Flaxseed (linseed) is the seed of the flax plant, and flaxseed oil is made from it; both supply alpha-linolenic acid (ALA), a plant omega-3 fat. Flaxseed and flaxseed oil supplements are promoted for the heart, brain and immune system.
Also known as: flax, linseed, flaxseed oil, Linum usitatissimum, flax lignans.
NCCIH gives no standard amount. Products include ground seed, oil, lignan extract and mucilage powder, which have been studied for different things.
It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling. The NIH Office of Dietary Supplements (ODS) says ALA is found in plant oils such as flaxseed, soybean and canola oils; the long-chain omega-3s EPA and DHA come from fish and algae.
What studies show, per NCCIH: one trial suggests flaxseed mucilage powder mixed with water might help weight loss in adults with overweight or obesity, but lignan extract and flaxseed oil do not seem to; in gestational diabetes, flaxseed oil with ALA might improve fasting measures and insulin resistance; and more research is needed on lignan extract for blood sugar in type 2 diabetes.
Safety, per NCCIH: do not eat raw or unripe flaxseeds, which may contain potentially toxic compounds. Limited amounts appear safe for up to 6 months; higher doses may cause bloating, fullness and diarrhea. There are theoretical reasons it might interact with blood thinners and antiplatelet drugs. Some studies suggest flaxseed may be unsafe in pregnancy, though the evidence is not conclusive, and little is known about breastfeeding.
We could not find a single published half-life or time to peak for flaxseed that applies to a supplement dose, so we do not list one. Plant and mushroom products are mixtures of many compounds, so no single figure would describe them.
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