Fish or Flax, Which is Best for Omega-3s?

If there's one thing most people in the wellness space can agree on, it's that omega-3 fats are really amazing for your body. They fuel your brain, put the damper on inflammation, and support the building blocks of your entire body. Omega-3 fatty acids offer a range of health benefits and have been well-studied for many years. But there's one thing that not everyone agrees on--and that's how you should go about getting more of these essential fats in your diet. Fish oil supplements are one option, though some suggest it's better to focus on eating more fish. Or, there's the plant-based option of flaxseed oil.

Flaxseed oil may seem like the more sustainable choice, but some experts say only fish oil provides the maximum omega-3 potency. We're here to settle the age-old question, which is better, fish or flax?

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Fish oil vs flaxseed oil

Both fish oil and flax seeds have some pretty amazing, and well-studied benefits, mostly because of their high content of omega-3 fatty acids. These essential fatty acids (EFA) can’t be synthesized in adequate amounts within your body, so you must consume them in your diet. Even with a brief look at the medical literature, you’ll find dozens of studies showing that omega-3 fats are great not only for heart health, but help to stabilize your mood, and even bolster immune function.

For example, one double-blind trial found that 2 g per day of omega-3 fats from fish oil lowered triglycerides and other inflammatory markers over the course of 12 weeks (1).

And in support of flax, another review found that adults who added 3 tablespoons of ground flaxseed to their diet experienced reduced blood pressure sufficient enough to reduce their risk of heart attack and stroke by as much as 50% (2).
So should you take fish oil or flaxseed oil for better health? Before we answer that question, let's dive a little deeper into why you should optimize these essential fatty acids in the first place.

Read more: Reduce Your Risk of Heart Disease with Integrative Medicine

Health Benefits of Omega-3s

Omega-3 fatty acids are a family of essential nutrients that play an important role in brain development and function. They reduce inflammation throughout the body, and they've also been linked to an improved mood.

The three types of omega-3s found in foods include ALA (alpha-linolenic acid), EPA (eicosapentaenoic acid), and DHA (docosahexaenoic acid). Most of the health benefits associated with omega-3 fatty acids come from EPA and DHA. All three of these nutrients are essential for brain and nervous system health, heart health, and the formation of cell membranes in your body.

Basically, they make up important parts of your cells, and your brain and body can't live without them.

Signs you're not getting enough omega-3 fatty acids:

  • Fatigue
  • Poor memory or difficulty concentrating
  • Worsening ADHD symptoms
  • Dry skin, rashes, eczema, or hair loss
  • Reproductive issues (in both men and women)
  • Mood swings or depression
  • Poor circulation

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Omega-3 fatty acids are great for your heart

The anti-inflammatory effects of omega-3 fatty acids are well documented and especially beneficial to reduce multiple cardiovascular risk factors, such as hypertension, high triglycerides, and chronic inflammation (3).

Taking fish oil has been shown to increase blood levels of eicosanoids, which are specialized signaling molecules made from fatty acids that help reduce inflammation in the body (4). This is important because inflammation has been associated with the development of numerous diseases.

Another study also found taking fish oil for just 5 weeks lowered triglycerides and inflammatory markers in postmenopausal women taking hormone replacement therapy (5).

Related: 4 Ways to Lower Cholesterol Naturally

Other Benefits of Omega-3s

In addition to being anti-inflammatory, essential fatty acids can benefit your mood, helping to

  • Improve symptoms of depression and anxiety. One study showed that people with low levels of omega-3 fatty acids had higher rates of clinical depression than those with adequate levels (4).
  • Improve cognition and memory, especially for elderly people. One review showed that DHA and EPA supplementation improved cognitive function in older adults who were beginning to develop signs of Alzheimer’s disease (6).
  • Improve symptoms of Attention Deficit Hyperactivity Disorder (ADHD). Serum omega-3 levels are lower in children who experience ADHD symptoms than those who do not. This suggests that increasing omega-3 fatty acids may improve ADHD symptoms like impulsivity (7).

The health benefits of omega-3 fats are plentiful, and there are two foods that are often the popular choice for omega-3 fats.

Should I take fish oil or flaxseeds?

As mentioned above, there are actually three different types of omega-3 fats, ALA, EPA, and DHA. Fish and fish oil are great sources of EPA and DHA, while flaxseed is a good source of the third type, ALA. If you’re trying to get the most benefits of omega-3s, fish or a fish oil supplement is a more “potent” source than flax.

But there may be a few issues with fish for some people. It’s not always easy to eat the recommended amount of oily fish like salmon, mackerel, or trout (about 3 ounces, 2-3 times per week, for reference). Then, there’s mercury to think about, which is a harmful heavy metal that accumulates in marine life further up the food chain—and in some of the fish that make good sources of omega-3 fatty acids.

Fortunately, many high-quality fish oil supplement manufacturers screen for mercury on a regular basis, and use molecular distillation to remove any potential environmental toxins (such as heavy metals, dioxins, PCBs, etc.).

Nordic Naturals is one such manufacturer, and you can browse their omega-3 supplements in the shop.

Why not flaxseed for omega-3s?

The 3rd type of omega-3 fat, ALA, is found in plant foods, but plant-based ALA must first be converted to EPA and DHA before your body can use it. This process only relies on a limited supply of enzymes in the body, and once they’re used up—that conversion process comes to a halt.

This means that for every serving of ALA-rich flax seeds you eat, you’re only seeing a max of about 10% of ALA make it through to become EPA and DHA. The rest of that ALA (about 90%) is metabolized as energy or in other ways (8,9).

So, even though a tablespoon of flaxseed oil may contain about 7 grams of essential fatty acids, less than 700 mg is converted to DHA and EPA—and that’s in an ideal scenario.

To sum up, the body can’t convert ALA to EPA and DHA very well, and for this reason, it’s best not to make flaxseed oil your primary source of omega-3 fatty acid intake.

Related: Heal Your Gut to Boost Your Immune System

So, why should you eat flax?

The ALA in flax might not be as powerful as that from marine sources, but flax seeds are rich in fiber, lignans, and other nutrients that make them a super versatile nutrition powerhouse all their own.

Eating more flaxseeds may have a positive impact on (10):

  • Cholesterol levels
  • Overall cardiovascular health
  • Digestive health
  • Breast cancer risk
  • Microbiome health
  • Hormone balance

Read more: Perimenopause, The Integrative Guide

Fiber for cardiovascular health

Fiber has been shown to lower the risk of heart disease and stroke, as well as help control blood sugar levels. It may also reduce cholesterol levels in people who have diabetes or high blood pressure (11).

Adequate dietary fiber has been shown to also lower blood triglyceride levels, and increase high-density lipoprotein (HDL) or “good” cholesterol by as much as 10% (12).

Related: Is Type 2 Diabetes Ever Reversible?

Other health benefits of fiber

Fiber may help reduce inflammation

Flaxseeds are a good source of both soluble and insoluble fiber, and here’s why that’s great news for you.

Soluble fiber (found in oats, beans, apples, carrots, barley, and psyllium) can be digested by bacteria in the intestine and converted into short-chain fatty acids (SCFAs). SCFAs have been shown to help regulate blood sugar levels and have anti-inflammatory properties that may help prevent cardiovascular disease, obesity, and certain gastrointestinal problems (13).

In contrast, other fibers, like lignin and resistant starch, are not soluble in water but do help food move through your digestive system and support the health of your colon.

Both soluble and insoluble fiber is important for your health. It’s advisable to eat a variety of high-fiber foods, including vegetables like broccoli and leafy greens, some fruits such as apples or citrus, beans and lentils, and minimally processed grains like barley or oats.

Read more: Alzheimer’s and Neurodegenerative Disease May Actually Begin in the Gut

7 Food sources high in fiber or omega-3s

  • Cold-water fatty fish. These are fish high in EPA and DHA and include salmon, mackerel, herring, sardines, and trout.
  • Nuts and seeds. Almonds, walnuts, chia, pistachios, flaxseeds, pumpkin seeds, and hemp seeds are great for cardiovascular health, hormone balance, and digestion. They provide essential fatty acids, minerals like potassium and zinc, or fiber.
  • Leafy greens. Dark, leafy greens like spinach, kale, and collard greens contain vitamin K and other nutrients that protect blood vessel function.
  • Avocados. Avocados are a good source of fiber, monounsaturated fatty acids,
  • Barley. Barley is particularly high in soluble fiber and beta-glucans, which can help reduce cholesterol levels and support immune function.
  • Dark chocolate. Dark chocolate (70% cacao or higher) has antioxidants and magnesium which are great for overall health and may help keep your blood vessels healthy.
  • Berries. Some of the highest antioxidant foods are blueberries and acai berries. (Plus, they’re low in sugar and higher in fiber).

Read more: Top 5 Anti-Inflammatory Foods + Anti-Inflammatory Diet

Taking fish oil for a healthy heart

While you work to optimize your diet for omega-3 fatty acids, it’s a great idea to have a fish oil supplement you trust as a handy backup. Here’s what to look for in quality fish oil:

  • Third-party testing for quality, purity, and freshness. This analysis indicates any levels of environmental toxins present and the oxidation (or freshness) of the oil.
  • Beware a strong fishy smell. Omega-3s are prone to oxidation, and an overly fishy aroma will let you know if it’s rancid. Rancid (or oxidized) fish oils should be avoided. Note: storing your fish oil in the fridge at home will help keep them fresh.
  • Triglyceride form. Triglyceride form omega-3 supplements are better absorbed than synthetic ethyl ester omegas (14).
  • Responsible fishing practices. An environmentally responsible fish oil manufacturer should offer transparency into their fishing practices. If not, their practices may be somewhat ‘fishy’.

Protecting your heart health with functional medicine

So, what’s the verdict? Should you load up on fish oil supplements or invest in some flaxseeds instead? The answer is both! Consuming more fatty fish like salmon, trout, and sardines will give you a good dose of omega-3s, but if you want to make sure you’re getting enough for optimal health benefits, consider taking a fish oil supplement as well. Plant-based sources like flaxseeds are great additions to your diet to improve digestion and they may help lower cholesterol, but they don’t have the same potency as marine-sourced omega-3s when it comes to DHA and EPA.

In summary, don’t leave any of these amazing benefits on the table! Increasing your intake of both fish and flaxseeds is a great way to improve your overall health and your cardiovascular function.


  1. https://pubmed.ncbi.nlm.nih.gov/19394939/
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6567199/
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257651/
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3976923/
  5. https://pubmed.ncbi.nlm.nih.gov/14505813/
  6. https://pubmed.ncbi.nlm.nih.gov/30084334
  7. https://www.sciencedirect.com/science/article/abs/pii/S0272735814000749
  8. https://pubmed.ncbi.nlm.nih.gov/17622276/
  9. https://pubmed.ncbi.nlm.nih.gov/11844977/
  10. https://www.sciencedirect.com/topics/medicine-and-dentistry/flax
  11. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/215976
  12. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4454936/
  13. https://www.frontiersin.org/articles/10.3389/fimmu.2020.590685/
  14. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4085663/


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