Flaxseed (Linum usitatissimum) Research

Latin Name: Linum usitatissimum

Family: Linaceae

Eating flaxseed may help with reducing cholesterol and blood sugar levels.  It has also shown in some research to help with estrogen levels in menopausal women, possibly aiding in the reduction of hot flashes and osteoporosis.

RESEARCH

The listings of research below represents a compilation of scientific articles found on the species, with a very brief overview description of each article/study.  Research found is catalogued by therapeutic action.  This categorized compilation of research articles does not necessarily imply that there are adequate results to demonstrate safe and/or effective human use.

GENERAL

• ​ACHS (2017).  Course Material:  Herb502.  Flaxseed Monograph.  www.achs.edu
• Natural Standard (2016).  Flaxseed Monograph.  www.naturalstandard.com

SAFETY / CONCERNS

• Flax may affect the absorption of the following medications and conditions:  acetominophen, antibiotics, anticoagulants, antiplatelets, antidiabetes, antihypertensive, estrogens, furosemides, ketoprofen, metoproolol, bleeding disorders, diabetes, gastrointestinal obstructions, hormone related cancers and conditions, hypertension, hypotension, and high blood sugar (Natural Standard, 2016).
• ​The linamarin constituent, if taken in excess, can cause poisoning.  This is found in raw flaxseed (ACHS, 2017).
• Flax may not be appropriate during pregnancy or lactation due to its mild estrogenic effect (Natural Standard, 2016)
• Excessive use can cause gastrointestinal discomfort, fullness, and flatulence.

ANTICANCER

• In rats, lignans in flaxseed reduced the early phase of carcinogenesis whereas the oil component was more effective at the stage when tumors were already established.  From:  Thompson, L. U., Rickard, S. E., Orcheson, L. J., & Seidl, M. M. (1996). SHORT COMMUNICATION: Flaxseed and its lignan and oil components reduce mammary tumor growth at a late stage of carcinogenesis. Carcinogenesis, 17(6), 1373-1376.
• Lignans in flaxseed had an antitumor effect when provided at the early promotion stage of tumorigenesis in rats.  From:  Thompson, L. U., Seidl, M. M., Rickard, S. E., Orcheson, L. J., & Fong, H. H. (1996). Antitumorigenic effect of a mammalian lignan precursor from flaxseed.
• A flaxseed-supplemented, fat-restricted diet reduced prostate cancer in men presurgery.  From:  Demark-Wahnefried, W., Price, D. T., Polascik, T. J., Robertson, C. N., Anderson, E. E., Paulson, D. F., … & Vollmer, R. T. (2001). Pilot study of dietary fat restriction and flaxseed supplementation in men with prostate cancer before surgery: exploring the effects on hormonal levels, prostate-specific antigen, and histopathologic features. Urology, 58(1), 47-52.
• Flaxseed muffins reduced tumor growth in women with breast cancer.  From:  Thompson, L. U., Chen, J. M., Li, T., Strasser-Weippl, K., & Goss, P. E. (2005). Dietary flaxseed alters tumor biological markers in postmenopausal breast cancer. Clinical cancer research, 11(10), 3828-3835
• Flaxseed lignans had a colon cancer protective effect in rats.  From:  Jenab, M., & Thompson, L. U. (1996). The influence of flaxseed and lignans on colon carcinogenesis and β-glucuronidase activity. Carcinogenesis, 17(6), 1343-1348.

​​​ANTIOXIDANT

• Lignans in flaxseed showed antioxidant activities in vitro at relatively low concentrations and may be the potential anticarcinogenic mechanism.  From:  Kitts, D. D., Yuan, Y. V., Wijewickreme, A. N., & Thompson, L. U. (1999). Antioxidant activity of the flaxseed lignan secoisolariciresinol diglycoside and its mammalian lignan metabolites enterodiol and enterolactone. Molecular and cellular biochemistry, 202(1), 91-100.

​​ANTI-INFLAMMATORY

• Inflammation was reduced in pregnant women who took an omega-3 flaxseed supplement for 25 weeks.  Inflammation declined in both maternal adipose and placental tissue.  From:  Kordoni, M. E., & Panagiotakos, D. (2018). Can Dietary Omega-3 Fatty Acid Supplementation Reduce Inflammation in Obese Pregnant Women: A Discussion of a Randomized Double-Blind Controlled Clinical Trial. Hellenic Journal οf Atherosclerosis, 8(4).

CHOLESTEROL LOWERING

• In a study of 60 women with polycystic ovary syndrome, taking a flaxseed omega-3 supplement twice daily for 12 weeks improved insulin metabolism and cholesterol levels with little effect on hormone levels and lipid levels.  From:  Mirmasoumi, G., Fazilati, M., Foroozanfard, F., Vahedpoor, Z., Mahmoodi, S., Taghizadeh, M., … & Asemi, Z. (2018). The Effects of flaxseed oil omega-3 fatty acids supplementation on metabolic status of patients with polycystic ovary syndrome: A randomized, double-blind, placebo-controlled trial. Experimental and Clinical Endocrinology & Diabetes, 126(04), 222-228.
• Defatted flaxseed lowered cholesterol levels in a study with twenty-nine hyperlipidemic subjects.   From:  Jenkins, D. J., Kendall, C. W., Vidgen, E., Agarwal, S., Rao, A. V., Rosenberg, R. S., … & Griffin, L. C. (1999). Health aspects of partially defatted flaxseed, including effects on serum lipids, oxidative measures, and ex vivo androgen and progestin activity: a controlled crossover trial. The American journal of clinical nutrition, 69(3), 395-402.
• A three month flaxseed supplement reduced cholesterol levels in postmenopausal women.  From:  Lucas, E. A., Wild, R. D., Hammond, L. J., Khalil, D. A., Juma, S., Daggy, B. P., … & Arjmandi, B. H. (2002). Flaxseed improves lipid profile without altering biomarkers of bone metabolism in postmenopausal women. The Journal of Clinical Endocrinology & Metabolism, 87(4), 1527-1532.
• In a study of 60 patients with diabetic neuropathy, taking an omega-3 flaxseed supplement for 12 weeks significantly reduced serum insulin, triglyceride, and cholesterol levels.  From:  Soleimani, A., Taghizadeh, M., Bahmani, F., Badroj, N., & Asemi, Z. (2017). Metabolic response to omega-3 fatty acid supplementation in patients with diabetic nephropathy: A randomized, double-blind, placebo-controlled trial. Clinical Nutrition, 36(1), 79-84.
• Hyperlipidemia was reduced in fat rats via alpha linolenic acid rich flaxseed oil.  From:  Vijaimohan, K., Jainu, M., Sabitha, K. E., Subramaniyam, S., Anandhan, C., & Devi, C. S. (2006). Beneficial effects of alpha linolenic acid rich flaxseed oil on growth performance and hepatic cholesterol metabolism in high fat diet fed rats. Life sciences, 79(5), 448-454.
• A flax and pumpkin seed mixture had a cholesterol lowering and hepatoprotective effect in rats. From:  Makni, M., Fetoui, H., Gargouri, N. K., Garoui, E. M., Jaber, H., Makni, J., … & Zeghal, N. (2008). Hypolipidemic and hepatoprotective effects of flax and pumpkin seed mixture rich in ω-3 and ω-6 fatty acids in hypercholesterolemic rats. Food and Chemical Toxicology, 46(12), 3714-3720.
• Lignans in flaxseed reduced hypercholesterolemic atherosclerosis by lowering LDL cholesterol in rabbits.  From:  Prasad, K. (1999). Reduction of serum cholesterol and hypercholesterolemic atherosclerosis in rabbits by secoisolariciresinol diglucoside isolated from flaxseed. Circulation, 99(10), 1355-1362.

​​REDUCED MENOPAUSAL SYMPTOMS

• Flaxseed at a dose of 40 g was effective as an oral estrogen-progesterone to improve mild menopausal symptoms and lower glucose and insulin levels in hypercholesterolemic menopausal women.  From:  Lemay, A., Dodin, S., Kadri, N., Jacques, H., & Forest, J. C. (2002). Flaxseed dietary supplement versus hormone replacement therapy in hypercholesterolemic menopausal women. Obstetrics & Gynecology, 100(3), 495-504.
• A review of seventeen trials of isoflavones and amino acid, showed they reduced hot flashes.  From:  Thomas, A. J., Ismail, R., Taylor-Swanson, L., Cray, L., Schnall, J. G., Mitchell, E. S., & Woods, N. F. (2014). Effects of isoflavones and amino acid therapies for hot flashes and co-occurring symptoms during the menopausal transition and early postmenopause: a systematic review. Maturitas, 78(4), 263-276.

​​OSTEOPOROSIS

• This article discussed existing research on phytoestrogens, in plants (soy and flaxseed) reducing bone loss in women. From:  Arjmandi, B. H. (2001). The role of phytoestrogens in the prevention and treatment of osteoporosis in ovarian hormone deficiency. Journal of the American College of Nutrition, 20(sup5), 398S-402S.
• Flax and low dose estrogen reduced bone loss in rats without ovaries.  From:  Sacco, S. M., Jiang, J. M., Reza-López, S., Ma, D. W., Thompson, L. U., & Ward, W. E. (2009). Flaxseed combined with low-dose estrogen therapy preserves bone tissue in ovariectomized rats. Menopause, 16(3), 545-554.

​​​CARDIAC HEALTH

• This article reviewed research on the cardiovascular protective effects of omega-3 fatty acids in flaxseed.  From:  Rodriguez-Leyva, D., Bassett, C. M., McCullough, R., & Pierce, G. N. (2010). The cardiovascular effects of flaxseed and its omega-3 fatty acid, alpha-linolenic acid. Canadian Journal of Cardiology, 26(9), 489-496.
• Consumption of flaxseed oil showed protective effects against cardiovascular symptoms in young men. From:  Allman, M. A., Pena, M. M., & Pang, D. (1995). Supplementation with flaxseed oil versus sunflowerseed oil in healthy young men consuming a low fat diet: effects on platelet composition and function. European journal of clinical nutrition, 49(3), 169-178.
• African Americans were given alpha linolenic acid capsules (a main constituent of flaxseed) that showed cardioprotective effects.   From:  Harper, C. R., Edwards, M. J., DeFilipis, A. P., & Jacobson, T. A. (2006). Flaxseed oil increases the plasma concentrations of cardioprotective (n-3) fatty acids in humans. The Journal of nutrition, 136(1), 83-87.
• Lignans from flaxseed reduced cholesterol and atherosclerosis in rabbits.  From  Prasad, K. (2005). Hypocholesterolemic and antiatherosclerotic effect of flax lignan complex isolated from flaxseed. Atherosclerosis, 179(2), 269-275.

ANTI-DIABETES

• Type 2 diabetes was found to be associated with oxidative stress and that flaxseed phytoestrogens reduced these in rats.  From:  Prasad, K. (2001). Secoisolariciresinol diglucoside from flaxseed delays the development of type 2 diabetes in Zucker rat. Journal of laboratory and clinical medicine, 138(1), 32-39.
• Flaxseed intake decreased glucose and insulin as well as insulin sensitivity a in overweight patients.  From:  Hutchins, A. M., Brown, B. D., Cunnane, S. C., Domitrovich, S. G., Adams, E. R., & Bobowiec, C. E. (2013). Daily flaxseed consumption improves glycemic control in obese men and women with pre-diabetes: a randomized study. Nutrition research, 33(5), 367-375.
• In a study of 60 women with polycystic ovary syndrome, taking a flaxseed omega-3 supplement twice daily for 12 weeks improved insulin metabolism and cholesterol levels with little effect on hormone levels and lipid levels.  From:  Mirmasoumi, G., Fazilati, M., Foroozanfard, F., Vahedpoor, Z., Mahmoodi, S., Taghizadeh, M., … & Asemi, Z. (2018). The Effects of flaxseed oil omega-3 fatty acids supplementation on metabolic status of patients with polycystic ovary syndrome: A randomized, double-blind, placebo-controlled trial. Experimental and Clinical Endocrinology & Diabetes, 126(04), 222-228.
• In a study of 60 patients with diabetic neuropathy, taking an omega-3 flaxseed supplement for 12 weeks significantly reduced serum insulin, triglyceride, and cholesterol levels.  From:  Soleimani, A., Taghizadeh, M., Bahmani, F., Badroj, N., & Asemi, Z. (2017). Metabolic response to omega-3 fatty acid supplementation in patients with diabetic nephropathy: A randomized, double-blind, placebo-controlled trial. Clinical Nutrition, 36(1), 79-84.

​WOUND HEALING

• A flaxseed oil omega 3 fatty acid supplement in a study of 60 patients with diabetic foot ulcers over 12 weeks significantly reduced symptoms compared to the placebo.  From:  Soleimani, Z., Hashemdokht, F., Bahmani, F., Taghizadeh, M., Memarzadeh, M. R., & Asemi, Z. (2017). 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. Journal of diabetes and its complications, 31(9), 1394-1400.

LUPUS

• In patients with lupus nephritis, 30 g flaxseed a day was well tolerated and beneficial to  renal function and inflammatory and atherogenic mechanisms associated with the disease.  From:  Clark, W. F., Parbtani, A., Huff, M. W., Spanner, E., de Salis, H., Chin-Yee, I., … & Holub, B. J. (1995). Flaxseed: a potential treatment for lupus nephritis. Kidney international, 48(2), 475-480.
• In patients with lupus nephritis, flaxseed was renoprotective.  From:  Clark, W. F., Kortas, C., Heidenheim, A. P., Garland, J., Spanner, E., & Parbtani, A. (2001). Flaxseed in lupus nephritis: a two-year nonplacebo-controlled crossover study. Journal of the American College of Nutrition, 20(2), 143-148. 

Compiled By: Kathy Sadowski

Updated:12/11/18