Flax seeds may be tiny but they pack an almighty punch in terms of health benefits and flavour and really are so easy to fit into your daily diet. Once you discover the range of health supportive nutrients they contain you’ll wonder why you’ve wasted so much time without them on your weekly shopping list!

Flax seed or Linum usitatissimum is derived from the flax plant and has been grown since the beginning of civilization. It is also commonly called linseed. According to historical records, people throughout the world have celebrated its usefulness as far back as 3000 B.C.E.  It is thought to have originated in Egypt and was first brought to North America by early colonists. Flax was first introduced and planted in Canada in the seventeenth century and is now produced world-wide, however Canada is currently the largest producer of this extremely beneficial seed representing about 40% of global production.

Flaxseeds Latin name translates to ‘very useful’ which couldn’t be more true when you realize how versatile it is. From a practical and commercial viewpoint, every part of the plant is utilized either directly or after it’s been processed. It comes in two basic varieties brown and yellow (or golden); brown flax is better known as an ingredient in varnish, paints, cattle feed and fibre.

The stem of the flax plant provides very strong and durable fibres which were used historically up until the 1990’s to produce cloth and paper. The oil and its by-products were used in animal feed formation.

In recent years interest in flaxseeds as a functional food with multiple health benefits has increased as researchers have identified some of its biologically active components. Flax seeds have a range of nutritional characteristics and are a particularly rich source of omega 3 fatty acid: alpha-linolenic acid (ALA) – as well as providing polyunsaturated fatty acids (PUFAs), lignans, proteins, soluble and insoluble fibres, phenolic compounds, numerous antioxidants, vitamins A, C & E and a range of minerals.

Omega 3 fatty acids are particularly important to human health as our bodies are unable to manufacture them so they have to be consumed as part of a varied diet. They have two primary functions in the body:

  1. As structural fats that make up our cell membranes
  1. As precursors for the production of substances called prostaglandins which are involved in controlling many physiological activities including blood clotting, blood pressure and immunity.

The conversion of omega 3 to the active substances EPA and DHA


In order for ALAs to be used as a precursor to prostaglandin, they first have to be converted to eicosapentaenoic acid (EPA) and docosahexaenoic (DHA). This depends upon the activity of an enzyme called delta-6-desaturase, which in some individuals is less available or less active than others. The function of delta-6-desaturase is also inhibited by the consumption of saturated fats and alcohol and in people with nutrient deficiencies or diabetes.

It was once thought that plant sourced omega 3s were poorly converted in the body compared to fish oils which already provide EPA and DHA without the need for conversion. However recent research has found that although more flax seed oil is needed (3.6g of flax seed oil vs 0.6 of fish oil), flax oil is still able to significantly raise EPA in the cells at a level of consumption achievable in a normal diet. Furthermore a 2010 dietary study concluded that non-fish eaters may have compensatory mechanisms in the body that boost their conversion of ALA from plant foods into EPA and DHA.

The importance of the omega3/omega 6 ratio in the diet


Evidence suggests that humans evolved on a diet that had an equal balance of omega 6 to omega 3. However over the centuries, human consumption of vegetable oils from sunflower seeds, corn, soybeans, safflower seeds and cotton seeds has increased and the western diet now typically has a ratio of 20:1or even higher of omega 6:3. This suggests that nowadays we are actually deficient in omega 3 fatty acids compared to our ancestors.

Omega 3 and omega 6 fatty acids have different metabolic functions and at times have important opposing physiological effects in the body, therefore maintaining the correct balance in the diet is extremely important. Excessive levels of omega 6 and a very high ratio of omega6:omega3 as is found in today’s modern diet has been found to promote the progression of many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune diseases. For this reason many government and public health authorities recommend increasing omega 3 fatty acids in the diet.

The impressive nutrient profile of flax seeds


Protein

Although flaxseed is not considered a ‘complete protein’ it is an excellent source containing between 20 to 30% and has an amino acid profile comparable to that of soybean. Not only is it a rich source of glutamic acid, glutamine, leucine, valine, tyrosine, phylalanine and arginine it is also free from gluten.

Lignans

The plant lignans found in flaxseeds are phenolic compounds that act as both antioxidants and phytoestrogens. Phyto (Plant) oestrogens are structurally and functionally similar to the female hormone oestrogens and under certain circumstances show some of the same activities although they exert a much weaker effect on the human body. Flax is an exceptionally rich source of lignans containing up to 800 times more than other plant foods. The phenolic compounds found in flax are converted by bacteria in the gut into lignans.

Minerals

The mineral content of flax includes: magnesium, potassium, iron, copper, zinc, sodium, phosphorous, manganese and copper. It has a particularly high content of potassium comparative to that of a banana. A high potassium intake has been associated with a reduced risk of stroke and blood clotting

Fibre

Throughout history, flax seed has been popularly used as a laxative. It is high in both soluble and insoluble dietary fibre and a gummy material called mucilage. These substances expand when they come into contact with water, so they add bulk to the stool enabling it to move more rapidly through the gastrointestinal tract, thereby acting as an effective laxative in cases of constipation. Research has shown that 6-24g of flax seeds daily for 3 months is more effective than psyllium in managing constipation, bloating and pain in individuals with IBS.

Oil/lipid content

Apart from being a rich source of omega 3s as noted above, flax is also low in saturated fatty acids (9%) has a moderate amount of monounsaturated fats (18%) and more than 70 per cent is of the healthful polyunsaturated type. In fact, a unique feature of flax is the high ratio of omega 3 to omega 6 fatty acids. These two PUFAs are considered essential as they cannot be made by humans and must be consumed in the diet.

Health Benefits


The growing popularity of flaxseeds is thanks to recognition of its many health benefits. These are attributed to its high content of omega 3, its rich source of soluble and insoluble fibre and its high lignin content offering antioxidant and phytoestrogen support. Scientific evidence backs up its anti-inflammatory activities and its use for decreasing cancer risk in particular the prostate and mammary gland. Results from available research also promote the use of flaxseeds for alleviating menopausal symptoms, reducing cardiovascular disease; its laxative effects and bone supportive properties.

Cardiovascular Health

Evidence from research shows that flax seeds may help to support heart health by lowering total cholesterol levels by 5-9% and LDL cholesterol by 8-18%. Flax seeds may also help to reduce levels of apolipoprotein A-1 and apolipoprotein B, which are indicators for coronary heart disease, by 6% and &.5% respectively. Additionally flax seeds have been found to decrease the inflammation markers, C reactive protein, serum amyloid A and interleukin-6.

Flaxseeds may also help to lower blood pressure and the production of unfavourable thromoboanes and fibrinogen. These compounds help to control the tendency of blood platelets to stick together forming clots. Individuals at high risk of coronary heart disease and stroke have been found to produce excessive amounts of thromboxane and fibrinogen.

Blood Pressure Benefits

Evidence from Canadian research suggests that flaxseed proteins may help to reduce blood pressure. The flaxseed proteins have been shown to inhibit ‘angiotensin converting enzymes’ which cause blood vessels to constrict. The implications from the Canadian study are that flax seeds could prevent vasoconstriction and therefore help maintain normal blood pressure.

Symptoms of Menopause

Flax seeds contain a class of phytoestrogens known as lignans. These are transformed by bacteria in the gut into enterodiol and enterolactone, both of which are structurally similar to oestrogen and produce weak oestrogenic and anti-oestrogenic effects. Clinical research has identified that taking 40g flaxseeds daily significantly reduces symptoms of hot flushes by about 35% and night sweats by about 44%.

During the menopause many women experience low mood and depression often due to hormonal changes. Several studies have identified that omega 3 fatty acids help to reduce symptoms of depression. Omega 3 fatty acids influence the fluidity of cell membranes which may have a positive effect on the balance of hormones and neurotransmitters that are commonly dysfunctional in depressed people. Flaxseeds provide an excellent source of hormone balancing omega 3s for vegetarians or those that don’t eat oily fish.

Pre-Menstrual-Syndrome (PMS)

The presence of ALA makes flaxseed useful in alleviating symptoms of PMS. Phytoestrogens present in flaxseed help to regulate heavy periods by balancing eostrogen levels in the body. Flaxseeds may also reduce the breast pain associated with menstruation. However, flaxseed oil is not effective because lignans are only present in the hull of flaxseed. Mood swings are frequent problems associated with PMS which may also be averted by eating flaxseeds.

Bone Health

The risk of developing osteoporosis is four times greater in women than men due to the sudden drop in bone protective hormones post menopause. Diabetes can also increase the likelihood of developing osteoporosis because it interferes with osteoblast activity – these are the cells that help to maintain bone strength.

Results from animal studies suggest that the addition of flaxseed oil to the diet may help to reduce the risk of osteoporosis in post-menopausal women and women suffering with diabetes. The researchers believe that the omega 3 fatty acids in flaxseed oil may somehow help to protect formation and mineralization of the bone matrix, which appear to be compromised by diabetes and the menopause.

Prostate Cancer

Some studies suggest that flaxseeds may provide benefits to men with prostate cancer and could also help to decrease PSA levels and reduce aggressiveness of prostate tumours. The results from a study on 141 men with prostate cancer published in 2013 indicated that the men who added flaxseeds into their diet had the lowest level of tumour growth. A similar result was also seen in a previous study whereby prostate cancer sufferers given 30g flaxseeds daily together with a low-fat diet, were found to have significantly lower tumour growth. Scientists believe that compounds in flax seeds probably interrupt the chain of events that eventually make cells multiply out of control and become tumours.

Breast cancer

Population studies as well as experimental studies in animals and humans have demonstrated that lignans from flaxseeds exert significant breast tumor-reducing effects. Enterodiol and enterolactone produced from flax lignans in the body are structurally similar to human estrogen-17β-estradiol, which gives them a binding affinity to estrogen receptors.

Flaxseed and its lignin components have been shown to weaken tumour growth via a reduction in cell proliferation and new blood vessel growth, as well as an increase in cell death by influencing the estrogen receptor and growth factor signaling pathways.

The potential breast cancer protective effect of flax lignans may be due not only to their weak estrogenic activity but also their antioxidant properties and their exceptionally high ALA content of flaxseed oil which is also thought to play an important role in breast cancer reduction.

Some research shows ALA is able to reduce human estrogen receptor-positive breast tumor growth by 33 % compared to controls. Women with malignant breast tumours have also been found to have 64% lower levels of ALA compared to women from the same study that had benign breast tumours.

Colon Cancer

Flax seeds may also help to protect against colon cancer. In studies with rats, flax seed oil and ground flax seeds have both been shown to reduce the incidence of’ aberrant crypt foci’.  These are clusters of abnormal tube-like glands located in the lining of the colon and rectum and are considered to be one of the earliest changes seen in the colon that may lead to cancer.

Easy ways to enjoy flax in your diet


Flaxseeds have a warm and earthy flavour with a subtly nutty edge which lends themselves well to many recipes. It’s perfectly safe to use whole flax seeds or ground flax seeds for cooking; however grinding the seeds enhances their digestibility and therefore nutritional value.

Whole or ground flaxseeds are stable at temperatures used to bake carb/gluten-free bread, biscuits and cakes etc. You can also add ground or whole flaxseeds to casseroles, curries, soups etc., but bear in mind that adding them to cooked foods will thicken any liquid if left too long because of the fibre content.

The seeds can also be sprinkled on salads or vegetables to add a nuttier flavour or mixed into all types of yogurt, or smoothies for extra protein. Try using flaxseed oil instead of other oils in dressings, as dipping oil for carb free bread, or to drizzle over steamed vegetables.

Storing flax seeds


It is best to purchase flaxseeds in packaged form preferably refrigerated, making sure there is no evidence of moisture. Whole flax/linseeds should be stored in an airtight container in a cool, dark dry cupboard. This way they stay fresh for several months. If you buy ground flax/linseeds, look for seeds that are in a vacuum-packed container or that have been refrigerated. Once ground the seeds are far more prone to oxidation and can deteriorate.

Keep ground flax/linseeds in a tightly sealed package in the refrigerator or freezer to prevent rancidity. If stored in the fridge it will maintain their freshness for 6 months if stored in the freezer they will stay fresh for a year. Always choose cold-pressed flaxseed oil in an opaque bottle that has been refrigerated. It should have a sweet nutty flavour. It is not suitable for use as oil in cooking but can be added to previously cooked foods.

Toxicity


Women who are pregnant or breastfeeding. 

Taking flaxseed by mouth during pregnancy is possibly unsafe because it acts like the hormone oestrogen which some medical experts worry might harm the pregnancy or baby via the breast milk. There is no reliable clinical evidence, however it is best to stay on the safe side.

Medications:

There is evidence that flaxseeds may interfere with some prescription drugs. Always check with your GP first.


References


  1. Amin T & Thakur M. (2014). Linum usitatissimum (Flaxseed)–A Multifarious Functional Food. Online International Interdisciplinary Research Journal; 4, (I): 220-238.
  2. Ankit Goyal, Vivek Sharma, Neelam Upadhyay, Sandeep Gill, and Manvesh Sihag Flax and flaxseed oil: an ancient medicine & modern functional food. J Food Sci Technol. 2014; 51(9): 1633–1653.
  3. Azrad, M., Vollmer, R. T., Madden, J., Dewhirst, M., Polascik, T. J., Snyder, D. C., Demark-Wahnefried, W. (2013). Flaxseed-Derived Enterolactone Is Inversely Associated with Tumor Cell Proliferation in Men with Localized Prostate Cancer. Journal of Medicinal Food16(4), 357–360.
  4. Barceló-Coblijn G et al. Flaxseed oil and fish-oil capsule consumption alters human red blood cell n-3 fattyacid composition:a multiple-dosing trial comparing 2 sources of n-3 fatty acid. Am J Clin Nutr. 2008; 88(3):801-9.
  5. Denmark-Wahnefried W, et al. Flaxseed supplementation (not dietary fat restriction) reduces prostate cancer proliferation rates in men presurgery. Cancer Epidemiol Biomarkers Prev. 2008;17(12):3577-3587.
  6. Dodin S, Lemay A, Jacques H etal. The effects of flaxseed dietary supplement on lipid profile, bone mineral density, and symptoms in menopausal women:a randomized, double-blind, wheat germ placebo-controlled clinical trial. JClinEndocrinolMetab.2005;90:1390-7.
  7. Eden J, Mackey R (1998). Phytoestrogens and the menopause. 1, (4):302-8.
  8. Ferretti A et al. Antithromboxane activity of dietary alpha-linolenicacid:a pilotstudy. Prostaglandins Leuk ot Essent FattyAcids.1996:54(6):451-5. 9.
  9. Flax council of America. A Focus on Fatty Acids. https://flaxcouncil.ca/resources/nutrition/general-nutrition-information/a-focus-on-fatty-acids/. [Accessed 24.7.16.]
  10. Grosso, G., Pajak, A., Marventano, S., Castellano, S., Galvano, F., Bucolo, C., Caraci, F. (2014). Role of Omega-3 Fatty Acids in the Treatment of Depressive Disorders: A Comprehensive Meta-Analysis of Randomized Clinical Trials. PLoS ONE9(5), e96905.
  11. Harvi et al. Impact of feeding flaxseed oil on delaying the development of osteoporosis in ovariectomized diabetic rats.  J. Food Safety, Nutrition and Public Health, 2009, 2, 189-201.
  12. Rallidis, LS et al. Dietary alphalinolenic acid decreases Creactiveprotein, serum amyloid A and interleukin–6in dyslipidaemic patients. Atherosclerosis.2003:167(2):237-242. 8.
  13. Rodriguez-Leyva D, Weighell W, Edel AL, Lavallee R, Dibrov E, Pinneker R, Maddaford TG, Ramjiawan B, Aliani M, Guzman R, Pierce GN. Potent antihypertensive action of dietary flaxseed in hypertensive patients. Hypertension. 2013;62(6):1081-9.
  14. Simopoulos AP. (2016) An Increase in the Omega-6/Omega-3 Fatty Acid Ratio Increases the Risk for Obesity Nutrients; 8(3): 128.
  15. Simopoulos A P. (2002) The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomed Pharmacother;56(8):365-79.
  16. Tarpila S et al. Efficacy of ground flaxseed on constipation in patients with irritable bowel syndrome. Curr Top Nutraceutical Res. 2004; 2(2):119-125.
  17. Welch AA, et al. Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the precursor-product ratio of á-linolenic acid to long chain n-3 polyunsaturated fatty acids:results from the EPIC-Norfolk cohort. AmJClinNutr. 2010; 92:1040-51.
  18. Williams D et al. Flaxseed oil and flaxseed meal reduce the formation of aberrant crypt foci (ACF) in azoxymethane-induced colon cancer in Fisher 344 male rats. Food Chem Toxicol. 2007Jan; 45(1):153-9.
  19. Welch AA, et al. Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the precursor-product ratio of á-linolenic acid to long chain n-3 polyunsaturated fatty acids:results from the EPIC-Norfolk cohort. AmJClinNutr. 2010; 92:1040-51.
  20. Williams D et al. Flaxseed oil and flaxseed meal reduce the formation of aberrant crypt foci (ACF) in azoxymethane-induced colon cancer in Fisher 344 male rats. Food Chem Toxicol. 2007Jan; 45(1):153-9.


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Jackie Newson
About the author...
Jackie Newson , BSc (Hons) Nutritional Therapy, is a nutritional consultant providing dietary analysis for recipes and menu plans and assess nutritional therapy students on line.
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