Flaxseed vs. Fish Oil: Which Choice is Right for You?

Table of Contents

Understanding Omega-3 Fatty Acids

Omega-3 fatty acids are vital healthy fats that your body can't make on its own, which means you need to consume them as part of a well-rounded diet. There are three core types:ALA is the primary plant-based omega-3, while EPA and DHA are the two main biologically active, animal-based omega-3

EPA (eicosapentaenoic acid), DHA (docosahexaenoic acid), and ALA (alpha-linolenic acid), all of which are essential building blocks in the cell membranes throughout your body. 

The key distinction lies in how your body uses them: While EPA and DHA can be used by your body directly via your cells, ALA must first change into its more active forms in order to deliver similar benefits. 

Research shows that the body typically converts just a small amount (less than 15%) of ALA into the active, usable forms. For this reason, experts from the U.S. National Institute for Health (NIH) say that this limited change means consuming EPA and DHA directly — through seafood sources — is more effective for elevating omega-3 fatty acids in the body. 

Omega-3s help form compounds affecting heart function, inflammation control, brain health, and overall wellness. Getting enough omega-3s supports everything from heart health to brain performance and cellular function.

What is Fish Oil?

Fish oil is derived from fatty fish like salmon, tuna, herring, anchovies and mackerel. It contains high levels of EPA and DHA, which are the active omega-3s more readily usable by the body. 

Experts from the American Heart Association (AHA) recommend eating at least 2 servings of fish — "particularly fatty fish" –  per week for optimal health benefits for everything from your heart to your brain. That being said, most Americans consume much less than the recommended amount, which is where supplementation may come in. 

Since fish receive omega-3s by consuming smaller marine organisms, the exact makeup of these nutrients varies between fish. For instance, cold-water, fatty fish like salmon and mackerel have high levels of omega-3s, while leaner types like tilapia contain much lower levels. 

Studies strongly support fish oil's benefits for heart health. Research shows it helps maintain healthy blood fats and supports normal inflammatory balance. Health experts suggest omega-3s may reduce certain heart health risks, particularly for people whose diets lack these nutrients. 

Fish oils are often sold as over-the-counter supplements, though they may also sometimes be sold via prescription at higher strengths. Experts recommend taking a fish oil supplement with a meal containing healthy fats in order to boost absorption and minimize potential side effects — more on those below. 

What is Flaxseed Oil?

Flaxseed oil comes from the dried, ripened seeds of the flax plant, which has origins in ancient China and Egypt. Through a gentle pressed extraction process, its nutrients remain intact, offering the richest plant-based source of omega-3s. Other sources include walnuts, canola oil, and soybeans.

Unlike whole flaxseeds, flaxseed oil lacks fiber but provides a more concentrated and bioavailable source of alpha-linolenic acid (ALA), the plant-based omega-3 fatty acid. While both flaxseed oil and fish oil contain beneficial oils, they serve different biological roles. Fish oil supplies EPA and DHA directly, while flaxseed oil relies on inefficient enzymatic conversion (with less than 5% of ALA converting to EPA and less than 1% to DHA). Flaxseed oil is not an equivalent substitute for fish oil when it comes to supporting brain function, cardiovascular health, and anti-inflammatory pathways.

You may find flaxseed oil in supplement form or in the cooking section, often added to salads, smoothies, and other cold foods. However, it should never be used for cooking, as heat oxidizes its fragile polyunsaturated fatty acid (PUFA) chains, breaking down its molecular structure and producing harmful lipid peroxides. This not only destroys its beneficial properties but also creates toxic byproducts that contribute to inflammation, oxidative stress, and cellular damage.

Flaxseed oil supplements typically come in liquid form or softgel capsules. For best results, store flaxseed oil in the refrigerator in a dark container to prevent oxidation, which can reduce its nutritional value.

Key Differences Between Flaxseed Oil and Fish Oil

The key differences between each type include: 

• Omega-3 forms. Fish oil contains EPA and DHA that are completely usable by your body. Flaxseed oil contains ALA, which needs to be converted to EPA and DHA in your body. Our bodies haven't proven to be very effective at this conversion, research shows, however, and most people convert less than 5% of ALA into active forms. 
• Absorption distinctions. Thus, research also shows that fish oil raises blood levels of active omega-3s more effectively than flaxseed oil. In one study, fish oil increased EPA levels by 300% and DHA levels by 42%. Meanwhile, flaxseed oil only raised EPA levels by 133% without any corresponding DHA boost. 
• Unique health benefits. Flaxseed oil may work more effectively for treating certain conditions. For instance, research found it was more effective at supporting a healthy inflammation response and reducing insulin levels in patients with diabetes and heart disease.
• Other nutrients. Cold-water fish like salmon, mackerel, sardines, anchovies, and cod provide a unique synergy of essential nutrients that support brain function, cardiovascular health, immune regulation, and cellular resilience. Unlike plant-based omega-3 sources, which rely on inefficient conversion, fish naturally supply bioavailable EPA and DHA, the essential fatty acids required for brain development, neuroplasticity, heart health, and inflammation regulation. 

These fish are also rich in vitamin A (retinol), which is critical for immune function, vision, and skin health, and vitamin D3, one of the few natural dietary sources of this essential hormone-like nutrient for bone health, mitochondrial function, and immune balance. Additionally, cold-water fish provide selenium and iodine, which are crucial for thyroid health and detoxification, as well as astaxanthin, a potent marine antioxidant that protects cellular membranes from oxidative damage. While flaxseed oil offers alpha-linolenic acid (ALA), lignans, and plant-based antioxidants with their own cardiovascular and hormonal benefits, it lacks the direct bioavailable EPA, DHA, and fat-soluble vitamins that make cold-water fish an irreplaceable nutritional powerhouse.

Health Benefits of Flaxseed and Fish Oil

Now let's take a look at some of flaxseed and fish oil's plentiful health benefits, including benefits for heart health, inflammation, blood pressure, and brain and eye health. 

Benefits for Heart Health

Both supplements support heart health via distinct mechanisms. According to some, omega-3 fatty acids from fish boost lipid profiles, blood pressure, and vascular function while also providing anti-inflammatory benefits.

Flaxseed oil's ALA content, meanwhile, also contributes to heart health, though sometimes with more modest effects due to conversion limitations. Research shows that flaxseed oil had similar effects to fish oil on insulin resistance markers in heart patients. 

Anti-Inflammatory Properties

Omega-3 fatty acids contribute to a healthy immune system response. According to research, fish oil's EPA content helps regulate and balance the inflammation response.

Flaxseed oil also has an anti-inflammatory response, with ALA appearing to decrease various inflammatory markers in the body. 

Role in Blood Pressure Regulation

Both oils appear to effectively contribute to healthy blood pressure management. Fish oil's heart-healthy benefits include boosting vascular function and nitric oxide production, as well as modestly improving blood sugar levels. 

Flaxseed oil may also benefit blood pressure levels. 

Brain and Eye Health 

DHA is not just a structural component of the retina—it is a quantum tunneling lipid that enables the conversion of light into electrical signals, making vision possible. The human eye is a biophotonic device, and DHA is uniquely designed to facilitate electron flow, photonic energy transfer, and signal transduction within the photoreceptor membranes. Its pi-electron cloud system allows for rapid charge separation, enabling the retina to process light with extreme efficiency. DHA is concentrated in the rod outer segment discs, where it optimizes photoexcitation in rhodopsin, stabilizes lipid rafts, and enhances the function of voltage-gated ion channels. 

When DHA is deficient, the retina loses its ability to transduce light efficiently, leading to impaired vision, disrupted circadian signaling, and increased susceptibility to neurodegeneration. Since the eye and brain are both non-visual photoreceptors, DHA plays a critical role in synchronizing circadian rhythms by supporting melanopsin signaling in the intrinsically photosensitive retinal ganglion cells (ipRGCs). Without sufficient DHA, the eye cannot properly anchor to the solar spectrum, disrupting mitochondrial energy production and the body's ability to regulate light, metabolism, and cognition.

Can You Take Flaxseed and Fish Oil Together?

Both ALA (alpha-linolenic acid) and DHA (docosahexaenoic acid) are essential for optimal health, but they serve distinct biological roles and should not be viewed as interchangeable. ALA is a critical signaling molecule that influences gene expression, cellular communication, and lipid metabolism, playing a fundamental role in maintaining redox balance and inflammatory regulation. However, ALA has very poor conversion efficiency to DHA in humans, making it an unreliable source for meeting the body's DHA demands. 

DHA, on the other hand, is irreplaceable for neurological function, mitochondrial efficiency, and membrane fluidity, particularly in the brain, retina, and nervous system. While ALA supports metabolic regulation and cardiovascular health, DHA is essential for cellular energy production, photoreception, and synaptic transmission. Combining ALA-rich sources like flaxseed oil with DHA-rich marine oils provides a more comprehensive approach to omega-3 balance, ensuring both proper lipid signaling and structural support for high-energy tissues like the brain and eyes.

Omega-3 supplements also don't often adversely interact with common medications like lipid-lowering, antihypertensive or hypoglycemic drugs. 

That being said, visiting a healthcare provider before introducing any new supplements or medications is always recommended. 

Choosing the Right Omega-3 Supplement for Your Needs

Which omega-3 supplement you choose ultimately comes down to your unique situation and health goals. For example, fish oil presents the premier choice for maximizing EPA and DHA intake, which can permit higher levels of omega-3s to be absorbed and used by the body. This increased bioavailability makes it particularly effective for cardiovascular and cognitive support. 

Flaxseed oil, meanwhile, offers an ideal alternative for vegans, vegetarians, or those with fish allergies. For patients with type 2 diabetes or coronary heart disease, flaxseed oil may be especially beneficial for reducing insulin levels and boosting a healthy immune response. 

Those primarily seeking heart and brain health support may prefer fish oil, while those interested in bone health or digestive benefits may want to consider flaxseed oil. 

Potential Side Effects and Considerations

Provided they are stored safely and correctly, both supplements have demonstrated good safety profiles. But always speak with a medical professional before incorporating either into your routine. 

Keep in mind that fish oil occasionally causes side effects like indigestion, belching, or stomach discomfort. To mitigate these effects, consume the supplement with meals. Your body will also adjust to the supplement over time. 

Final Thoughts on Flaxseed vs. Fish Oil

Neither supplement is inherently superior. Whichever supplement works best for you ultimately depends on your unique needs. Fish oil delivers a form of omega-3 with a more readily-usable form of its nutrients, while flaxseed oil offers an effective plant-based alternative.

For best results, choose high-quality products, store them safely in a cool, dark area, and use them as directed by your healthcare provider. 

Support Your Health with the Right Omega-3s  

Choosing between flaxseed oil and fish oil comes down to your unique health goals. If you're looking for the most bioavailable source of omega-3s to support heart, brain, and overall cellular health, BodyBio Fish Oil+ delivers high-quality EPA and DHA. If you prefer a plant-based option, BodyBio Balance Oil provides a carefully balanced blend of essential fatty acids to support your wellness. Take the next step in optimizing your health—explore these powerful omega-3 supplements today!