Omega-3 Alpha-Linolenic Acid

Of the three forms of Omega-3 Essential fatty acids, only alpha-linolenic acid (ALA) cannot be synthesized by the body, potentially making it the only "essential" omega-3 fatty acid. Each omega-3 fatty acid performs necessary functions within the body, ALA included. However, more research is needed to determine dietary requirements of each of the omega-3 fatty acids, as well as the rate of conversion by the body of ALA to DHA and EPA.

Dietary sources of ALA are plant based, of which flax contains the highest amount of ALA.

+An Overview of Alpha-Linolenic Acid (ALA)

Do Not Put All Your Omega-3 Eggs in One Basket

Many say that because the conversion rate of ALA to EPA and DHA is so low, it is inefficient to get your omega-3 fatty acids needs just from ALA sources. Therefore, many think you should just eat fish and/or take fish oil supplements. In fact, because of this, most of the research into the health benefits of omega-3 fatty acids has been done using strictly fish oil. Recent research is showing that fish oil alone may be an equally inefficient source of omega-3 fatty acids.

While the conversion rate may be low, ALA carries its own unique importance in the body:

· ALA is essential because the body can not manufacture it and consequently, must obtain it from dietary sources.
· ALA competes with LA (omega-6 fatty acid) for the same elongase and desaturase enzymes to synthesize them into their associated longer chain fatty acids. The average western diet is considered to be excessively high in omega-6 fatty acids (like LA) and intake of ALA can help bring the omega-6: omega-3 ratio into better balance by reducing the ability of the LA to be elongated and desaturated. Many consider this imbalance to be the reason for the increase in certain diseases in the last 75 years.
· Most dietary sources of ALA are plant based and therefore, carry a dietary fiber benefit with them. Dietary fiber has been shown to have numerous heart healthy benefits.

The conclusion is that all three forms of omega-3 are essential to proper functioning of the human body. While ALA, as the parent omega-3, can be synthesized by the body into both DHA and EPA, the rate is low. Additionally, because of the excess of omega-6 in the standard western diet, there is greater competition by LA (omega-6) for the enzymes needed for synthesis, further impacting the efficiency of ALA to be converted to DHA and EPA. Therefore, dietary intake of sources for all omega-3 EFAs (ALA, DHA and EPA) would be beneficial. Lastly, the health benefits of omega-3 EFAs can be increased by also reducing the consumption of omega-6 fatty acids.

Research Abstract: What is the role of alpha-linolenic acid for mammals?
Sinclair AJ, Attar-Bashi NM, Li D. in Lipids. 2002 Dec;37(12):1113-23

This review examines the data pertaining to an important and often underrated EFA, alpha-linolenic acid (ALA). It examines its sources, metabolism, and biological effects in various population studies, in vitro, animal, and human intervention studies. The main role of ALA was assumed to be as a precursor to the longer-chain n-3 PUFA, EPA and DHA, and particularly for supplying DHA for neural tissue. This paper reveals that the major metabolic route of ALA metabolism is beta-oxidation. Furthermore, ALA accumulates in specific sites in the body of mammals (carcass, adipose, and skin), and only a small proportion of the fed ALA is converted to DHA. There is some evidence that ALA may be involved with skin and fur function. There is continuing debate regarding whether ALA has actions of its own in relation to the cardiovascular system and neural function. Cardiovascular disease and cancer are two of the major burdens of disease in the 21st century, and emerging evidence suggests that diets containing ALA are associated with reductions in total deaths and sudden cardiac death. There may be aspects of the action and, more importantly, the metabolism of ALA that need to be elucidated, and these will help us understand the biological effects of this compound better. Additionally, we must not forget that ALA is part of the whole diet and should be seen in this context, not in isolation.

+The Effect of ALA on Cardiovascular Disease

ALA and Cardiovascular Disease (CVD)

CVD is an area of research where the consumption of ALA appears to show the greatest potential for health benefit. Three distinct, but interdependent, pathological phenomena may occur that ultimately lead to CVD: thrombosis, fibrillation, and atherosclerosis. Various clinical manifestations such as stable angina from atherosclerosis, infarction (obstruction of blood vessels) and stroke from thrombosis, and sudden death (cardiac arrhythmia) as a result of fibrillation, may result. Numerous intervention studies have established the beneficial effects of ALA on cardiac events.

The Health Professional Follow-up Study, which began in 1986 with a cohort of 51,529 health professionals, demonstrated that a 1% increase in ALA intake expressed as percent of energy was associated with a 40% reduction in the risk of non-fatal coronary heart disease (CHD).

The landmark Lyon Diet Heart Study included participants who had previously survived a myocardial infarction. The experimental group consumed a typical Mediterranean style diet rich in ALA, whereas the control group consumed a typical Western-type diet low in ALA. Results demonstrated a 75% reduction in non-fatal myocardial infarction and a 70% reduction in total death amongst the experimental group, in comparison to the control group.

The Nurse’s Health Study consisted of a 10-year follow-up of 76,283 women with no previously diagnosed cancer or CVD. After adjustment for age, standard coronary heart disease risk factors, and dietary intake, results demonstrated that a higher intake of ALA was associated with a lower relative risk of fatal and non-fatal myocardial infarction.

In the Moselle study, the diets of two groups of fifty Moselle farmers were analyzed for different constituents. It was reported that a lower dietary intake of LA, coupled with higher intakes of ALA (dietary LA:ALA ratio of approximately 5:1), markedly decreased platelet reactivity (i.e. the tendency of platelets to "clot").

A recent review of studies focusing on flax and ALA concluded that the fatty acid can reduce ventricular fibrillation, and may be more effective than either eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), both of which are found in high levels in fatty fish and fish oils.

ALA has been shown to inhibit the growth of atherosclerotic plaques.

Women who consumed 50g of milled flaxseed a day for four weeks exhibited total blood and LDL-cholesterol ("bad" cholesterol) level reductions of 9% and 18%, respectively. These effects were attributed to ALA as well as to the high amount of beneficial soluble fiber found in the flaxseed. Some research has indicated that ALA from flaxseed may reduce serum triglyceride levels, another blood lipid associated with CVD, without altering HDL-cholesterol ("good" cholesterol) levels. Altering lipid profiles is especially important in the prevention and management of CVD.

The cardio-protective effects of ALA may be attributed to improvements in arrhythmia (abnormal heart rhythms) and to reductions in platelet aggregation (blood platelet stickiness).

References

· Ascherio, A., Rimm, E.B., Giovannucci, E.L., et.al. 1996. Dietary fat and risk of coronary heart disease in men: Cohort follow-up study in the United States. Br Med J; 313:84-90.
· Renaud, S., de Lorgeril, M., Delaye, J., et.al. 1995. Cretan Mediterranean diet for prevention of coronary heart disease. Am J Clin Nutr; 61(Suppl); 1360S-7S.
· Hu, F.B., Stampfer, M.J., Manson, J.E., et.al. 1999. Dietary intake of alpha-linolenic acid and risk of fatal ischaemic heart disease among women. Am J Clin Nutr; 69: 890-7.
· Renaud, S., Godsey, P., Dumont, E., Thevenon, C., Orrchanian, E. 1986. Influence of diet modification on platelet function and composition in Moselle farmers. Am J Clin Nutr; 43:136-150.
· Lanzmann-Petithory, D. 2001. Alpha-Linolenic Acid and Cardiovascular Diseases. J Nutr Health Aging; 5(3): 179-183.
· Jacob, R., et.al. Prolongation of life span in hypertensive rats by dietary interventions. 1997. Effects of garlic and linseed oil. Basic Res Cardiology; 92(4): 223-32.
· Cunnane, S.C., et.al. 1995. Nutritional attributes of traditional flaxseed in healthy young adults. Am J Clin Nutr; 61(1):62-8.

+The Effect of ALA on Coronary Heart Disease

ALA: Impact on Coronary Heart Disease (CHD)

A newly published report from the Harvard Medical School demonstrated that ALA may decrease the risk of fatal CHD through a reduction in fatal ventricular arrhythmias and sudden cardiac death. A negative association between ALA and the risk of sudden cardiac death was found among 76,763 women participating in the Nurses' Health Study. The public impact of diets containing ALA in flaxseed oil, which is low-cost and easily accessible, could be significant.

References

· Albert, C.M., Oh, K., Whang, W., et al. 2005. Dietary Alpha-Linolenic Acid Intake and Risk of Sudden Cardiac Death and Coronary Heart Disease Circulation. 112:3232-3238.

Research Abstract: Long-term effect of dietary alpha-linolenic (ALA) or docosahexaenoic acid (DHA) on the incorporation of DHA in membranes and its influence on rat heart in vivo Adey Ayalew-Pervanchon1, Delphine Rousseau, Daniel Moreau, Patrick Assayag, Pierre Weill5, and Alain Grynberg. Am J Physiol Heart Circ Physiol (May 25, 2007). doi:10.1152/ajpheart.00194.2007

This study was designed to evaluate if a long-term dietary ALA intake supplied as whole grain extruded linseed can increase the endogenous production of n-3 LC-PUFAs in healthy adult rats, influence heart rate (HR) and adrenergic response like DHA-rich diets do. The DHA enrichment was evaluated using fatty acid analysis of tissue phospholipids after 8, 16, 24 and 32 weeks of feeding in male Wistar rats randomly assigned to 3 dietary groups (n=8 in each group/ period) fed a reference fat (RFD) or ALA-rich diet (ALA) or DHA-rich diet (DHA). A week before sacrifice, under anaesthesia, HR was measured from ECG recordings during an adrenergic stimulation challenge (n=8). Dietary ALA produced a significant increase of DHA in cardiac membranes as compared to RFD-fed rats. The DHA content in cardiac membrane was close to 10% with ALA rich diet vs 20% with the DHA rich diet and 4% with the RFD diet. The cardiac fatty acid-profile was established after 2 months and remained mainly unchanged after. Whatever the diet, DHA in heart decreased with age. Nevertheless it remained over 15% with pure DHA and heart from older ALA-fed rats remained richer in DHA than those from younger RFD fed rats. Basal HR decreased with ALA (395±24.9 bpm) intermediate between those of DHA (375±26.4 bpm) and RFD (407±36.7 bpm). Both n-3 dietary intakes contribute to enhance the chronotropic response to adrenergic agonist stimulation. The regulation of HR by nuro-humoral mediators may be controlled by lower content of DHA, such as those brought by a dietary supply of extruded linseed (ALA).

+The Effect of ALA on Inflammatory Biomarkers

ALA and Effects on Inflammatory Biomarkers

ALA may lower Coronary Heart Disease risk through effects on inflammatory biomarkers  most notably C-reactive protein (CRP). Lowering blood levels of CRP which promotes arterial inflammation may be as important as reducing LDL cholesterol for preventing heart attacks and strokes. Half of all heart attacks and strokes in Canada and the United States occur in people with normal cholesterol levels and 20% of all events occur in people with no major risk factors.

It has been demonstrated that CRP levels, when added to the traditional ways of measuring risk, provide a better way of detecting who is a high-risk patient, than assessment of serum lipids alone. In randomized, controlled, crossover studies (the "gold standard" for clinical research) conducted in hypercholesterolemic men and women, a diet high in ALA (from flaxseed oil and walnuts) dramatically decreased CRP. Cross-sectional data from women involved in the Nurses' Health Study demonstrated an inverse association between ALA intake and plasma concentrations of CRP.

References

· American Heart Association. Inflammation, Heart Disease and Stroke: The Role of C-Reactive Protein. http://www.americanheart.org/presenter.
· Bemelmans, W.J.E., Lefrandt, J.D., Feskens, E.J.M., et al. 2004. Increased alpha-linolenic acid intake lowers C-reactive protein, but has no effect on markers of atherosclerosis. Eur J Clin Nutr. 58:1083-89
· Lopez-Garcia, E, Schulze, MB, Manson, JE, et al. 2004. Consumption of n3 fatty acids is related to plasma biomarkers of inflammation and endothelial activation in women. J Nutr. 134:1806-1811

+The Effect of ALA on Osteoporosis and Bone Loss

ALA: Osteoporosis

ALA may help prevent bone loss and osteoporosis by blocking the production of cytokines, especially tumor necrosis factor α (TNF-α), which promotes bone resorption and inhibits bone formation. A study of overweight or obese adults (20 men and 3 women) found significant reductions in TNF-α when the volunteers consumed for 6 weeks a diet rich in ALA obtained from walnuts, walnut oil and flax oil compared with when they consumed an average American diet (99).

When bone metabolism was measured in these same volunteers, the high-ALA diet reduced bone resorption without reducing bone formation. The decrease in bone resorption may have been due to a decrease in the dietary n-6/n-3 ratio as a result of the high-ALA diet.

References

· Morris, Diane H. 2007. Flax - A Health and Nutrition Primer, Fourth Edition, 2007, courtesy of Flax Council of Canada.
· Boyce BF, Li P, Yao Z, et al. 2005. TNF-α and pathologic bone resorption. Keio J. Med. 54: 127-131.
· Teitelbaum SL. Osteoclasts: culprits in inflammatory osteolysis. Arthritis Res. Ther. 8: 201. DOI: 10.1186/ar1857. [Internet]. 2006. [cited 2007 July 3]. Available from: http://arthritis-research.com/content/8/1/201
· Griel AE, Kris-Etherton PM, Hilpert KF, et al. 2007. An increase in dietary n-3 fatty acids decreases a marker of bone resorption in humans. Nutr. J. 6: 2. DOI: 10.1186/1475-2891-6-2. [Internet]. [cited 2007 April 16]. Available from: http://www.nutritionj.com/content/6/1/2

+The Effect of ALA on Other Clinical Conditions

Potential of ALA in Other Clinical Conditions

Inflammatory Disorders

ALA may have protective effects in inflammatory disorders such as rheumatoid arthritis and systemic lupus erythmetosus. The anti-inflammatory actions of ALA are attributed to its ability to inhibit the production of pro-inflammatory eicosanoids such as TXB2.

Immune Function

ALA in flaxseed has been shown to have positive effects on immune function, which is the body’s ability to defend itself against infection. This may be particularly important in the management of autoimmune disorders such as lupus nephritis. In a 1995 study, nine patients were fed 15g of flaxseed daily for four weeks. The dosage was then increased to 30g and then 45g daily for subsequent periods of four weeks. The researchers concluded that 30g of flaxseed showed benefit in terms of kidney function as well as other inflammatory parameters. The positive effects of ALA on immune function are believed to be due to its effects on membrane phospholipids, as well as eicosanoid and cytokine production.

Cancer

A review of the literature on the anti-carcinogenic properties of ALA and omega-3 fatty acids indicated an inhibitory effect of dietary ALA on tumor incidence and growth in animal models using chemically induced, transplantable and spontaneous tumors. These results have been reported for cancers of the breast, colon, pancreas, and splenocytes.

References

· Das, U.N. 1991. Interaction(s) between essential fatty acids, eicosanoids, cytokines, growth factors and free radicals: relevance to new therapeutic strategies in rheumatoid arthritis and other collagen vascular diseases. Prostaglandins Leukot Essent Fatty Acids; 44(4):201-10.
· Mohan, I.K., Das, U.N. 1997. Oxidant stress, anti-oxidants and essential fatty acids in systemic lupus erythematosus. Prostaglandins Leukot Essent Fatty Acids; 56(3):193-8.
· Clark, W.F., Parbtani, A., Huff, M.W., Spanner, E., de Salis, H., Chin-Yee, I., Philbrick, D.J., Holub, B.J. 1995. Flaxseed: A Potential Treatment for Lupus Nephritis. Kidney Inter.; 48:475.
· Calder, P. 1998. Immunoregulatory and anti-inflammatory effects of n-3 polyunsaturated fatty acids. Braz J Med Biol Res., 31(4):467-90.
· Lanzmann-Petithory, D. 2001. Alpha-Linolenic Acid and Cardiovascular Diseases. J Nutr Health Aging; 5(3): 179-183.<
· Johnson, P.V. 1995. Flaxseed Oil and cancer: alpha-linolenic acid and carcinogenesis. In: Flaxseed in Human Nutrition. eds. S.C. Cunnane and L.U. Thompson, AOCS Press. Champaign, IL, p. 207-218.

Download Printer Friendly Version (PDF)

*These statements have not been evaluated by the FDA. The information provided is intended solely for informational and educational purposes. Our products are not intended to diagnose, treat, cure or prevent any disease. They are intended to be included as part of a healthy diet that includes regular exercise. Please consult a medical or health professional regarding questions about your health.