Flaxseed

Overview

Flaxseed oil is well known as one of the best sources of the essential fatty acids. It contains approximately 50-60% of the omega-3 essential fatty acid known as linolenic acid or alpha-linolenic acid and roughly 18-20% of the omega-6 essential fatty acid known as linoleic acid. Although flaxseed oil contains ample amounts of both essential fatty acids, its true importance is due to the fact that it is nature’s richest source of linolenic acid, which is frequently deficient in American diets. The essential fatty acids have several important functions. They are a necessary component of cell walls and cellular membranes throughout the body, they play an important role in energy production, and they regulate the metabolism of cholesterol and triglycerides. The essential fatty acids are also the precursors for the prostaglandins, which are hormone-like compounds that control a great deal of the biochemical activity within the body. Consequently, the essential fatty acids play a role in a wide range of health conditions.

Unfortunately, most Americans consume diets that contain too much of the omega-6 fatty acids along with a serious lack of omega-3 fatty acids. Since flaxseed oil is nature’s best source of the parent omega-3 fatty acid, linolenic acid, it has become a very important nutritional supplement.

Two forms of flaxseed oil are available. When natural components such as lignans and other soluble and insoluble fibers have been removed, the resulting oil has a golden yellow color. However, many people prefer flaxseed oil with lignans because lignans are known to provide additional anti-cancer activity. (1) Flaxseed oil that retains the lignans and other fiber components has a dark "muddy" appearance. Since these substances tend to settle out, this form of flaxseed oil should be shaken well before using.

Dosage Info

Dosage Range

From 1 to 2 tablespoonsful daily.

Most Common Dosage

1 tablespoonful daily.

Dosage Forms

Oil, gelcaps, and seeds.

Adult RDI

None established

Adult ODA

None established

Active Forms

Flaxseed oil (filtered) and flaxseed oil (unfiltered)

Absorption

The fats in flaxseed oil are absorbed from the small intestine in humans.

Toxicities & Precautions

General

Flaxseed oil contains unsaturated fatty acids, which are highly susceptible to rancidification, otherwise know as oxidation. This process generates free radicals, which can be very destructive. When flaxseed oil becomes rancid, it develops a sharp/bitter taste, which signifies that it should be discarded.

Flaxseed oil should be protected from heat, light, and oxygen because these conditions promote its oxidation.

Flaxseed oil should never be used for cooking and should be kept refrigerated after opening the bottle.

Individuals taking flaxseed oil should be encouraged to take adequate antioxidant nutrients, especially vitamin E.

Functions in the Body

Phospholipids

The essential fatty acids in flaxseed oil are vital components of the phospholipids that are a major part of the architectural structure of cellular membranes throughout the body. (2)

Prostaglandins

The essential fatty acids are precursors in the production of prostaglandins, which are hormone-like regulatory chemicals that control a tremendous amount of biochemical activity in all cells of the body. (3)

Cholesterol Metabolism

The essential fatty acids are important regulators of cholesterol metabolism in the body. (4)

Clinical Applications

Cardiovascular Disease

Omega-3 fatty acids lower plasma triglycerides, reduce platelet aggregation, relax blood vessels, and lower blood pressure. (5)

Skin Conditions

Abnormalities in fatty acid metabolism found in people with problems such as psoriasis and eczema and therapy with omega-3 fatty acids is frequently beneficial. (6)

Depression

Epidemiological studies from various countries and in the United States suggest that decreased consumption of omega-3 fatty acids correlates with increasing rates of depression. (7)

Elevated Cholesterol

Dietary alpha-linolenic acid is reported to lower cholesterol levels in the blood and in liver tissues. (8) , (9) , (10)

Osteoporosis

Flaxseed oil supplementation in healthy humans reduces the production of inflammatory cytokines, which results in increased calcium absorption and increased bone density. (11)

Strokes

In the Edinburgh Artery Study, individuals with strokes had significantly lower levels of alpha-linolenic in their red blood cell phospholipids, which suggests that supplementation with flaxseed oil could play a role in preventing strokes. (12)

Vegetarians

Studies report that vegetarians have lower platelet and plasma concentrations of n-3 polyunsaturated fatty acids and increased platelet stickiness compared to omnivores. Supplementation with flaxseed oil increased the omega-3 fatty acid concentrations in the platelet phospholipids and plasma lipids of male vegetarian volunteers. (13)

Asthma

Supplemental omega-3 resulted in a decrease in asthma attacks and a reduction in the use of medications. (14)

Immune Enhancement

When additional dietary linolenic acid is administered to healthy men, several different measurements of immune function improved. (15)

ADHD

Children with Attention Deficit Hyperactivity Disorder (ADHD) have significantly lower concentrations of EPA and DHA compared to controls. (16)

Cancer

Low levels of omega-3 fatty acids are associated with increased incidence of breast cancer, (17) prostate cancer, (18) and colon cancer. (19)

Hypertension

Supplementation with the longer-chain omega-3 fatty acids provides a slight lowering of blood pressure. Reductions range between 3 and 10 mm Hg for both systolic and diastolic pressures. (20)

Rheumatoid Arthritis

Patients in a year-long double-blind study who took 2.6 gm of omega-3 daily experienced significant global improvements and pain reduction, which allowed a corresponding reduction in the use of pain medication. (21)

Symptoms and Causes of Deficiency

Since flaxseed oil is not produced in the body, no flaxseed oil deficiency condition exists. However, the diets of many people do not provide optimal amounts of the essential fatty acids, which is a problem that can cause or contribute to a wide variety of health problems. In general, many health problems are associated with a deficiency of omega-3 fatty acids and an excess of omega-6 fatty acids. With a ratio of approximately 60% omega-3 to 20% omega-6, flaxseed oil is one of the best options available to help reverse the imbalance between omege-3 and omega-6 that is so common in the United States.

Dietary Sources

Flaxseed oil is contained in flaxseeds. However, eating flaxseeds does not provide adequate amounts of flaxseed oil. Generally flaxseed oil is purchased as a commercial product after manufacturers have safely extracted and bottled the oil.

References

  1. View Abstract: Thompson LU. Experimental studies on lignans and cancer. Baillieres Clin Endocrinol Metab. Dec1998;12(4):691-705.
  2. View Abstract: Innis SM. Essential fatty acid requirements in human nutrition. Can J Physiol Pharmacol. Sep1993;71(9):699-706.
  3. Bender DA, Bender AE. Nutrition: A Reference Handbook. New York: Oxford University Press; 1997:131-133.
  4. View Abstract: Horrobin DF, Manku MS. How do polyunsaturated fatty acids lower plasma cholesterol levels? Lipids. Aug1983;18(8):558-62.
  5. View Abstract: Kinsella JE, et al. Dietary n-3 Polyunsaturated Fatty Acids and Amelioration of Cardiovascular Disease: Possible Mechanisms. Am J Clin Nutr. Jul1990;52(1):1-28.
  6. View Abstract: Isseroff RR. Fish Again for Dinner! The Role of Fish and other Dietary Oils in the Therapy of Skin Disease. J Am Acad Dermatol. Dec1988;19(6):073-80.
  7. View Abstract: Hibbeln JR, et al. Dietary polyunsaturated fatty acids and depression: when cholesterol does not satisfy. Am J Clin Nutr. Jul1995;62(1):1-9.
  8. View Abstract: Garg ML, et al. Alpha-linolenic Acid and Metabolism of Cholesterol and Long-chain Fatty Acids. Nutrition. May1992;8(3):208-10.
  9. View Abstract: Ranhotra G, Gelroth J, Glaser B, et al. Lipidemic responses in rats fed flaxseed and sunflower oils. Cereal Chemistry. 1992;69(6):623-625.
  10. View Abstract: Ranhotra G, Gelroth J, Glaser B, Potnis PS. Lipidemic responses in rats fed flaxseed oil and meal. Cereal Chemistry. 1993;70(3):364-366.
  11. View Abstract: Endres S. n-3 polyunsaturated fatty acids and human cytokine synthesis. Lipids. Mar1996;31(Suppl):S239-42.
  12. View Abstract: Leng GC, Taylor GS, Lee AJ. Essential fatty acids and cardiovascular disease: the Edinburgh Artery Study. Vasc Med. 1999;4(4):219-26.
  13. View Abstract: Li D, Sinclair A, Wilson A, et al. Effect of dietary alpha-linolenic acid on thrombotic risk factors in vegetarian men. Am J Clin Nutr. 1999 May;69(5):872-82.
  14. View Abstract: Masuev KA. The Effect of Polyunsaturated Fatty Acids of the Omega-3 Class on the Late Phase of the Allergic Reaction in Bronchial Asthma Patients. Ter Arkh. 1997;69(3):31-33.
  15. View Abstract: Kelley DS, et al. Dietary alpha-linolenic acid and immunocompetence in humans. Am J Clin Nutr. Jan1991;53(1):40-6.
  16. View Abstract: Stevens L, et al. Essential fatty acid metabolism in boys with attention-deficit hyperactivity disorder. Am J Clin Nutr. 1995;62:761-768.
  17. View Abstract: Bagga D, et al. Dietary Modulation of Omega-3/Omega-6 Polyunsaturated Fatty Acid Ratios in Patients with Breast Cancer. J Natl Cancer Inst. Aug1997;89(15):1123-31.
  18. View Abstract: Pandalai PK, et al. The Effects of Omega-3 and Omega-6 Fatty Acids on in Vitro Prostate Cancer Growth. Anticancer Res. Mar1996;16(2):815-20.
  19. View Abstract: Anti M, et al. Effect of Omega-3 Fatty Acids on Rectal Mucosal Cell Proliferation in Subjects at Risk for Colon Cancer. Gastroenterology. Sep1992;103(3):883-91.
  20. View Abstract: Knapp HR, et al. The Antihypertensive Effects of Fish Oil. A Controlled Study of Polyunsaturated Fatty Acid Supplements in Essential Hypertension. N Engl J Med. Apr1989;320(16):1037-43.
  21. View Abstract: Geusens P, et al. Long-term Effect of Omega-3 Fatty Acid Supplementation in Active Rheumatoid Arthritis. A 12-month, Double-blind, Controlled Study. Arthritis Rheum. Jun1994;37(6):824-29.