Flaxseed possesses a very healthy fatty acid profile. The oil from the seed is very low in saturated fat (approximately 9%), contains moderate amounts of monounsaturated fat (approximately 18%), and is high in polyunsaturated fats (approximately 73%). Flaxseed oil does not contain trans fatty acids which have been implicated in significant increases in coronary heart disease risk. Of the nutritionally beneficial polyunsaturated fats, about 16% belong to the omega-6 family primarily as linoleic acid (LA). The remaining 57% is the omega-3 fatty acid, alpha-linolenic acid (ALA). Both LA and ALA are essential fatty acids (EFAs) – “essential to life” as they can not be produced by the body and therefore must be obtained from the diet. EFAs are incorporated into the membranes of our body cells to keep them fluid. As a result, they act as “gate-keepers” to allow the entry into cells of important nutrients as well as the removal of toxins. More importantly, EFAs are converted to hormone like substances known as eicosanoids that effect physiological functions such as cell growth and division, platelet aggregation (blood clotting), inflammatory responses, hemorrhage, vasoconstriction and vasodilation of blood vessels, blood pressure, and immune function. The activity of the eicosanoids impacts clinical conditions involved in cardiovascular health, inflammatory disorders, immunity, and certain cancers.
Critical for proper functioning of body cells is an optimal dietary ratio of omega-6:omega-3 fatty acids. The omega‑6 and the omega‑3 fatty acid families form different eicosanoids with different activities and they compete with one another for the enzymes responsible for the synthesis of these eicosanoids. For instance, some eicosanoids stimulate pro-inflammatory and hypertensive events whereas other eicsoanoids have opposite effects. Thus, a proper balance of essential fatty acids in the diet is important. For optimal health, Health Canada recommends an omega 6:omega 3 fatty acid dietary ratio of 4:1 to 10:1 (1). The U.S. Food and Drug Administration has yet to set an official recommendation in this area.
In the past, dietary intake of omega-6 and omega-3 fatty acids were approximately equal, but modern diets have significantly changed resulting in very high omega-6 to omega-3 ratios (16:1 or higher (2). Technological developments, such as food processing, has depleted much of the ALA and omega-3 content from foods, which contributes to an imbalanced omega 6:omega 3 ratio.
Not only are people eating less omega 3, the overall availability of omega-6 LA in the food supply has increased from about 2.79% to 7.21% of energy from 1909 to 1999. The level of ALA in the food supply has only increased from 0.39% to 0.72% of energy due mostly to modifications in food processing. These changes resulted in the ratio of LA to ALA increasing from 6.4:1 in 1909 to 10.0:1 in 1999 (3). Consumption of soybean oil, which is comprised of approximately 54% LA, has increased from 0.009 kg per capita per year in 1909 to 11.64 kg per capita per year in 1999, a 1163-fold increase (3).
It is speculated that in today’s Western society the ratio of omega-6:omega-3 fatty acids may be as high as 20-30:1 (4). Overall, North Americans are consuming too much LA and not enough ALA and other omega-3 fatty acids, a situation that may negatively impact health. A great deal of attention, therefore, has been focused on ALA and the omega-3 fatty acid family due to their deficiency in today’s diet, as well as their beneficial effects on numerous clinical conditions.
Flaxseed as the best choice for omega-3’s from plants
Flaxseed contains more than three times as much omega-3 fatty acids than omega-6 fatty acids, with an omega-6 to omega-3 ratio of 0.3:1 (5). When comparing to other common plant based oils, corn oil has an omega-6:omega-3 ratio of 58:1, soybean oil 7:1, and canola oil 2:1 (6). Due to the current high intake of the omega-6 fatty acid LA, coupled with the deficiency of omega-3 fatty acids in today’s typical North American diet, flaxseed oil clearly provides the best overall dietary fatty acid ratio. Supplementing the diet with flaxseed provides a good source of the plant based omega-3 fatty acid ALA, as well as low levels of LA as well as a healthy and optimal omega-6:omega-3 ratio.
References
- Health and Welfare Canada. 1990. Nutrition Recommendations. The Report of the Scientific Review Committee. Department of Supply and Services. Cat.No.H49-42/1990E. Ottawa, On.
- Liu J, et al. Nutrients 2014;6:5184-5223.
- Blasbalg TL, et al. Am J Clin Nutr 2011;93:950-962.
- Simopoulos, A.P. 1999. Essential fatty acids in health and chronic disease. Am J Clin Nutr. 70(suppl):560S-569S.
- Bhatty, R.S. 1995. Nutrient composition of whole flaxseed and flaxseed meal. In: Flaxseed in Human Nutrition, eds SC Cunnane and LU Thompson. AOCS Press. Champaign, IL, pp 22-42.
- Vaisey-Genser, M., Morris, D.H. Flaxseed – Health, Nutrition and Functionality. Revised Edition. pp. 24.