by Dr. Leo Galland
I have long championed the benefits of flaxseeds in scientific papers, lectures, books and interviews. When I featured flaxseeds in Superimmunity for Kids, readers took notice.
Now flaxseeds are turning up as a star ingredient for recipes in magazines, and for good reason: these little seeds pack a big nutritional punch.
But then again, flaxseeds have been famous for quite a while. Cultivated since the dawn of history, the flax plant provided an important source of nutrition in the form of flaxseeds, and its stem was used as the fiber to make linen clothing. Later, soldiers of the Roman legions were fed ground flaxseed, baked into bread, as they expanded their empire.
Studies indicate that consumption of flaxseeds may be associated with:
• reduced cholesterol (including the dangerous LDL-cholesterol)
• reduced triglycerides, another risk factor for heart disease
• reduced absorption of sugar from food
• decreased levels of chemicals involved in producing inflammation, like C-reactive protein (CRP).
• increased blood levels of EPA (eicosapentaenoic acid) the omega-3 fatty acid that boosts mood and fights inflammation
Ground flaxseed contains three beneficial components:
• alpha-linolenic acid, an omega-3 fat, which accounts for about 20% of the mass of most flaxseed, and
• lignans, a group of phenolic anti-oxidants with anti-inflammatory and cholesterol-lowering effects.
According to research, flaxseed can help maintain a healthy ratio of estrogen to progesterone during the menstrual cycle and helps metabolize estrogen.
In order to get the nutritional benefits of the alpha-linolenic acid and the high concentration of lignans found in flaxseed fiber, I like to use freshly ground flaxseed rather than flaxseed oil. Because flaxseeds have a hard external shell you’re unlikely to absorb any significant amount of lignans or alpha-linolenic acid from intact flaxseed. When buying flaxseeds I prefer organic, because pesticides can accumulate in the fat-containing seeds. I grind flaxseed fresh, using a coffee grinder, just before using it. Grinding takes about 10 seconds.
Research Abstracts on Flaxseeds:
Appl Physiol Nutr Metab. 2009 Oct;34(5):965-74. Experimental and clinical research findings on the cardiovascular benefits of consuming flaxseed.
Bassett CM, Rodriguez-Leyva D, Pierce GN. Institute of Cardiovascular Sciences, St Boniface Hospital Research Centre and the Department of Physiology, Faculties of Medicine and Pharmacy, University of Manitoba, Winnipeg, MB, Canada.
Functional foods and nutraceuticals are becoming popular alternatives to pharmacological treatments by providing health benefits and (or) reducing the risk of chronic diseases. Flaxseed is a rich source of 3 components with demonstrated cardioprotective effects: the omega-3 fatty acid alpha-linolenic acid (ALA), dietary fibre, and phytoestrogen lignans. Multiple clinical dietary intervention trials report that consuming flaxseed daily can modestly reduce circulating total cholesterol (TC) by 6%-11% and low-density lipoprotein (LDL) cholesterol by 9%-18% in normolipemic humans and by 5%-17% for TC and 4%-10% for LDL cholesterol in hypercholesterolemic patients, as well as lower various markers associated with atherosclerotic cardiovascular disease in humans. Evidence to date suggests that the dietary fibre and (or) lignan content of flaxseed provides the hypocholesterolemic action. The omega-3 ALA found in the flaxseed oil fraction also contributes to the antiatherogenic effects of flaxseed via anti-inflammatory and antiproliferative mechanisms. Dietary flaxseed may also protect against ischemic heart disease by improving vascular relaxation responses and by inhibiting the incidence of ventricular fibrillation.
Br J Nutr.:1-10. [Epub ahead of print] Health effects with consumption of the flax lignan secoisolariciresinol diglucoside.
Adolphe JL, Whiting SJ, Juurlink BH, Thorpe LU, Alcorn J. College of Pharmacy and Nutrition, University of Saskatchewan, 110 Science Place, Saskatoon, SK, Canada S7N 5C9.
Flaxseed is the richest source of the lignan secoisolariciresinol diglucoside (SDG). After ingestion, SDG is converted to secoisolariciresinol, which is further metabolised to the mammalian lignans enterodiol and enterolactone. A growing body of evidence suggests that SDG metabolites may provide health benefits due to their weak oestrogenic or anti-oestrogenic effects, antioxidant activity, ability to induce phase 2 proteins and/or inhibit the activity of certain enzymes, or by mechanisms yet unidentified. Human and animal studies identify the benefits of SDG consumption. SDG metabolites may protect against CVD and the metabolic syndrome by reducing lipid and glucose concentrations, lowering blood pressure, and decreasing oxidative stress and inflammation. Flax lignans may also reduce cancer risk by preventing pre-cancerous cellular changes and by reducing angiogenesis and metastasis. Thus, dietary SDG has the potential to decrease the incidence of several chronic diseases that result in significant morbidity and mortality in industrialised countries. The available literature, though, makes it difficult to clearly identify SDG health effects because of the wide variability in study methods. However, the current evidence suggests that a dose of at least 500 mg SDG/d for approximately 8 weeks is needed to observe positive effects on cardiovascular risk factors in human patients. Flaxseed and its lignan extracts appear to be safe for most adult populations, though animal studies suggest that pregnant women should limit their exposure. The present review discusses the potential health benefits of SDG in humans, with supporting evidence from animal studies, and offers suggestions for future research.
Am J Clin Nutr. 2009 Aug;90(2):288-97. Epub 2009 Jun 10. Meta-analysis of the effects of flaxseed interventions on blood lipids.
Pan A, Yu D, Demark-Wahnefried W, Franco OH, Lin X. Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Graduate School of the Chinese Academy of Sciences, Shanghai 200031, China.
BACKGROUND: Several clinical trials have investigated the effects of flaxseed and flaxseed-derived products (flaxseed oil or lignans) on blood lipids; however, the findings have been inconsistent.
OBJECTIVE: We aimed to identify and quantify the effectiveness of flaxseed and its derivatives on blood lipid profiles.
DESIGN: A comprehensive literature search was performed on the basis of English reports of randomized controlled trials of flaxseed or its derivatives on lipid profiles in adults, which were published from January 1990 to October 2008. Attempts also were made to access unpublished data. Study quality was assessed by using the Jadad score, and a meta-analysis was conducted.
RESULTS: Twenty-eight studies were included. Flaxseed interventions reduced total and LDL cholesterol by 0.10 mmol/L (95% CI: -0.20, 0.00 mmol/L) and 0.08 mmol/L (95% CI: -0.16, 0.00 mmol/L), respectively; significant reductions were observed with whole flaxseed (-0.21 and -0.16 mmol/L, respectively) and lignan (-0.28 and -0.16 mmol/L, respectively) supplements but not with flaxseed oil. The cholesterol-lowering effects were more apparent in females (particularly postmenopausal women), individuals with high initial cholesterol concentrations, and studies with higher Jadad scores. No significant changes were found in the concentrations of HDL cholesterol and triglycerides.
CONCLUSIONS: Flaxseed significantly reduced circulating total and LDL-cholesterol concentrations, but the changes were dependent on the type of intervention, sex, and initial lipid profiles of the subjects. Further studies are needed to determine the efficiency of flaxseed on lipid profiles in men and premenopausal women and to explore its potential benefits on other cardiometabolic risk factors and prevention of cardiovascular disease.