Flaxseed

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What other names is Flaxseed known by?

Alasi, Aliviraaii, Brown Flaxseed, Brown-Seeded Flax, Common Flax, Echter Lein, Flachs, Flachssamen, Flax, Flax Hull, Flax Lignans, Flax Meal, Flax Seed, Gemeiner Flachs, Golden Flax, Graine de Lin, Kattan, Keten, Leinsamen, Lignanes de Lin, Lignans, Lin, Lin Commun, Lin Oléagineux, Lin Textile, Linaza, Lini Semen, Linho, Lino, Lino Comune, Lino Mazzese, Lino Usuale, Linseed, Linseed Flax, Lint Bells, Linum, Linum crepitans, Linum humile, Linum usitatissimum, Malsag, Phytoestrogen, Phyto-œstrogène, Saatlein, Ta Ma, Tisii, Winterlien.

What is Flaxseed?

Flaxseed is the seed from the plant Linum usitatissimum. The seed or the seed oil is used to make medicine. The information on this page concerns medicine made from the SEED only. There is a separate listing for flaxseed OIL.

People use flaxseed for many conditions related to the gastrointestinal (GI) tract, including ongoing constipation, colon damage due to overuse of laxatives, diarrhea, inflammation of the lining of the large intestine (diverticulitis), irritable bowel syndrome (IBS) or irritable colon, sores in the lining of the large intestine (ulcerative colitis), inflammation of the lining of the stomach (gastritis), and inflammation of the small intestine (enteritis).

Flaxseed is also used for disorders of the heart and blood vessels, including high cholesterol, "hardening of the arteries" (atherosclerosis), high blood pressure (hypertension), and coronary artery disease.

Flaxseed is also used for acne, attention deficit-hyperactivity disorder (ADHD), kidney problems in people with a disease called systemic lupus erythematosus (SLE), symptoms of menopause, and breast pain. It is also used for diabetes, obesity and weight loss, HIV/AIDS, depression, bladder infections, malaria, and rheumatoid arthritis.

Other uses include treatment of sore throat, upper respiratory tract infections (URTI), and cough.

Some people use flaxseed to lower their risk of getting weak bones (osteoporosis) and to protect against breast cancer, lung cancer, colon cancer, and prostate cancer.

Flaxseed is sometimes applied to the skin for acne, burns, boils, eczema, psoriasis, and to soothe inflammation.

Possibly Effective for...

  • Diabetes. Research shows that taking a specific flaxseed product (FlaxEssence, Jarrow Formulas) three times daily for 3 months lowers hemoglobin A1C, a measure of average blood sugar level, in people with type 2 diabetes. Other clinical research shows that taking flaxseed powder for one month can reduce fasting blood glucose in people with type 2 diabetes, and taking flaxseed for 3 months can reduce blood sugar levels in people with glucose-intolerance. However, taking milled flaxseed does not seem to lower fasting blood sugar, insulin levels, or blood fats in people with type 2 diabetes.
  • High cholesterol. Research shows that various flaxseed preparations, including ground flaxseed, partially defatted flaxseed, and flaxseed bread and muffins, seem to reduce total cholesterol and the "bad cholesterol," low-density lipoprotein (LDL) cholesterol, in people with normal cholesterol levels and in men and pre-menopausal women with high cholesterol. However, flaxseed does not have much effect on "good cholesterol," high-density lipoprotein (HDL) cholesterol. Most flaxseed preparations do not affect triglyceride levels. However, partially defatted flaxseed (flaxseed without as much alpha-linolenic acid content) can increase triglycerides.
  • Autoimmune disorder (systemic lupus erythematosus, SLE). Taking flaxseed by mouth seems to improve kidney function in people with SLE.

Possibly Ineffective for...

  • Osteoporosis. Research shows that consuming 40 grams of ground flaxseed daily for up to one year does not improve bone density in women. Similar findings were found for older men and women who took flaxseed extract.

Insufficient Evidence to Rate Effectiveness for...

  • Enlarged prostate (benign prostatic hyperplasia; BPH). Early research shows that taking a specific flaxseed product (Beneflax) daily for 4 months reduces urinary tract symptoms associated with BPH and improves quality of life.
  • Breast cancer. Early research shows that eating a muffin containing 25 grams of flaxseed daily for about 40 days reduces tumor cell growth in women recently diagnosed with breast cancer. However, it is unclear if this effect significantly improves overall breast cancer outcomes. There is inconsistent evidence regarding the effects of dietary flaxseed on breast cancer development.
  • Heart disease. Research suggests that dietary intake of lignans, which are found in flaxseed and other foods, does not reduce the risk of heart disease.
  • Colorectal cancer. Research on the effect of flaxseed on colorectal cancer risk is inconsistent. Some research shows that consumption of lignans, which are in flaxseed, is not associated with a reduced risk of colorectal cancer. However, other research suggests that it is.
  • Constipation. Flaxseed is a good source of dietary fiber. Eating flaxseed-containing muffins seems to increase bowel movements in young adults, while eating flaxseed-containing yogurt seems to increase bowel movements in elderly people.
  • Endometrial cancer. Research suggests that blood levels of lignans, which are found in flaxseed and other foods, are not associated with endometrial cancer risk.
  • High blood pressure. Early research shows that taking flaxseed extract three times daily for 6 months reduces blood pressure in men but not in women.
  • Irritable bowel syndrome (IBS). Early research shows that taking 24 grams of flaxseed daily for 4 weeks does not improve quality of life or the severity of IBS symptoms in people with IBS.
  • Lung cancer. Research suggests that people who eat more phytoestrogens, such as those found in flaxseed, might have a lower risk of developing lung cancer than those who eat less.
  • Breast pain (mastalgia). In early research, eating a flaxseed muffin each day for 3 months reduced breast pain associated with the start of the menstrual cycle. The muffins each contained 25 grams of flaxseed.
  • Menopausal symptoms. It is not clear if flaxseed works for reducing symptoms of menopause such as hot flashes. Some research has found that it might modestly reduce symptoms. However, other studies show that it does not work any better than taking a sugar pill placebo. The difference in effectiveness might be due to the dose of flaxseed used.
  • Metabolic syndrome (a condition that increases risk for diabetes and heart disease). Evidence on the use of flaxseed for metabolic syndrome is inconsistent. Early research shows that taking flaxseed extract reduces the risk of metabolic syndrome. However, other research shows that taking flaxseed does not improve markers of metabolic syndrome in people also following lifestyle modifications compared to those who just follow lifestyle modifications.
  • Prostate cancer. Early research suggests that taking flaxseed and following a low-fat diet can lower prostate-specific antigen (PSA), a marker for prostate cancer, in men who have a precancerous prostate condition. However, in men who have prostate cancer, adding flaxseed to the diet does not lower PSA, but it does seem to lower levels of the hormone testosterone and slow the rate at which cancer cells multiply.
  • Weight loss. Research in young adults who are not obese suggests that taking flaxseed fiber before a meal might reduce appetite and food intake. However, other research suggests that taking 40 grams of flaxseed daily for 12 weeks does not reduce body weight or mass in obese adults.
  • Diverticulitis.
  • Stomach upset.
  • Bladder inflammation.
  • Skin irritation.
  • Attention deficit-hyperactivity disorder (ADHD) .
  • Other conditions.
More evidence is needed to rate of flaxseed for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

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How does Flaxseed work?

Flaxseed is a good source of dietary fiber and omega-3 fatty acids. The fiber in flaxseed is found primarily in the seed coat. Taken before a meal, flaxseed fiber seems to make people feel less hungry, so that they might eat less food. Researchers believe this fiber binds with cholesterol in the intestine and prevents it from being absorbed. Flaxseed also seems to make platelets, the blood cells involved in clotting, less sticky. Overall, flaxseed's effects on cholesterol and blood clotting may lower the risk of "hardening of the arteries" (atherosclerosis).

Flaxseed is sometimes tried for cancer because it is broken down by the body into chemicals called "lignans." Lignans are similar to the female hormone estrogen - so similar, in fact, that they compete with estrogen for a part in certain chemical reactions. As a result, natural estrogens seem to become less powerful in the body. Some researchers believe that lignans may be able to slow down the progress of certain breast cancers and other types of cancers that need estrogen to thrive.

For systemic lupus erythematosus (SLE), flaxseed is thought to improve kidney function by decreasing the thickness of blood, reducing cholesterol levels, and reducing swelling.

Are there safety concerns?

Flaxseed is LIKELY SAFE for most adults when taken by mouth. Adding flaxseed to the diet might increase the number of bowel movements each day. It might also cause gastrointestinal (GI) side effects such as bloating, gas, abdominal pain, constipation, diarrhea, stomachache, and nausea. Higher doses are likely to cause more GI side effects.

There is some concern that taking large amounts of flaxseed could block the intestines due to the bulk-forming laxative effects of flaxseed. Flaxseed should be taken with plenty of water to prevent this from happening.

Taking flaxseed extracts that contain lignans in concentrated form is POSSIBLY SAFE. Lignans are the chemicals in flaxseed that are thought to be responsible for many of the effects. Some clinical research shows that a specific flaxseed lignan extract (Flax Essence, Jarrow Formulas) can be safely used for up to 12 weeks.

Products that contain partially defatted flaxseed, which is flaxseed with less alpha-linolenic acid content, are available. Some men choose these products because they have heard that alpha-linolenic acid might raise their risk of getting prostate cancer. It's important to remember that the source of the alpha-linolenic acid is key. Alpha-linolenic acid from dairy and meat sources has been positively associated with prostate cancer. However, alpha-linolenic acid from plant sources, such as flaxseed, does not seem to affect prostate cancer risk. Men should not worry about getting alpha-linoleic acid from flaxseed. On the other hand, there is a concern that partially defatted flaxseed might raise triglyceride levels too much. Triglycerides are a type of blood fat.

Raw or unripe flaxseed is POSSIBLY UNSAFE. Flaxseed in these forms is thought to be poisonous.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Taking flaxseed by mouth during pregnancy is POSSIBLY UNSAFE. Flaxseed can act like the hormone estrogen. Some healthcare providers worry that this might harm the pregnancy, although to date there is no reliable clinical evidence about the effects of flaxseed on pregnancy outcomes. The effect of flaxseed on breast-fed infants is unknown at this time. Stay on the safe side, and don't use flaxseed if you are pregnant or breast-feeding.

Bleeding disorders: Flaxseed might slow clotting. This raises the concern that it could increase the risk of bleeding in people with bleeding disorders. Don't use it, if you have a bleeding disorder.

Diabetes: There is some evidence that flaxseed can lower blood sugar levels and might increase the blood sugar-lowering effects of some medicines used for diabetes. There is a concern that blood sugar could drop too low. If you have diabetes and use flaxseed, monitor your blood sugar levels closely.

Gastrointestinal (GI) obstruction: People with a bowel obstruction, a narrowed esophagus (the tube between the throat and the stomach), or an inflamed (swollen) intestine should avoid flaxseed. The high fiber content of flaxseed might make the obstruction worse.

Hormone-sensitive cancers or conditions: Because flaxseed might act somewhat like the hormone estrogen, there is some concern that flaxseed might make hormone-sensitive conditions worse. Some of these conditions include breast, uterine, and ovarian cancer; endometriosis; and uterine fibroids. However, some early laboratory and animal research suggests that flaxseed might actually oppose estrogen and might be protective against hormone-dependent cancer. Still, until more is known, avoid excessive use of flaxseed if you have a hormone-sensitive condition.

High triglyceride levels (hypertriglyceridemia): Partially defatted flaxseed (flaxseed with less alpha linolenic acid content) might increase triglyceride levels. If your triglyceride levels are too high, don't take flaxseed.

Low blood pressure (hypotension): Flaxseeds might lower diastolic blood pressure. Theoretically, taking flaxseeds might cause blood pressure to become too low in individuals with low blood pressure.

High blood pressure (hypertension): Flaxseeds might lower diastolic blood pressure. Theoretically, taking flaxseeds might cause blood pressure to become too low in individuals with high blood pressure who are taking blood pressure-lowering medication.

Are there any interactions with medications?



Acetaminophen (Tylenol)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

There is some evidence that flaxseed might interfere with the body's ability to take in and use acetaminophen. It's not known, though, whether this interaction is important.



Antibiotic drugs
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Bacteria in the intestine convert some of the chemicals in flaxseed into lignans, which are thought to be responsible for many of the possible benefits of flaxseed. However, because antibiotics kill these bacteria, lignans might not be formed as usual. This might alter the effects of flaxseed.



Estrogens
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Flaxseed can act like the female hormone estrogen. It can compete with estrogens that are included in birth control pills and hormone replacement treatments. Healthcare providers are concerned that flaxseed might make these estrogen-containing drugs less effective.



Furosemide (Lasix)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

There is some evidence that flaxseed might interfere with the body's ability to take in and use furosemide. It's not known, though, whether this interaction is important.



Ketoprofen (Orudis, Oruvail)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

There is some evidence that flaxseed might interfere with the body's ability to take in and use ketoprofen. It's not known, though, whether this interaction is important.



Medications for diabetes (Antidiabetes drugs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Some evidence suggests that flaxseed can lower blood sugar levels. Diabetes medications are also used to lower blood sugar. Taking flaxseed along with diabetes medications might cause your blood sugar to become too low. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.

Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, metformin (Glucophage), pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others.



Medications taken by mouth (Oral drugs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Flaxseed can act like a laxative. There is some concern that it might interfere with the body's ability to absorb medications taken by mouth because it might sweep them out of the digestive tract too quickly. To avoid this problem, take medications an hour before or two hours after taking flaxseed.



Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Flaxseed might slow blood clotting. Taking flaxseed along with medications that also slow clotting might increase the chances of bruising and bleeding.

Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, ticlopidine (Ticlid), warfarin (Coumadin), and others.



Metoprolol (Toprol)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

There is some evidence that flaxseed might interfere with the body's ability to take in and use metoprolol. It's not known, though, if this interaction is important.

Dosing considerations for Flaxseed.

The following doses have been studied in scientific research:

BY MOUTH:
  • For type 2 diabetes: 600 mg of a specific flaxseed lignan extract (Flax Essence, Jarrow Formulas) three times daily, providing 320 mg lignans, for 12 weeks.
  • For high cholesterol: Baked goods such as muffins or bread containing flaxseed and ground flaxseed to provide a daily dose of 40-50 grams of flaxseed.
  • For improving kidney function in people with systemic lupus erythematosus (SLE): 15 grams of ground flaxseed twice daily with cereal, or tomato or orange juice.
  • For improving mild menopausal symptoms: 40 grams of crushed flaxseed or flaxseed in bread daily.
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Reviewed on 3/29/2011 12:35:40 PM

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