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Flax and Flaxseed Oil (Linum usitatissimum): A Review by the Natural Standard Research Collaboration
Abstract
The objective of this study was to evaluate the scientific evidence on flaxseed, including expert opinion, folkloric precedent, history, pharmacology, kinetics/dynamics, interactions, adverse effects, toxicology, and dosing. Electronic searches were conducted in 9 databases, 20 additional journals (not indexed in common databases), and bibliographies from 50 selected secondary references. No restrictions were placed on the language or quality of the publications. All literature collected pertained to efficacy in humans, dosing, precautions, adverse effects, use in pregnancy/lactation, interactions, alteration of laboratory assays, and mechanisms of action. Standardized inclusion/exclusion criteria are used for selection. Grades were assigned using an evidence-based grading rationale. A review of the literature on flaxseed yielded 13 categories for which flaxseed had been studied in humans, including constipation/laxative, attention-deficit hyperactivity disorder, hyperlipidemia, atherosclerosis/coronary artery disease, breast cancer, cyclic mastalgia (breast pain), menopausal symptoms, hyperglycemia/diabetes, hypertension, lupus nephritis, human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS), and prostate cancer. Most of the available evidence investigates the efficacy of alpha-linoleic acid found in flaxseed compared with fish oil, and almost all of the available studies are poor quality. Although flaxseed and flaxseed oil have several promising future uses, the available literature does not support recommendation for any condition at this time.
... Studies including olive oil (n ¼ 9) [11][12][13][14][15][16][17][18][19], coconut oil (n ¼ 9) [20][21][22][23][24][25][26][27][28], flaxseed oil (n ¼ 8) [29][30][31][32][33][34][35][36], palm oil (n ¼ 7) [37][38][39][40][41][42][43], canola oil (n ¼ 6) [44][45][46][47][48][49], sesame oil (n ¼ 3) [50][51][52], rice bran oil (n ¼ 2) [53,54], virgin olive oil (n ¼ 2) [55,56], palm olein (n ¼ 1) [57] and peanut oil (n ¼ 1) [58] consumption and their health outcomes were examined (Table 1 ). Of these, 39 studies included meta-analyses that reported 206 summary odds ratio, risk ratio (RR), or mean differences for respective health outcomes. ...
... Lipid parameters were the most commonly reported health outcomes in all studies. A total of 24 studies reported the effects of vegetable oils on lipid parameters: coconut oil (n ¼ 5), [20,[22][23][24][25], canola oil (n ¼ 5) [44][45][46][47]49], palm oil (n ¼ 5) [37,39,41,43,57], olive oil (n ¼ 3) [11,55,56], rice bran oil (n ¼ 2) [53,54], flaxseed oil (n ¼ 2) [33,34], peanut oil (n ¼ 1) [58] and sesame oil (n ¼ 1) [51]. The degree of effects on lipid parameters, namely serum total cholesterol (TC), serum triglyceride (TG), serum LDL cholesterol, serum VLDL, serum HDL cholesterol, TC: HDL ratio, LDL: HDL ratio, TG: HDL ratio, and apolipoproteins varied among the vegetable oils. ...
Vegetable oils, derived from diverse sources such as seeds, nuts, and some fruits, play a significant role in dietary health. However, the current evidence on the health effects of different types of vegetable oil consumption remains controversial. This umbrella review aims to synthesize evidence from systematic reviews and meta-analyses to assess the health outcomes associated with various vegetable oils. A comprehensive literature search was performed up to 31 July, 2023 on 12 databases for studies examining the association of different vegetable oils with health outcomes in adults. Data was extracted independently by 2 authors, with evidence strength assessed using the grading of recommendations, assessment, development, and evaluation criteria. A total of 48 studies, including 206 meta-analyses, were included. Moderate to very low certainty evidence showed that monounsaturated and polyunsaturated fatty acids such as canola oil, virgin olive oil, and rice bran oil are beneficial in reducing serum total cholesterol and low-density lipoprotein (LDL) concentrations. Conversely, low to very low certainty evidence suggests that oils high in saturated fats, such as coconut oil and palm oil, increase total cholesterol and LDL concentrations but also raise high-density lipoprotein concentrations. Very low certainty evidence showed the consumption of olive oil, sesame oil, and coconut oil could improve blood sugar control. Low certainty evidence showed olive oil consumption reduced risk of breast, digestive, and other cancers. Moderate to very low certainty evidence suggested that canola oil and sesame oil consumption reduced body weight. The consumption of vegetable oil appears to offer different health benefits, with summary estimates indicating beneficial effects on reducing lipid concentrations, especially with monounsaturated and polyunsaturated rich oils when consumed in recommended amounts. Future research should focus on long-term studies and comprehensive dietary assessments to better understand the health impacts of vegetable oils, providing a basis for informed dietary recommendations.
This study was registered at PROSPERO as CRD42021239210.
... Linum usitatissimum L. (fam. Linaceae, linseed) consumption is commonly used to alleviate various ailments, including circulatory, respiratory, urinary, and digestive systems, or skin irritations [18]. In dentistry, there is an economical, plant-derived saliva substitute [19,20] accepted in clinical practice for dry mouth feeling, but the mechanism of its effectiveness is not clearly understood. ...
Oral inflammation and the immune response are distinct but related processes where Linum usitatissimum L., fam. Linaceae represents a possible use for localized relief. Oral lichen planus (OLP) is an oral potentially malignant disorder (OPMD) with an inflammatory background that mainly affects post- and peri-menopausal women. The presented methodology was threefold. Firstly, the plant extracts were made from flaxseeds of selected cultivars (Szafir [SZ] and Jantarol [JA]) containing plant lignans. In silico docking affinity was performed to verify the beta and alpha estrogen receptors of keratinocytes’ (ERα and ERβ) affinity for lignans from the plant extracts. Lastly, tests using living keratinocyte cell lines were performed. Adding the studied extracts from two cultivars of flaxseed—JA and SZ (10 µg/mL) reduced lipopolysaccharides (LPS)—induced cell inflammation markers levels of COX-2 and IL-6. The effect of JA was more pronounced than that of SZ, with statistical significance (p < 0.05). A high in silico affinity was provided during secoisolariciresinol diglucoside (SDG) docking to ERα and ERβ. Flaxseed’s action could be based on the docking affinity of its major components to the estrogen receptors and the overall concentration of the elements of the extracts.
... Linseed (Linum usitatissimum L.), also known as flaxseed or flax, is an ancient crop of paramount importance cultivated globally for its stem fibre and seed oil. It has garnered considerable attention and popularity in recent times as a functional food due to its numerous health-promoting properties associated with its high levels of omega-3 fatty acid (alpha-linolenic acid), lignans (particularly Secoisolariciresinol diglucoside) and dietary fibre (Basch et al., 2007;Saroha et al., 2023;Thompson et al., 1997;Yadav et al., 2022). Typically grown in rain-fed or moisture-scarce (utera/paira relay cultivation) environments across various regions worldwide (Kaur et al., 2018Soto-Cerda et al., 2019;Saroha et al., 2022aSaroha et al., , 2022b, linseed is susceptible to variations in soil moisture levels exacerbated by rising temperatures, which can impact its yield potential, oil content and fatty acid composition to a significant extent (Casa et al., 1999;Fofana et al., 2006;Zare et al., 2021). ...
Water constraint is a crucial factor in determining the productivity and production of linseed or flaxseed globally. The root system of flaxseed consists of a single taproot mainly confined to the topsoil; thus, the structure of the root system significantly impacts the uptake of water from the soil. This research conducted root–shoot phenotyping on a diverse range of linseed germplasm under PEG‐induced water deficit stress conditions to unravel the potential of genebank germplasm for drought tolerance. Varied responses to stress and substantial diversity in genotypic response were observed among the linseed accessions for all growth parameters under both normal and stress conditions. The application of PEG led to a decrease (ranging from 7.39% to 62.02%) in all parameters except chlorophyll content, which exhibited an increase of 13.76% in response to stress conditions. Principal component analysis revealed that the first four principal components (PCs) with Eigenvalue >1 explained 74.23% of the total variance, with the first PC alone accounting for 42.15% of the total variance contributed by various traits such as leaf width, shoot length, root–shoot biomass, root length, surface area, and volume. Assessing the comparative performance based on the stress susceptibility index (SSI) for shoot–root length and root surface area, a subset of 12 drought tolerant (SSI ≤ 0.50) and 5 susceptible (SSI > 1.00), genotypes was constituted for validation at the adult plant stage. The accessions IC0096648, IC0523799, IC0249015, IC0096587, IC0385336, IC0498744, IC0499170, EC0041481, IC0526017, IC0623723, IC0113110, and IC0621685 exhibiting tolerance to PEG‐induced water stress during the initial (seedling stage) growth maintained physiological efficiency and yield at the adult plant stage. The elite drought‐tolerant genotypes identified in the present study will provide access to genetically diverse material in breeding to enhance drought tolerance in linseed.
... Second, individuals may be more Flaxseed, scientifically named Linum usitatissimum, is a functional food and a member of the family Linaceae [14]. It has been used for centuries for various purposes such as drying oil in painting, varnishing, and for medical conditions including abdominal pain, urinary tract infections, respiratory disorders, constipation, and skin inflammation [15]. The seeds and compounds within them are known for their health benefits in reducing risks associated with heart disease, cancer, stroke, diabetes, and metabolic syndrome [16]. ...
This systematic review and meta-analysis study aimed to evaluate the effectiveness of flaxseed supplementation on blood pressure (BP) in patients with hypertension based on the data from randomized clinical trials (RCTs). Three databases (PubMed [MEDLINE], Scopus, and ISI Web of Science) were searched from inception up to August 10, 2024. Relevant studies meeting our eligibility criteria were obtained. A random-effects model was used to estimate pooled weighted mean differences (WMDs) with 95% confidence intervals (CIs). The methodological quality of individual studies was assessed using the Cochrane Collaboration risk of bias tool. A total of 5 studies were included and analyzed using STATA software version 12. The results show that there is a significant decrease in systolic BP (WMD, −8.64 mmHg; 95% CI, −15.41 to −1.87; p ≤ 0.001) and diastolic BP (WMD, −4.87 mmHg; 95% CI, −8.37 to −1.37; p = 0.006) of patients with hypertension as compared to control groups. This study supported that flaxseed supplementation had favorable effects on BP control in hypertensive patients. It may be a promising adjuvant therapy for patients with hypertension.
... Flaxseed oil is sometimes called linseed oil. It is a primordial oil with antifungal qualities that is used in paints, varnishes, astringents, bio-insecticides, herbicides, and medical purposes [4,5] . The functions and properties of the linseed plant and its seeds are almost the same. ...
Tukhm-i-Katān is a seed obtained from an annual herb Linum usitatissimum L. of Linaceae family. It is also known as Flaxseeds which are smooth, lustrous, and dark brown in colour. It has a mucilaginous, oily, and mildly bitter flavour. In USM it is used for various medicinal properties like anti-inflammatory, spermatogenic, vesicant, phlegm expectorant, aphrodisiac, lithotriptic and calculus removal, general tonic, galactagogue, and emmenagogue. So, it is used in pneumonia, arthritis, dyspnoea, pleuritis, peritonitis. The aim of this review paper is to collect the data on the phytochemicals, traditional applications, and therapeutic uses. Various pharmacological activities have been carried out on linseed like Antifungal, Antibacterial, Analgesic, Anti-inflammatory and Wound healing.
... At the same time, the other omega-3 components in the form of APA are low in concentration. Alpha-linolenic acid (APA) is usually easily obtained from nuts such as flaxseed (Basch et al., 2007). While omega-6 fatty acids from research results amounted to 0.52% of the total ingredients or equivalent to 2.17% of total fat, much smaller than in species Emerita talpoida and Emerita analoga contained 11.80% and 12.94% omega-6 (Mursyidin, 2007). ...
Sand crab (Emerita sp.) is a marine biodiversity, but it has not been used as a fish feed ingredient. This study aimed to evaluate the nutritional value of sand crabs and to understand its effect when used as feed ingredient on the performance of Koi carp. The study was conducted in two steps, which is evaluation of the nutritional value of sand crab and its effect on fish performance. The proximate composition, amino acids, and fatty acids were measured using AOAC methods, and then the carotenoid content was determined by spectrophotometry. In the second step, the sand crab was added to fish feed at doses of 0, 5, 10, and 15 percent, and fed to koi fish for 42 days. The parameters observed were length gain (LG), weight gain (WG), and feed efficiency (FE). Nutritional data were analyzed by description and compared with fish feed ingredients from previous studies. Fish performance were analyzed by one-way ANOVA. When significant, Tukey’s significant mean test was applied. The result showed that the nutritional value of sand crab was comparable to other feed ingredients with a protein content of 37.88%, while carotenoid content was superior. The best performance of Koi carp was obtained with a dose of 15% sand crab in the diet, with LG, WG, and FE values of 0.93 ± 0.05 cm, 0.48 ± 0.06 g, and 63.50 ± 7.05 %, respectively. Based on this result, it can be concluded that sand crab has a high nutritional value and can be used up to 15% in Koi carp diet.
Diabetes Mellitus (DM) receives significant attention from most scientists due to being a major global public health threat. Diabetes is considered one of the leading causes of death due to its micro and macrovascular complications. This insidious killer is estimated to reach a staggering number of 578 million (700 million by 2045) cases by 2030.
In this book, utilizing the disciplines of clinical sciences, various contemporary topics related to diabetes are extensively discussed. These include the classification of diabetes, underlying causes, epidemiology, pathogenesis, impact on sexual functions, association with cancer, clinical manifestations, diagnostic methods, complications, and treatment options. Furthermore, intriguing and current subjects such as ""antidiabetic phytotherapy"" and ""the relationship between oral health and diabetes"" are also covered. By doing so, readers will acquire comprehensive and detailed knowledge about the clinical management of diabetes. Thus, this book not only serves those who seek to understand the scientific aspects of diabetes but also proves to be a valuable resource for healthcare professionals, researchers, and students in a clinical setting. We believe that this book will contribute to understanding the complexity of diabetes and provide beneficial solutions while shedding light on future studies.
Amis: Wound infections are one of the most important problems in human life. Continued use of antimicrobial agents against wound infections leads to the appearance of antibiotic-resistant bacteria strains. Flaxseed has important pharmacological properties against various diseases. This study aimed to determine the antibacterial activity of flaxseed extracts against different bacteria isolated from wound infections. Materials & Methods: This experimental study used phytochemical screening for flaxseed extracts. Also, the agar well diffusion method was used to examine the antibacterial activity of aqueous, ethanolic extract, and flaxseed oil (200, 100, 50, and 25mg/ml) against gram-positive and gram-negative bacteria. Findings: Phytochemical screening for the crude aqueous and ethyl extracts of flaxseeds revealed alkaloids, terpenoids, tannins, flavonoids, glycosides, saponins, steroids, phenolic compounds proteins, and carbohydrates. Aqueous extract showed inhibition zones only for Staphylococcus aureus and Streptococcus faecalis at 50, 100, and 200mg/ml. All the concentrations of the ethanolic extract showed inhibitory effects against all tested bacteria. The maximum antibacterial effect of ethanol extract on aqueous extract was 200mg/ml. Also, 200mg/ml of flaxseed oil had the most powerful inhibitory effects on all tested bacteria Conclusion: Flaxseed ethanolic extract and flaxseed oil have an inhibitory effect against different species of both gram-positive and gram-negative bacteria isolated from wound infections.
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.
Graphical Abstract
Short-term intervention studies have shown that diets rich in polyunsaturated fats have hypotensive properties. We have studied the long-term effects of dietary fat on blood pressure (BP) using adipose-tissue, fatty acid composition analysis in 399 free-living male subjects (average age, 47 yr). Stepwise-regression analysis showed that adipose linoleic acid (18:2 n-6) was not associated with BP, whereas an absolute 1% increase in linolenic acid (18:3 n-3) was associated with a decrease of 5 mm Hg in the systolic, diastolic, and composite mean arterial BP. Linolenic acid (18:3) comprised only one-eighth the amount of linoleic acid (18:2)--the major polyunsaturate in adipose tissue and hence in the diet (2% vs 16%)--and yet it had a disproportionate association with BP. This may be related to its role as a precursor for the production of prostaglandins and/or other vasoregulators. Dietary manipulation with n-3 fatty acids may be helpful in the treatment and prevention of hypertension.
The association between the levels of various fatty acids in adipose breast tissue and the emergence of visceral metastases was prospectively studied in a cohort of 121 patients with an initially localised breast cancer. Adipose breast tissue was obtained at the time of initial surgery, and its fatty acid content analysed by capillary gas chromatography. A low level of alpha-linolenic acid (18:3n-3) in adipose breast tissue was associated with positive axillary lymph node status and with the presence of vascular invasion, but not with tumour size or mitotic index. After an average 31 months of follow-up, 21 patients developed metastases. Large tumour size, high mitotic index, presence of vascular invasion and low level of 18:3n-3 were single factors significantly associated with an increased risk of metastasis. A Cox proportional hazard regression model was used to identify prognostic factors. Low 18:3n-3 level and large tumour size were the two factors predictive of metastases. These results suggest that host alpha-linolenic acid has a specific role in the metastatic process in vivo. Further understanding of the biology of this essential fatty acid of the n-3 series is needed in breast carcinoma.
To determine whether certain nutrients and dietary factors act as modulators of the immune system and improve the nutritional status of immunocompromised patients.
Controlled, double-blind, crossover phase trials of the effects of a fortified formula in patients infected with the human immunodeficiency virus (HIV). Patients consumed a control formula for 4 months and a study formula for 4 months.
Ten men with symptomatic HIV infection who were following stable medication regimens and had no malignancies, mycobacteriosis, or additional virus infection requiring systemic treatment.
Formula fortified with alpha-linolenic acid (1.8 g/day), arginine (7.8 g/day), and RNA (0.75 g/day) and a standard formula.
Nutritional status determined by anthropometric, bioelectrical, biochemical, and dietary assessment; energy expenditure determined by indirect calorimetry; disease progression; CD4 lymphocyte counts; HIV p24 antigen plasma concentrations; tumor necrosis factor (TNF) receptor proteins; and compliance control parameters.
Student's t tests for paired and unpaired data.
Fortified nutrition resulted in a weight gain (+ 2.9 kg/4 months vs -0.5 kg/4 months with the control formula, P < .05), an incorporation of eicosaenoic acid into erythrocyte cell membranes (+ 47% of baseline values, P < .05), and increased plasma arginine concentrations (96.8 +/- 45.1 vs 51.8 +/- 20.9 mumol/L, P < .01). The serum concentrations of the soluble tumor necrosis factor receptor (sTNFR) proteins increased during the study period (sTNFR 55 = + 0.23 vs -0.40 ng/mL, P < .001; sTNFR 75 = + 0.90 vs -0.36 ng/mL, P < .01), whereas no changes in CD4+ lymphocyte counts were observed.
Increasing dietary intakes of n-3 polyunsaturated fatty acids, L-arginine, and RNA increased body weight, possibly by modulating the negative effects of TNF.
To investigate the effects of flaxseed supplementation (13.5 g/d) on lignan and sex hormone metabolism, six healthy young men were studied. The subjects consumed whole wheat/flaxseed (WWF) bread for six weeks. Three-day dietary records, fasting blood samples and 24-h urine collections were obtained. Energy intake remained constant. Urinary levels of enterodiol and enterolactone were significantly higher following 1, 2, 4 and 6 weeks of WWF feeding, exceeding by 7–28 fold the amounts found at baseline. Urinary enterolactone excretion was 5–10 fold greater than enterodiol excretion. Flaxseed supplementation yielded, on average, 4.2 μmol urinary lignans/g flaxseed flour/d. No significant change in plasma total testosterone, free testosterone or sex-hormone-binding globulin was observed. Although dietary lignans may influence hormone-dependent cancer incidence by modulating the hormonal environment, an increase in short-term flaxseed consumption did not lead to significant differences in the hormonal milieu. Further study delineating the effect of lignans on steroid hormone metabolism and risk of hormone-dependent cancer is Warranted.
Lignans and isoflavonoids are diphenolic compounds found in plant foods, particularly whole grains and legumes. They have been shown to have anticarcinogenic properties in animal and cell studies, and have been associated with reduced cancer risk in epidemiological studies. In order to perform further epidemiological and metabolic studies on these compounds, it is necessary to be able to monitor concentrations in biological samples. In this study, we examined the effects of consumption of flaxseed, a concentrated source of lignans, on fecal lignan excretion and evaluated the effect of high lignan consumption on fecal excretion of isoflavonoids. Thirteen women were studied for two diet periods of three menstrual cycles each in a cross-over design. During the control period, they consumed their usual diets; during the treatment period they consumed their usual diets supplemented with 10 g/day ground flaxseed. Feces were collected on days 7-11 of the last menstrual cycle in each diet period. Five-day fecal composites were analyzed for lignans and isoflavonoids by isotope dilution gas chromatography-mass spectrometry. Fecal excretion of the lignans enterodiol, enterolactone, and matairesinol increased significantly with flax consumption, from 80.0 +/- 80.0 (SD) to 2560 +/- 3100; 640 +/- 480 to 10,300 +/- 7580; and 7.33 +/- 10.0 to 11.9 +/- 8.06 nmol/day, respectively. There were no differences in fecal excretion of the isoflavonoids, daidzein, equol, genistein, and O-demethylangolensin.
Nutrients rich in omega-3 fatty acids (fish oil and flaxseed) have the potential to abrogate inflammatory and atherosclerotic mechanisms known to be involved in the pathogenesis of vascular damage of systemic lupus erythematosus nephritis. Fish oil dietary supplementation decreases proteinuria and preserves renal morphology in the NZB/NZW, BXSB, and MRL/lpr mouse models of lupus nephritis and decreases mortality in the NZB/NZW and BXSB models. The anti-inflammatory and anti-atherosclerotic potential, coupled with the animal experimental data, encouraged us to carry out a dosing study of low (6 g) and higher (18 g) doses of fish oil (MaxEPA) therapy in human lupus nephritis. At the lower dose, the fish oil inhibited inflammatory mechanisms; at the higher dose, it altered both the inflammatory and atherosclerotic mechanisms. This led to a double-blind cross-over study of fish oil therapy in 26 patients with lupus nephritis followed for 2 years 10 weeks. The fish oil dietary supplementation had no significant effect on proteinuria, isotope glomerular filration rate, disease activity index, or steroid consumption. However, it did have a significant effect on lipid levels. The cross-over design suffered carryover effects (even with a 10-week wash-out period) and placebo effects of the olive oil, which created a risk of type II error. Our interest in omega-3 fatty acids led us to assess the effects of dietary supplementation with flaxseed. Not only is the flaxseed a major source of alpha-linolenic acid but it is also the richest natural source of lignan, a natural platelet-activating factor receptor antagonist.(ABSTRACT TRUNCATED AT 250 WORDS)
A diet supplemented with flaxseed, rich in alpha-linolenic acid and plant lignans (the latter, potent platelet-activating factor receptor antagonists), was tested in a murine model of lupus nephritis. MRL/lpr female mice (n = 25) were fed 15% flaxseed diet for 14 weeks commencing at 10 weeks of age. As controls, 30 MRL/lpr mice received a standard rodent diet without flaxseed. Isotope-glomerular filtration rate (14C-inulin clearance) was measured at 9, 16, and 24 weeks of age. Proteinuria was assessed at 2-week intervals. Spleen lymphocyte proliferation, quantitated by DNA analysis, was evaluated using flow cytometry at 9, 13, 19, and 21 weeks of age. Mortality was recorded throughout the study. Glomerular filtration rate at 16 weeks was greater in flaxseed-fed mice (0.15 +/- 0.03 mL/min) compared with controls (0.06 +/- 0.04 mL/min; P = 0.01). The onset of proteinuria (Albustix, Ames Division, Miles Laboratories, Rexdale, Ontario, Canada; > or = 2+) was delayed by 4 weeks in the flax-treated mice. The percentage of flaxseed-fed mice with proteinuria was lower than the control mice up to 21 weeks of age (39% v 58%; P = 0.01). Spleen lymphocyte proliferation (percentage of cells in S-phase) at 13 weeks of age was significantly higher in the control group (22.9 +/- 5.0, P = 0.01) but not in the flaxseed group (17.2 +/- 4.9) compared with baseline (9 weeks of age) values (13.0 +/- 3.5). Mortality was lower in the flaxseed-fed mice versus the control mice (assessed by Mantel-Haenszel (log-rank) test; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)