Common Names: flaxseed, flax, linseed

Scientific Name: Linum usitatissimum

Background

• Flaxseed has been used for centuries both for medicinal and practical reasons. First cultivated in regions around the Middle East, flax was later valued in ancient Egypt for producing linen, served in dishes in Ethiopia, and used as a laxative in Greece. Early European settlers in North America used flaxseed in poultices for minor wounds and burns, and its oil for making paint.

• In modern times, flaxseed and its oil are often marketed as supplements believed to support heart, brain, and immune health. These contain alpha-linolenic acid (ALA), an omega-3 fatty acid derived from flaxseed or flaxseed oil.

How Much Do We Know?

• Several studies of varying quality have explored how flaxseed and its oil may affect human health, though findings are still emerging.

What Have We Learned?

• One clinical study found that a water-based powder made from flaxseed mucilage may help with weight loss in overweight or obese adults. However, supplements made from flaxseed oil or lignans didn’t show the same results.

• Some research on pregnant individuals with gestational diabetes indicates that flaxseed oil rich in ALA might improve fasting blood sugar levels and insulin response.

• Further studies are being conducted to examine whether flaxseed lignan extract can aid blood sugar control in those with type 2 diabetes.

• It’s still unknown if flaxseed oil supplements benefit other people with diabetes, including those with complications like foot ulcers.

• Ongoing research is looking into how flaxseed may influence gut bacteria and reduce inflammation.

What Do We Know About Safety?

• Avoid consuming raw or unripe flaxseeds, as they may have harmful compounds.

• Small amounts of flaxseed mucilage or lignan supplements, and flaxseed oil taken orally, appear to be safe for short-term use (up to six months). Larger doses may lead to unwanted digestive issues such as gas, a feeling of fullness, and diarrhea.

• Since flaxseed and its oil might interfere with medications like blood thinners, always check with your doctor before using them, especially if you’re on any other prescriptions.

• Some studies suggest possible risks of using flaxseed during pregnancy, but evidence is limited. There is also a lack of solid information on the effects during breastfeeding.

• The safety of flaxseed oil use during pregnancy or nursing is also uncertain.

Keep in Mind

• It’s important to be proactive about your health. Discuss any complementary or alternative approaches with your healthcare provider to make well-informed decisions together.

• Herbal products are regulated differently depending on their contents, purpose, and method of use. Most oral herbal remedies are sold as dietary supplements, which are subject to fewer regulations than pharmaceutical drugs.

• Unlike approved medications, dietary supplements do not need FDA approval before hitting the market. However, the FDA can take steps to remove unsafe products if needed. It is up to supplement makers and sellers to ensure their products follow safety and labeling laws.

For More Information

• Learn how to safely use dietary supplements.

• Understand how supplements and medications might interact.

• Discover how to read and interpret scientific journal articles.

NCCIH Clearinghouse

The NCCIH Clearinghouse offers resources on various complementary health strategies and provides access to federal scientific literature. It does not give medical advice or referrals.

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PubMed®

PubMed® is an online service from the National Library of Medicine that contains summaries and citations from science and medical journals. It is a valuable tool for exploring research studies.

Office of Dietary Supplements (ODS), National Institutes of Health (NIH)

The ODS aims to deepen public understanding of dietary supplements by promoting research, sharing results, and educational outreach. It offers resources on various supplements and nutrients.

Key References

• Bongartz U, Hochmann U, Grube B, et al. A 12-week study found that flaxseed mucilage (IQP-LU-104) may assist in reducing body weight in overweight and slightly obese adults. Obesity Facts. 2022.

• Natural Medicines databases were accessed in March 2024 for information on flaxseed and flaxseed oil. [Subscription resources]

• Jamilian M, Tabassi Z, Reiner Z, et al. A randomized clinical trial studied flaxseed oil’s impact on genetic and metabolic markers in people with gestational diabetes. British Journal of Nutrition. 2020.

• Office of Dietary Supplements. Omega-3 Fatty Acids. Fact Sheet accessed in November 2023.

• Thompson LU, Mason JK. Flaxseed entry in the Encyclopedia of Dietary Supplements. 2nd edition. 2010.

• Toulabi T, Yarahmadi M, Goudarzi F, et al. A study examining flaxseed’s effects on blood pressure, cholesterol, and body mass index in those with hypertension. Explore (NY). 2022.

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The information here is provided by NCCIH for educational purposes. It is not a substitute for the guidance of a medical professional. Be sure to consult your provider before starting any treatment. Mention of any product or therapy is not an endorsement.