Flaxseed Oil

Medically reviewed by Prof. Giorgi Pkhakadze, MD, MPH, PhD — GMJ Editorial Board

What is Flaxseed Oil?

Flaxseed oil, also known as linseed oil, is derived from the seeds of the flax plant (Linum usitatissimum). This golden-colored oil is one of the richest plant-based sources of alpha-linolenic acid (ALA), an essential omega-3 fatty acid that the human body cannot produce on its own. Flaxseed oil contains approximately 50-60% ALA, making it a popular supplement for those seeking to increase their omega-3 intake, particularly vegetarians and vegans who may not consume fish-based sources.

The oil is extracted through cold-pressing or solvent extraction methods, with cold-pressed varieties generally preferred for nutritional supplements due to better preservation of beneficial compounds. Flaxseed oil is available in liquid form, softgel capsules, and as an ingredient in various functional foods.

Health benefits & uses

Cardiovascular health (Moderate evidence): Research suggests that flaxseed oil may help improve cardiovascular risk factors. Studies have shown potential benefits for reducing blood pressure, improving cholesterol profiles, and decreasing inflammation markers. The ALA content may help reduce the risk of heart disease, though the evidence is stronger for marine-based omega-3s.

Submit Your Paper

Inflammatory conditions (Limited evidence): Some studies indicate that flaxseed oil may help reduce inflammatory markers in the body, potentially benefiting conditions like rheumatoid arthritis. However, more robust clinical trials are needed to establish definitive therapeutic effects.

Skin health (Limited evidence): Preliminary research suggests flaxseed oil supplementation may improve skin barrier function and reduce skin sensitivity, possibly due to its anti-inflammatory properties and essential fatty acid content.

Digestive health (Limited evidence): Some studies suggest flaxseed oil may have mild benefits for digestive health, though whole flaxseeds are generally preferred for fiber-related digestive benefits.

How it works

Flaxseed oil primarily works through its high concentration of ALA, which the body can convert to other omega-3 fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), though this conversion is limited and inefficient in humans (typically less than 10-15% for EPA and 2-5% for DHA).

ALA and its metabolites become incorporated into cell membranes, where they influence membrane fluidity and cellular signaling. These omega-3 fatty acids serve as precursors to specialized pro-resolving mediators that help resolve inflammation and support normal immune function. They also compete with omega-6 fatty acids for the same enzymatic pathways, potentially helping to balance the omega-6 to omega-3 ratio in the diet.

Dosage

There is no established Recommended Dietary Allowance (RDA) or Tolerable Upper Limit (UL) specifically for flaxseed oil. However, the adequate intake (AI) for ALA is 1.6 grams per day for adult men and 1.1 grams per day for adult women.

Typical supplemental dosages range from 1-3 tablespoons (15-45 mL) of oil daily, providing approximately 7-20 grams of ALA. In capsule form, common dosages range from 1-6 grams daily. Some studies have used doses up to 30 grams daily without significant adverse effects.

It’s important to start with lower doses and gradually increase as tolerated. Consultation with a healthcare provider is recommended, especially for individuals with existing health conditions or those taking medications.

Food sources

While flaxseed oil provides the most concentrated source of ALA from flax, other dietary sources include:

• Whole flaxseeds (ground flaxseeds are better absorbed)
• Chia seeds
• Hemp seeds
• Walnuts
• Canola oil
• Soybean oil
• Purslane (leafy green)

Whole flaxseeds provide additional benefits including fiber, lignans, and protein, though the oil provides more concentrated ALA per serving.

Safety & side effects

Flaxseed oil is generally considered safe for most people when consumed in typical supplemental amounts. Potential side effects may include:

• Digestive upset, including diarrhea, bloating, or nausea, particularly with higher doses
• Allergic reactions in sensitive individuals
• Potential blood-thinning effects at very high doses

Flaxseed oil is highly susceptible to oxidation and rancidity. It should be stored in the refrigerator, kept away from light and heat, and used within the expiration date. Rancid oil may cause digestive upset and provide no nutritional benefits.

Interactions

Flaxseed oil may interact with certain medications and supplements:

Blood-thinning medications: High doses may enhance the effects of warfarin, aspirin, and other anticoagulant medications, potentially increasing bleeding risk.

Diabetes medications: Some evidence suggests flaxseed products may affect blood sugar levels, potentially requiring medication adjustments.

Other omega-3 supplements: Combining with fish oil or other omega-3 supplements may increase the total omega-3 intake and potential for blood-thinning effects.

Who should be cautious

Certain individuals should exercise caution or avoid flaxseed oil:

• People with bleeding disorders or those taking anticoagulant medications
• Individuals scheduled for surgery (discontinue 2 weeks prior)
• Those with inflammatory bowel conditions (may worsen symptoms in some cases)
• People with hormone-sensitive conditions should consult healthcare providers, as whole flaxseeds contain phytoestrogens (though oil contains minimal amounts)
• Pregnant and breastfeeding women should consult healthcare providers before use

Frequently asked questions

Is flaxseed oil as effective as fish oil?

Flaxseed oil provides ALA, while fish oil provides EPA and DHA. The body’s conversion of ALA to EPA and DHA is limited, making fish oil generally more effective for obtaining these specific omega-3s. However, flaxseed oil can be a valuable plant-based alternative, especially for vegetarians and vegans.

How should I store flaxseed oil?

Store flaxseed oil in the refrigerator in a dark container, away from light and heat. Use within the expiration date and discard if it develops a bitter or off smell, which indicates rancidity.

Can I cook with flaxseed oil?

Flaxseed oil has a low smoke point and is sensitive to heat, making it unsuitable for cooking. It’s best used as a finishing oil, added to smoothies, or taken as a supplement.

How long does it take to see benefits?

Benefits may vary depending on the health outcome. Some studies show changes in blood lipids within 4-12 weeks, while other effects may take longer to manifest.

Is whole flaxseed better than flaxseed oil?

Whole ground flaxseeds provide fiber, lignans, and protein in addition to ALA, offering more comprehensive nutritional benefits. However, flaxseed oil provides more concentrated ALA per serving.