Flaxseed
Flaxseed
Description
Flaxseed (also called linseed) comes from the flax plant (Linum usitatissimum ), which belongs to the Linaceae plant family. The flax plant is a small, single-stemmed annual that grows to about 2 ft (0.6 m) tall and has grayish green leaves and sky-blue flowers. Historically, flax has been cultivated for thousands of years. Linen made from flax has been found in the tombs of Egyptian pharaohs and is referred to in the Bible and in Homer's Odyssey. The Roman naturalist Pliny wrote about the laxative and therapeutic powers of flax in the first century a.d., and many authorities believe it has been used as a folk remedy since ancient times. Flax is believed to be native to Egypt, but its origins are questionable since it has been used widely around the world. It is cultivated in many places, including Europe, South America, Asia, and parts of the United States. Only the seeds (flaxseed) and oil of the flax plant (flaxseed oil) are used medicinally. Linseed oil is the term usually used for the oil found in polishes, varnishes, and paints.
Flaxseed oil is derived from the flax plant's crushed seeds, which resemble common sesame seeds but are darker. The amber oil is very rich in a type of fat called alpha-linolenic acid (ALA), an omega-3 fatty acid that is good for the heart and found in certain plants. High amounts of omega-3 fatty acids are found in fish and smaller amounts are found in green leafy vegetables, soy-derived foods, and nuts. Many doctors consider these acids important for cardiovascular health. Studies suggest that they can lower triglyceride levels and reduce blood pressure. Omega-3 fatty acids may also decrease the risk of heart attacks and strokes by preventing the formation of dangerous blood clots within arteries. In high dosages, the fatty acids may help to alleviate arthritis, though flaxseed products have not yet been shown to be effective for this purpose.
In addition to omega-3 fatty acids, flaxseed products also contain potentially therapeutic chemicals called lignans. Lignans are believed to have antioxidant properties and may also act as phytoestrogens, very weak forms of estrogen found in fruits, vegetables, whole grains, and beans. Unlike human estrogen, phytoestrogens have dual properties: they can mimic the effects of the hormone in some parts of the body while blocking its effects in others. Many herbalists believe that phytoestrogens can be useful in the prevention or treatment of a variety of diseases, including cancer , cardiovascular disease, and osteoporosis . The estrogen-blocking effects of phytoestrogens may be particularly effective at combating certain cancers that depend on hormones, such as cancers of the breast or uterus. Women who consume large amounts of lignans appear to have lower rates of breast cancer . The fact that heart disease and certain cancers occur less frequently in Asian countries is sometimes attributed to a diet rich in plant foods containing phytoestrogens.
General use
While not approved by the United States Food and Drug Administration (FDA), flaxseed products are reputed to have a number of beneficial effects. Flaxseed is sometimes referred to as a nutraceutical, a recently coined term that includes any food or food ingredient thought to confer health benefits, including preventing and treating disease. Several studies, some conducted in people, suggest that flaxseed products (or agents contained in them) may help to keep the heart and cardiovascular system healthy. Flaxseed products may lower cholesterol levels, help control blood pressure, and may reduce the buildup of plaque in arteries. Test tube and rat studies suggest that chemicals in flaxseed may help to prevent or shrink cancerous tumors. Due to its estrogen-like effects, some women use flaxseed oil to ease breast tenderness, alleviate symptoms of premenstrual syndrome (PMS), and help control menopausal symptoms. Flaxseed oil has also been recommended to treat skin conditions, inflammation, and arthritis. It is usually taken internally for all the purposes mentioned above. The oil may be used externally to help the healing of scalds and burns .
More recently, flaxseed has been shown to be beneficial for people suffering from digestive disorders. It is now recommended as an "effective herbal agent" for treating irritable bowel syndrome (IBS).
The link between flaxseed and heart disease has been examined in a number of published studies. One of these studies published in the journal Atherosclerosis in 1997, observed the effects of adding flaxseed to the diet of rabbits with atherosclerosis . Researchers found that flaxseed reduced the development of plaque build-up by almost 50%. The authors concluded that flaxseed may help to prevent heart attacks and strokes related to high cholesterol levels. A study involving several dozen men with mild high blood pressure, which was published in the Journal of Human Hypertension in 1990, suggests that flaxseed oil may slightly lower blood pressure.
Research also suggests that flaxseed products may have potential as cancer fighters. One study, published in Cancer Letters in 1998, investigated how dietary flaxseed affects the development of cancer. Mice were fed a diet supplemented with 2.5%, 5%, or 10% flaxseed for several weeks before and after being injected with cancerous cells. The more flaxseed the mice received, the fewer tumors they developed. Depending on how much flaxseed they received, mice who were fed the herb developed fewer tumors than the mice who did not receive the flaxseed. Additionally, the tumors that developed in flaxseed-fed mice were smaller than those found in mice who did not receive flaxseed. The authors of the study concluded that flaxseed may be a useful nutritional aid in preventing the spread of cancer in people. In another study, which focused on breast cancer in rats, flaxseed flour was associated with a reduction in tumor size. In the study, which was published in Nutrition and Cancer in 1992, flaxseed flour also reduced the number of tumors that developed. However, researchers noted that more studies were needed in this area.
While the cancer-inhibiting effects of flaxseed have not been thoroughly studied in people, some practitioners of alternative medicine are already recommending the herb as a potential anticancer agent. Prominent herbalists maintain that the lignans found in flaxseed may help to control cancer of the breast or uterus. Some also recommend the herb for the prevention and treatment of endometriosis .
The therapeutic effects of flaxseed are not limited to people, according to some authorities. It is sometimes used as a purgative in horses and sheep. In addition, flaxseed is included in a rapidly expanding list of nutraceutical products for dogs, cats, and other domestic pets.
Preparations
Flaxseed products are commercially available as whole or ground seeds, gelatin capsules, and oil. Some herbalists recommend adding the ground or whole seeds to the diet to get the maximum benefit from the herb. Whole seeds can be stored in a cool, dry place for up to one year. Crushed seeds should be used immediately or frozen for future use. No standard guidelines have been established on how much of these forms should be consumed. Research subjects have been given as much as 1/4 cup of ground flaxseed per day, but a Canadian nutrition expert suggests that 1–2 tablespoons per day is enough for most adults.
Several nutraceutical companies are marketing a flaxseed ingredient as of 2002. The flaxseed ingredient is a fine-milled flour with 5% lignan content, intended for addition to commercial baked goods, snack foods, cereals, dry pet foods, and similar products.
Capsules can be taken according to package directions. Some herbalists feel that the capsules available are highly processed, contain fewer beneficial properties, and may be an expensive alternative to flaxseed oil.
The optimum daily dosage of flaxseed oil has not been established. Usually, 1 tablespoon daily of the oil can be taken for general health. As a remedy, 1-3 tablespoons may be taken daily based on the person's weight and health needs. Some people consume the oil as an ingredient in salad dressing. The oil is often combined with limewater when used to treat burns and scalds.
Precautions
Flaxseed products are not known to be harmful when taken in recommended dosages, though it is important to remember that the long-term effects of taking flax-derived remedies (in any amount) have not been studied. Due to lack of sufficient medical study, flaxseed products should be used with caution in children, women who are pregnant or breast-feeding, and people with liver or kidney disease.
Because flaxseed oil tends to become rancid relatively quickly, it should be kept in the refrigerator. While the oil may be added to cooked food, it should not be used during cooking because heat can destroy the effectiveness of the oil.
Persons who are adding ground flaxseed to their diet for its fiber content are advised to start off with small amounts and increase them gradually, and to drink plenty of water. Otherwise the high fiber content of flaxseed can produce intestinal cramping and diarrhea .
Consumers should read the labels of all flaxseed products to insure that the product is for medicinal or nutritional purposes.
Side effects
When taken in recommended dosages, flaxseed products are not associated with any significant side effects.
Interactions
Consumers should consult their healthcare professional for information on flaxseed products and interactions with medications and other remedies. More specifically, the omega-3 fatty acids in flaxseed may increase the blood-thinning effects of such medications as aspirin or warfarin. Flaxseed may help a group of medications known as statins (lovastatin, simvastatin, etc.), which are given to lower blood cholesterol, to work more effectively.
Flaxseed may help to reduce the toxic side effects (kidney damage and high blood pressure) of cyclosporine, which is a drug given to organ transplant patients to prevent rejection of the new organ.
Flaxseed appears to reduce the risk of ulcers from high doses of NSAIDs.
In general, flaxseed oil should not be taken at the same time of day as prescription medications or other dietary supplements, as it will slow down the body's absorption of them.
Resources
BOOKS
Gruenwald, Joerg. PDR for Herbal Medicines. Montvale, NJ: Medical Economics, 1998.
Pelletier, Kenneth R., MD. The Best Alternative Medicine, Part I: Food for Thought. New York: Simon & Schuster, 2002.
PERIODICALS
Aubertin, Amy. "Flaxseed Comes of Age: Good Nutrition in a Small Package." Environmental Nutrition 25 (August 2002): 2.
"Flaxseed Ingredient." (Suppliers' Corner) Nutraceuticals World 5 (September 2002): 95.
Greenberg, Michael, Heather Amitrone, and Edward M. Galiczynski, Jr. "A Contemporary Review of Irritable Bowel Syndrome. (Recertification Series)." Physician Assistant 26 (August 2002): 26-33.
"Is There Flaxseed in Your Fridge Yet?" Tufts University Health and Nutrition Letter 20 (September 2002): 3.
Lemay, A., S. Dodin, N. Kadri, et al. "Flaxseed Dietary Supplement Versus Hormone Replacement Therapy in Hypercholesterolemic Menopausal Women." Obstetrics and Gynecology 100 (September 2002): 495-504.
Prasad, K. "Dietary Flax Seed in Prevention of Hypercholesterolemic Atherosclerosis." Atherosclerosis 132, no. 1 (1997): 69-76.
Yan, L., J.A. Yee, D. Li, et al. "Dietary Flaxseed Supplementation and Experimental Metastasis of Melanoma Cells in Mice." Cancer Letters 124, no. 2 (1998): 181-186.
ORGANIZATIONS
American Botanical Council. P.O. Box 144345, Austin, TX 78714-4345. http://www.herbalgram.org.
United States Food and Drug Administration (FDA), Center for Food Safety and Applied Nutrition. 5100 Paint Branch Parkway, College Park, MD 20740. (888) SAFEFOOD. <www.cfsan.fda.gov>.
Greg Annussek
Rebecca J. Frey, PhD
Flaxseed
Flaxseed
Definition
Flaxseed is the seed of the plant Linum usitatissi-mum It is a rich source of alpha-linolenic acid (ALA), an essential nutrient in the human diet. Flaxseed has health and possibly medical benefits. Flaxseed oil is a vegetable oil derived from pressed flaxseed. Flaxseed.
and flaxseed oil have different properties and nutritional values.
Purpose
Flaxseed is a good source of ALA and is thought to improve health by lowering blood cholesterol. Flax-seeds may also protect against certain cancers. It can also be used as a laxative.
Description
L. usitatissimum is a slender plant with narrow leaves and blue flowers that grows anywhere from 8– 45 in (20–130 cm) tall. The plant originated in India but has been farmed across the world for thousands of years. Archeologists discovered evidence that flax was cultivated in ancient Babylon as early as 3,000 b.c. Today, in Europe and Asia, a tall variety of flax is grown primarily for its fibers, which are used to make linen. A shorter, bushier variety is grown for its seeds in North America. The Canadian provinces of Alberta, Manitoba, and Saskatchewan are the leading producers of flax in North America. North Dakota produces most of the flax grown in the United States.
Seed flax is grown for both consumption and industrial use. The seed is about 42% oil. Solvent-extracted oil from flax seeds is used for industrial purposes and is often called linseed oil. It is used in manufacturing oil paints, varnishes, and linoleum. The material that remains after oil has been extracted from the seeds is called linseed cake or linseed meal. It is often added to animal feed as a protein and omega-3 fatty acid supplement. Omega-3 enriched eggs, for example, come from chickens fed flax. Omega-3 enriched pork is available in.
KEY TERMS
Dietary supplement —A product, such as a vitamin, mineral, herb, amino acid, or enzyme, that is intended to be consumed in addition to an individual’s diet with the expectation that it will improve health.
Fatty acids —Complex molecules found in fats and oils. Essential fatty acids are fatty acids that the body needs but cannot synthesize. Essential fatty acids are made by plants and must be present in the diet to maintain health.
Lignans —A group of compounds found in plants that have characteristics similar to the female hormone estrogen. They appear to have some anti-cancer and anti-oxidant effects.
Triglycerides —A type of fat found in the blood. High levels of triglycerides can increase the risk of coronary artery disease.
Canada and Japan. The fiber in the stems of seed flax is used in the production of cigarette papers.
Human consumption of flaxseed and flaxseed oil has increased substantially since the mid-1990s. Flax-seed oil for human consumption is produced through solvent-free cold pressing at low temperatures. The oil is sold in bottles to be used as food or in capsules to be taken as a dietary supplement.
Flax seeds come in brown, golden, and yellow varieties and have a slightly nutty flavor. All colors of seed have the same nutritional value. Seeds are sold whole or ground (milled flax). Whole seeds can be stored at room temperature for up to one year. Ground seeds are easier to digest than whole seeds, but they spoil and develop an unpleasant taste more rapidly. Ground seeds can be kept in an airtight container in the refrigerator for up to three months. However, when ground flax is needed, it is preferable to grind whole seeds in a coffee grinder, blender, or food processor immediately before use. Flaxseed and flax-seed oil are sold primarily in health food stores or by mail order.
Nutritional information
Flaxseed is an excellent source of alpha-linolenic acid. ALA is an essential fatty acid for humans. Essential fatty acids are molecules the body needs but cannot synthesize for itself from other nutrients. Thus, essential fatty acids, just like essential vitamins, must be obtained through diet. Eating 1 tbsp (8 g) of ground flax or 1 tsp (5 g) of flax oil provides enough ALA to meet daily diet requirements.
According to the Flax Council of Canada, 1 tbsp ground flaxseed provides about 36 calories, 1.8 g of ALA, 1.6 g of protein, and 2.2 grams of dietary fiber. Ground flax is preferred over whole seeds because it is easier to digest. One teaspoon of flax oil provides 44 calories and 2.8 g of ALA, but contains no protein or fiber. The oil in flaxseed is very high in polyunsatu-rated fat (a healthy type of fat) and contains no trans fat or cholesterol. Flaxseed also provides vitamins C, E, K, B1 (thiamin ), B2 (riboflavin ), and B6, along with the mineralscalcium, iron, magnesium, phosphorous, zinc, copper, manganese, and selenium Flaxseed is low in sodium and carbohydrates The seed, but not the oil, is also an excellent source of lignin, a nutrient thought to have anti-cancer properties.
Flaxseed can be added to the diet in several ways. Ground, a daily serving can be sprinkled on hot or cold cereal or mixed into yogurt or smoothies. Larger amounts can be added to pancake or waffle mix or baked goods such as muffins or cookies. Flax oil can be added to salad dressings or smoothies. Frying in flax oil is not recommended. Three tablespoons of ground flax can replace one tablespoon of butter, margarine, or vegetable oil in recipes. One tablespoon of ground flax mixed with three tablespoons of water, when left to stand for two minutes before use, can replace one egg in many recipes.
Health claims
Major health claims for flaxseed and flax oil arise from the fact that these products contain high levels of ALA. ALA can be converted by the body into two different long chain omega-3 fatty acids. Long chain omega-3 fatty acids have been shown to lower the risk of heart attack in people with heart disease. They appear to lower the level of cholesterol in the blood, especially low-density lipoprotein (LDL) or “bad” cholesterol. Other health claims for omega-3 fatty acids include lowering blood pressure, lowering trigly-cerides (fats) in the blood, and reducing the tendency of blood to clot in veins.
Cold-water oily fish such as salmon and fresh tuna (canned is not a source) are good sources of omega-3 fatty acids. Vegans and vegetarians use flaxseed, along with walnuts and canola oil, get enough ALA in their diet, which is then converted into beneficial omega-3 fatty acids. However, many of the health benefits claimed for omega-3 fatty acids require higher doses than necessary to meet daily dietary requirements. Flaxseed and flaxseed oil have been found to lower blood cholesterol levels in animal studies, but few high-quality human studies have been done using flax products. Results that do exist have been mixed.
Another health claim for flaxseed (but not flax oil) is that it has anti-cancer properties. Flaxseed and sesame seed both contain large amounts of lignans. Lignans are naturally occurring molecules found in plants that mimic the effect of the female hormone estrogen. Lignans compete with estrogen for binding sites on cells. They can either act as antagonists and lessen the estrogen response where there is continual estrogen exposure (increasing risk of breast cancer ) or they can mimic estrogen and boost the response where exposure is limited (post menopause) helping to prevent post menopausal symptoms. Few well-designed, well-controlled human studies of the effect of lignans on cancer have been completed. Although the results of animal studies are encouraging, there is not enough evidence to say that lignans, or flaxseed, can slow or prevent cancer.
Researchers generally agree that ground flaxseed is an effective laxative. Flaxseed provides dietary fiber and, along with the oil it naturally contains, helps move material through the bowel. Whole seed may have the reverse effect, swelling and blocking the bowel.
Some studies have shown that flaxseed oil supplements can reduce symptoms of attention deficit-hyperactivity disorder (ADHD) in some children. Other studies claim that flaxseed can lower blood sugar levels in people with diabetes. Initial results also suggest that flaxseed may reduce symptoms of menopause. None of these health claims have been substantiated with large, well-controlled human studies.
Precautions
ALA, which is found in large quantities in flax-seed, appears to increase the risk of developing prostate cancer. This finding is preliminary and not yet substantiated. Individuals with prostate cancer or a history of prostate cancer should consult their oncologist before using flax products.
Although no health risks are known when flaxseed and flax oil are used in reasonable and moderate quantities, no studies have been done on the safety of flax in pregnant or breastfeeding women or in children.
Interactions
No specific drug interactions are known.
Complications
Complications are unlikely to occur when flax products are used to meet daily dietary needs. Whole flaxseed can cause blockage of the intestines when taken with inadequate amounts of liquids.
Parental concerns
Parents should be aware that the safe dose of many herbal supplements has not been established for children. Accidental overdose may occur if children are given adult dietary supplements .
Resources
BOOKS
Muir, Alister D., and Neil D. Westcott, eds. Flax: The Genus Linum New York: Routledge 2003.
PDR for Herbal Medicines, 3rd ed. Montvale, NJ: Thompson Healthcare, 2004.
Pierce, Andrea. The American Pharmaceutical Association Practical Guide to Natural Medicines New York: William Morrow, 1999.
Reinhardt-Martin, Jane. The Amazing Flax Cookbook Moline: IL, TSA Press, 2004.
Wildman, Robert E. C., ed. Handbook of Nutraceuticals and Functional Foods, 2nd ed. Boca Raton, FL: CRC/ Taylor&Francis, 2007.
PERIODICALS
Covington, M. B. “Omega-3 Fatty Acids.” American Family Physician 70, no.1 (2004): 133-40.
ORGANIZATIONS
Alternative Medicine Foundation. P.O. Box 60016, Potomac, MD 20859. Telephone: (301) 340-1960. Fax: (301) 340-1936. Website: <http://www.amfoundation.org>.
Flax Council of Canada. 465-167 Lombard Avenue, Winnipeg, MB R3B 0T6. Telephone: (204) 982-2115. Fax: (204) 942-1841. Website: <http://www.flaxcouncil.ca>
Natural Standard. 245 First Street, 18th Floor, Cambridge, MA 02142. Telephone: (617) 444-8629. Fax: (617) 444-8642. Website: <http://www.naturalstandards.com>
Office of Dietary Supplements, National Institutes of Health. 6100 Executive Blvd., Room 3B01, MSC 7517, Bethesda, MD 20892-7517. Telephone: (301) 435-2920. Fax: (301) 480-1845. Website: <http://dietary-supplements.info.nih.gov>
OTHER
Carter, Jack. “Flaxseed as Functional Food for People and as Feed for Other Animals.”North Dakota State University. [cited May 7, 2007].<http://www.ag.ndsu.nodak.edu/plantsci/flaxseed.htm>
Flax FAQ Flax Council of Canada. [cited May 7, 2007].<http://www.flaxcouncil.ca/english/index.php?p=faq>
“Flaxseed and Flaxseed Oil.”National Center for Complementary and Alternative Medicine. June 1, 2006. [cited May 7, 2007]. <http://nccam.nih.gov/health/flaxseed/index.htm>
Martin, Diane H. “Food Sources of Alpha-Linolenic Acid.”Flax Council of Canada. November 2005. [cited May 7,2007].http://www.flaxcouncil.ca/>
Natural Standard Research Collaboration. “Flaxseed and Flaxseed Oil. (Linum usitatissimum)” MedlinePlusJanuary 23, 2007. [cited May 7, 2007]. <http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html>
Tish Davidson, A.M.
Linseed
Linseed
The flax plant has been cultivated in Europe, North Africa, and the Middle East—especially Egypt, the Caucasus, and the Black Sea—since antiquity. In Latin America it has been cultivated in Mexico, Chile, and Brazil. In Argentina, however, it became an especially important crop that provided the necessary infrastructure for several industries. Agronomist Martín José de Altolaguirre first introduced it to Argentina as an experiment in 1784. He grew the plant at his farm near the convent of La Recoleta in Buenos Aires and then extracted oil from the seed (linseed). In Argentina the plant was more greatly appreciated for that seed than for its use in the production of linen. After 1850 European immigrants began to cultivate the plant in Buenos Aires, Santa Fe, Córdoba, and Entre Ríos provinces. From 1899 until the 1940s, the acreage devoted to its cultivation steadily increased.
At the beginning of the twentieth century, the Bemberg Company began growing linseed in Baradero and Rojas in the province of Buenos Aires. A key ingredient in the production of paints and printer's ink, linseed was exported as raw material for European manufacturers until the 1950s. By 1913 Argentina was exporting more than a million tons of linseed each year and was devoting more acreage to this crop than any other country. The value of Argentine linseed exports was exceeded only by that of wheat, corn, and oats.
During World War I, Argentine exporters began to ship crushed, rather than whole, seed in order to reduce cargo space. The Depression and the development of modernized seed processing stimulated import substitution so that companies previously involved in exporting seed began to invest in domestic processing plants to extract oil and other by-products. World War II accelerated the growth of domestic seed oil production, and exports of Argentine linseed oil grew dramatically until the industry began a gradual decline after the 1960s. Overall world demand has not changed dramatically since the 1960s. Still, Argentina remains the largest exporter of linseed oil.
BIBLIOGRAPHY
Carlos De Alberti Girola, El cultivo del trigo para la producción de la semilla en la Argentina (1915).
Raúl Ramella, El lino oleaginoso (1944).
Emilio A. Gruget, Aprovechamiento industrial de los rastrojos del lino oleaginoso (1949).
Carlos Remussi, El lino textil (1951).
Additional Bibliography
Barsky, Osvaldo, and Jorge Gelman. Historia del agro argentino: Desde la conquista hasta fines del siglo XX. Buenos Aires: Grijalbo Mondadori, 2001.
Donna J. Guy
linseed
lin·seed / ˈlinˌsēd/ • n. the seeds of the flax plant, which are the source of linseed oil and linseed cake. Also called flaxseed. ∎ the flax plant, esp. when grown for linseed oil.
flaxseed
flax·seed / ˈflak(s)ˌsēd/ • n. another term for linseed. ∎ a pupa of the Hessian fly, which resembles a seed of flax.