What Is Flaxseed Oil?

Flaxseed oil is made from ground and pressed flaxseeds, traditionally used as laxatives and for wound healing. Flaxseed oil contains many active compounds that are thought to provide benefits, including:

• Alpha-linolenic acid (ALA), an omega-3 fatty acid
• Linoleic acid (LA), an omega-6 fatty acid
• Oleic acid, an omega-9 fatty acid
• Fiber
• Lignans, glycosides, and peptides

Purported flaxseed oil benefits include lowering inflammation, preventing heart disease, and promoting digestive health.

This article discusses the evidence for these and other possible health benefits, along with side effects to be aware of and precautions to take when adding flaxseed oil to your diet.

Uses of Flaxseed Oil

Evidence supports some of flaxseed's many purported health benefits.

Reduce Inflammation 

Because flaxseed oil contains omega-3 fatty acids, it's commonly thought to reduce inflammation. However, studies in humans have yielded mixed results. 

One analysis of multiple human studies found flaxseed contained compounds helpful for reducing C-reactive protein (an inflammation marker) in some study participants who experienced experienced obesity. It didn't seem beneficial in patients who did not have obesity. The analysis suggests that flaxseed oil may affect people differently; therefore, more research is needed to determine its effects on inflammation in the general population.

In another meta-analysis (collection) of 12 studies, flaxseed oil was shown to decrease two inflammatory markers called interleukin-6 (IL-6) and malondialdehyde (MDA). Inflammatory markers show what is occurring in the body, so reduced levels suggest less inflammation or swelling. Flaxseed oil had no significant effect on other markers of inflammation, however.

The bottom line is that more study is needed to confirm flaxseed oil's effects on decreasing inflammation.

Promote Heart Health

The American Heart Association recommends incorporating polyunsaturated fats, like flaxseed oil, into your diet. Eating moderate amounts of these healthy fats is correlated with a lower risk of heart disease.

Studies have found that flaxseed oil supplements can increase levels of omega-3 fatty acids in the body, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

EPA and DHA are essential compounds for promoting a healthy heart and preventing heart disease. ALA is a primary component of flaxseed oil converted to EPA and DHA in the body.

Further clinical trials are needed to support its use for heart health.

Improve Gut Health 

Flaxseed oil has laxative properties. A study of 50 patients on hemodialysis (a treatment that filters waste and water from the blood) showed that daily flaxseed oil supplementation relieved constipation.

A study of 75 people with ulcerative colitis, a type of inflammatory bowel disease (IBD), found that flaxseed and flaxseed oil helped reduce inflammatory markers, disease severity, blood pressure, and waist circumference.

While flaxseed may benefit the gut, more human studies are needed to confirm these results.

Additional Uses

In addition to the potential health benefits listed above, some people may use flaxseed oil for the following:

• Reduce breast cancer risk
  
• Manage carpal tunnel syndrome
• Relieve dry eye
• Lower high blood pressure in patients with metabolic syndrome
  
• Manage menopausal symptoms like hot flashes
• Treat metabolic dysfunction-associated steatotic liver disease (MASLD, formerly known as NAFLD)
  
• Prevent renal anemia in hemodialysis patients
• Improve skin and hair health

It's important to note that more research is needed before flaxseed oil can be routinely recommended for any of these uses. There is currently very little evidence to support flaxseed oil supplementation for these conditions.

What Are the Side Effects of Flaxseed Oil?

Your provider may suggest flaxseed oil for heart health, stomach complaints, or other reasons. However, consuming a supplement like flaxseed oil may cause side effects. These side effects may be common or severe.

Common Side Effects

When taken in the right doses and in the short term, flaxseed oil is usually safe for most adults. Possible side effects include:

• Diarrhea and loose stools
• Worsening constipation

These side effects can be minimized by taking flaxseed oil with plenty of water and by taking it at recommended doses.

Severe Side Effects

Rarely, flaxseed may cause intestinal blockage, but flaxseed oil doesn't seem to carry this risk. Allergic reactions are also possible. 

Precautions

Avoid flaxseed oil if you are:

• Allergic: Avoid using flaxseed products if you have a known allergy to it or its ingredients. Ask your pharmacist or healthcare provider for a complete list of the ingredients if you're unsure.
• Pregnant: It may have adverse effects in pregnancy, including an increased risk for premature birth.
• A child: There has not been enough evidence on the safety of flaxseed oil when taken by children, although it may be safe for children to consume small amounts of flaxseed.
• Breastfeeding: There isn’t enough reliable information about the safety of flaxseed oil for people who are breastfeeding.
• Experiencing a bleeding disorder: There is some debate about whether flaxseed oil may increase the risk of bleeding. If you have a bleeding disorder, talk to your healthcare provider before using flaxseed oil in food, in supplement form, or as a topical treatment.
• Going in for surgery: Flaxseed oil should be stopped before surgery to prevent bleeding.

Ask your healthcare provider if a flaxseed oil supplement is right for you.

Dosage: How Much Flaxseed Oil Should I Take?

There are no standard dosing guidelines for flaxseed oil dosage. The recommended dose varies based on the manufacturer.

The dose of flaxseed oil is often calculated based on the ALA content and advertised as milligrams of omega-3. Many studies used a dose of 1,000 milligrams (mg) of flaxseed oil omega-3 fatty acids.

Recommended daily values of ALA are 1,100 mg for people assigned female at birth and 1,600 mg for people assigned male at birth. To achieve these levels, many manufacturers suggest 1 or 2 tablespoonfuls of liquid flaxseed oil daily. Note that the amount of ALA in 1 tablespoon of flaxseed oil is close to 7,000 mg. However, the body can only convert about 10% of this into usable omega-3 fatty acids like EPA and DHA.

Check the manufacturer's suggested dose for capsule supplements. And run the suggested dosage by your healthcare provider. Recommended doses can range from one capsule twice a day to three capsules three times a day, depending on the ALA content.

What Happens If I Take Too Much Flaxseed Oil?

There seems to be little risk for flaxseed oil toxicity, but taking too much flaxseed oil may increase the risk of side effects.

Interactions

Taking flaxseed oil with medications that slow down blood clotting (like aspirin, diclofenac, or warfarin) may increase the risk of bleeding and bruising.

Taking flaxseed oil with medications that lower cholesterol levels, such as Crestor (rosuvastatin), Lipitor (atorvastatin), or Zocor (simvastatin), may have additive effects, meaning it can increase the effects of the medication.

It is essential to carefully read a supplement's ingredients list and nutrition facts panel to learn which ingredients are in the product and how much of each ingredient is included. Please review this supplement label with your healthcare provider to discuss potential interactions with foods, other supplements, and medications.

How to Store Flaxseed Oil

Liquid flaxseed oil typically comes in dark bottles to protect it from light, and often needs to be refrigerated after opening. Check the packaging to see when to discard it. Some products will only last six to eight weeks after opening.

Similar Supplements

Fish oil is another popular supplement that contains omega-3 fatty acids and may be taken for heart health. Studies have shown that flaxseed oil has similar heart-protective properties as fish oil. Because it comes from a plant rather than an animal source, flaxseed oil is a helpful alternative for people who follow a vegan or vegetarian diet.

Some other popular supplements touted for heart health include:

• Red yeast rice
• Coenzyme Q10
• Olive oil
• Garlic

Sources of Flaxseed Oil & What to Look For

Flaxseed oil is available commercially in liquid and capsule form.

Food Sources of Flaxseed Oil

You may find flaxseed oil in the refrigerated section of your health food store or on store shelves. Some brands add antioxidants to make their products shelf stable, meaning they don't need refrigeration until opened.

Fresh flaxseed oil has a mild, nutty aroma reminiscent of sunflower or sesame seeds and tastes crisp and mildly nutty. Oil that is cloudy, smells fishy or like fried oil, or has a bitter or burnt flavor is rancid and should not be used. If you notice this or the product is past its expiration date, throw it out.

Here are some ways to use it:

• Use as a salad oil or in cold sauces.
• Add to juice, shakes, or smoothies.
• Do not use in stir-fries or when baking. When exposed to heat, the oil can form harmful chemicals.

Flaxseed oil is also a common additive in commercially available foods.

Flaxseed Oil Supplements

Supplements are available as softgel capsules.

To ensure the best quality, check whether your product has been tested by a trusted third party, like USP, ConsumerLab, or NSF.

And keep in mind that because supplements aren't required to be tested or approved by the FDA, there can be great variability between products.

Summary

Flaxseed oil, made from ground flaxseed, is widely credited with aiding inflammation, gut health, and heart health. Science offers some support for these claims, but flaxseed oil is not a miracle cure for any condition.

Ensuring that your overall diet contains fiber and nutrients from vegetables and fruit is vital for heart health. Movement is too. If you have heart health concerns, consider asking your healthcare provider about referring you to a registered dietitian (RD).

When taken in the right dose, flaxseed oil has few side effects. It can be added to juice, salads, smoothies, body cream, or your hair.

If you're pregnant, breastfeeding, have an upcoming surgery or have a bleeding disorder, you should consult your healthcare provider before trying this supplement.