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Flaxseed oil and fish oil are both promoted for their health benefits.
Both oils provide omega-3 fatty acids and have been shown to reduce risk factors of heart disease, such as high blood pressure (1).
Yet, you may wonder how they’re different — and if one is more beneficial.
This article explores the similarities and differences between flaxseed oil and fish oil, so you can see which is the best choice for you.
The flax plant (Linum usitatissimum) is an ancient crop that has been cultivated since the beginning of civilization (2).
It was first used in the United States to make fabric for clothing and other textile goods.
The flax plant contains nutritious seeds commonly known as flax seeds.
Flaxseed oil is obtained by cold-pressing ripened and dried flax seeds. The oil is also commonly known as linseed oil.
Flaxseed oil can be used in a variety of ways. It’s available commercially in both liquid and capsule form.
Countless studies have linked flaxseed oil to powerful health benefits, likely related to its high content of heart-healthy omega-3 fatty acids (3).
Flaxseed oil is made by pressing dried flax seeds. This oil is rich in omega-3 fatty acids and has been associated with numerous health benefits.
Fish oil is one of the most popular consumed dietary supplements on the market.
It’s made by extracting oil from fish tissue.
Supplements are usually made with oil extracted from fatty fish, such as herring, mackerel, or tuna, which are particularly rich in omega-3 fatty acids (4).
The American Heart Association (AHA) recommends eating a variety of fatty fish at least twice a week to get the heart health benefits from the omega-3 fatty acids (5).
Still, many individuals fall short of this recommendation.
Fish oil supplements can help you consume adequate omega-3 fatty acids, especially if you’re not much of a seafood fan.
Typical fish oil supplements contain 1,000 mg of omega-3 fatty acids, which is proportionate to a 3-ounce (85-gram) serving of fatty fish (4).
Like flaxseed oil, a lot of the benefits of fish oil appear to come from its omega-3 fatty acids.
Numerous studies have linked fish oil to improved markers of heart disease (6, 7).
In fact, certain fish oil supplements are often prescribed by healthcare providers to lower blood triglyceride levels.
Fish oil supplements are made from the oil that’s extracted from fish tissue. Fish oil supplements are rich in omega-3 fatty acids and may reduce the risk factors associated with heart disease.
Omega-3 fatty acids are essential fats, meaning you must get them from the food you eat, as your body can’t make them.
They’ve been associated with numerous health benefits, such as a reduced risk of heart disease, reduced inflammation, and improved mood (8, 9, 10).
Fish oil and flaxseed oil each contain an impressive amount of omega-3 fatty acids.
The main types of omega-3s in fish oil are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (11).
A typical fish oil supplement contains 180 mg of EPA and 120 mg of DHA, but the amount varies depending on the supplement and brand (4).
On the other hand, flaxseed oil contains the omega-3 fatty acid known as alpha-linoleic acid (ALA) (12).
EPA and DHA are predominantly found in animal foods like fatty fish, while ALA is mostly found in plants.
The Adequate Intake (AI) for ALA is 1.1 grams per day for adult women and 1.6 grams per day for adult men (4).
In just 1 tablespoon (15 mL), flaxseed oil contains a whopping 7.3 grams of ALA, which greatly exceeds your daily needs (4, 13).
However, ALA isn’t biologically active and needs to be converted to EPA and DHA to be used for something other than just stored energy like other types of fat (14).
While ALA is still an essential fatty acid, EPA and DHA are linked to many more health benefits (15).
Additionally, the conversion process from ALA to EPA and DHA is quite inefficient in humans (16).
For example, one study found that only 5% of ALA is converted to EPA and less than 0.5% of ALA is converted to DHA in adults (17).
Both fish oil and flaxseed oil are rich in omega-3 fatty acids. Fish oil is high in EPA and DHA, while flaxseed oil is rich in ALA.
While fish oil and flaxseed oil differ, they may provide some of the same health benefits.
Heart disease is the leading cause of death globally (18).
Many studies have found that both flaxseed oil and fish oil may benefit heart health.
Specifically, supplementing with these oils has been shown to lower blood pressure levels in adults, even in small doses (19, 20, 21, 22).
Additionally, fish oil supplements have been strongly linked to decreased triglycerides.
What’s more, supplementing with fish oil also improves HDL (good) cholesterol and may lower your blood triglycerides by up to 30% (23, 24).
Flaxseed oil may also have beneficial effects on cholesterol levels when taken as a supplement. Some studies have shown that flaxseed oil may be effective in reducing LDL (bad) cholesterol and boosting protective HDL cholesterol (25, 26, 27).
Flaxseed oil and fish oil benefit your skin, largely due to their omega-3 fatty acid content.
Numerous studies have shown that fish oil supplements may improve a number of skin disorders, including dermatitis, psoriasis, and skin damage attributed to ultraviolet (UV) exposure (28).
Similarly, flaxseed oil may aid in treating multiple skin disorders.
For instance, one small study in 13 women found that ingesting flaxseed oil for 12 weeks improved skin properties like skin sensitivity, hydration, and smoothness (29).
Chronic inflammation is linked to an increased risk of conditions like diabetes and Crohn’s disease.
Controlling inflammation may decrease the symptoms associated with these illnesses.
Fish oil has been shown to have anti-inflammatory properties in research studies, due to its omega-3 fatty acid content (30).
For example, fish oil has been associated with decreased production of inflammatory markers known as cytokines (31, 32).
Furthermore, numerous studies have noted fish oil’s beneficial effects on inflammation associated with chronic conditions, such as inflammatory bowel disease, rheumatoid arthritis, and lupus (33).
However, the research on flaxseed oil and its effect on inflammation is mixed.
While some animal studies have identified flaxseed oil’s anti-inflammatory potential, results involving humans are mixed (34, 35).
Ultimately, more research is warranted to fully understand flaxseed oil’s anti-inflammatory effect in humans.
Both oils may help to lower blood pressure and improve triglyceride and cholesterol levels. Flaxseed oil and fish oil both promote skin health. Fish oil has proven to have potent anti-inflammatory properties, while research is mixed for flaxseed oil.
In addition to its above shared health benefits with fish oil, flaxseed oil may also be beneficial in treating gastrointestinal symptoms.
Studies have shown flaxseed oil may be helpful in treating both constipation and diarrhea.
One animal study proved flaxseed oil to have both laxative and antidiarrheal effects (36).
Another study showed that daily use of 4 mL of flaxseed oil helped improve bowel regularity and stool consistency in people with end stage renal disease on dialysis (37).
While these two studies are promising, more research is warranted to fully understand flaxseed oil’s effectiveness in treating constipation and diarrhea.
Flaxseed oil may be beneficial in the treatment of both constipation and diarrhea, but more research is needed.
Fish oil has been associated with a handful of other health benefits.
For example, fish oil has been shown to improve symptoms of certain mental health disorders, including depression, bipolar disorder, and schizophrenia (38, 39, 40).
Additionally, fish oil may help treat behavioral disorders in children.
Numerous studies have linked fish oil supplements with an improvement in hyperactivity, attentiveness, and aggression in young children (41, 42).
Fish oil may be beneficial in improving symptoms of certain mental health conditions in adults and behavioral disorders in children.
Both fish oil and flaxseed oil promote health and have quality research to support their respective health claims.
However, while each oil has its individual benefits, when it comes to shared benefits, fish oil may have an advantage.
This is likely because only fish oil contains the active EPA and DHA omega-3 fatty acids.
What’s more, ALA isn’t efficiently converted into EPA and DHA. Because only a very small amount of ALA is converted into DHA and EPA, it’s likely that taking EPA- and DHA-rich fish oil will provide more clinical benefits than taking flaxseed oil.
Also, there’s more quality research that supports fish oil’s anti-inflammatory effects and its effect on improving heart disease risk indicators, such as lowering triglycerides and improving cholesterol levels.
However, fish oil supplements may not be suitable for everyone.
For instance, some fish oil supplements may contain small amounts of fish or shellfish proteins.
As a result, many fish oil supplements contain the warning, “Avoid this product if you are allergic to fish or shellfish” on the bottle.
Therefore, flaxseed oil may be a more appropriate choice for those with a fish or shellfish allergy.
Additionally, flaxseed may also be a better fit for those following a vegetarian or vegan diet.
However, there are other more effective vegan omega-3 supplements including algae oil.
While both flaxseed oil and fish oil have individual benefits, fish oil may be more advantageous in their shared benefits such as heart health and inflammation.
Flaxseed oil and fish oil provide similar health benefits, including for skin and blood pressure control.
Only fish oil contains the active EPA and DHA omega-3 fatty acids and may be more helpful in improving overall heart health, inflammation, and mental health symptoms.
However, flaxseed oil poses its own benefits for gastrointestinal health and may be a good way to boost ALA omega-3 fatty acids for those with fish allergies or following a vegan diet.
In any case, if you’re interested in trying flaxseed oil or fish oil to improve health, it’s best to speak with your healthcare provider first.
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