Natural Standard Monograph, Copyright © 2014 (www.naturalstandard.com). Commercial distribution prohibited. This monograph is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified health care professional before making decisions about therapies and/or health conditions.
Uses based on scientific evidence
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare professional.
Good evidence suggests that flaxseed (not flaxseed oil) produces laxative effects. Loose stools have been seen in people taking flaxseed. Further research is needed to establish efficacy and dosing. Flaxseed in large doses, or when taken without enough water, may cause bowel obstruction.
Attention-deficit hyperactivity disorder (ADHD)
Early evidence suggests that low levels or imbalances in certain highly unsaturated fatty acids may contribute ADHD. ALA-rich nutritional supplementation in the form of flax oil may improve symptoms of ADHD. More research is needed to confirm these results.
The effect of flaxseed oil in children with bipolar disorder has been examined. However, a significant effect was not reported. Further research is needed.
It has been proposed that the lignan components of flaxseed may protect against hormone-sensitive cancers. Early evidence suggests that flaxseed supplementation may benefit the prevention or treatment of breast cancer. Additional research is needed in this area.
Flaxseed (not flaxseed oil) contains lignans that may alter estrogen activity. The hormonal effects of flaxseed may improve symptoms of breast pain. However, further research is needed before a conclusion may be drawn.
Flaxseed may improve clogged arteries or cardiovascular outcomes, based on antioxidant and lipid-lowering properties. n-3 polyunsaturated fatty acids and ALA may benefit individuals with heart disease. Diets rich in ALA, such as the Mediterranean diet, have improved outcomes in people with a previous heart attack. Additional research is needed in this area.
Flax has been studied for its effects on blood sugar, but reports are inconclusive. Further research is needed in this area.
Dry eye syndrome
Limited research suggests that flaxseed oil capsules daily may be useful in the treatment of dry eye syndrome. Additional research is needed in this area.
A flaxseed lignan extract has been reported to improve urinary tract symptoms in people with benign prostatic hyperplasia (enlarged prostate). Additional well-designed trials are needed before a conclusion may be drawn.
Flaxseed may improve clogged arteries or cardiovascular outcomes, based on antioxidant and lipid-lowering properties. In humans, increased consumption of ALA may protect against stroke. However, evidence is mixed. Additional research is needed in this area.
High blood pressure
Early evidence suggests that higher levels of ALA in fat tissues may be associated with lower blood pressure. Flaxseed-supplemented diets have lowered blood pressure in human studies. However, future research is needed in this area.
Flaxseed and flaxseed oil have been reported to have lipid-lowering properties. Multiple human studies on flax had mixed results on cholesterol. Additional research is needed in this area.
HIV/AIDS (weight gain)
Limited research suggests that ALA (derived from flax) with arginine and yeast RNA aided weight gain in people with HIV. Further research is needed before a conclusion may be drawn.
It has been suggested that flaxseed (not flaxseed oil) produces laxative effects. Loose stools have been observed in people taking flaxseed. Further research is needed to establish efficacy and dosing. In large doses, or when taken without enough water, flaxseed may cause bowel obstruction.
Limited research suggests flaxseed may improve kidney function in people with lupus nephritis (inflamed kidney). Further research is needed before a conclusion may be drawn.
Early research suggests that flaxseed may improve menopausal symptoms, such as bone mineral density and cholesterol. However, the effects of flaxseed on menopausal symptoms are mixed. Additional research is needed.
Flaxseed has been studied for disorders of metabolic syndrome (high blood pressure, cholesterol, and diabetes) with mixed results. Trials on people with metabolic syndrome are also inconclusive. Further research is needed.
Limited research exists on the effects of flaxseed in obese patients. Early research has lacked evidence of benefit in weight loss. Flaxseed has caused a reduction in hunger and an increase in fullness. Further research is needed.
Pneumonia (community acquired)
Limited data exists on flaxseed use for community-acquired pneumonia. Seeds from the plant have historically been used for upper respiratory infections. Further well-controlled trials are needed to confirm this conclusion.
Polycystic ovarian syndrome (hormonal disorder)
Flaxseed has been studied for several aspects of polycystic ovarian syndrome, including insulin resistance, obesity, and hormone changes, with mixed results. Further research is needed in this area.
It has been proposed that ALA may delay the timing of spontaneous delivery, but the available evidence lacks support for this use. The use of a flaxseed pillow in premature infants has also been studied.
Flaxseed dressings on pressure ulcers have been studied. Future well-controlled trials are needed in this area.
There are conflicting reports on ALA and prostate cancer. Several studies suggest benefit while other studies have associated ALA with an increased risk of prostate cancer. Additional high quality studies are needed.
Skin conditions (sensitivity)
Seeds from the flax plant have historically been used for skin inflammation. Flaxseed oil has been applied to the skin as a salve or used for sore throat. Flaxseed oral supplementation has been studied in women with skin sensitivities. Further research is needed in this area.
Flaxseed oil and its lignin have been found to possess antioxidant properties. Diets supplemented with flaxseed (not flaxseed oil) have been associated with an increase in cell damage. Additional research is needed.
Exercise performance enhancement
Limited research exists on the effects of flaxseed for improving resistance training. Taking flax oil lacked an effect on resistance training. Further research is needed.
Phytoestrogens, like flaxseed, have been studied for their effects on the prevention and treatment of osteoporosis. Several studies have lacked a significant effect of flaxseed on osteoporosis risk or bone mineral density. Further study is needed in this area.
*Key to grades:
A: Strong scientific evidence for this use;B: Good scientific evidence for this use; C: Unclear scientific evidence for this use;D: Fair scientific evidence against this use (it may not work);F: Strong scientific evidence against this use (it likely does not work).
For full grading rationale, click here.
Uses based on tradition or theory
The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified health care professional
Acne, acute respiratory distress syndrome (ARDS), allergic reactions, bladder inflammation, blood thinner, boils, bronchial irritation, burns (poultice), catarrh (inflammation of mucous membranes), colon cancer, common cold / upper respiratory tract infection, cough suppressant, diabetic nephropathy (kidney disease), diarrhea, diverticulitis (growths in colon), dysentery (severe diarrhea), enteritis (small intestine inflammation), expectorant, gastritis (stomach inflammation), gonorrhea, headache, infections, inflammation, inflammatory bowel disease (ulcerative colitis), kidney disorders, laxative-induced colon damage, liver protection, malaria, menstrual luteal phase disorders, multiple sclerosis, ovarian disorders, psoriasis (skin disorder), rheumatoid arthritis, skin cancer, skin infections, skin inflammation, sore throat, stomach pain, stomach upset, stroke, urinary tract infection, vaginitis (vaginal inflammation), vision improvement.
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy. Consult a healthcare professional immediately if you experience side effects.
Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy.
Natural Standard developed the above evidence-based information based on a systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.
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