High dose flaxseed oil supplementation may affect fasting blood serum glucose management in human type 2 diabetics

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.

Fatty acid correlations with HOMA-IR and HOMA-% β are differentially dictated by their serum free and total pools and flaxseed oil supplementation

Objective. The intent of the present study was to test two hypotheses. The primary hypothesis was that there would be differences between blood serum individual free fatty acids (SIFFA) and serum individual total fatty acids (SITFA) in terms of their different relationships (correlations) to each of homeostatic model assessment-individual insulin resistance (HOMA-IR) and homeostatic model assessment-individual insulin resistance-percentage β-cell function (HOMA-% β) remaining in human type 2 diabetic patients with pre-flaxseed oil (FXO) and pre-safflower oil (SFO) administration. The secondary hypothesis was that FXO (rich in alpha-linolenic acid, ALA) supplementation would alter these correlations differently in the SIFFA and STIFFA pools in comparison with the placebo SFO (poor in ALA). Methods. Patients were recruited via a newspaper advertisement and two physicians. All patients came to visit 1 and three months later to visit 2. At visit 2, the subjects were randomly assigned (double-blind) to flaxseed or safflower oil (placebo) treatment for three months until visit 3. Results. There were pre-intervention differences in the SIFFA and STIFA pool's relationships with each of HOMA-IR and HOMA-% β. These relatioships remained either unchanged or became significant after intervention (treatment or placebo). There was a negative correlation found between HOMA-IR and serum free ALA (SFALA) mol % after FXO. Serum total ALA (STALA) mol % had no significant correlations with HOMA-IR and HOMA- % β before and after flaxseed oil administration. Conclusions. The SIFFA and SITFA pools have different relationships with HOMA-IR and HOMA-% β for each of pre- and post-intervention. It is concluded that the data support both the primary and the secondary hypotheses indicating that they are correct.

Effectiveness and Safety of Ayurvedic Medicines in Type 2 Diabetes Mellitus Management: A Systematic Review and Meta-Analysis

Introduction: Many Ayurvedic medicines have the potential for managing type 2 diabetes mellitus (T2DM), with previous systematic reviews demonstrating effectiveness and safety for specific Ayurvedic medicines. However, many of the reviews need updating and none provide a comprehensive summary of all the Ayurvedic medicines evaluated for managing T2DM.

Objective: The objective of this systematic review was to evaluate and synthesize evidence on the effectiveness and safety of Ayurvedic medicines for managing T2DM.

Inclusion criteria: Published and unpublished RCTs assessing the effectiveness and safety of Ayurvedic medicines for managing T2DM in adults.

Methods: The JBI systematic review methodology was followed. A comprehensive search of sources (including 18 electronic databases) from inception to 16 January 2021 was made. No language restrictions were applied. Data synthesis was conducted using narrative synthesis and random effects meta-analyses, where appropriate. Pooled results are reported as mean differences (MD) with 95% confidence intervals (CI).

Results: Out of 32,519 records identified from the searches, 219 articles were included in the systematic review representing 199 RCTs (21,191 participants) of 98 Ayurvedic medicines. Overall, in the studies reviewed the methodology was not adequately reported, resulting in poorer methodological quality scoring. Glycated hemoglobin (HbA1c) was reduced using Aegle marmelos (L.) Corrêa (MD -1.6%; 95% CI −3 to −0.3), Boswellia serrata Roxb. (−0.5; −0.7 to −0.4), Gynostemma pentaphyllum (Thunb.) Makino (−1; −1.5 to −0.6), Momordica charantia L. (−0.3; −0.4 to −0.1), Nigella sativa L. (−0.4; −0.6 to −0.1), Plantago ovata Forssk. (−0.9; −1.4 to −0.3), Tinospora cordifolia (Willd.) Hook.f. and Thomson (−0.5; −0.6 to −0.5), Trigonella foenum-graecum L. (−0.6; −0.9 to −0.4), and Urtica dioica L. (−1.3; −2.4 to −0.2) compared to control. Similarly, fasting blood glucose (FBG) was reduced by 4–56 mg/dl for a range of Ayurvedic medicines. Very few studies assessed health-related quality of life (HRQoL). Adverse events were not reported in many studies, and if reported, these were mostly none to mild and predominately related to the gastrointestinal tract.

Conclusion: The current evidence suggests the benefit of a range of Ayurvedic medicines in improving glycemic control in T2DM patients. Given the limitations of the available evidence and to strengthen the evidence base, high-quality RCTs should be conducted and reported.

The review of alpha-linolenic acid: Sources, metabolism, and pharmacology

α-linolenic acid (ALA, 18:3n-3) is a carboxylic acid composed of 18 carbon atoms and three cis double bonds, and is an essential fatty acid indispensable to the human body. This study aims to systematically review related studies on the dietary sources, metabolism, and pharmacological effects of ALA. Information on ALA was collected from the internet database PubMed, Elsevier, ResearchGate, Web of Science, Wiley Online Library, and Europe PMC using a combination of keywords including "pharmacology," "metabolism," "sources." The following findings are mainly contained. (a) ALA can only be ingested from food and then converted into eicosapentaenoic acid and docosahexaenoic acid in the body. (b) This conversion process is relatively limited and affected by many factors such as dose, gender, and disease. (c) Pharmacological research shows that ALA has the anti-metabolic syndrome, anticancer, antiinflammatory, anti-oxidant, anti-obesity, neuroprotection, and regulation of the intestinal flora properties. (d) There are the most studies that prove ALA has anti-metabolic syndrome effects, including experimental studies and clinical trials. (e) The therapeutic effect of ALA will be affected by the dosage. In short, ALA is expected to treat many diseases, but further high quality studies are needed to firmly establish the clinical efficacy of ALA.

Exploring Phytotherapeutic Alternatives for Obesity, Insulin Resistance and Diabetes Mellitus

At present, the pathologic spectrum of obesity-insulin resistance (IR)-diabetes mellitus (DM) represents not only a pressing matter in public health but also a paramount object of study in biomedical research, as they constitute major risk factors for cardiovascular disease (CVD), and other chronic non-communicable diseases (NCD). Phytotherapy, the use of medicinal herbs (MH) with treatment purposes, offers a wide array of opportunities for innovation in the management of these disorders; mainly as pharmacological research on small molecules accumulates. Several MH has displayed varied mechanisms of action relevant to the pathogenesis of obesity, IR and DM, including immunological and endocrine modulation, reduction of inflammation and oxidative stress (OS), regulation of appetite, thermogenesis and energy homeostasis, sensitisation to insulin function and potentiation of insulin release, among many others. However, the clinical correlates of these molecular phenomena remain relatively uncertain, with only a handful of MH boasting convincing clinical evidence in this regard. This review comprises an exploration of currently available preclinical and clinical research on the role of MH in the management of obesity, IR, and DM.

Flaxseed and/or hesperidin supplementation in metabolic syndrome: an open-labeled randomized controlled trial

PURPOSE

The aim of the present study was to compare the clinical effect of flaxseed and hesperidin alone and with combination in patients with metabolic syndrome. Number of participants with treated metabolic syndrome was assessed as a primary end point.

METHODS

In this 12-week randomized controlled trial, ninety-eight patients with metabolic syndrome randomly assigned to receive either whole flaxseed powder (30 g/day), or hesperidin (1 g/day), or combination of 30 g flaxseed and 1 g hesperidin or no supplement while adhering a lifestyle modification program.

RESULTS

In comparison to control group, systolic blood pressure (- 5.68 vs. - 2.91 mmHg, P = 0.041) and serum concentrations of triglyceride (- 50.06 vs. 3.87 mg/dL, P = 0.033) in hesperidin group showed a significant reduction over 12 weeks of intervention. Comparison of the results of flaxseed group with the control group showed a significant improvement in serum concentrations of triglyceride (- 66 vs. 3.87 mg/dL, P = 0.028), insulin (- 4.27 vs. - 2.51 mU/L, P = 0.003) and accordingly insulin resistance (- 1.19 vs. - 0.76, P = 0.005) and sensitivity (0.03 vs. 0.01, P = 0.022) indices in flaxseed group. Combination of flaxseed and hesperidin improved three of five metabolic syndrome components including serum concentrations of triglyceride, glucose and systolic blood pressure as compared to placebo. Interestingly, co-administration of flaxseed and hesperidin with 77.3% reduction in the prevalence of defined metabolic syndrome was revealed to be most effective in controlling the metabolic syndrome, after which the group of flaxseed with 76% reduction and hesperidin group with 54.5% reduction were ranked second and third, respectively.

CONCLUSIONS

It can be concluded that co-administration of flaxseed and hesperidin appears to be superior to either supplementation alone on metabolic syndrome treatment, while the effects of flaxseed are stronger than hesperidin supplementation.

Seeds

A wide variety of plant species provide edible seeds. Seeds are the dominant source of human calories and protein. The most important and popular seed food sources are cereals, followed by legumes and nuts. Their nutritional content of fiber, protein, and monounsaturated/polyunsaturated fats make them extremely nutritious. They are important additions to our daily food consumption. When consumed as part of a healthy diet, seeds can help reduce blood sugar, cholesterol, and blood pressure.

Linseed Essential Oil - Source of Lipids as Active Ingredients for Pharmaceuticals and Nutraceuticals

Linseed - also known as flaxseed - is known for its beneficial effects on animal health attributed to its composition. Linseed comprises linoleic and α-linolenic fatty acids, various dietary fibers and lignans, which are beneficial to health because they reduce the risk of cardiovascular diseases, as well as cancer, decreasing the levels of cholesterol and relaxing the smooth muscle cells in arteries increasing the blood flow. Essential fatty acids from flax participate in several metabolic processes of the cell, not only as structuring components of the cell membrane but also as storage lipids. Flax, being considered a functional food, can be consumed in a variety of ways, including seeds, oil or flour, contributing to basic nutrition. Several formulations containing flax are available on the market in the form of e.g. capsules and microencapsulated powders having potential as nutraceuticals. This paper revises the different lipid classes found in flaxseeds and their genomics. It also discusses the beneficial effects of flax and flaxseed oil and their biological advantages as ingredients in pharmaceuticals and in nutraceuticals products.

A comparison between the effects of flaxseed oil and fish oil supplementation on cardiovascular health in type 2 diabetic patients with coronary heart disease: A randomized, double-blinded, placebo-controlled trial

This study compared the effects of flaxseed and fish oil supplementation on cardiovascular risk parameters in diabetic patients with coronary heart disease. Participants were randomly allocated into three intervention groups to receive either 1,000 mg of omega-3 fatty acids from fish oil or 1,000 mg of omega-3 fatty acids from flaxseed oil or placebo (n = 30 each group) twice a day for 12 weeks. A significant reduction in insulin levels (.04) was observed following flaxseed oil and fish oil supplementation compared with the placebo. In addition, a significant reduction in high-sensitivity C-reactive protein (.02) was seen after flaxseed oil supplementation compared with the placebo and a significant increase in total nitrite (.001) was seen after flaxseed oil and fish oil intake compared with placebo. Additionally, a significant increase in total antioxidant capacity (p < .001) after consuming flaxseed oil and fish oil compared with placebo and glutathione levels (.001) after consuming fish oil compared with flaxseed oil and placebo was observed. Overall, our study revealed the beneficial effects of flaxseed oil and fish oil supplementation on few metabolic profiles. This study suggests that the effect of flaxseed oil in reducing insulin and increasing total nitrite and total antioxidant capacity is similar to fish oil.

Polyunsaturated Fatty Acids and Glycemic Control in Type 2 Diabetes

The impact of dietary fat on the risk of cardiovascular disease (CVD) has been extensively studied in recent decades. Solid evidence indicates that replacing saturated fatty acids (SFAs) with polyunsaturated fatty acids (PUFAs) decreases blood cholesterol levels and prevents CVD and CVD mortality. Studies indicate that fat quality also may affect insulin sensitivity and hence, the risk of type 2 diabetes (T2D). A high intake of SFAs has shown to increase the risk of T2D in prospective studies, while a high intake of PUFAs reduces the risk. Whether PUFAs from marine or vegetable sources affect glycemic regulation differently in T2D remains to be elucidated. The aim of the present review was therefore to summarize research on human randomized, controlled intervention studies investigating the effect of dietary PUFAs on glycemic regulation in T2D. About half of the studies investigating the effect of fish, fish oils, vegetable oils, or nuts found changes related to glycemic control in people with T2D, while the other half found no effects. Even though some of the studies used SFA as controls, the majority of the included studies compared PUFAs of different quality. Considering that both marine and vegetable oils are high in PUFAs and hence both oils may affect glycemic regulation, the lack of effect in several of the included studies may be explained by the use of an inappropriate control group. It is therefore not possible to draw a firm conclusion, and more studies are needed.

Effects of Maternal Flaxseed Supplementation on Female Offspring of Diabetic Rats in Serum Concentration of Glucose, Insulin, and Thyroid Hormones

Objective: This study aimed to evaluate the effect of maternal consumption of flaxseed flour and oil on serum concentrations of glucose, insulin, and thyroid hormones of the adult female offspring of diabetic rats. Methods: Wistar rats were induced to diabetes by a high-fat diet (60%) and streptozotocin (35 mg/kg). Rats were mated and once pregnancy was confirmed, were divided into the following groups: Control Group (CG): casein-based diet; High-fat Group (HG): high-fat diet (49%); High-fat Flaxseed Group (HFG): high-fat diet supplemented with 25% flaxseed flour; High-fat Flaxseed Oil group (HOG): high-fat diet, where soya oil was replaced with flaxseed oil. After weaning, female pups (n = 6) from each group were separated, received a commercial rat diet and were sacrificed after 180 days. Serum insulin concentrations were determined by ELISA, the levels of triiodothyronine (T3), thyroxine (T4) and thyroid-stimulating hormone (TSH) were determined by chemiluminescence. Results: There was a significant reduction in body weight at weaning in HG (-31%), HFG (-33%) and HOG (44%) compared to CG (p = 0.002), which became similar by the end of 180 days. Blood glucose levels were reduced in HFG (-10%, p = 0.044) when compared to CG, and there was no significant difference between groups in relation to insulin, T3, T4, and TSH after 180 days. Conclusions: Maternal severe hyperglycemia during pregnancy and lactation resulted in a microsomal offspring. Maternal consumption of flaxseed reduces blood glucose levels in adult offspring without significant effects on insulin levels and thyroid hormones.

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.

Herbal Therapy in Pregnancy-What to Expect when you Expect?

The use of herbal therapy in pregnancy is common for pregnancy related nausea, vomiting, gestational diabetes, anxiety, insomnia, and preparation for labor, as well as for treating infections. Many conventional drugs may interfere with fetal development and herbal products are considered to be safe. However, herbal therapy requires competent healthcare professional advice before prescribing. Knowledge about the possible adverse effects of active compounds of the herbs on pregnancy outcome is limited. Interference of herbal ingredients with conventional medication or the ailment should also not be excluded. For many herbal products, the pharmacological effect is not clinically proven, and the safe usage in pregnancy is not guaranteed. Here, based on published clinical trials, an overview is given of the efficacy and safety for fetal development and pregnancy outcome of the most frequently used herbs: ginger, cranberry, echinacea, mint, chamomile, valerian, flaxseed, tea and raspberry leaf.

Clinical and metabolic response to flaxseed oil omega-3 fatty acids supplementation in patients with diabetic foot ulcer: A randomized, double-blind, placebo-controlled trial

BACKGROUND

Data on the effects of flaxseed oil omega-3 fatty acids supplementation on wound healing and metabolic status in subjects with diabetic foot ulcer (DFU) are scarce.

OBJECTIVE

This study was conducted to evaluate the effects of flaxseed oil omega-3 fatty acids supplementation on wound healing and metabolic status in subjects with DFU.

METHODS

The current randomized, double-blind, placebo-controlled trial was conducted among 60 subjects (aged 40-85years old) with grade 3 DFU. Subjects were randomly allocated into two groups (30 subjects each group) to receive either 1000mg omega-3 fatty acids from flaxseed oil supplements or placebo twice a day for 12weeks.

RESULTS

After the 12-week intervention, compared with the placebo, omega-3 fatty acids supplementation resulted in significant decreases in ulcer length (-2.0±2.3 vs. -1.0±1.1cm, P=0.03), width (-1.8±1.7 vs. -1.0±1.0cm, P=0.02) and depth (-0.8±0.6 vs. -0.5±0.5cm, P=0.01). Additionally, significant reductions in serum insulin concentrations (-4.4±5.5 vs. +1.4±8.3 μIU/mL, P=0.002), homeostasis model of assessment-estimated insulin resistance (-2.1±3.0 vs. +1.0±5.0, P=0.005) and HbA1c (-0.9±1.5 vs. -0.1±0.4%, P=0.01), and a significant rise in the quantitative insulin sensitivity check index (+0.01±0.01 vs. -0.005±0.02, P=0.002) were seen following supplementation with omega-3 fatty acids compared with the placebo. In addition, omega-3 fatty acids supplementation significantly decreased serum high sensitivity C-reactive protein (hs-CRP) (-25.5±31.5 vs. -8.2±18.9μg/mL, P=0.01), and significantly increased plasma total antioxidant capacity (TAC) (+83.5±111.7 vs. -73.4±195.5mmol/L, P<0.001) and glutathione (GSH) concentrations (+60.7±140.2 vs. -15.5±129.7μmol/L, P=0.03) compared with the placebo.

CONCLUSIONS

Overall, omega-3 fatty acids supplementation for 12weeks among subjects with DFU had beneficial effects on parameters of ulcer size, markers of insulin metabolism, serum hs-CRP, plasma TAC and GSH levels. In addition, flaxseed oil omega-3 fatty acids may have played an indirect role in wound healing due to its effects on improved metabolic profiles.

Physical and Oxidative Stability of Flaxseed Oil-in-Water Emulsions Fabricated from Sunflower Lecithins: Impact of Blending Lecithins with Different Phospholipid Profiles

There is great interest in the formulation of plant-based foods enriched with nutrients that promote health, such as polyunsaturated fatty acids. This study evaluated the impact of sunflower phospholipid type on the formation and stability of flaxseed oil-in-water emulsions. Two sunflower lecithins (Sunlipon 50 and 90) with different phosphatidylcholine (PC) levels (59 and 90%, respectively) were used in varying ratios to form emulsions. Emulsion droplet size, charge, appearance, microstructure, and oxidation were measured during storage at 55 °C in the dark. The physical and chemical stability increased as the PC content of the lecithin blends decreased. The oxidative stability of emulsions formulated using Sunlipon 50 was better than emulsions formulated using synthetic surfactants (SDS or Tween 20). The results are interpreted in terms of the impact of emulsifier type on the colloidal interactions between oil droplets and on the molecular interactions between pro-oxidants and oil droplet surfaces.

The Effects of Omega-3 Fatty Acids and Vitamin E Co-Supplementation on Indices of Insulin Resistance and Hormonal Parameters in Patients with Polycystic Ovary Syndrome: A Randomized, Double-Blind, Placebo-Controlled Trial

This study was conducted to determine the effects of omega-3 fatty acids and vitamin E co-supplementation on indices of insulin resistance and hormonal parameters in women with polycystic ovary syndrome (PCOS). This randomized double-blind, placebo-controlled trial was done on 68 women diagnosed with PCOS according to the Rotterdam criteria aged 18-40 years old. Participants were randomly assigned into 2 groups to receive either 1 000 mg omega-3 fatty acids from flaxseed oil containing 400 mg α-Linolenic acid plus 400 IU vitamin E supplements (n=34) or placebo (n=34) for 12 weeks. Hormonal parameters were quantified at the beginning of the study and after 12-week intervention. After 12 weeks of intervention, compared to the placebo, omega-3 fatty acids and vitamin E co-supplementation resulted in a significant decrease in insulin (-1.0±3.5 vs. +2.7±6.6 µIU/mL, P=0.004), homeostasis model of assessment-estimated insulin resistance (-0.2±0.8 vs. +0.6±1.5, P=0.005), homeostasis model of assessment-estimated B cell function (-4.3±14.3 vs. +10.5±24.5, P=0.004) and a significant increase in quantitative insulin sensitivity check index (+0.006±0.02 vs. -0.01±0.04, P=0.008). Supplementation with omega-3 fatty acids plus vitamin E led to significant reductions in serum total testosterone (-0.5±0.7 vs. -0.1±0.5 ng/mL, P=0.008) and free testosterone (-1.2±2.1 vs. -0.2±1.7, P=0.04) compared to the placebo group. We did not observe any significant effect of omega-3 fatty acids and vitamin E co-supplementation on fasting plasma glucose and other hormonal profiles. Omega-3 fatty acids and vitamin E co-supplementation for 12 weeks in PCOS women significantly improved indices of insulin resistance, total and free testosterone.

Flaxseed oil supplementation manipulates correlations between serum individual mol % free fatty acid levels and insulin resistance in type 2 diabetics. Insulin resistance and percent remaining pancreatic β-cell function are unaffected

Objectives. Elevated total serum free fatty acids (FFAs) concentrations have been suggested, controversially, to enhance insulin resistance and decrease percent remaining β-cell function. However, concentrations of individual serum FFAs have never been published in terms of their relationship (correlation) to homeostatic model assessment-insulin resistance (HOMA-IR) and percent remaining β-cell function (HOMA-%β) in the type 2 diabetics (T2Ds). Alpha-linolenic acid consumption has a negative correlation with the insulin resistance, which in turn is negatively correlated with the remaining β-cell function. The primary objective was to test the hypothesis that there would be different relationship (correlation) between the blood serum individual free FFA mol % levels and HOMA-IR and/or HOMA-%β in T2D. The secondary objective was to test the hypothesis that flaxseed oil, previously being shown to be ineffective in the glycemic control in T2Ds, may alter these correlations in a statistically significant manner as well as HOMA-IR and/or HOMA-%β.

Methods. Patients were recruited via a newspaper advertisement and two physicians have been employed. All the patients came to visit one and three months later for a second visit. At the second visit, the subjects were randomly assigned (double blind) to flaxseed or safflower oil treatment for three months, until the third visit.

Results. Different statistically significant correlations or trends towards among some serum individual free FFA mol % levels and HOMA-IR and HOMA-%β, pre- and post-flaxseed and safflower oil supplementation were found. However, flaxseed oil had no impact on HOMA-IR or HOMA-%β despite statistically significant alterations in correlations compared to baseline HOMA-IR.

Conclusions. The obtained data indicate that high doses of flaxseed oil have no statistically significant effect on HOMA-IR or HOMA-%β in T2Ds, probably due to the additive effects of negative and positive correlations.

Effects of n-3 fatty acid supplements on glycemic traits in Chinese type 2 diabetic patients: A double-blind randomized controlled trial

SCOPE

To investigate the effects of n-3 fatty acid supplements, both marine and plant-based, on glycemic traits in Chinese type 2 diabetes patients.

METHOD AND RESULTS

In a double-blind randomized controlled trial, 185 recruited Chinese type 2 diabetes patients were randomized to either fish oil (FO, n = 63), flaxseed oil (FSO, n = 61), or corn oil group (served as control group, n = 61) for 180 days. The patients were asked to take corresponding oil capsules (four capsules/day), which totally provided 2 g/day of eicosapentaenoic acid + docosahexaenoic acid in FO group and 2.5 g/day of alpha-linolenic acid in FSO group. No group × time interaction was observed for homeostatic model assessment of insulin resistance, fasting insulin, or glucose. Significant group × time interaction (P = 0.035) was observed for glycated hemoglobin A_1c (HbA1c), with HbA1c decreased in FO group compared with corn oil group (P = 0.037). We also found significant group × time interactions for lipid traits, including LDL cholesterol (P = 0.043), total cholesterol (P = 0.021), total cholesterol/HDL cholesterol (P = 0.009), and triacylglycerol (P = 0.003), with the lipid profiles improved in FO group. No significant effects of FSO on glycemic traits or blood lipids were observed.

CONCLUSIONS

Marine n-3 PUFA supplements may improve glycemic control and lipid profiles among Chinese type 2 diabetic patients.

The effect of flaxseed powder on insulin resistance indices and blood pressure in prediabetic individuals: A randomized controlled clinical trial

BACKGROUND

Designing the effective and early interventions can prevent progression of prediabetes to diabetes. Few studies have shown the effect of flaxseed on glycemic control. This study aimed to assess the effect of flaxseed powder on insulin resistance (IR) indices and blood pressure in prediabetic individuals.

MATERIALS AND METHODS

In a randomized clinical trial, 99 prediabetic individuals were randomly divided into three groups: two groups received 40 g (FG40) and 20 g (FG20) flaxseed powder daily for 12 weeks and the third group was the control (CG). Before and after the intervention, anthropometric measurements, blood pressure, fasting serum glucose (FSG), insulin, homeostasis model assessment IR index (HOMA-IR), beta-cell function, and insulin sensitivity were measured.

RESULTS

FSG significantly declined overall in all groups compared to the baseline (P = 0.002 in CG and FG20 groups and P = 0.001 in FG40). In contrast, mean of the changes in FSG was not significantly different between groups. Insulin concentration did not change significantly within and between the investigated groups. Although HOMA-IR reduced in FG20 (P = 0.033), the mean of changes was not significant between the three groups. Mean of beta-cell function increased in CG and FG40 groups compared to the baseline (P = 0.044 and P = 0.018, respectively), but mean of its changes did not show any difference between the three groups. The mean of changes in IR indices was not significant between the three groups. FG40 group had significantly lowered systolic blood pressure after the intervention (P = 0.005).

CONCLUSION

Daily intake of flaxseed powder lowered blood pressure in prediabetes but did not improve glycemic and IR indices.

Flaxseed supplementation in non-alcoholic fatty liver disease: a pilot randomized, open labeled, controlled study

A two-arm randomized open labeled controlled clinical trial was conducted on 50 patients with non-alcoholic fatty liver disease (NAFLD). Participants were assigned to take either a lifestyle modification (LM), or LM +30 g/day brown milled flaxseed for 12 weeks. At the end of the study, body weight, liver enzymes, insulin resistance and hepatic fibrosis and steatosis decreased significantly in both groups (p< 0.05); however, this reduction was significantly greater in those who took flaxseed supplementation (p < 0.05). The significant mean differences were reached in hepatic markers between flaxseed and control group, respectively: ALT [-11.12 compared with -3.7 U/L; P< 0.001], AST [-8.29 compared with -4 U/L; p < 0.001], GGT [-15.7 compared with -2.62 U/L; p < 0.001], fibrosis score [-1.26 compared with -0.77 kPa; p = 0.013] and steatosis score [-47 compared with -15.45 dB/m; p = 0.022]. In conclusion, flaxseed supplementation plus lifestyle modification is more effective than lifestyle modification alone for NAFLD management.

Flax and flaxseed oil: an ancient medicine & modern functional food

Flaxseed is emerging as an important functional food ingredient because of its rich contents of α-linolenic acid (ALA, omega-3 fatty acid), lignans, and fiber. Flaxseed oil, fibers and flax lignans have potential health benefits such as in reduction of cardiovascular disease, atherosclerosis, diabetes, cancer, arthritis, osteoporosis, autoimmune and neurological disorders. Flax protein helps in the prevention and treatment of heart disease and in supporting the immune system. As a functional food ingredient, flax or flaxseed oil has been incorporated into baked foods, juices, milk and dairy products, muffins, dry pasta products, macaroni and meat products. The present review focuses on the evidences of the potential health benefits of flaxseed through human and animals' recent studies and commercial use in various food products.

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

OBJECTIVE

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

DESIGN

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

SETTING

Australian Longitudinal Study on Women's Health, Australia.

SUBJECTS

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

RESULTS

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

CONCLUSIONS

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

α-Linolenic acid: nutraceutical, pharmacological and toxicological evaluation

α-Linolenic acid (ALA), a carboxylic acid with 18 carbons and three cis double bonds, is an essential fatty acid needed for human health and can be acquired via regular dietary intake of foods that contain ALA or dietary supplementation of foods high in ALA, for example flaxseed. ALA has been reported to have cardiovascular-protective, anti-cancer, neuro-protective, anti-osteoporotic, anti-inflammatory, and antioxidative effects. ALA is the precursor of longer chain omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), but its beneficial effects on risk factors for cardiovascular diseases are still inconclusive. The recommended intake of ALA for cardiovascular health is reported to be 1.1-2.2g/day. Although there are limited toxicological data for ALA, no serious adverse effects have been reported. The evidence on an increased prostate cancer risk in association with dietary ALA is not conclusive. Based on the limited data currently available, it may be concluded that ALA may be beneficial as a nutraceutical/pharmaceutical candidate and is safe for use as a food ingredient.

Type 2 diabetes, PUFAs, and vitamin D: their relation to inflammation

Chronic diseases have become one of the most important public health problems, due to their high costs for treatment and prevention. Until now, researchers have considered that the etiology of Type 2 diabetes mellitus (T2DM) is multifactorial. Recently, the study of the innate immune system has offered an explanation model of the pathogenesis of T2DM. On the other hand, there is evidence about the beneficial effect of polyunsaturated fatty acids (PUFA) n-3 and n-6 in patients with chronic inflammatory diseases including diabetes. Furthermore, high vitamin D plasmatic concentrations have been associated with the best performance of pancreatic β cells and the improving of this disease. In conclusion, certain fatty acids in the adequate proportion as well as 25-hydroxivitamin D can modulate the inflammatory response in diabetic people, modifying the evolution of this disease.

Role of dietary n-3 polyunsaturated fatty acids in type 2 diabetes: a review of epidemiological and clinical studies

The worldwide increasing prevalence of type 2 diabetes mellitus (T2DM) poses an immense public health hazard leading to a variety of complications such as cardiovascular diseases, nephropathy and neuropathy. Diet, as a key component of a healthy human lifestyle, plays an important role in the prevention and management of T2DM and its complications. The dietary n-3 polyunsaturated fatty acids (PUFAs) have been associated with various favourable functions such as anti-inflammatory effects, improving endothelial function, controlling the blood pressure, and reducing hypertriglyceridemia and insulin insensitivity. According to some epidemiological studies, a lower prevalence of T2DM was found in populations consuming large amounts of seafood products, which are rich in n-3 PUFAs. However, the evidence on the relation between fish intake, dietary n-3 PUFAs, and risk of T2DM is controversial. Therefore, this paper aimed to review the epidemiological and clinical studies on the role of dietary n-3 PUFAs in T2DM. Also, the limitations of these studies and the need for potential further research on the subject are discussed.

Effects of a rapeseed oil-enriched hypoenergetic diet with a high content of α-linolenic acid on body weight and cardiovascular risk profile in patients with the metabolic syndrome

In therapy of the metabolic syndrome, the optimal dietary approach with regard to its macronutrient composition and metabolically favourable food components, such as the plant-derived n-3 fatty acid α-linolenic acid (ALA), is still a matter of debate. We investigated the effects of a hypoenergetic diet with low energy density (ED) enriched in rapeseed oil, resulting in high MUFA content and an ALA intake of 3·5 g/d on body weight and cardiovascular risk profile in eighty-one patients with the metabolic syndrome in comparison with an olive oil diet rich in MUFA, but with a low ALA content. After a 6-month dietary intervention, body weight was significantly reduced in the rapeseed oil and olive oil groups ( − 7·8 v. − 6·0 kg; P < 0·05). There were significant decreases in systolic blood pressure, total cholesterol and LDL-cholesterol, and insulin levels in both groups (P < 0·05). For all of these changes, no inter-group differences were observed. After the rapeseed oil diet, diastolic blood pressure declined more than after the olive oil diet (P < 0·05 for time × group interaction). Furthermore, concentrations of serum TAG were significantly reduced after the high ALA intake, but not in the low ALA group (P < 0·05 for time × group interaction). In conclusion, our dietary food pattern with a low ED and high intakes of MUFA and ALA may be a practical approach for long-term dietary treatment in patients with the metabolic syndrome, leading to weight reduction and an improvement in the overall cardiovascular risk profile.

Metabolic and endocrine effects of long-chain versus essential omega-3 polyunsaturated fatty acids in polycystic ovary syndrome

The objective of the study was to compare the effects of essential vs long-chain omega (n)-3 polyunsaturated fatty acids (PUFAs) in polycystic ovary syndrome. In this 6-week, prospective, double-blinded, placebo (soybean oil)-controlled study, 51 completers received 3.5 g n-3 PUFA per day (essential PUFA from flaxseed oil or long-chain PUFA from fish oil). Anthropometric variables, cardiovascular risk factors, and androgens were measured; oral glucose tolerance test (OGTT) and frequently sampled intravenous GTT (IVGTT) were conducted at baseline and 6 weeks. Between-group comparisons showed significant differences in serum triglyceride response (P = .0368), whereas the changes in disposition index also tended to differ (P = .0621). When within-group changes (after vs before intervention) were considered, fish oil and flaxseed oil lowered serum triglyceride (P = .0154 and P = .0176, respectively). Fish oil increased glucose at 120 minutes of OGTT (P = .0355), decreased the Matsuda index (P = .0378), and tended to decrease acute insulin response during IVGTT (P = .0871). Soybean oil increased glucose at 30 (P = .0030) and 60 minutes (P = .0121) and AUC for glucose (P = .0122) during OGTT, tended to decrease acute insulin response during IVGTT (P = .0848), reduced testosterone (P = .0216), and tended to reduce sex hormone-binding globulin (P = .0858). Fasting glucose, insulin, adiponectin, leptin, or high-sensitivity C-reactive protein did not change with any intervention. Long-chain vs essential n-3 PUFA-rich oils have distinct metabolic and endocrine effects in polycystic ovary syndrome; and therefore, they should not be used interchangeably.

Dietary milled flaxseed and flaxseed oil improve N-3 fatty acid status and do not affect glycemic control in individuals with well-controlled type 2 diabetes

OBJECTIVE

To determine the effects of dietary consumption of milled flaxseed or flaxseed oil on glycemic control, n-3 fatty acid status, anthropometrics, and adipokines in individuals with type 2 diabetes.

DESIGN

Thirty-four participants were randomized into a parallel, controlled trial.

SUBJECTS

The participants were adults with type 2 diabetes (age 52.4 +/- 1.5 years, body mass index 32.4 +/- 1.0 kg/m(2), n = 17 men and 17 women).

INTERVENTIONS

Participants consumed a selection of bakery products containing no flax (control group [CTL], n = 9), milled flaxseed (FXS, n = 13; 32 g/d), or flaxseed oil (FXO, n = 12; 13 g/d) daily for 12 weeks. The FXS and FXO groups received equivalent amounts of alpha-linolenic acid (ALA; 7.4 g/day).

MEASURES OF OUTCOME

The primary outcome measures were fasting plasma hemoglobin A(1c), glucose, insulin, and phospholipid fatty acid composition. The secondary outcome measures were fasting circulating leptin and adiponectin, as well as body weight, body mass index, and waist circumference. Dietary intake assessment and calculations for homeostasis model assessment for insulin resistance and quantified insulin sensitivity check were also completed.

RESULTS

The FXS and FXO groups had increases in plasma phospholipid n-3 fatty acids (ALA, eicosapentaenoic acid [EPA], or decosapentaenoic acid [DPA], but not docosahexaenoic acid), and the FXO group had more EPA and DPA in plasma phospholipids compared to the FXS group. All groups had similar caloric intakes; however, the CTL group experienced a 4% weight gain compared to baseline (p < 0.05), while both flax groups had constant body weights during the study period. All other parameters, including glycemic control, were unchanged by dietary treatment.

CONCLUSIONS

Milled FXS and FXO intake does not affect glycemic control in adults with well-controlled type 2 diabetes. Possible prevention of weight gain by flax consumption warrants further investigation.

(n-3) Fatty Acids: Clinical Trials in People with Type 2 Diabetes

Recent human clinical trials of the effects of (n-3) fatty acids on participants with type 2 diabetes (T2D) were reviewed, focusing on 11 clinical trials conducted within the past 4 y, and subsequent to a Cochrane Database meta-analysis of this topic. Doses of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in these studies were mostly in the range of ∼2 g/d provided for 6 wk to 6 mo. Summarizing across these studies, there were no changes in fasting glucose or insulin compared with baseline or placebo. (n-3) Fatty acids generally decreased serum triglycerides but had varying effects on serum cholesterol, LDL cholesterol, and HDL cholesterol. A few studies indicated beneficial effects of (n-3) fatty acids on arterial blood flow. The effects of EPA and/or DHA have not yet been studied in clinical trials in participants at risk for T2D; the prevention or exacerbation of T2D by fish oil or EPA and DHA supplements of amounts >0.5 g/d deserves study. The prevention of adverse vascular effects of T2D by (n-3) fatty acids may be a promising direction for further study.

Are all n-3 polyunsaturated fatty acids created equal?

N-3 Polyunsaturated fatty acids have been shown to have potential beneficial effects for chronic diseases including cancer, insulin resistance and cardiovascular disease. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in particular have been studied extensively, whereas substantive evidence for a biological role for the precursor, alpha-linolenic acid (ALA), is lacking. It is not enough to assume that ALA exerts effects through conversion to EPA and DHA, as the process is highly inefficient in humans. Thus, clarification of ALA's involvement in health and disease is essential, as it is the principle n-3 polyunsaturated fatty acid consumed in the North American diet and intakes of EPA and DHA are typically very low. There is evidence suggesting that ALA, EPA and DHA have specific and potentially independent effects on chronic disease. Therefore, this review will assess our current understanding of the differential effects of ALA, EPA and DHA on cancer, insulin resistance, and cardiovascular disease. Potential mechanisms of action will also be reviewed. Overall, a better understanding of the individual role for ALA, EPA and DHA is needed in order to make appropriate dietary recommendations regarding n-3 polyunsaturated fatty acid consumption.