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Flaxseed is the tiny seed that comes from the flax plant. It is high in healthy fat and fiber. Flaxseed has been used to ease symptoms of menopause, lower blood pressure, and promote weight loss. It can be eaten plain or used in cooking and baking. Flaxseed can also be taken as a pill or powder.
25 to 30 grams once daily
Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.
It is likely safe for most adults to take flaxseed in small doses for a short time, but intestinal fullness and allergic reactions are possible.L1-L4 Not enough studies have been done to say whether it is safe to use for a long period. It is also not known whether it is safe to take by women who are pregnant or breastfeeding.
Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse.
A. Benign Prostatic Hyperplasia
A1. Zhang W, Wang X, et al. Effects of dietary flaxseed lignan extract on symptoms of benign prostatic hyperplasia. J Med Food. 2008 Jun;11(2):207-214.
B. Breast Cancer
B1. Flower G, Fritz H, et al. Flax and Breast Cancer: A Systematic Review. Integr Cancer Ther. 2014 May;13(3):181-192.
C1. Pan A, Sun J, et al. Effects of a flaxseed-derived lignan supplement in type 2 diabetic patients: a randomized, double-blind, cross-over trial. PLoS One. 2007 Nov 7;2(11):e1148.
D. High Blood Pressure
D1. Rodriguez-Leyva D, Weighell W, et al. Potent antihypertensive action of dietary flaxseed in hypertensive patients. Hypertension. 2013;62(6):1081-1089.
D2. Khalesi S, Irwin C, et al. Flaxseed consumption may reduce blood pressure: a systematic review and meta-analysis of controlled trials. J Nutr. 2015 Apr;145(4):758-765.
D3. Ursoniu S, Sahebkar A, et al. Effects of flaxseed supplements on blood pressure: A systematic review and meta-analysis of controlled clinical trial. Clin Nutr. 2016 Jun;35(3):615-625.
E1. Pan A, Yu D, et al. Meta-analysis of the effects of flaxseed interventions on blood lipids. AM J Clin Nutr. 2009;90(2):288-297.
E2. Torkan M, Entezari MH, et al. Effect of flaxseed on blood lipid level in hyperlipidemic patients. Rec Recent Clin Trials. 2015;10(1):61-67.
F. Impaired Glucose Tolerance
F1. Demmers A, Korthout H, et al. Effects of medicinal food plants on impaired glucose tolerance: A systematic review of randomized controlled trials. Diabetes Res Clin Pract. 2017 Sep;131:91-106.
G1. Dew TP, Williamson G. Controlled flax interventions for the improvement of menopausal symptoms and postmenopausal bone health: a systematic review. Menopause. 2013 Nov;20(11):1207-1215.
G2. Cetisli NE, Saruhan A, et al. The effects of flaxseed on menopausal symptoms and quality of life. Holist Nurs Pract. 2015;29(3):151-157.
H1. Mirghafourvand M,Mohammad-Alizadeh-Charandabi S, et al. Effects of Vitex agnus and Flaxseed on cyclic mastalgia: A randomized controlled trial. Complement Ther Med. 2016;24:90-95.
I. Metabolic Syndrome
I1. van den Driessche JJ, Plat J, et al. Effects of superfoods on risk factors of metabolic syndrome: a systematic review of human intervention trials. Food Funct. 2018 Apr 25;9(4):1944-1966.
J1. Mohammadi-Sartang M, Mazloom Z, et al. The effect of flaxseed supplementation on body weight and body composition: a systematic review and meta-analysis of 45 randomized placebo-controlled trials. Obese Rev. 2017;18(9):1096-1107.
J2. Mohammadi-Sartang M, Mazloom Z, et al. The effect of flaxseed supplementation on body weight and body composition: a systematic review and meta-analysis of 45 randomized placebo-controlled trials. Obes Rev. 2017 Sep;18(9):1096-1107.
K. Peripheral Artery Disease
K1. Ede AL, Rodriguez-Leyva D, et al. Dietary flaxseed independently lowers circulating cholesterol and lowers it beyond the effects of cholesterol-lowering medications alone in patients with peripheral artery disease. J Nutr. 2015;145(4):749-757.
L1. Alonso L, Marcos ML, et al. Anaphylaxis caused by linseed (flaxseed) intake. J Allergy Clin Immunol. 1996 Aug;98(2):469-470.
L2. Tsai HH, Lin HW, et al. Evaluation of documented drug interactions and contraindications associated with herbs and dietary supplements: a systematic literature review. Int J Clin Pract. 2012 Nov;66(11):1056-1078.
L3. Alvarez-Perea A, Alzate -Pérez D, et al. Anaphylaxis caused by flaxseed. J Investig Allergol Clin Immunol. 2013;23(6):446-447.
L4. Patel A, Bahna SL. Hypersensitivities to sesame and other common edible seeds. Allergy. 2016 Oct;71(10):1405-1413.
Last reviewed March 2020 by EBSCO NAT Review Board Eric Hurwitz, DC Last Updated: 6/29/2020