants with higher BMI (≥ 27 kg m^-2 ) had positive effects on body composition. Whole flaxseed is a good choice for weight management particularly for weight reduction in overweight and obese participants.

Flaxseed used since pregnancy by the mother and after weaning by the offspring benefits the retina and optic nerve development in rats

OBJECTIVE

This study aimed to evaluate the influence of a diet based on flaxseed upon the development of the nervous system, more specifically, the optic nerve and retina.

METHODS

Rats were divided into three groups: Control (CG), Flaxseed (FG), and Modified Control (MCG). The analyses were performed in the offspring (n = 6/group) at the immediate postnatal period (P0), 14 d of life (P14) and 30 d of life (P30). Descriptive analysis and histomorphometry of optic nerve and retina were performed.

RESULTS

There was a great evolution in the development of the nervous fascicles, connective trabeculae, and blood vessels, when comparing the three ages studied, and these characteristics were more evident in FG at all three ages. The P0, P14, and P30 retina showed similar morphology to that described in the literature. In histomorphometry, at P14, the FG presented the retina and its layers with significant increase in thickness, except for internal granular and ganglionar, whereas MCG had greater retina and photoreceptor layers thickness, inner plexiform and external granular when compared with CG (p < .05).

CONCLUSION

The use of flaxseed in the pre-and postnatal period displays favourable influence on the development of rat optic nerve and retina, probably leading to myelination.

SSR and morphological trait based population structure analysis of 130 diverse flax (Linum usitatissimum L.) accessions

A total of 130 flax accessions of diverse morphotypes and worldwide origin were assessed for genetic diversity and population structure using 11 morphological traits and microsatellite markers (15 gSSRs and 7 EST-SSRs). Analysis performed after classifying these accessions on the basis of plant height, branching pattern, seed size, Indian/foreign origin into six categories called sub-populations viz. fibre type exotic, fibre type indigenous, intermediate type exotic, intermediate type indigenous, linseed type exotic and linseed type indigenous. The study assessed different diversity indices, AMOVA, population structure and included a principal coordinate analysis based on different marker systems. The highest diversity was exhibited by gSSR markers (SI=0.46; He=0.31; P=85.11). AMOVA based on all markers explained significant difference among fibre type, intermediate type and linseed type populations of flax. In terms of variation explained by different markers, EST-SSR markers (12%) better differentiated flax populations compared to morphological (9%) and gSSR (6%) markers at P=0.01. The maximum Nei's unbiased genetic distance (D=0.11) was observed between fibre type and linseed type exotic sub-populations based on EST-SSR markers. The combined structure analysis by using all markers grouped Indian fibre type accessions (63.4%) in a separate cluster along with the Indian intermediate type (48.7%), whereas Indian accessions (82.16%) of linseed type constituted an independent cluster. These findings were supported by the results of the principal coordinate analysis. Morphological markers employed in the study found complementary with microsatellite based markers in deciphering genetic diversity and population structure of the flax germplasm.

Antioxidant Properties of Water-Soluble Gum from Flaxseed Hulls

Soluble flaxseed gum (SFG) was extracted from flax (Linum usitatissimum) hulls using hot water, and its functional groups and antioxidant properties were investigated using infrared spectroscopy and different antioxidant assays (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), reducing power capacity, and β-carotene bleaching inhibition assay), respectively. The antioxidant capacity of SFG showed interesting DPPH radical-scavenging capacity (IC₅₀ SFG = 2.5 mg·mL⁻¹), strong ABTS radical scavenging activity (% inhibition ABTS = 75.6% ± 2.6% at 40 mg·mL⁻¹), high reducing power capacity (RP_SFG = 5 mg·mL⁻¹), and potent β-carotene bleaching inhibition activity (IC₅₀ SFG = 10 mg·mL⁻¹). All of the obtained results demonstrate the promising potential use of SFG in numerous industrial applications, and a way to valorize flaxseed hulls.

Therapeutic Efficacy of an ω-3-Fatty Acid-Containing 17-β Estradiol Nano-Delivery System against Experimental Atherosclerosis

Atherosclerosis and its consequences remain prevalent clinical challenges throughout the world. Initiation and progression of atherosclerosis involves a complex, dynamic interplay among inflammation, hyperlipidemia, and endothelial dysfunction. A multicomponent treatment approach targeted for delivery within diseased vessels could prove beneficial in treating atherosclerosis. This study was undertaken to evaluate the multimodal effects of a novel ω-3-fatty acid-rich, 17-β-estradiol (17-βE)-loaded, CREKA-peptide-modified nanoemulsion system on experimental atherosclerosis. In vitro treatment of cultured human aortic endothelial cells (ECs) with the 17-βE-loaded, CREKA-peptide-modified nanoemulsion system increased cellular nitrate/nitrite, indicating improved nitric oxide formation. In vivo, systemic administration of this nanoemulsion system to apolipoprotein-E knock out (ApoE-/-) mice fed a high-fat diet significantly improved multiple parameters related to the etiology and development of occlusive atherosclerotic vasculopathy: lesion area, circulating plasma lipid levels, and expression of aortic-wall inflammatory markers. These salutary effects were attributed selectively to the 17-βE and/or ω-3 polyunsaturated fatty acid components of the nano-delivery system. At therapeutic doses, the 17-βE-loaded, CREKA-peptide modified nanoemulsion system appeared to be biocompatible in that it elicited no apparent adverse/toxic effects, as indexed by body weight, plasma alanine aminotransferase/aspartate aminotransferase levels, and liver and kidney histopathology. The study demonstrates the therapeutic potential of a novel, 17-βE-loaded, CREKA-peptide-modified nanoemulsion system against atherosclerosis in a multimodal fashion by reducing lesion size, lowering the levels of circulating plasma lipids and decreasing the gene expression of inflammatory markers associated with the disease.

Heterologous expression of flax PHOSPHOLIPID:DIACYLGLYCEROL CHOLINEPHOSPHOTRANSFERASE (PDCT) increases polyunsaturated fatty acid content in yeast and Arabidopsis seeds

Background

Flax (Linum usitatissimum L.) is an agriculturally important crop with seed oil enriched in α-linolenic acid (18:3 ^{cisΔ9, 12, 15}; ALA). This polyunsaturated fatty acid (PUFA) is the major determinant for the quality of flax seed oil in food, nutraceuticals and industrial applications. The recently identified enzyme: phosphatidylcholine diacylglycerol cholinephosphotransferase (PDCT), catalyzes the interconversion between phosphatidylcholine (PC) and diacylglycerol (DAG), and has been shown to play an important role in PUFA accumulation in Arabidopsis thaliana seeds.

Methods

Two flax PDCT genes were identified using homology-based approach.

Results

In this study, we describe the isolation and characterization of two PDCT genes from flax (LuPDCT1 and LuPDCT2) with very high nucleotide sequence identity (97%) whose deduced amino acid sequences exhibited approximately 55% identity with that of A. thaliana PDCT (AtROD1). The genes encoded functionally active enzymes that were strongly expressed in developing embryos. Complementation studies with the A. thaliana rod1 mutant demonstrated that the flax PDCTs were capable of restoring PUFA levels in planta. Furthermore, PUFA levels increased in Saccharomyces cerevisiae when the flax PDCTs were co-expressed with FATTY ACID DESATURASES (FADs), FAD2 and FAD3, while seed-specific expression of LuPDCT1 and LuPDCT2 in A. thaliana resulted in 16.4% and 19.7% increases in C18-PUFAs, respectively, with a concomitant decrease in the proportion of oleic acid (18:1^cisΔ9; OA).

Conclusions

The two novel PDCT homologs from flax are capable of increasing C18-PUFA levels substantially in metabolically engineered yeast and transgenic A. thaliana seeds. These flax PDCT proteins appear to play an important dual role in the determination of PUFA content by efficiently channelling monounsaturated FAs into PC for desaturation and moving the resulting PUFAs out of PC for subsequent use in TAG synthesis. These results indicate that flax PDCTs would be useful for bioengineering of oil crops to increase PUFA levels for applications in human food and nutritional supplements, animal feed and industrial bioproducts.

Electronic supplementary material

The online version of this article (doi:10.1186/s12896-015-0156-6) contains supplementary material, which is available to authorized users.

Gut metabolites and bacterial community networks during a pilot intervention study with flaxseeds in healthy adult men

SCOPE

Flaxseeds contain the phytoestrogens lignans that must be activated to enterolignans by intestinal bacteria. We investigated the impact of flaxseeds on fecal bacterial communities and their associations with fecal and blood metabolites.

METHODS AND RESULTS

Nine healthy male adult subjects ingested 0.3 g/kg/day flaxseeds during 1 week. Gut bacteria as well as blood and fecal metabolites were analyzed. Ingestion of flaxseeds triggered a significant increase in the blood concentration of enterolignans, accompanied by fecal excretion of propionate and glycerol. Overall diversity and composition of dominant fecal bacteria remained individual specific throughout the study. Enterolactone production was linked to the abundance of two molecular species identified as Ruminococcus bromii and Ruminococcus lactaris. Most dominant species of the order Bacteroidales were positively associated with fecal concentrations of either acetic, isovaleric, or isobutyric acid, the latter being negatively correlated with blood levels of triglycerides. The relative sequence abundance of one Gemmiger species (Ruminococcaceae) and of Coprococcus comes (Lachnospiraceae) correlated positively with blood levels of LDL cholesterol and triglycerides, respectively.

CONCLUSION

Flaxseeds increase enterolignan production but do not markedly alter fecal metabolome and dominant bacterial communities. The data underline the possible role of members of the family Ruminococcaceae in the regulation of enterolignan production and blood lipids.

Impact of weight loss diet associated with flaxseed on inflammatory markers in men with cardiovascular risk factors: a clinical study

Background

Flaxseed has received attention for its anti-inflammatory and antioxidant role. The present study hypothesizes if flaxseed added to a weight loss diet could improve the lipid and metabolic profiles and decrease risk factors related to cardiovascular disease.

Methods

In a prospective, single blinded 42 days protocol, subjects were allocated into two groups with low carbohydrates intake: G_riceLC (35% of carbohydrate and 60g of raw rice powder per day) and G_flaxLC (32% of carbohydrate and 60g of flaxseed powder per day). Blood pressure, anthropometric measures and serum levels of isoprostane, C-reactive protein, Tumor Necrosis Factor-alpha, glucose, lipidic profile, uric acid, adiponectin, leptin and insulin were measured at baseline and at the end of interventions. Serum and urinary enterodiol and enterolactione were also measured.

Results

A total of 27 men with cardiovascular risk factors were evaluated, with mean age of 33 ± 10 years to G_riceLC and 40 ± 9 years to G_flaxLC. Both groups experienced weight loss and systolic blood pressure reduction. A decrease in inflammatory markers (CRP and TNF-α) was observed after flaxseed intake (mean decrease of 25% and 46% for G_flaxLC respectively). All groups also showed improvement in levels of total cholesterol, LDL-c, uric acid and adiponectin. Only G_flaxLC group showed a decrease in triglyceride levels.

Conclusion

This study suggests that flaxseed added to a weight loss diet could be an important nutritional strategy to reduce inflammation markers such as CRP and TNF-α.

Trial registration

ClinicalTrials.gov NCT02132728.

Electronic supplementary material

The online version of this article (doi:10.1186/1475-2891-14-5) contains supplementary material, which is available to authorized users.

The evidence for α-linolenic acid and cardiovascular disease benefits: Comparisons with eicosapentaenoic acid and docosahexaenoic acid

Our understanding of the cardiovascular disease (CVD) benefits of α-linolenic acid (ALA, 18:3n-3) has advanced markedly during the past decade. It is now evident that ALA benefits CVD risk. The expansion of the ALA evidence base has occurred in parallel with ongoing research on eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) and CVD. The available evidence enables comparisons to be made for ALA vs. EPA + DHA for CVD risk reduction. The epidemiologic evidence suggests comparable benefits of plant-based and marine-derived n-3 (omega-3) PUFAs. The clinical trial evidence for ALA is not as extensive; however, there have been CVD event benefits reported. Those that have been reported for EPA + DHA are stronger because only EPA + DHA differed between the treatment and control groups, whereas in the ALA studies there were diet differences beyond ALA between the treatment and control groups. Despite this, the evidence suggests many comparable CVD benefits of ALA vs. EPA + DHA. Thus, we believe that it is time to revisit what the contemporary dietary recommendation should be for ALA to decrease the risk of CVD. Our perspective is that increasing dietary ALA will decrease CVD risk; however, randomized controlled clinical trials are necessary to confirm this and to determine what the recommendation should be. With a stronger evidence base, the nutrition community will be better positioned to revise the dietary recommendation for ALA for CVD risk reduction.

Dietary flaxseed intake exacerbates acute colonic mucosal injury and inflammation induced by dextran sodium sulfate

Flaxseed (FS), a dietary oilseed, contains a variety of anti-inflammatory bioactives, including fermentable fiber, phenolic compounds (lignans), and the n-3 polyunsaturated fatty acid (PUFA) α-linolenic acid. The objective of this study was to determine the effects of FS and its n-3 PUFA-rich kernel or lignan- and soluble fiber-rich hull on colitis severity in a mouse model of acute colonic inflammation. C57BL/6 male mice were fed a basal diet (negative control) or a basal diet supplemented with 10% FS, 6% kernel, or 4% hull for 3 wk prior to and during colitis induction via 5 days of 2% (wt/vol) dextran sodium sulfate (DSS) in their drinking water (n = 12/group). An increase in anti-inflammatory metabolites (hepatic n-3 PUFAs, serum mammalian lignans, and cecal short-chain fatty acids) was associated with consumption of all FS-based diets, but not with anti-inflammatory effects in DSS-exposed mice. Dietary FS exacerbated DSS-induced acute colitis, as indicated by a heightened disease activity index and an increase in colonic injury and inflammatory biomarkers [histological damage, apoptosis, myeloperoxidase, inflammatory cytokines (IL-6 and IL-1β), and NF-κB signaling-related genes (Nfkb1, Ccl5, Bcl2a1a, Egfr, Relb, Birc3, and Atf1)]. Additionally, the adverse effect of the FS diet was extended systemically, as serum cytokines (IL-6, IFNγ, and IL-1β) and hepatic cholesterol levels were increased. The adverse effects of FS were not associated with alterations in fecal microbial load or systemic bacterial translocation (endotoxemia). Collectively, this study demonstrates that although consumption of a 10% FS diet enhanced the levels of n-3 PUFAs, short-chain polyunsaturated fatty acids, and lignans in mice, it exacerbated DSS-induced colonic injury and inflammation.

Elevated levels of pro-inflammatory oxylipins in older subjects are normalized by flaxseed consumption

BACKGROUND AND AIMS

Oxylipins, including eicosanoids, are highly bioactive molecules endogenously produced from polyunsaturated fatty acids. Oxylipins play a key role in chronic disease progression. It is possible, but unknown, if oxylipin concentrations change with the consumption of functional foods or differ with subject age.

METHODS

Therefore, in a parallel comparator trial, 20 healthy individuals were recruited into a younger (19-28years) or older (45-64years) age group (n=10/group). Participants ingested one muffin/day containing 30g of milled flaxseed (6g alpha-linolenic acid) for 4weeks. Plasma oxylipins were isolated through solid phase extraction, analyzed with HPLC-MS/MS targeted lipidomics, and quantified with the stable isotope dilution method.

RESULTS

At baseline, the older group exhibited 13 oxylipins ≥2-fold the concentration of the younger group. Specifically, pro-inflammatory oxylipins 5-hydroxyeicosatetraenoic acid, 9,10,13-trihydroxyoctadecenoic acid, and 9,12,13-trihydroxyoctadecenoic acid were significantly greater in the older (1.1±0.23nM, 5.6±0.84nM, and 4.5±0.58nM, respectively) versus the younger group (0.34±0.12nM, 3.5±0.33nM, and 3.0±0.24nM, respectively) (p<0.05). After 4weeks of flaxseed consumption the number of oxylipins that were ≥2-fold higher in the older versus the younger group was reduced to 3. 5-Hydroxyeicosatetraenoic acid, 9,10,13-trihydroxyoctadecenoic acid, and 9,12,13-trihydroxyoctadecenoic acid decreased in the older group to concentrations equivalent to the younger group after flaxseed consumption.

CONCLUSION

These data suggest a potential role for oxylipins in the aging process and how nutritional interventions like flaxseed can beneficially disrupt these biological changes associated with inflammation and aging.

Favorable effects of flaxseed supplemented diet on liver and kidney functions in hypertensive Wistar rats

Hypertension is a major risk factor for cardiovascular diseases and is detrimental to several organs including the liver and kidneys. The flaxseed-derived polyunsaturated fatty acids including the omega-3 and omega-6 essential fatty acids have been shown to blunt the effects of hypertension. It is however, unclear whether the flaxseed, which is rich in these essential fatty acids, could improve the liver and kidney dysfunctions observed in the hypertensive condition. To test this, functional markers of the liver and kidneys, including aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN), uric acid (UA), creatinine, and renin were examined in hypertensive male Wistar rats fed a flaxseed diet. Normotensive rats maintained on a standard diet were rendered hypertensive with a daily administration of cyclosporin A (CYS) (25 mg/kg) for 4 weeks. Subsequently, hypertensive rats were either fed a standard diet alone or a flaxseed-supplemented standard diet (FLX; 10% W/W) for 8 weeks. Compared to normotensive rats, standard diet-fed hypertensive rats had significantly elevated blood pressure, altered lipid profile, and increased plasma levels of tissue markers measured immediately following the CYS treatment and thereafter at 4 and 8 week intervals. On the other hand, rats fed the FLX-supplemented diet had significantly lower blood pressure, an improved lipid profile and decreased tissue marker levels measured after 4 and 8 week durations. The data demonstrate for the first time the favourable effects of FLX in improving liver and kidney functions in the hypertensive condition. These effects are likely to be mediated by the alpha-linolenic acid (ALA) and linoleic acid (LA) contents of flaxseed oil due to its demonstrated ability to lower the blood pressure.

Omega-3 fatty acid enriched chevon (goat meat) lowers plasma cholesterol levels and alters gene expressions in rats

In this study, control chevon (goat meat) and omega-3 fatty acid enriched chevon were obtained from goats fed a 50% oil palm frond diet and commercial goat concentrate for 100 days, respectively. Goats fed the 50% oil palm frond diet contained high amounts of α-linolenic acid (ALA) in their meat compared to goats fed the control diet. The chevon was then used to prepare two types of pellets (control or enriched chevon) that were then fed to twenty-male-four-month-old Sprague-Dawley rats (n = 10 in each group) for 12 weeks to evaluate their effects on plasma cholesterol levels, tissue fatty acids, and gene expression. There was a significant increase in ALA and docosahexaenoic acid (DHA) in the muscle tissues and liver of the rats fed the enriched chevon compared with the control group. Plasma cholesterol also decreased (P < 0.05) in rats fed the enriched chevon compared to the control group. The rat pellets containing enriched chevon significantly upregulated the key transcription factor PPAR-γ and downregulated SREBP-1c expression relative to the control group. The results showed that the omega-3 fatty acid enriched chevon increased the omega-3 fatty acids in the rat tissues and altered PPAR-γ and SREBP-1c genes expression.

Beneficial effects of flaxseed oil and fish oil diet are through modulation of different hepatic genes involved in lipid metabolism in streptozotocin-nicotinamide induced diabetic rats

Dietary omega-3 fatty acids have been demonstrated to have positive physiological effects on lipid metabolism, cardiovascular system and insulin resistance. Type-2 diabetes (T2DM) is known for perturbations in fatty acid metabolism leading to dyslipidemia. Our objective was to investigate beneficial effects of dietary flaxseed oil and fish oil in streptozotocin-nicotinamide induced diabetic rats. Thirty-six adult, male, Wistar rats were divided into six groups: three diabetic and three non-diabetic. Diabetes was induced by an injection of nicotinamide (110 mg/kg) and STZ (65 mg/kg). The animals received either control, flaxseed oil or fish oil (10 % w/w) enriched diets for 35 days. Both diets lowered serum triglycerides and very low-density lipoprotein cholesterol levels and elevated serum high-density lipoprotein cholesterol levels in diabetic rats, while serum total cholesterol and LDL-C levels remained unaffected. Both the diets increased omega-3 levels in plasma and RBCs of diabetic rats. Flaxseed oil diet significantly up-regulated the key transcription factor peroxisome proliferator-activated receptor-α (PPAR-α ) and down-regulated sterol regulatory element-binding protein-1 (SREBP-1) in diabetic rats, which would have increased β-oxidation of fatty acids and concomitantly reduced lipogenesis respectively, thereby reducing TG levels. Fish oil diet, on the contrary lowered serum TG levels without altering PPAR-α while it showed a non-significant reduction in SREBP-1 expression in diabetic rats. Another key finding of the study is the activation of D5 and D6 desaturases in diabetic rats by flaxseed oil diet or fish oil diets, which may have resulted in an improved omega-3 status and comparable effects shown by both diets. The reduced expression of Liver-fatty acid binding protein in diabetic rats was restored by fish oil alone, while both diets showed equal effects on adipocyte fatty acid-binding protein expression. We also observed down-regulation of atherogenic cytokines tumor necrosis factor-α and interleukin-6 by both the diets. In conclusion, dietary flaxseed oil and fish oil have therapeutic potential in preventing lipid abnormalities in T2DM.

Effect of flaxseed supplementation and exercise training on lipid profile, oxidative stress and inflammation in rats with myocardial ischemia

Background

Flaxseed has recently gained attention in the area of cardiovascular disease primarily because of its rich contents of α-linolenic acid (ALA), lignans, and fiber. Although the benefits of exercise on any single risk factor are unquestionable, the effect of exercise on overall cardiovascular risk, when combined with other lifestyle modifications such as proper nutrition, can be dramatic.

This study was carried out to evaluate the protective role of flaxseed and exercise on cardiac markers, lipids profile and inflammatory markers in isoproterenol (ISO)-induced myocardial ischemia in rats.

Methods

The research was conducted on 40 male albino rats, divided into 4 groups (n=10): group I served as control, group II has acute myocardial ischemia induced by isoproterenol, groups III and IV have acute myocardial ischemia induced by isoproterenol pretreated with flaxseed supplementation orally for 6 weeks, additionally group IV practiced muscular exercise through swimming.

Results

Alterations of lipid profile, cardiac and inflammatory markers (Il-1β, PTX 3 and TNF- α) were observed in myocardial ischemia group. Flaxseed supplementation combined with exercise training showed significant increase of HDL and PON 1, on the other hand cardiac troponin, Il- 1β and TNF- α levels significantly decreased as compared to myocardial ischemic group. Receiver Operating Characteristics (ROC) analysis of cTnI, PTX 3, Il-1β and TNF- α revealed a satisfactory level of sensitivity and specificity.

Conclusion

Regular exercise enhances the improvement in plasma lipoprotein levels and cardiovascular protection that results from flaxseed supplementation by mitigating the pathophysiology of atherosclerosis. Elevation of HDL, the antioxidant PON 1 and the cardioprotective marker PTX 3 emphasizes the protective effects of flaxseed and muscular exercise mutually against the harmful effects of acute myocardial ischemia.

Vascular effects of phytoestrogens and alternative menopausal hormone therapy in cardiovascular disease

Phytoestrogens are estrogenic compounds of plant origin classified into different groups including isoflavones, lignans, coumestans and stilbenes. Isoflavones such as genistein and daidzein are the most studied and most potent phytoestrogens, and are found mainly in soy based foods. The effects of phytoestrogens are partly mediated via estrogen receptors (ERs): ERα, ERβ and possibly GPER. The interaction of phytoestrogens with ERs is thought to induce both genomic and non-genomic effects in many tissues including the vasculature. Some phytoestrogens such as genistein have additional non-ER-mediated effects involving signaling pathways such as tyrosine kinase. Experimental studies have shown beneficial effects of phytoestrogens on endothelial cells, vascular smooth muscle, and extracellular matrix. Phytoestrogens may also affect other pathophysiologic vascular processes such as lipid profile, angiogenesis, inflammation, tissue damage by reactive oxygen species, and these effects could delay the progression of atherosclerosis. As recent clinical trials showed no vascular benefits or even increased risk of cardiovascular disease (CVD) and CV events with conventional menopausal hormone therapy (MHT), phytoestrogens are being considered as alternatives to pharmacologic MHT. Epidemiological studies in the Far East population suggest that dietary intake of phytoestrogens may contribute to the decreased incidence of postmenopausal CVD and thromboembolic events. Also, the WHO-CARDIAC study supported that consumption of high soybean diet is associated with lower mortalities from coronary artery disease. However, as with estrogen, there has been some discrepancy between the experimental studies demonstrating the vascular benefits of phytoestrogens and the data from clinical trials. This is likely because the phytoestrogens clinical trials have been limited in many aspects including the number of participants enrolled, the clinical end points investigated, and the lack of long-term follow-up. Further investigation of the cellular mechanisms underlying the vascular effects of phytoestrogens and careful evaluation of the epidemiological evidence and clinical trials of their potential vascular benefits would put forward the use of phytoestrogens as an alternative MHT for the relief of menopausal symptoms and amelioration of postmenopausal CVD.