Flax

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Linum usitatissimum L.

[Fam. Linaceae]

Overview

Flax has become popular in the mainstream market in many forms including raw seeds and expressed oils, and as an ingredient in breads, muffins, cereals, and breakfast bars (Blumenthal et al., 2000). The oil from flaxseed, also called linseed, is one of the most concentrated plant sources of omega-3 fatty acids. It is also one of the most concentrated sources of lignans (phenolic resins found in many plants) containing 100–800 times the amount found in other foods (Mazur et al., 1998; Mazur, 1998; Thompson et al., 1991). Current research suggests that flax lignans are anti-atherogenic (Prasad, 1997), antioxidant, hypocholesterolemic, and anticarcinogenic (Nesbitt and Thompson, 1997). Flax, and some of its derivatives, is being studied for lowering LDL serum cholesterol, prevention of some cancers, and treatment of systemic lupus erythematosus (SLE). The largest flax producer is Canada (Haggerty, 1999). Flaxseed is an increasingly common ingredient in conventional foods, and is eaten either raw or in baked goods. Because phytochemicals (lignans and alpha-linolenic acid) from whole flaxseeds are poorly absorbed in the body, many people prefer to crush the seeds in order to obtain the optimal health benefit.

Description

Flax preparations consist of the dried, ripe seed of all varieties of Linum usitatissimum L. [Fam. Linaceae] (Blumenthal et al., 1998). The seeds can be consumed raw or in baked foods. Commercial preparations include ground seed, gruel, and expressed oil. The oil is marketed in bottles or in soft-gel capsules and contains 59% alpha-linolenic acid (ALA) (Bhatty, 1995).

Primary Uses

Internal

Cardiovascular

Hyperlipidemia (Jenkins et al., 1999; Arjmandi et al., 1998a; Nestel et al., 1997; Bierenbaum et al., 1993; Cunnane et al., 1995)

Atherosclerosis (risk reduction) (Caughey et al., 1996; Allman et al., 1995; Bierenbaum et al., 1993)

Breast Cancer

May reduce risk of breast cancer and metastasis (Haggans et al., 1999; Ingram et al., 1997; Phipps et al., 1993; Bougnoux et al., 1994; Willett et al., 1992)

Gastrointestinal

Chronic constipation (Cunnane et al., 1995; Blumenthal et al., 1998)

Colon damage by laxative abuse (Blumenthal et al., 1998)

Irritable colon (Blumenthal et al., 1998)

Diverticulitis (Blumenthal et al., 1998)

Gastritis and enteritis, as a mucilage (Blumenthal et al., 1998)

Other Potential Uses

Internal

Osteoporosis (reduction of resorption rate) (Arjmandi et al., 1998b)

Lupus nephritis (Clark et al., 1995)

Prostate cancer (may reduce hormone and cell proliferation levels, may increase apoptosis) (Demark-Wahnefried et al., 2001)

Rheumatoid arthritis (Nordstrom et al., 1995; Caughey et al., 1996)

External

Inflammation, local, as a poultice (Blumenthal et al., 1998)

Dosage

Internal

Crude Preparations

Bruised or whole seed: 1 tablespoon (5 g) of whole, “bruised”, or ground seed, is soaked in water, and taken with a glassful of liquid 3 times daily. It is usually preferable to grind the seeds to improve the absorption of phytochemicals and the resulting therapeutic efficacy. Note: The effect typically begins 18–24 hours later (ESCOP, 1997).

Mucilage (gruel): 2–3 tablespoons of milled flaxseed are soaked in 200–300 ml water and strained after 30 minutes.

Oil: 1–2 tablespoons daily (Blumenthal et al., 1998)

Flax oil capsules: 3–6 capsules containing 1,000 mg each oil for general health maintenance.

External

Crude Preparations

Cataplasm (poultice): Semisolid paste containing 30–50 g flaxseed flour for a moist-heat direct application to the skin, used like a poultice as a counter-irritant. Draws blood to the surface to remove deep-seated inflammation. Note: Flaxseed meal is traditionally mixed with mustard seed powder in this application.

Compress or fomentation: Cloth saturated with a hot semisolid preparation containing 30–50 g flaxseed flour. Folded and applied firmly for a moist-heat direct application to the skin to relieve pain or inflammation (Blumenthal et al., 1998).

Note about proper storage: Flax oil and ground flaxseeds must be stored in air tight containers in a cool area away from direct sun. Flax oil soft-gel capsules can be stored at room temperature in air tight bottles.

Duration of Administration

Internal

Crude Preparations (from flaxseeds)

Flax can be used continuously as a nutritional source (Bhatty, 1995), or as a bulk laxative.

Chemistry

Flaxseed contains 30–45% fixed oil, including triglycerides of alpha-linolenic, linoleic, oleic, stearic, palmitic, and myristic acids; 20–25% proteins; 3–10% mucilage, composed of neutral and acidic polysaccharides which, after hydrolysis, yield 8–10% galactose, 9–12% arabinose, 13–29% rhamnose, 25–27% xylose and galacturonic and about 30% mannuronic acids, sterols, and triterpenes (campesterol, stigmasterol, and sitosterol); 0.1–1.5% cyanogenic glycosides, mostly linustatin and neolinustatin and the monoglycosides linamarin and lotaustralin; and secoisolariciresinol diglucoside (SDG) (a precursor of lignans in mammals) (Bhatty, 1995; Budavari, 1996; ESCOP, 1997). A rapid RP-HPLC method was developed to quantify the lignan SDG in baked goods containing flaxseed or flax meal. Finely ground materials were found to have a significantly greater content of SDG than course materials (Muir and Westcott, 2000).

Pharmacological Actions

Crude Preparations

Laxative (Cunnane et al., 1995; Blumenthal et al., 1998).

Ground Flax or Oil Preparations

Human

Develops brain function (Simopoulos, 1991); lowers LDL serum cholesterol (Jenkins et al., 1999; Arjmandi et al., 1998a; Bierenbaum et al., 1993); antiplatelet aggregation (Allman et al., 1995; Bierenbaum et al., 1993); anti-inflammatory (Caughey et al., 1996); antimetastatic (Bougnoux et al., 1994); reduces proteinuria; increases creatinine clearance; and reduces glomerulosclerosis (Clark et al., 1995).

Animal

Develops neurotransmission, neuromusculation, and cognition (Walker, 1967; Lamptey et al., 1976; Delion et al., 1994, 1996; Frances et al., 1995, 1996); may reduce breast and colon cancer risk (Serraino and Thompson, 1991, 1992a, 1992b; Jenab and Thompson, 1996); suppresses mammary tumor growth (Thompson et al., 1996); prevents atherosclerosis (Prasad, 1997); regulates fertility and sperm quality (Kelso et al. 1997; Arya and Caglj, 1993).

In vitro

Anti-cancer in human breast, lung, and prostate cells, and in mouse myeloma cells (Begin et al., 1986; Kumar and Das, 1995).

Mechanism of Action

Stimulates bowels. Flax binds to water, mucilage swells, and stool volume increases (Weiss and Fintelmann, 2000; De Smet et al, 1997).

Facilitates passage of feces through bowel through lubrication by the oil (Weiss and Fintelmann, 2000; De Smet et al., 1997).

Supports and develops brain function by increasing levels of docosahexaenoic acid (DHA), the major component of cell membranes of cerebral cortex and myelin sheaths (Horrobin, 1982; Simopouls, 1991).

Reduces cholesterol levels by increasing prostaglandins E1 and E3 (PGE1 and PGE3), which inhibit cholesterol synthesis and stimulate cholesterol movement across cell membranes (Horrobin, 1982).

Reduces platelet aggregation by increasing levels of PGE1 and PGE3 (Horrobin, 1982).

Reduces inflammation by lowering arachidonic acid levels and driving synthesis of series 1 and 3 prostaglandins (Horrobin, 1982).

Increases concentrations of sex hormone binding globulin (SHBG) by lignans (Adlercreutz et al., 1987, 1992).

Binds steroid hormones to its insoluble fiber, thereby reducing estrogen concentrations in circulation (Whitten and Shultz, 1988; Goldin et al., 1982).

Protects against degenerative disease by supplying omega-3 essential fatty acids (EFAs) (Budwig, 1953).

Contraindications

Ileus of any origin (flaxseeds) (Blumenthal et al., 1998).

Pregnancy and Lactation: No known restrictions. EFA supplementation during pregnancy and nursing is beneficial for fetal and infant brain development and visual function (Simopoulos, 1991; Horrobin, 1982).

Adverse Effects

None known at therapeutic dosages and following directions (i.e., consumption of adequate amounts of liquid, 1:10) (Blumenthal et al., 1998).

Drug Interactions

As with any other mucilage, the whole or crushed seeds may negatively affect the absorption of other orally ingested drugs (Blumenthal et al., 1998), although this is mainly speculative (Brinker, 2001). May also inhibit absorption of dietary nutrients (McGuffin et al., 1997).

Flax Oil: None known.

American Herbal Products Association (AHPA) Safety Rating

Class 2d: Can be safely consumed with the following restriction: Take with at least 150 ml (6 ounces) liquid. Contraindicated in bowel obstruction (i.e., flaxseeds).

Regulatory Status

Austria: Dried ripe seed official in the Austrian Pharmacopoeia, ÖAB (Meyer-Buchtela, 1999; Wichtl, 1997).

Canada: Flaxseed is approved as a component of multiple-ingredient Schedule OTC (over-the-counter) Traditional Herbal Medicines (THMs), as a component of Schedule OTC nutritional agents, and as a single-ingredient homeopathic drug, all requiring premarket registration and assignment of a Drug Identification Number (DIN) (Health Canada, 2001).

China: Dried ripe seed official in the Pharmacopoeia of the People’s Republic of China (PPRC, 1997).

European Union: Dried ripe seed official in the European Pharmacopoeia (Ph.Eur. 1997).

France: Dried ripe seed official in the French Pharmacopoeia, Ph.Fr.X (Bruneton, 1999).

Germany: Approved non-prescription drug of the German Commission E Monographs for both internal and external use (Blumenthal et al., 1998). The gruel dosage form is an approved non-prescription drug of the German Standard License monographs (Braun et al., 1996).

India: Dried ripe seed official in the Government of India Ayurvedic Pharmacopoeia of India (API I, 1989) and is an approved single-drug dispensed in the Unani system of medicine (CCRUM, 1992).

Sweden: Component of multiple-herb products regulated as food without health claim (Tunón, 1999). As of January 2001, no flax products are listed in the Medical Products Agency (MPA) “Authorised Natural Remedies” (MPA, 2001).

Switzerland: Dried, ripe seed official in the Swiss Pharmacopoeia, Ph.Helv. (Wichtl, 1997). Component of multiple-ingredient herbal medicines with positive classification (List D) by the Interkantonale Konstrollstelle für Heilmittel (IKS) and corresponding sales category D, with sale limited to pharmacies and drugstores, without prescription (Morant and Ruppanner, 2001; Codex, 2000/01).

U.K.: Linseed oil is on the General Sale List, Schedule 1 (medicinal product requiring a full product license), Table B (external use only) (GSL, 1994).

U.S.: Food or dietary supplement if structure-function label statement is made (USC, 1994).

Clinical Review

Eighteen studies are outlined in the following table, “Clinical Studies on Flax” including a total of 90,648 participants. All but two of these studies (Nordstrom et al., 1995; McManus et al., 1996), demonstrated positive effects for cardiovascular health, breast cancer, prostate cancer, lupus, and arthritis. One randomized, double-blind, placebo-controlled (R, DB, PC) study performed on 22 participants using flaxseed oil concluded that the duration of supplementation may have been too short to have an effect on rheumatoid arthritis, or that missing co-factors may have interfered with the clinical outcomes of this study (Nordstrom et al., 1995). Two R, DB crossover trials found that flaxseed baked in food products produced a significant decrease in LDL cholesterol and in retarding the rate of bone resorption (Arjmandi et al., 1998a; Arjmandi et al., 1998b). In another study, consumption of flaxseed oil had no effect on glycemic control or insulin secretion (McManus et al., 1996). A R, PC, single-blind, crossover trial found partially defatted flaxseed baked in food products reduced LDL serum cholesterol levels to concentrations associated with ingestion of full-fat flaxseed (Jenkins et al., 1999). One study found secondary prevention of heart attack (De Lorgeril et al., 1994). Two epidemiological reports found a reduction in the incidence of breast cancer or metastasis in women who used flaxseed oil (Bougnoux et al., 1994; Willett et al., 1992). One recent pilot study using flaxseed with and without a low-fat diet in older men with prostate cancer showed reduction in testosterone and prostate cancer cell proliferation rates and higher rates of apoptosis (Demark-Wahnefried et al., 2001).

Branded Products

Alena™: ENRECO / P.O. Box 186 / Newton, WI 53063-0186 / U.S.A. / Tel.: 800-962-9536 / Fax: 920-926-4224 / Email: info@enreco.com / www.enreco.com. Ground stabilized flaxseed, 1,450 mg omega-3 fatty acids per tablespoon.

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