Flaxseed and Human Health: Reviewing Benefits and Adverse Effects

Plant-Based Oil-in-Water Food Emulsions: Exploring the Influence of Different Formulations on Their Physicochemical Properties

The global focus on incorporating natural ingredients into the diet for health improvement encompasses ω-3 polyunsaturated fatty acids (PUFAs) derived from plant sources, such as flaxseed oil. ω-3 PUFAs are susceptible to oxidation, but oil-in-water (O/W) emulsions can serve to protect PUFAs from this phenomenon. This study aimed to create O/W emulsions using flaxseed oil and either soy lecithin or Quillaja saponins, thickened with modified starch, while assessing their physical properties (oil droplet size, ζ-potential, and rheology) and physical stability. Emulsions with different oil concentrations (25% and 30% w/w) and oil-to-surfactant ratio (5:1 and 10:1) were fabricated using high-pressure homogenization (800 bar, five cycles). Moreover, emulsions were thickened with modified starch and their rheological properties were measured. The physical stability of all emulsions was assessed over a 7-day storage period using the TSI (Turbiscan Stability Index). Saponin-stabilized emulsions exhibited smaller droplet diameters (0.11-0.19 µm) compared to lecithin (0.40-1.30 µm), and an increase in surfactant concentration led to a reduction in droplet diameter. Both surfactants generated droplets with a high negative charge (-63 to -72 mV), but lecithin-stabilized emulsions showed greater negative charge, resulting in more intense electrostatic repulsion. Saponin-stabilized emulsions showed higher apparent viscosity (3.9-11.6 mPa·s) when compared to lecithin-stabilized ones (1.19-4.36 mPa·s). The addition of starch significantly increased the apparent viscosity of saponin-stabilized emulsions, rising from 11.6 mPa s to 2117 mPa s. Emulsions stabilized by saponin exhibited higher stability than those stabilized by lecithin. This study confirms that plant-based ingredients, particularly saponins and lecithin, effectively produce stable O/W emulsions with flaxseed oil, offering opportunities for creating natural ingredient-based food emulsions.

Flaxseed Lignan Alleviates the Paracetamol-Induced Hepatotoxicity Associated with Regulation of Gut Microbiota and Serum Metabolome

This study examined the protective effect of flaxseed lignans on liver damage caused by an overdose of paracetamol (PAM). The findings demonstrated that administering 800 mg/kg/d flaxseed lignan prior to PAM significantly decreased the serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total bilirubin (TBi) levels, while it increased liver superoxide dismutase (SOD) and glutathione (GSH) levels in mice. Flaxseed lignan renovated the gut microbiota dysbiosis induced by PAM by promoting the proliferation of sulfonolipid (SL) producing bacteria such as Alistipes and lignan-deglycosolating bacteria such as Ruminococcus while inhibiting the growth of opportunistic pathogen bacteria such as Acinetobacter and Clostridium. Furthermore, flaxseed lignan modulated the serum metabolomic profile after PAM administration, specifically in the taurine and hypotaurine metabolism, phenylalanine metabolism, and pyrimidine metabolism. The study identified eight potential biomarkers, including enterolactone, cervonyl carnitine, acutilobin, and PC (20:3(5Z, 8Z, 11Z)/20:0). Overall, the results suggest that flaxseed lignan can alleviate PAM-induced hepatotoxicity and may be beneficial in preventing drug-induced microbiome and metabolomic disorders.

Effects of flaxseed supplementation on weight loss, lipid profiles, glucose, and high-sensitivity C-reactive protein in patients with coronary artery disease: A systematic review and meta-analysis of randomized controlled trials

This meta-analysis aimed to evaluate the effects of flaxseed supplementation on weight loss, lipid profiles, high-sensitivity C-reactive protein (hs-CRP), and glucose levels in patients with coronary artery disease (CAD). A systematic search was performed using various online databases, including Scopus, PubMed, Web of Science, EMBASE, and Cochrane Library, to identify relevant randomized controlled trials (RCTs) until June 2023. To evaluate heterogeneity among the selected studies, the Q-test and I2 statistics were employed. Data were combined using either a fixed- or random-effects model and presented as a weighted mean difference (WMD) with a 95% confidence interval (CI). Of the 428 citations, six RCTs were included. The pooled results did not show significant changes in the WMD of lipid factors (high-density lipoprotein cholesterol, triglycerides (TG), low-density lipoprotein cholesterol, and total cholesterol) following flaxseed intake. However, after performing a sensitivity analysis to determine the source of heterogeneity, flaxseed supplementation resulted in a significant decrease in TG levels (WMD = -18.39 mg/dL; 95% CI: -35.02, -1.75). Moreover, no significant differences were observed in either weight or BMI following flaxseed intake. However, the circulating levels of fasting blood glucose (WMD = -8.35 mg/dL; 95% CI: -15.01, -1.69, p = .01) and hs-CRP (WMD = -1.35 mg/L; 95% CI: -1.93, -0.77, p < .01) significantly decreased after the intervention. Flaxseed supplementation was associated with lowering FBS, hs-CRP, and TG levels but did not affect weight loss parameters and other lipid markers in CAD.

Effect of Flaxseed Addition on the Quality and Storage Stability of Sesame Paste

The flaxseed-sesame paste (FSP) was prepared by mixing the heat-treated flaxseed and sesame seeds in different proportions and grinding them in a colloid mill to obtain a FSP. In this study, flaxseed was added to sesame paste (SP) at different addition to assess its effect on the rheological properties, textural properties, and particle size. The effect of flaxseed addition on lipid oxidation and volatile aldehydes and ketones during storage of SP was investigated by accelerated oxidation experiments (63°C, 60 days). Notably, the addition of all different additions of flaxseed increased the linolenic acid content, and also enhanced the hardness, cohesiveness, and viscosity of SP. However, it increased the rate of lipid oxidation in SP during storage, mainly in the form of higher acid value (AV) and malondialdehyde (MDA) content. The content of volatile aldehydes and ketones from lipid oxidation increased significantly with storage time. It was found by using cluster analysis that mixing flaxseed with SP at a ratio of 20 g/100 g had little effect on its storage stability, the sample had a higher overall quality than the addition of 40 g/100 g flaxseed, and its linolenic acid content was 18.7 times higher than that of the SP. Collectively, the results indicated that the addition of flaxseed at an appropriate proportion might be a feasible way to prepare the functional formulated SP.

Composition, processing, and quality control of whole flaxseed products used to fortify foods

Whole flaxseed (flour) as a good source of omega-3 fatty acid and phytochemicals with excellent nutritional and functional attributes has been used to enrich foods for health promotion and disease prevention. However, several limitations and contemporary challenges still impact the development of whole flaxseed (flour)-enriched products on the global market, such as naturally occurring antinutritional factors and entrapment of nutrients within food matrix. Whole flaxseed (flour) with different existing forms could variably alter the techno-functional performance of food matrix, and ultimately affect the edible qualities of fortified food products. The potential interaction mechanism between the subject and object components in fortified products has not been elucidated yet. Hence, in this paper, the physical structure and component changes of flaxseed (flour) by pretreatments coupled with their potential influences on the edible qualities of multiple fortified food products were summarized and analyzed. In addition, several typical food products, including baked, noodle, and dairy products were preferentially selected to investigate the potential influencing mechanisms of flaxseed (flour) on different substrate components. In particular, the altered balance between water absorption of flaxseed protein/gum polysaccharides and the interruption of gluten network, lipid lubrication, lipid-amylose complexes, syneresis, and so forth, were thoroughly elucidated. The overall impact of incorporating whole flaxseed (flour) on the quality and nutritional attributes of fortified food products, coupled with the possible solutions against negative influences are aimed. This paper could provide useful information for expanding the application of whole flaxseed (flour) based on the optimal edible and nutritional properties of fortified food products.

A review of flaxseed lignan and the extraction and refinement of secoisolariciresinol diglucoside

Lignan is a class of diphenolic compounds that arise from the condensation of two phenylpropanoid moieties. Oilseed and cereal crops (e.g., flaxseed, sesame seed, wheat, barley, oats, rye, etc.) are major sources of plant lignan. Methods for commercial isolation of the lignan secoisolariciresinol diglucoside (SDG) are not well reported, as most publications describing the detection, extraction, and enrichment of SDG use methods that have not been optimized for commercial scale lignan recovery. Simply scaling up laboratory methods would require expensive infrastructure to achieve a marketable yield and reproducible product quality. Therefore, establishing standard protocols to produce SDG and its derivatives on an industrial scale is critical to decrease lignan cost and increase market opportunities. This review summarizes the human health benefits of flaxseed lignan consumption, lignan physicochemical properties, and mammalian lignan metabolism, and describes methods for detecting, extracting, and enriching flaxseed lignan. Refining and optimization of these methods could lead to the development of inexpensive lignan sources for application as an ingredient in medicines, dietary supplements, and other healthy ingredients.

The effect of flaxseed intake on appetite reduction: A systematic review of randomized clinical trials

Appetite control has attracted many scientists' attention recently since it can lead to weight management and the prevention of further metabolic disorders. Many studies have been carried out to assess the effect of flaxseed on satiety perception but the results are controversial. This study aims to review these results comprehensively. PubMed/Medline, Web of Science, Scopus, and Cochrane databases were searched for related papers on June 2021. The searched keywords for appetite were: visual analog scale, appetite, desire to eat, satiation, satiety, hunger, fullness, and for Flaxseed they were: flax, flax*, linseed*, lignin*, Linseed Oil, flaxseed, ground flaxseed, flaxseed oil, and Linum usitatissimum. The 13 included studies were inconsistent in results and some of them found no significant effect of flaxseed on the considered outcomes. However, three studies revealed a significant reduction in hunger perception as well as appetite. Moreover, two studies found a decreasing effect on prospective consumption. Three studies observed a positive significant effect on fullness and satiety. Although there are a limited number of documents related to the effect of flaxseed on appetite perception, or its equivalent terms, the available studies suggest the potential role of flaxseed in decreasing appetite and hunger.

The effect of flaxseed oil consumtion on blood pressure among patients with metabolic syndrome and related disorders: A systematic review and meta-analysis of randomized clinical trials

We systematically reviewed randomized clinical trials (RCTs) to elucidate the overall effects of flaxseed oil consumption on blood pressure (BP) in patients with metabolic syndrome and related disorders. PubMed, Scopus, Cochrane Library, and ISI Web of Science databases were systematically searched until March 31, 2020, to find RCTs that examined the effect of flaxseed oil consumption on BP. Weighed mean difference (WMD) was pooled using a random-effects model. Standard methods were used for the assessment of heterogeneity, sensitivity analysis, and publication bias. Meta-analysis of five trials (6 arms) showed significant reductions in systolic (WMD: -3.86 mmHg, 95% CI: -7.59 to -0.13, p = .04) BP (SBP) after flaxseed oil consumption. However, the overall effect illustrated no significant change in diastolic (WMD: -1.71 mmHg, 95% CI: -3.67 to 0.26, p = .09) BP (DBP) in the intervention group compared with the control group. Our findings revealed that flaxseed oil consumption has favorable effects on SBP in patients with metabolic syndrome and related disorders. However, further investigations are needed to provide more reliable evidence.

A comprehensive review of flaxseed (Linum usitatissimum L.): health-affecting compounds, mechanism of toxicity, detoxification, anticancer and potential risk

Flaxseed consumption (Linum usitatissimum L.) has increased due to its potential health benefits, such as protection against inflammation, diabetes, cancer, and cardiovascular diseases. However, flaxseeds also contains various anti-nutritive and toxic compounds such as cyanogenic glycosides, and phytic acids etc. In this case, the long-term consumption of flaxseed may pose health risks due to these non-nutritional substances, which may be life threatening if consumed in high doses, although if appropriately utilized these may prevent/treat various diseases by preventing/inhibiting and or reversing the toxicity induced by other compounds. Therefore, it is necessary to remove or suppress the harmful and anti-nutritive effects of flaxseeds before these are utilized for large-scale as food for human consumption. Interestingly, the toxic compounds of flaxseed also undergoes biochemical detoxification in the body, transforming into less toxic or inactive forms like α-ketoglutarate cyanohydrin etc. However, such detoxification is also a challenge for the development, scalability, and real-time quantification of these bioactive substances. This review focuses on the health affecting composition of flaxseed, along with health benefits and potential toxicity of its components, detoxification methods and mechanisms with evidence supported by animal and human studies.

The Effect of Abiotic Stresses on the Protein Composition of Four Hungarian Wheat Varieties

Global climate change in recent years has resulted in extreme heat and drought events that significantly influence crop production and endanger food security. Such abiotic stress during the growing season has a negative effect on yield as well as on the functional properties of wheat grain protein content and composition. This reduces the value of grain, as these factors significantly reduce end-use quality. In this study, four Hungarian bread wheat cultivars (Triticum aestivum ssp. aestivum) with different drought and heat tolerance were examined. Changes in the size- and hydrophobicity-based distribution of the total proteins of the samples have been monitored by SE- and RP-HPLC, respectively, together with parallel investigations of changes in the amounts of the R5 and G12 antibodies related to celiac disease immunoreactive peptides. Significant difference in yield, protein content and composition have been observed in each cultivar, altering the amounts of CD-related gliadin, as well as the protein parameters directly related to techno-functional properties (Glu/Gli ratio, UPP%). The extent of changes largely depended on the timing of the abiotic stress. The severity of the negative effect depended on the growth stage in which abiotic stress occurred.

Effect of the Addition of Whole and Milled Flaxseed on the Quality Characteristics of Yogurt

The present study aimed to analyze the effect of the addition of whole and milled flaxseed on the quality characteristics of yogurt. In the first stage of the research, the optimal dose of flaxseed was determined. In the second stage of the research, it was assessed whether the selected qualities of yogurt were affected by the form of flaxseed (whole or milled) and the time of addition (before or after fermentation). The yogurts obtained were stored at 5 °C for 21 days, and the changes in active acidity, apparent viscosity, syneresis, and the number of yogurt bacteria were determined. The results of the second stage of the study were subjected to two-way analysis of variance (ANOVA) (p < 0.05). The study showed that the addition of milled flaxseed to yogurts in the amount of 1% was optimal. Time and form of flaxseed supplementation significantly influenced the changes in active acidity, apparent viscosity, and syneresis in the tested yogurts. The addition of flaxseed did not significantly change the content of yogurt bacteria. The results indicate that to achieve increased apparent viscosity and reduced syneresis, it is more advantageous to use milled flaxseed rather than whole flaxseed.

Defatted flaxseed flour improves weight loss and lipid profile in overweight and obese adults: a randomized controlled trial

SCOPE

Studies have suggested that foods rich in dietary fiber may contribute to body weight loss and lower triacylglycerol (TG) levels. This study aimed to investigate the effect of flaxseed meal (FM) (a by-product of flaxseed after oil processing) supplemented biscuits on body weight, body composition, and blood lipids in overweight and obese participants.

METHOD AND RESULTS

In a double-blind randomized controlled trial, 53 overweight and obese adults (18-36 years of age) were recruited and randomized to consume control biscuits or biscuits supplemented with FM for their breakfast for 60 days (approximately 100 g per day). Significant group × time interaction (P = 0.011) was observed for body weight, and the body weight of the FM group was significantly lower than that of the control group (P = 0.049). We also found significant group × time interactions for body mass index (BMI) (P = 0.008), TG (P = 0.041) and interleukin-6 (IL-6) (P = 0.016). In addition, after 60 days of intervention, the body weight, BMI and TG levels of the FM group significantly decreased compared to those of the control group. On day 60, the serum concentration of IL-6 in the FM group was significantly lower than that in the control group.

CONCLUSIONS

FM supplemented biscuits have a beneficial effect on body weight, BMI and TG of overweight and obese subjects (ClinicalTrials.gov registration number: ChiCTR1900022833).

Complete symptom resolution as predictor of Helicobacter pylori eradication and factors affecting symptom resolution: Prospective follow up study

BACKGROUND

Symptom resolution is the most common clinical practice during assessment and evaluation of helicobacter pylori infected patients after employing eradication therapy.

OBJECTIVE

Prediction of eradication of H. pylori with symptom resolution and assess factors affecting symptom resolution.

METHOD

Facility based follow up study was done on consented H. pylori positive adult patients who received standard triple therapy consisting of a proton pump inhibitor, amoxicillin, and clarithromycin from May 2016 to April 2018 at Bahir Dar city in Ethiopia. Sociodemographic and clinical data was collected before and after eradication therapy by using pre-developed structured questionnaire. Both positive and negative predictive values were calculated. SPSS version 23 was used to conduct bivariate and backward stepwise multivariate logistic regression to analyze data. P-value < 0.05 at 95%CI was considered as significant.

RESULT

The study involved a total of 421 patients who completed follow up. Patients' mean age and body weight (±SD) were 30.63 (± 10.74) years and 56.71 (± 10.19) kg, respectively. Complete symptom resolution was achieved in 84.3% of the patients and eradication of H. pylori was successful in 90% of patients. Positive predictive value of complete symptom resolution for H. pylori eradication was 98.9% (351/355) and whereas negative predictive value was 57.6%(38/66). Factors associated with complete symptom resolution were regimen completion (AOR: 2.77 95%CI (1.12-6.86), p = 0.028) and no use of traditional homemade supplements prepared from Fenugreek or Flaxseed (AOR: 2.09 95%CI (1.22-3.58), p = 0.007).

CONCLUSION

Complete symptom resolution is a powerful predictor of success of H. pylori eradication and can be used to assess H. pylori status after eradication therapy. Assessment of complete symptom resolution should consider regimen completion and traditional practice of using homemade supplements prepared from Fenugreek or Flaxseed.

Optimization of flaxseed milk fermentation for the production of functional peptides and estimation of their bioactivities

Bioactive peptides are protein fragments which have a positive impact on the functions and conditions of living organisms. Apart from other animal and plant sources flaxseed is an excellent source of bioactive peptides. In recent years, fermentation has been explored as effective way for bioactive peptides generation. Hence, the present study has been carried out to evaluate an indigenous Lactobacillus plantarum strain NCDC 374 for fermentation and peptides generation in flaxseed milk. Optimization of fermentation condition to obtain maximum functional properties (Proteolytic activity, Antioxidant activity and ACE inhibition %) was investigated using response surface methodology. Optimal condition to produce the functional peptides were found to be 4.20% inoculum size with 126 hours of fermentation time. The fermented milk resulted in 67.38% inhibition in DPPH, 41.35% inhibition in ACE and 30.38 micro gram leucine/ml proteolytic activity. Molecular weight cut off membrane (Viva spin) were used to fractionate the peptides. 10 kDa peptides showed optimal results for % DPPH inhibition, ACE inhibition, Antimicrobial activity and DPP-IV inhibition as compared to 5 kDa.

Lignans from linseed (Linum usitatissimum L.) and its allied species: Retrospect, introspect and prospect

Lignans are complex diphenolic compounds representing phytoestrogens and occur widely across the plant kingdom. Formed by the coupling of two coniferyl alcohol residues, lignans constitute major plant "specialized metabolites" with exceptional biological attributes that aid in plant defence and provide health benefits in humans by reducing the risk of ailments such as cancer, diabetes etc. Linseed (Linum usitatissimum L.) is one of the richest sources of lignans followed by cereals and legumes. Among the various types of lignans, secoisolariciresinol diglucoside (SDG) is considered as the essential and nutrient rich lignan in linseed. Lignans exhibit established antimitotic, antiviral and anti-tumor properties that contribute to their medicinal value. The present review seeks to provide a holistic view of research in the past and present times revolving around lignans from linseed and its allied species. This review attempts to elucidate sources, structures and functional properties of lignans, along with detailed biosynthetic mechanisms operating in plants. It summarizes various methods for the determination of lignan content in plants. Biotechnological interventions (in planta and in vitro) aimed at enriching lignan content and adoption of integrative approaches that might further enhance lignan content and medicinal and nutraceutical value of Linum spp. have also been discussed.

Flaxseed Enriched Pasta-Chemical Composition and Cooking Quality

Pasta production is a good opportunity for product innovation in different forms. The aim of this work was to assess the use of flaxseed components for pasta production. We examined the chemical composition and cooking quality, at different contents of flaxseed flour (FF) and flaxseed cake (FC), added for pasta processing. The analysis showed that the addition of flaxseed components to the dough caused a substantial difference in the International Commission on Illumination color model (CIE) parameter, compared to control samples. The samples of pasta with FF and FC were darker, redder, and less yellow than the control. The minimum cooking time for the enriched pasta was longer than that for the control pasta, although cooking losses were lower. The increasing content of flaxseed components did not significantly change the weight and volume increase index. The enrichment of pasta with 23% FF and 17% FC yielded good quality pasta. The results of the chemical composition of the flaxseed-enriched pasta indicate considerably enhanced nutritional quality, particularly the levels of protein, fat, and dietary fiber of the pasta, without affecting its quality. Moreover, flaxseed cake can be an important source of nutritional ingredients for pasta production, although it is a by-product of the oil cold pressing technology.

A Comparative Study of the Effect of Flaxseed Oil and Sunflower Oil on the Coagulation Score, Selected Oxidative and Inflammatory Parameters in Metabolic Syndrome Patients

Metabolic syndrome (MetS) is a chronic disease with inflammatory and hypercoagulable states. The current study aimed to compare the effects of flaxseed oil and sunflower oil consumption on the coagulation score and selected oxidative and inflammatory parameters in patients with MetS. In this randomized controlled clinical trial, 60 patients with MetS were allocated into 2 groups. One group received 25 mL/day flaxseed oil and the other group received 25 mL/day sunflower oil for 7 weeks. Maintenance diet including 15% protein, 55% carbohydrate, and 30% fat from daily total energy intake was designed for each participant. Serum levels of total antioxidant capacity (TAC) and interleukin 6 (IL-6), as well as coagulation score were measured before and after the intervention. Three 24-hour food records were taken during the study. Fifty-two of participants (27 in sunflower oil and 25 in flaxseed oil groups) completed the study. The baseline characteristics and dietary intakes were similar between patients. After 7 weeks, no significant difference was observed between the 2 groups regarding the serum TAC level and coagulation score (p > 0.05). However, serum IL-6 levels significantly decreased in the flaxseed oil group compared to the sunflower oil group (p = 0.017). No side effect was observed during the study due to the use of sunflower and flaxseed oils. We observed that consumption of flaxseed oil improved serum IL-6 levels but had no effect on oxidative stress and coagulation score in patients with MetS. Further studies are needed to confirm the veracity of our results.

The effects of flaxseed supplementation on metabolic status in women with polycystic ovary syndrome: a randomized open-labeled controlled clinical trial

BACKGROUND

Polycystic Ovary Syndrome (PCOS) is known as the most common endocrine disorder of women in reproductive ages. With the increasing prevalence of PCOS in different countries, the use of herbal medicine as an alternative treatment is growing in these patients. This study aimed to evaluate the effects of flaxseed powder supplementation on metabolic biomarkers of patients with PCOS.

METHODS

This randomized open-labeled controlled clinical trial was conducted on 41 patients with PCOS. The participants were randomized to take either flaxseed powder (30 g/day) plus lifestyle modification or only lifestyle modification for 12 weeks. Anthropometric and biochemical evaluations were performed for all patients at the beginning and end of the study.

RESULTS

The flaxseed group showed a significant reduction in body weight, insulin concentration, Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), Triglycerides (TG), high-sensitivity C-Reactive Protein (hs-CRP), and leptin and an increase in Quantitative Insulin-Sensitivity Check Index (QUICKI), High Density Lipoprotein (HDL), and adiponectin compared to the baseline (p < 0.05). Flaxseed supplementation also led to a significant reduction in insulin concentration, HOMA-IR, TG, hs-CRP, Interleukin 6 (IL- 6), and leptin and an increase in QUICKI, HDL, and adiponectin compared to the control group (p < 0.05). No significant changes were observed in other parameters.

CONCLUSIONS

Flaxseed supplementation plus lifestyle modification was more effective compared to lifestyle modification alone in biochemical and anthropometric variables in patients with PCOS.

TRIAL REGISTRATION

The trial protocol was approved by the Ethics Board at Ahvaz Jundishapur University of Medical Sciences and was registered at Iranian Registry of Clinical Trials (code: IRCT20120704010181N11).

Secoisolariciresinol Diglucoside of Flaxseed and Its Metabolites: Biosynthesis and Potential for Nutraceuticals

Secoisolariciresinol diglucoside (SDG), found mainly in flaxseed, is one of the essential lignans. SDG, as well as the beneficial fatty acid composition and high fiber content, has made flaxseed an important source of functional food or nutraceutical ingredients. Various studies have shown that SDG offers several health benefits, including protective effects against cardiovascular diseases, diabetes, cancer, and mental stress. These health benefits have been attributed to the antioxidant properties of SDG. Additionally, SDG metabolites, namely mammalian lignans, enterodiol and enterolactone, have shown promising effects against cancer. Therefore, understanding the biosynthetic pathway of SDG and its molecular mechanisms is a key to enable the production of new flaxseed cultivars rich in nutraceutical content. The present review highlights studies on the different health benefits of SDG, as well as lignan biosynthesis in flaxseed and genes involved in the biosynthetic pathway. Since SDG, the predominant lignan in flaxseed, is a glycosylated lignan, we also focus on studies investigating the genes involved in secoisolariciresinol glycosylation. These genes can be used to produce new cultivars with a novel level of glycosylation or lignan composition to maximize the yields of lignans with a therapeutic or protective potential.

Intake of Protein Hydrolysates and Phenolic Fractions Isolated from Flaxseed Ameliorates TNBS-Induced Colitis

SCOPE

In the attempt to develop new therapeutic treatments for colitis, fractions containing phenolic compound isolate (Phi) and phenolic reduced-flaxseed protein hydrolysate (phr-FPH) from flaxseed are evaluated for their effects on the in vitro production of pro-inflammatory mediators and on the course of experimental colitis.

METHODS AND RESULTS

The anti-inflammatory effects of Phi and phr-FPH from flaxseeds are studied in RAW264.7 cells and in trinitrobenzene sulphonic acid (TNBS) colitis model. It is observed that the incubation with Phi or phr-FPH result in lower levels of tumor necrosis factor α and nitric oxide in macrophages stimulated with bacterial lipopolysaccharide + interferon-γ. Prophylactic and therapeutic treatments with Phi and phr-FPH, respectively, greatly contribute to the prevention of weight loss and colon inflammation in colitic BALB/c mice. T cell proliferation, expansion of TH1 and TH17 cells, and pro-inflammatory cytokines are lower, whereas Treg cells are higher in spleen cell cultures from Phi-treated mice. In addition, therapeutic phr-FPH treatment is able to reduce the expansion of TH17 in splenic cell cultures.

CONCLUSION

The consumption of phenolic and protein compounds extracted from flaxseeds has a protective effect on TNBS-induced colitis, and may be useful in the control of other inflammatory disorders.

Addition of pooled pumpkin seed to mixed meals reduced postprandial glycemia: a randomized placebo-controlled clinical trial

We investigated if pumpkin and flaxseeds could improve postprandial glycemic, food intake, and appetitive responses. Herein, we hypothesize based on the literature that pumpkin seed has potential to lower postprandial glycemic effects. Therefore, we conducted a randomized, single-blind, placebo-controlled, crossover design study involving normoglycemic adults (food intake: n = 25; glycemia: n = 15). Three high-carbohydrate mixed meals presenting no seed (control [C]) or 65 g of the tested seeds (pumpkin seed [P] or flaxseed [F]) were consumed in 3 nonconsecutive days. Test meals had similar nutritional composition. Blood glucose was measured by capillary finger blood at 0 (immediately before), 15, 30, 45, 60, 90, and 120 minutes after the ingestion of each meal, and the incremental area under glycemic response curves (iAUC) were calculated. Appetitive responses were assessed, and dietary records were used to evaluate food intake on testing days. Glucose iAUC was significantly lower in P compared with C (reduction of ~35%, P = .025). There was no significant differences in glucose iAUC between F and C (P = .257). Glycemic response at each time point did not differ between C, P, and F (P_{group × time} = .238). Fiber consumption was higher in F (P = .009) than in C, but there were no differences in appetitive responses, energy, or macronutrient consumptions between dietary interventions. Acute consumption of 65 g of pumpkin seed markedly reduced postprandial glycemia. Pumpkin seed has potential as a hypoglycemic food, which now deserves to be confirmed in long-term studies.

Modification of the lipid profile and antioxidant status of the blood plasma of turkey hens fed mixtures with raw or extruded linseed

The aim of the study was to determine the most beneficial proportion of raw linseed in complete feed mixtures for turkey hens on the basis of lipid and redox indicators in the blood. In experiment 1, the turkey hens received the complete mixture with 2%, 4% or 6% linseed. On the basis of the results obtained in experiment 1, we selected the most effective proportion of linseed, which was given to the birds in the group receiving a 4% linseed additive. In experiment 2, the birds were fed mixtures with a 4% addition of raw or extruded linseed. The use of 4% raw linseed was found to improve production effects (improvement of weight gain, and lower feed conversion ratios), while extruded linseed in the diet of turkey hens did not affect growth performance. The use of linseed (4% and 6%) as a feed component for turkey hens led to an increase in indicators of antioxidant potential, that is the total antioxidant potential of the plasma, vitamins E and C, bilirubin and creatinine. A benefit resulting from the use of linseed, particularly in the amounts of 2% and 4% was a marked improvement in lipid indicators in the blood. The reduced percentage of unsaturated fatty acids (n-3) following the use of extruded linseed resulted in a decrease in lipid peroxidation (lower content of malondialdehyde, superoxide and vitamins C and E in the blood). The most effective dose and form of linseed in the diet of turkey hens is 4% raw linseed.

Influence of Protein-Phenolic Complex on the Antioxidant Capacity of Flaxseed (Linum usitatissimum L.) Products

The impact of the naturally present phenolic compounds and/or proteins on the antioxidant capacity of flaxseed products (phenolic fraction, protein concentrates, and hydrolysates) before and after simulated gastrointestinal digestion was studied. For that, whole and phenolic reduced products were assessed. Four glycosylated phenolic compounds (secoisolariciresinol and ferulic, p-coumaric, and caffeic acids) were identified in flaxseed products. Phenolic fraction exerts the highest antioxidant capacity that increased by alkaline hydrolysis and by simulated gastrointestinal digestion. The action of Alcalase and digestive enzymes resulted in an increase of the antioxidant capacity of whole and phenolic reduced products. Principal component analysis showed that proteinaceous samples act as antioxidant is by H⁺ transfer, while those samples containing phenolic compounds exert their effects by both electron donation and H⁺ transfer mechanisms. Protein/peptide-phenolic complexation, confirmed by fluorescence spectra, exerted a positive effect on the antioxidant capacity, mainly in protein concentrates.

Secoisolariciresinol Diglucoside and Cyanogenic Glycosides in Gluten-free Bread Fortified with Flaxseed Meal

Flaxseed (Linum usitatissimum L.) meal contains cyanogenic glycosides (CGs) and the lignan secoisolariciresinol diglucoside (1). Gluten-free (GF) doughs and baked goods were produced with added flaxseed meal (20%, w/w) then 1, and CGs were determined in fortified flour, dough, and bread with storage (0, 1, 2, and 4 weeks) at different temperatures (-18, 4, and 22-23 °C). 1 was present in flour, dough, and GF bread after baking. 1 was stable with extensive storage (up to 4 weeks) and was not affected by storage temperature. CGs in flaxseed meal and fortified GF samples were analyzed by ¹H NMR of the cyanohydrins. Linamarin and/or linustatin were the primary CGs in both flaxseed meal and fortified flour. CGs decreased with storage in dough fortified with flaxseed meal or GF bread after baking. GF bakery food products fortified with flaxseed meal had reduced CGs but remained a good source of dietary 1.

A Vitamin B-6 Antagonist from Flaxseed Perturbs Amino Acid Metabolism in Moderately Vitamin B-6-Deficient Male Rats

BACKGROUND

Pyridoxal 5'-phosphate (PLP) plays a crucial role as a cofactor in amino acid metabolism. There is a prevalence of moderate vitamin B-6 deficiency in the population that may be exacerbated through the ingestion of 1-amino d-proline (1ADP), a vitamin B-6 antagonist found in flaxseed.

OBJECTIVE

Given prior evidence of the impact of synthetic 1ADP on indexes of pyridoxine metabolism, the current study was designed to investigate the effects of 1ADP derived from flaxseed on amino acid metabolism in moderately vitamin B-6-deficient rats.

METHODS

Male weanling rats (n = 8/treatment) consumed a semipurified diet containing either 7 mg pyridoxine hydrochloride/kg diet [optimum vitamin B-6 (OB)] or 0.7 mg pyridoxine hydrochloride/kg diet [moderately vitamin B-6 deficient (MB)], each with 0 or 10 mg vitamin B-6 antagonist/kg diet, in either a synthetic form (1ADP) or as a flaxseed extract (FE), for 5 wk. At the end of the experiment, plasma vitamin B-6 and amino acid concentrations and the activities of hepatic PLP-dependent enzymes were analyzed.

RESULTS

Compared with the MB control group, plasma PLP concentrations were 26% and 69% lower, respectively, in the MB+FE and MB+1ADP rats (P ≤ 0.001). In the MB+FE group, the plasma cystathionine concentration was 100% greater and the plasma α-aminobutyric acid and glutamic acid concentrations were 59% and 30% lower, respectively, than in the MB control group. Both synthetic 1ADP and FE significantly (P < 0.001) inhibited the in vitro hepatic activities of 2 PLP-dependent enzymes, cystathionine β-synthase (up to 44%) and cystathionine γ-lyase (up to 60%), irrespective of vitamin B-6 concentrations. Because of vitamin B-6 antagonist exposure, observed perturbations in plasma biomarkers and hepatic enzyme activities were not evident or of lesser magnitude in rats consuming adequate vitamin B-6.

CONCLUSION

The current data from a rat model provide evidence that a vitamin B-6 antagonist now prevalent in the human food supply may pose challenges to individuals of moderate vitamin B-6 status.

Development of stable flaxseed oil emulsions as a potential delivery system of ω-3 fatty acids

The objective of the present study was to develop a stable flaxseed oil emulsion for the delivery of omega-3 (ω-3) fatty acids through food fortification. Oil-in-water emulsions containing 12.5 % flaxseed oil, 10 % lactose and whey protein concentrate (WPC)-80 ranging from 5 to 12.5 % were prepared at 1,500, 3,000 and 4,500 psi homogenization pressure. Flaxseed oil emulsions were studied for its physical stability, oxidative stability (peroxide value), particle size distribution, zeta (ζ)-potential and rheological properties. Emulsions homogenized at 1,500 and 4,500 psi pressure showed oil separation and curdling of WPC, respectively, during preparation or storage. All the combinations of emulsions (homogenized at 3,000 psi) were physically stable for 28 days at 4-7 ºC temperature and did not show separation of phases. Emulsion with 7.5 % WPC showed the narrowest particle size distribution (190 to 615 nm) and maximum zeta (ζ)-potential (-33.5 mV). There was a slight increase in peroxide value (~20.98 %) of all the emulsions (except 5 % WPC emulsion), as compared to that of free flaxseed oil (~44.26 %) after 4 weeks of storage. Emulsions showed flow behavior index (n) in the range of 0.206 to 0.591, indicating higher shear thinning behavior, which is a characteristic of food emulsions. Results indicated that the most stable emulsion of flaxseed oil (12.5 %) can be formulated with 7.5 % WPC-80 and 10 % lactose (filler), homogenized at 3,000 psi pressure. The formulated emulsion can be used as potential omega-3 (ω-3) fatty acids delivery system in developing functional foods such as pastry, ice-creams, curd, milk, yogurt, cakes, etc.

Effect of Dose and Administration Period of Seed Cake of Genetically Modified and Non-Modified Flax on Selected Antioxidative Activities in Rats

Flaxseed cake containing antioxidants is a valuable dietary component. Its nutritional effect may be diminished by the presence of anti-nutrients. The work was aimed at determining the effect of different contents of flaxseed cake in diets and their administration period on the development of rats and selected parameters of their health status. Diets with 15% and 30% addition of genetically modified (GM) flax seed cake with enhanced synthesis of polyphenols, as well as Linola non-GM flax were administered in short-term (33 days) and long-term (90 days) experiments. The 30% addition of flaxseed cake reduced digestibility of dietary nutrients, GM flaxseed cake lowered body weight gains. The relative weight of selected organs, hematological blood markers and serum activities of aspartate and alanine aminotransferases (AST, ALT) were not affected. Flaxseed cake consumption reduced serum concentration of albumins and increased globulins. Administration of 30% flaxseed cake improved plasma total antioxidant status and 30% GM flaxseed cake lowered liver thiobarbituric acid reactive substances. The activities of superoxide dismutase in erythrocytes, glutathione peroxidase in plasma and the liver concentration of 8-oxo-2′-deoxyguanosine were not changed. Most morphometric parameters of the small intestine did not differ between feeding groups. The administration of diets with 30% addition of flaxseed cake for 90 days improved the antioxidant status in rats.