Dietary flaxseeds (linseeds) are a rich source of fibre, lignans and omega-3 fatty acids including alpha-linolenic acid (ALA). Lignans are one of the major phytoestrogens that have antioxidant and anti-inflammatory properties. Similarly, omega-3 fatty acids have been shown to have anti-inflammatory, antioxidant and angiogenic properties (formation of new blood cells). The amount of ALA contained in flaxseed is quite high, approximately 57%. In addition, 30% of flaxseed is dietary fibre, it plays an important role in reducing blood glucose and cholesterol levels by reducing and delaying their absorption from the intestine. Find out more about why flaxseeds may improve your overall health.
1. Flaxseeds may lower elevated blood pressure
High blood pressure (hypertension) is positively associated with an increased risk of developing chronic diseases including heart failure, stroke, ischemic heart disease and kidney disease. Hypertension is responsible for 14% of global mortality. It can be controlled and prevented through adequate diet and lifestyle modifications. A diet rich in fruits, vegetables, omega-3 fatty acids, garlic and green tea has been shown to improve blood pressure.
Flaxseeds are one of the richest sources of dietary omega-3 fatty acids, fibre and lignans. Dietary fibre, especially soluble fibre, can reduce blood pressure by improving lipid profiles such as cholesterol, reducing insulin resistance, improving the gut microbiome which may improve lignan absorption, reduction in body weight and its antioxidant properties. A recent meta-analysis demonstrated daily consumption of whole flaxseeds over 12 weeks had an average reduction of 1.77mm Hg systolic blood pressure and 1.16mm Hg diastolic blood pressure (Samen et al., 2015). A reduction of 2mm Hg of systolic blood pressure has been shown to reduce stroke mortality by 10%. Therefore, the results of this meta-analysis suggest that daily flaxseed consumption should be considered for the prevention and control of elevated blood pressure, in addition to a whole food diet.
2. Flaxseeds may reduce inflammatory markers
Chronic disorders are positively associated with markers of inflammation such as tumour necrosis factor (TNFα), C-reactive protein (CRP), and interleukin 6 (IL6). TNFα and IL6 are important cytokines that are released in large amounts during inflammation and play a critical role as mediators in cardiovascular disease (CVD) and other chronic diseases such as insulin resistance and metabolic syndrome. They are also potent stimulants for CRP production (a protein made by the liver), which has been found to be a strong risk factor for chronic disorders.
Anti-inflammatory properties have been found in dietary fibre, phytoestrogens, lignans, isoflavones and omega-3 fatty acids including ALA. Flaxseeds are the richest source of lignans which have been shown to reduce CRP concentration (a low-grade inflammatory marker). A recent meta-analysis determined that the consumption of whole flaxseeds had a beneficial effect on high-sensitivity CRP levels and TNFα (Rahim et al., 2019). Whereas, flaxseed oil has been shown to have lowering effects on IL-6 and high-sensitivity CRP. In addition, flaxseed consumption is more likely to reduce systemic inflammatory markers in subjects with high concentrations of inflammatory factors such as a CRP greater than 3 mg/L. The effects of these studies demonstrate that daily flaxseed consumption may have anti-inflammatory effects, especially for those with elevated inflammatory markers.
3. Flaxseeds may reduce frequency of hot flushes in postmenopausal women
Menopause is characterised by a decrease in oestrogen levels after the cessation of menses. Decreasing oestrogen states trigger symptoms of hot flushes, night sweats, sleep disturbances and vaginal dryness. Phytoestrogens are plant compounds with oestrogen-like properties as the chemical structures are similar to estradiol, exhibiting both estrogenic and antiestrogenic effects. The two major classes include isoflavones found in soybeans, and lignans found in flaxseed, whole grains, legumes, fruit and vegetables. Phytoestrogens are commonly found in the Asian diet, leading to fewer vasomotor symptoms experienced by Asian women than American and European women.
Hot flushes occur in up to 74% of postmenopausal women and can have a negative impact on quality of life. A meta-analysis demonstrated that daily consumption of flaxseeds resulted in a reduction in hot flush frequency in postmenopausal women (Chen et al., 2014). Therefore, flaxseeds may benefit postmenopausal women experiencing hot flushes.
4. Flaxseeds may reduce lipid profiles in dyslipidemia (cholesterol & triglycerides)
Dyslipidemia is the imbalance of lipids including total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol and triglycerides. Primary causes of dyslipidemia are linked to inherited gene mutations that result in over-production or defective clearance of triglycerides and cholesterol. Secondary causes of dyslipidemia are due to unhealthy lifestyle factors such as poor diet and obesity, and underlying medical conditions or medications. Secondary dyslipidemia accounts for 30-40% of all dyslipidemia, which may be preventable with dietary and lifestyle changes. Elevated lipids (hyperlipidemia) have become one of the greatest risk factors contributing to coronary heart disease (CHD), atherosclerosis, and nonalcoholic fatty acids disease (NAFLD). Atherosclerosis is a buildup of fats, cholesterol and other substances inside the arterial wall, causing obstruction to blood flow. Chronic inflammation represents another important factor in the development of dyslipidemia-related diseases.
Dietary flaxseeds contain one of the richest sources of lignans, specifically secoisolariciresinol diglucoside (SDG). It is responsible for its antioxidant, anti-inflammatory, phytoestrogenic, and potent angiogenic (formation of new blood cells) properties, which play an important role in lowering cholesterol (anti-atherosclerosis). A meta-analysis determined the consumption of whole flaxseeds (average 28g per day) had a significant reduction in total cholesterol, LDL cholesterol (0.4mmol/L) and triglycerides (0.7mmol/L) in hyperlipidemic and overweight patients (Yang et al., 2021). Flaxseed oil, mainly for its antioxidant activity may reduce oxidation of LDL cholesterol rather than lipid concentrations. In addition, the meta-analysis found a significant reduction in weight (0.4kg) compared to the control groups which is attributed to a control of energy intake and increased satiety (feeling of fullness) due to containing fibre. Therefore, daily consumption of flaxseeds may reduce lipid profiles in dyslipidemia which reduces the risk of developing atherosclerosis.
5. Flaxseeds may have protective effects against breast cancer
Breast cancer is one of the most commonly diagnosed conditions in Australian women. Fibre intake has been associated with a decrease in breast cancer risk and recurrence. Fibre is essential for hormone metabolism and the elimination of hormones through regular stool evacuation. Flaxseeds are one of the densest sources of lignins, especially SDG. They possess both oestrogenic and anti-oestrogenic effects. Plant lignans are metabolised by intestinal microbes and converted into enterolactone and enterodiol which are chemically similar to oestradiol. These metabolites appear to be responsible for the ‘anti-cancer’ effects attributed to lignans. Enterolactone production may be reduced by up to 30% by the use of antibiotics, smoking and poor digestive function. Enterolactones have been shown to interact with oestrogen receptors, behaving as weak oestrogen agonists.
A meta-analysis determined that in postmenopausal women, the consumption of flaxseeds (25g per day), may decrease the risk of breast cancer development and exert anti-tumour effects in women with breast cancer (Flower et al., 2013). Flaxseeds may be safe for consumption in women with breast cancer due to having no significant effect on endogenous oestrogen levels in the majority of human trials. Dietary lignans are not only found in flaxseeds, they can also be found in fruit, vegetables, tea and whole grains.
Whole flaxseeds vs ground flaxseeds
Whole flaxseeds are an essential source of high-quality protein and soluble fibre, as well as a combination of multiple nutrients including ALA and lignans, which result in synergistic interactions. Baking may improve the bioavailability of some of the flaxseed phytochemicals. Generally, it is recommended to use freshly ground flaxseeds due to their overall benefit on health. Freshly ground flaxseeds can be kept in the freezer to avoid rancidity and kept fresh (no, they won’t freeze).
Flaxseed oil is mainly for its antioxidant activity and may reduce oxidation of LDL cholesterol rather than lipid concentrations. Flaxseed oil demonstrated an anti-inflammatory effect on IL-6 and high-sensitivity CRP, rather than lipid profiles. Flaxseed oil contains the highest amount of ALA, although it is also found in ground flaxseeds. Generally, it is recommended to purchase flaxseed oil that is already refrigerated and keep it stored in the fridge to avoid rancidity.
How to add flaxseeds into your daily diet
The benefits of flaxseeds align with regular consumption. Consider adding freshly ground flaxseeds to your daily breakfast, morning smoothie or baking. Aim for 25-30g per day, build-up slowly when adding fibre in the diet. If using flaxseed oil, try it in your homemade salad dressings. Freshly ground flaxseeds and oil should be kept in the fridge or freezer to avoid rancidity.
Key takeaway for the benefits of flaxseeds:
Flaxseeds are one of the richest sources of dietary omega-3 fatty acids, fibre and lignans.
A diet rich in fruits, vegetables, omega-3 fatty acids, garlic and green tea has been shown to improve blood pressure.
Anti-inflammatory properties have been found in dietary fibre, phytoestrogens, lignans, isoflavones and omega-3 fatty acids including ALA. Flaxseeds are the richest source of lignans which have been shown to reduce CRP concentration.
Regular consumption of flaxseeds can reduce the frequency of post-menopausal hot flushes.
Secondary dyslipidemia accounts for 30-40% of all dyslipidemia, which may be preventable with dietary and lifestyle changes.
Lowering cholesterol and triglyceride effects are due to the lignans found in flaxseeds (specifically SDGs).
Fibre intake and foods high in lignans have been associated with a decrease in breast cancer risk and recurrence.
This blog article is for education and entertainment purposes. Please consult with your health practitioner.
Reference list
Chen, M. N., Lin, C. C., & Liu, C. F. (2015). Efficacy of phytoestrogens for menopausal symptoms: a meta-analysis and systematic review. Climacteric: The Journal of the International Menopause Society, 18(2), 260–269. https://doi.org/10.3109/13697137.2014.966241
Flower, G., Fritz, H., Balneaves, L. G., Verma, S., Skidmore, B., Fernandes, R., Kennedy, D., Cooley, K., Wong, R., Sagar, S., Fergusson, D., & Seely, D. (2014). Flax and breast cancer: A systematic review. Integrative Cancer Therapies, 13(3), 181–192. https://doi.org/10.1177/1534735413502076
Khalesi, S., Irwin, C., & Schubert, M. (2015). Flaxseed consumption may reduce blood pressure: a systematic review and meta-analysis of controlled trials. The Journal of Nutrition, 145(4), 758–765. https://doi.org/10.3945/jn.114.205302
National Breast Cancer Foundation (2023). Breast cancer stats. https://nbcf.org.au/about-breast-cancer/breast-cancer-stats
Rahimlou, M., Jahromi, N. B., Hasanyani, N., & Ahmadi, A. R. (2019). Effects of Flaxseed Interventions on Circulating Inflammatory Biomarkers: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Advances in Nutrition, 10(6), 1108–1119. https://doi.org/10.1093/advances/nmz048
Yang, C., Xia, H., Wan, M., Lu, Y., Xu, D., Yang, X., Yang, L., & Sun, G. (2021). Comparisons of the effects of different flaxseed products consumption on lipid profiles, inflammatory cytokines and anthropometric indices in patients with dyslipidemia related diseases: systematic review and a dose-response meta-analysis of randomized controlled trials. Nutrition & Metabolism, 18(1), 91. https://doi.org/10.1186/s12986-021-00619-3
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