Flax Seed: A Valuable Dietary Supplement

Flax seed contains a wealth of compounds—like EFAs and lignans—that can exert beneficial health effects on the body.

Flax seed naturally contains a complex of different categories of essential fatty acids (EFAs), including the omega-3 alpha-linolenic acid (ALA), omega-6 linoleic acid (LA) and omega-9 oleic acid. Much of flax seed’s benefits are a function of its content of ALA, which can be converted in the body to the longer-chain omega-3 eicosapentaenoic acid (EPA). Research has shown supplementation with flax seed oil can effectively increase EPA concentrations in tissues.¹

One of the strongest areas of research has been inflammation. Many factors contribute to the complex course of inflammatory reactions, including the omega- 6 fatty acid, arachidonic acid (AA). AA can be converted via an enzymatic process into pro-inflammatory substances, including series-2 prostaglandins, leukotrienes and cytokines. Flax ALA can convert into EPA, which has the ability to convert into series-3 prostaglandins that have anti-inflammatory properties. In states of inflammation, ALA and EPA are able to compete with AA for enzymatic metabolism, which results in less production of pro-inflammatory substances.² Studies have found the use of flax seed oil in domestic food preparation can reduce production of inflammatory cytokines.³

Studies have shown the ability of omega-3 rich fish oil to inhibit inflammatory mechanisms in the autoimmune disease lupus nephritis,⁴ leading to investigations into whether flax may also have activity in this area. In one trial, nine people with kidney damage due to systemic lupus erythematosus (SLE) were fed increasing amounts of flax seed for 12 weeks.⁵ Researchers found 30 g/d was the optimal intake for improving kidney function, decreasing inflammation and reducing at herosclerotic development. Flax seed also contains antioxidants, which may be helpful to those with SLE.⁶

Research has also investigated the hormonal modulating effects of ingesting lignans, antioxidant and phytoestrogenic compounds found in flax seed. There is epidemiological, laboratory and clinical evidence indicating phytoestrogens have an anti-cancer effect on the breast.⁷ Experimental studies in animals and humans have demonstrated flax’s anti-cancer effects.⁸ In fact, a 1998 review indicated consumption of flax seed may be used as a secondary prevention method for breast cancer.⁹

Flax seed may also promote prostate health. Jonathon Wright, M.D., said his clinical experience suggests flax seed oil can play a key role in the treatment of an enlarged prostate.¹⁰ Animal research supports the idea; in one such study, rats with lifetime exposure to 5-percent flax seed diets experienced a reduction in relative prostate weight and cell proliferation, suggesting potential protect ion against prostatic disease.¹¹

The cardiovascular system is another area of research focus for flax. In one study, 15 subjects with high serum cholesterol levels who were taking vitamin E were given 15 g/d of a flax seed supplement.¹² After three months, serum total and low-density lipoprotein (LDL) cholesterol levels were reduced significantly, but high-density lipoprotein (LDL) cholesterol did not change. Other research has shown serum lipid level reduction, but fairly large amounts of flax seed had to be consumed in these studies to emulate the same lipid-lowering effect of fish oils.¹³ In one such study, young healthy adults given 50 g/d of flax seed for four weeks experienced an 8 percent reduction in plasma LDL cholesterol.¹⁴ In a similar study, healthy female volunteers consuming 50 g/d of flax seed for four weeks experienced a 9 percent reduction in serum total cholesterol, and an 18 percent reduction in LDL cholesterol.¹⁵

Flax lignans also possess antiplatelet activating factor activity (i .e., preventing blood platelet s from clumping, thereby improving circulation) and antioxidant activity. In animal research, flaxseed reduced the development of aortic atherosclerosis by 46 percent and suppressed oxygen- free radicals. Researchers concluded: “Dietary flaxseed supplementation could, therefore, prevent hypercholesterolemia-related heart attack and strokes.”¹⁶

Finally, the elasticity of arteries is an important indicator of circulatory function, which diminishes as cardiovascular risk increases. Research has shown obese people who consumed a diet high in ALA from flax seed oil experienced a marked rise in arterial elasticity, reflecting a rapid functional improvement in the arterial circulation.¹⁷

While f lax seed offers many potential benefits, ingesting the correct form of supplemental flax seed is critical to realizing them. Although flax seed oil supplements are a good source of EFAs, they do not provide appreciable amounts of the valuable lignans. On the other hand, whole or ground flax seed, though effective, is not especially palatable. The best option may be a flax seed powder in capsule form, delivering EFAs and lignans. Although some of the aforementioned research utilized extremely high quantities of flax seed, the nutritional value and certain beneficial results could be realized by consuming about 3,000 mg (3 g) daily.

References

1. Mantzioris E et al. Am J Clin Nutr. 1994;59(6):1304-9.

2. Heller A et al. Drugs. 1998;55(4):487-96.

3. James MJ, Gibson RA, Cleland LG. Am J Clin Nutr. 2000;71(1Suppl):343S-8S.

4. Clark WF, Parbtani A. Am J Kidney Dis. 1994;23(5):644-7.

5. Clark WF et al. Kidney Int. 1995;48:475–80.

6. Prasad K. Mol Cell Biochem. 1997;168:117–23.

7. Brzezinski A, Debi A. Eur J Obstet Gynecol Reprod Biol. 1999; 85(1):47-51.

8. Thompson LU. Bailliere’s Clin Endocrinol Metab. 1998;12(4):691-705.

9. Goss PE, Sierra S. J Clin Oncol. 1998;16(1):338-47.

10. Personal communication with Dr. Jonathon Wright, June 2000.

11. Tou JC, Chen J, Thompson LU. J Toxicol Environ Health. 1999;56(8):555-70.

12. Bierenbaum ML, Reichstein R, Watkins TR. J Am Coll Nutr. 1993;12(5):501-4.

13. Harris WS. Am J Clin Nutr. 1997;65(5 Suppl):1645S.

14. Cunnane SC et al. Am J Clin Nutr. 1995;61(1):62-8.

15. Cunnane SC et al. Br J Nutr. 1993;69(2):443-53.

16. Prasad K. Atherosclerosis. 1997;132(1):69-76.

17. Nestel PJ et al. Arterioscler Thromb Vasc Biol. 1997;17(6):1163-70.

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