This information describes the common uses of Flaxseed, how it works, and its possible side effects.

Common Name

Flax, Linseed, Lint bells, Linum

How It Works

Flaxseed may help improve menopausal symptoms and reduce blood pressure, but evidence of its ability to improve cholesterol levels is mixed.

Flaxseed is a concentrated source of phytoestrogenic compounds called lignans, which have hormone-like effects on the body. These lignans are likely the reason why flaxseed can affect menstrual cycle length and menopausal symptoms. It contains alpha-linolenic acid (ALA), a building block of omega-3 fatty acids. ALA has been shown to have numerous effects on the body including protecting the kidneys from damage.

Results from clinical studies are mixed on flaxseed’s ability to reduce cholesterol. Other studies suggest it may reduce blood pressure and help with some aspects of diabetes or related conditions, especially along with other lifestyle modifications.

Flaxseed has also been shown to affect intracellular signals within the body that may play a role in breast and prostate cancer growth. Because flaxseed has phytoestrogenic effects, patients with estrogen receptor positive (ER+) breast cancer should consult their physicians before using flaxseed.

Purported Uses

  • Cancer prevention
    Studies of postmenopausal women showed that flaxseed supplementation improved the ratio of hormones that are thought to help prevent breast cancer. Studies in animals have shown promising results, but human data are lacking.
  • Diabetes and associated conditions
    Some studies suggest supplementation with flaxseed may help some aspects of diabetes or related conditions, especially along with other lifestyle modifications.
  • High cholesterol
    Study results are mixed.
  • Menopausal symptoms
    A study showed flaxseed to be as effective as hormone replacement therapy in the management of menopausal symptoms.
  • Mucositis
    One study indicated that flaxseed was not effective for mucositis.
  • Periodontal disease
    Flaxseed was shown ineffective against periodontal disease in a study.

Do Not Take If

  • You are undergoing radiological procedures: Flax or linseed may interfere with the reading of certain tests.

Side Effects

  • Allergic reactions
  • Longer luteal phase of the menstrual cycle
  • Increased bowel movement
  • Constipation
  • Flatulence

Case Reports

  • Anaphylaxis following intake of flaxseeds