Flaxseed and Flaxseed Oil : Dosing and Safety

by MedlinePlus

(Page 2 of 3)

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Standardization

Standardization involves measuring the amount of certain chemicals in products to try to make different preparations similar to each other. It is not always known if the chemicals being measured are the "active" ingredients. In general, flaxseed products are not standardized based on specific chemical components, although products are often evaluated by manufacturers using a number of chemical tests.

Adults (18 years and older)

Flaxseed oil should be kept refrigerated in an opaque (non-transparent) bottle, since its chemical parts may break down if exposed to light, oxygen, or heat. Whole flaxseed can be stored for up to one year in a dry location. Ground flaxseed can be kept in a refrigerator for three months or in a freezer for six months. Flaxseed oil and powder/flour will break down at high temperatures, such as in cooking.

Flaxseed Oil (Liquid Form): Flaxseed oil contains only the alpha-linolenic acid (ALA) component of flax, not the fiber found in flaxseed. Flaxseed oil is most often used in a liquid form, which contains approximately 7 grams of ALA per 15-milliliter tablespoon and may contain approximately 130 calories.

Flaxseed Oil (Capsule Form): Flaxseed oil is available in a capsule form, which often contains 500 milligrams alpha-linolenic acid per 1000-milligram capsule (10 calories).

Flaxseed Powder/Flour/Soluble Fiber: Several studies report adults taking ground, raw flaxseeds by mouth in doses up to 50 grams daily for up to four weeks. For shorter periods of time (less than 2 weeks), studies use doses of 10 to 60 grams by mouth daily. A dose of 50 grams of flaxseeds may be equal to 250 grams of flaxseed flour. A dose of flaxseed that has been used for stomach or abdominal discomfort is 1 tablespoon of whole or bruised seed mixed with 150 milliliters (about 2/3 cup) of liquid, taken by mouth 2-3 times a day. As a laxative, 2-3 tablespoons of bulk seed mixed in 10 times the amount of water has been used. Human studies report that doses of 45 grams daily have laxative effects. For lupus nephritis, 30 grams of flaxseed daily has been studied. For menopausal symptoms, 40 grams of flaxseed daily has been studied.

Flaxseed Liquid: Whole or bruised (not ground) flaxseed can be mixed with liquid and taken by mouth. Generally, one tablespoon in this form is mixed with 6 to 12 ounces of liquid and taken by mouth up to three times a day. Some studies use doses of soluble flaxseed mucilage/fiber as high as 60 to 80 grams per kilogram (1 kilogram equals 2.2 pounds) of the person's weight. These liquid forms of flaxseed should not be confused with preparations of flaxseed oil.

Leaf: There is not enough scientific information to recommend the use of flaxseed leaves for any medical condition.

In Foods: At high temperatures, for example when cooking, flaxseed oil and powder/flour will break down. Reports show that eating four eggs per day from chickens fed flaxseed can increase the levels of total omega-3 fatty acids in the blood. Long-term effects are not clear.

Applied to the skin (flaxseed poultice): Anecdotally, 30 to 100 grams of flaxseed flour can be mixed with warm or hot water to form a moist compress and can be used up to three times a day. It is not clear how long a flaxseed poultice should be used.

Applied to the eye (flaxseed): Flaxseeds are historically used for removing debris from the eye. A single whole flaxseed is placed under the eyelid, allowing the debris and mucus to collect around it and thereby to allow removal. This process may be unsafe. Seek the help of a healthcare professional for removal of eye debris.

Children (younger than 18 years)

Not enough information is available to advise use of flaxseed or flaxseed oil in children.

Safety

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 provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

People with known allergy to flaxseed, flaxseed oil, or any other members of the Linaceae plant family or Linum genus plant family should avoid flaxseed products. Workers are reported to have developed allergy-like reactions after inhaling flaxseed powder. Two reports describe adults with possible allergic reactions, whose symptoms include itching, hives, eye watering, nasal congestion, sneezing, nausea, abdominal pain, diarrhea, and mild shortness of breath. In these reports, multiple symptoms developed within minutes of taking a spoonful of linseed oil (from flaxseed) by mouth or eating multigrain bread. Allergy tests show that both people were allergic to flaxseed.

Side Effects and Warnings

There are few studies of flaxseed safety in humans. Flaxseed and flaxseed oil supplements do appear to be well tolerated in the available research, and there is long-standing historical use of flaxseed products without many reports of side effects. However, unripe flaxseed pods are believed to be poisonous and should not be eaten. Raw flaxseed or flaxseed plant may increase blood levels of cyanide, a toxic chemical (this effect has not been reported when flaxseed supplements are taken at recommended doses). Do not apply flaxseed or flaxseed oil to open wounds or broken skin.

Based on animal studies, overdose of flaxseed may cause shortness of breath, rapid breathing, weakness, or difficulty walking, and may cause seizures or paralysis. Theoretically, flaxseed ( not flaxseed oil) may increase the risk of cell damage from a reaction called oxidative stress. Studies report conflicting results in this area. Based on one study, flaxseed or flaxseed oil taken by mouth may cause mania or hypomania in people with bipolar disorder. In theory, the laxative effects of flaxseed ( not flaxseed oil) may cause diarrhea, increased number of bowel movements, and abdominal discomfort. Laxative effects are reported in several studies of people taking flaxseed or omega-3 acids. Large amounts of flaxseed by mouth may cause the intestines to stop moving (ileus). People with diarrhea, irritable bowel syndrome, diverticulitis, or inflammatory bowel disease (Crohn's disease or ulcerative colitis) should avoid flaxseed due to its possible laxative effects. Nausea, vomiting, and abdominal pain are reported in two individuals shortly after taking flaxseed products by mouth; these reactions may have been caused by allergy.

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