Flaxseed or linseed (Linum usitatissimum L.) comes from the flax plant, an annual herb. The ancient Egyptians used flaxseed as both food and medicine.In the past, flaxseed was used mostly as a laxative. It is high in fiber and has a gummy material called mucilage, both of whichexpand when they come in contact with water. They add bulk to stool and help it move more quickly through the intestines.
Flaxseed and flaxseed oil have healthy ingredients, too. They are rich in alpha-linolenic acid (ALA), an omega-3 fatty acid that may be helpful for heart disease, inflammatory bowel disease, arthritis, and other health problems. Other omega-3 fatty acids include those found in fish oil (docosahexaenoic acid or DHA, and eicosapentaenoic acid or EPA). Mackerel, salmon, and walnuts are good sources of omega-3 fatty acids.
Flaxseed oil has only ALA, not the fiber or lignans found in the flaxseed. Other plants that have ALA include canola (rapeseed), soybean oil, walnuts, and pumpkin seed. Studies suggest that flaxseed may help prevent and treat of the following health conditions:
People who eat a Mediterranean diet tend to have higher HDL ("good") cholesterol levels. The Mediterranean diet includes whole grains, root and green vegetables, fruits, fish and poultry, olive and canola oils, and ALA from flaxseed, flaxseed oil, and walnuts. It limits the amount of red meat, butter, and cream.
In lab tests and animal studies, flaxseed and flaxseed oil have been reported to lower cholesterol. Human studies have had mixed results. One human study found that people who added flaxseed to a low-cholesterol diet lowered their LDL ("bad") cholesterol and triglycerides (fats in the blood).
A diet rich in fruits, vegetables, whole grains, nuts or legumes, and foods with ALA may reduce the risk of heart attack and stroke, both for people who have never had either problem and for those who ahve already had a heart attack or stroke.
One of the best ways to help prevent and treat heart disease is to eat a diet low in saturated fat and transfat and eat foods that are rich in monounsaturated and polyunsaturated fats, including omega-3 fatty acids from flaxseed. Evidence suggests that people who eat an ALA-rich diet are less likely to have a fatal heart attack.
Several human studies suggest that diets rich in omega-3 fatty acids (including ALA) may lower blood pressure in people with hypertension.
One small study compared flaxseed to hormone replacement therapy (HRT) in menopausal women. It reported that 40 g of flaxseed worked as well as HRT for mild menopausal symptoms (hot flashes, mood disturbances, vaginal dryness). But the study was not well designed, and another, larger study found that flaxseed did not improve symptoms like hot flashes nor did it protect against bone loss.
Lignans from flaxseed
In addition to the important omega-3 fatty acid ALA, flaxseed -- but not the oil -- also has a group of chemicals called lignans that may help protect the body from cancer. Lignans are phytoestrogens,substances in plants that act like the hormone estrogen.
Because lignans in flaxseed may act like estrogen in the body, scientists arent sure whether flaxseed would be harmful or helpful for breast cancer. Laboratory studies have reported that flaxseed reduced breast tumor growth and metastasis (spreading) in rats.
There has been only one clinical study in humans. In that study,postmenopausal women who were newly diagnosed with breast cancer ate a muffin with 25 grams dietary flaxseed every day for 40 days. The study found that adding flaxseed to the diet may have the potential to reduce tumor growth in women with breast cancer, but much more research is needed.
Animal studies show that lignans may slow the growth of colon tumor cells. Population studies suggest that flaxseed may reduce the number of abnormal cell growths, which are early markers of colon cancer. Clinical trials in people are needed, however.
Results from studies are confusing when it comes to prostate cancer and flaxseed. A few studies have seemed to show that ALA intake was associated with an increased risk for prostate cancer. But other studies have found that flaxseed may benefit men at risk for prostate cancer. In one study, men with a precancerous prostate condition called PIN had lower PSA levels (a marker of prostate cancer) when they ate 30 g of flaxseed daily along with a low-fat diet. In men who had prostate cancer, 30 g of flaxseed daily and a low-fat diet did not lower PSA levels, but it did appear to lower levels of testosterone and slow down the rate of tissue growth. More studies are needed to understand how flaxseed may affect prostate cancer.
Researchers are investigating whether omega-3 fatty acids may help protect against certain infections and in treating conditions including ulcers, migraine headaches, attention deficit/hyperactivity disorder, addiction, eating disorders, preterm labor, emphysema, psoriasis, glaucoma, Lyme disease, lupus, and panic attacks.
Flax is an annual plant that thrives in deep moist soils rich in sand, silt, and clay. The small, oval-shaped seeds of the flax plant contain oil, sometimes called linseed oil.
What's It Made Of?
Flaxseed has several plant chemicals that may be healthy, including:
Flaxseed actslike a laxative because of its fiber and mucilage content. Phytoestrogens, plant chemicals calledlignans, may help protect against some kinds of cancer. Other health benefits of flaxseed, such as protection from heart disease and arthritis, are probably due to a high concentration of the omega-3 fatty acid ALA.
Flaxseed oil should be refrigerated. Use whole flaxseeds within 24 hours of grinding, otherwise the ingredients lose their activity. Flaxseeds are also available ground in a special mylar package so that the components in the flaxseeds stay active. Ripe seeds, linseed cakes, powder, capsules, and flaxseed oil are all available at health food and grocery stores.
How to Take It
Flaxseed oil may be added to a child's diet to help balance fatty acids.
Children (2 - 12 years): Ask your doctor to help you determine the right dose. One example is using 1 teaspoonful (tsp) of ground flaxseeds, or 1 tsp of fresh flaxseed oil for constipation.
Flaxseed: Take 1 tablespoonful (tbsp), 2 - 3 times daily or 2 - 4 tbsp, 1 time daily. Grind before eating and take with lots of water.
Flaxseed oil: Take 1 - 2 tablespoonfuls daily, or 1 - 2 capsules daily. Flaxseed oil is often used in a liquid form, which contains about 7 g of ALA per 15 mL tbsp.
The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, can have side effects and interact with other herbs, supplements, or medications. For these reasons, herbs should be taken with care, under the supervision of a health care provider qualified in the field of botanical medicine.
Although studies have found that eating fish -- which includes omega-3 fatty acids -- regularly may reduce the risk of macular degeneration, a recent study of two large groups of men and women found that diets rich in ALA may increase the risk of macular degeneration. Talk to your health care provider.
Do not eat raw or unripe flaxseeds -- they may be poisonous.
Women with breast, uterine, and ovarian cancer or endometriosis should ask their doctor before taking flaxseed, because it may act like estrogen in the body.
Some researchers think pregnant women shouldn't take flaxseed, because it may act like estrogen in the body. Ask your doctor before taking flaxseed if you are pregnant or breastfeeding.
Men with prostate cancer should ask their doctor before taking flaxseed.
People with a bowel obstruction, inflamed bowel, or narrowed esophagus should not take flaxseed. It is high in fiber and could make the condition worse.
Flaxseed supplements may alter the effects of some prescription and nonprescription medications. If you are currently being treated with any of the following medications, you should not use flaxseed without first talking to your health care provider:
Blood-thinning medications -- Omega-3 fatty acids may increase the risk of bleeding, especially if you also take blood thinners such as warfarin (Coumadin), clopidogrel (Plavix),or aspirin. In some cases, the combination of aspirin and omega-3 fatty acids may be helpful, but they should not be taken together except under a doctors supervision.
Medications for diabetes -- Flaxseed may lower blood sugar levels. If you are taking medicines for diabetes, including insulin, you should use flaxseed (ALA) only under your doctors supervision.
Birth control pills or hormonal replacement therapy (HRT) -- Flaxseed may change hormonal levels and change the effects of oral contraceptives or HRT. If you are taking oral contraceptive or HRT, ask your doctor before taking flaxseed.
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Review Date: 1/26/2011
Reviewed By: Steven D. Ehrlich, NMD, Solutions Acupuncture, a private practice specializing in complementary and alternative medicine, Phoenix, AZ. Review provided by VeriMed Healthcare Network.
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