Botanical name(s):

Linum usitatissimum. Family: Linaceae

Other name(s):

flax, linseed, lint bells, winterlien

General description

Flaxseed is an annual plant grown for its fiber and its seeds. It’s grown in temperate and tropical regions. Oil from the seeds is used as an alternative to fish oil. Flaxseed has a nutty flavor. It’s used in bread and bakery products. The seeds from the flaxseed plant are also used to make linseed cakes and in liniments. The stem of the plant is used to make linen thread.

Flaxseed contains the omega-3 fatty acid alpha-linolenic acid. This acid may help prevent and treat hardening of the arteries (atherosclerosis). It may also reduce total blood cholesterol. It may help reduce inflammatory conditions. These include psoriasis, rheumatoid arthritis, eczema, multiple sclerosis, and ulcerative colitis.

Flaxseed also contains compounds called lignans. These are plant-based phytoestrogens that may be helpful for health.

Medically valid uses

Raw or unripe flaxseeds may contain potentially toxic compounds. Don't eat them.

Flaxseed oil helps prevent atherosclerosis and heart attack. It can be substituted for other vegetable oils when making foods.

Unsubstantiated claims

There may be benefits that haven't yet been proven through research.

Flaxseed may help treat:

  • Bladder inflammation

  • Gastritis

  • Benign prostatic hyperplasia

  • Vaginitis

  • Hot flashes during menopause

  • Rheumatoid arthritis

  • Gallstones

  • High cholesterol

  • Low lipoprotein A (involved in atherosclerosis)

  • Weight loss

  • Asthma

  • Chronic cough

  • Lupus nephritis

  • Constipation

Some theories suggest that the lignans in flaxseed may block estrogen-stimulated breast cancer. It may also have sugar-reducing effects. It may also have antibacterial, antifungal, and antiviral effects.

Forms of flaxseed

Flaxseed is available as whole, milled, or ground seeds and as flaxseed oil. The seeds can be sprinkled on foods such as yogurt, oatmeal, pasta, and other dishes, and added to baked goods. The oil can be put on salads or vegetables. It can also be used in place of other oils when baking.

As a dietary supplement, flaxseed comes in different forms such as capsules, tablets, and powder.

Side effects, toxicity, and interactions

When you take it as directed, flaxseed doesn’t cause side effects. But taking large amounts of it as a laxative without drinking enough fluids can worsen constipation. In rare cases, it can cause an intestinal blockage.

Women who are pregnant or breastfeeding should talk with their healthcare providers before taking any herbal medicines. Flaxseed can have mild estrogenic effects. This may harm a pregnancy. But there is no evidence that flaxseed can harm a pregnancy at this time.

You shouldn’t take flaxseed if you have ileus or an esophageal or gastrointestinal stricture. You also shouldn’t take it if you have an acute inflammatory illness of the intestine, stomach, or stomach entrance.

Flaxseed may delay how quickly you absorb other medicines if you take them at the same time.

Online Medical Reviewer: Brittany Poulson MDA RDN CD CDE
Online Medical Reviewer: Heather M Trevino BSN RNC
Date Last Reviewed: 8/1/2023