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Omega-3s From Plants vs. Fish: Is One Source Better Than The Other?

Korin Miller
Author: Expert reviewer:
December 24, 2021
Korin Miller
Contributing writer
By Korin Miller
Contributing writer
Korin Miller is a freelance writer specializing in general wellness, relationships, and lifestyle trends with a master’s degree from American University. Her work has appeared in Women’s Health, Prevention, Self, Glamour, and more.
Ashley Jordan Ferira, Ph.D., RDN
Expert review by
Ashley Jordan Ferira, Ph.D., RDN
mbg Vice President of Scientific Affairs
Ashley Jordan Ferira, Ph.D., RDN is Vice President of Scientific Affairs at mindbodygreen. She received her bachelor's degree in Biological Basis of Behavior from the University of Pennsylvania and Ph.D. in Foods and Nutrition from the University of Georgia.
December 24, 2021
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It's no secret that omega-3 fatty acids are essential for keeping your body healthy; they've been linked to everything from cardiovascular and immune health1 to joint2, eye3, and brain function4—and the body of research exploring their benefits is ever-growing.*

Those aren't the only reasons omega-3 fatty acids are considered critical, though. Here's the thing: We can't produce the omega-3s we need on our own (technically we can produce EPA and DHA from ALA, but the process is inefficient and variable5) and therefore need to get them through the food and supplements we consume. That's where things get a little confusing. Different foods and supplements offer different types of omega-3s, so depending on whether you're eating plant sources or seafood (marine sources), the specific omega-3s and their concentrations you're taking in will vary.

Which leads us to an often-discussed (and misunderstood) question: Is it better to get your omega-3s from marine or plant life? Vice versa? Should we really be pitting these two categories of omega-3-rich sources against each other at all? Here's what you need to know. 

What are omega-3s, really?

Quick recap: Omega-3 fatty acids are technically a class of polyunsaturated fatty acids. Since the body is "very inefficient" at making omega-3s on its own, it's best to get them through food or supplements, explains William S. Harris, Ph.D., president and founder of the Fatty Acid Research Institute.*

There are three main types of omega-3 fatty acids: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).

In general, omega-3s are important components of the membranes that surround each cell6 in your body and help support optimal cellular communication, oxidant balance, and anti-inflammatory pathways, not to mention functions in your heart, blood vessels, lungs, immune system, and endocrine system.*

What to know about marine-based omega-3s.

When most people think about omega-3s, they automatically think of EPA and DHA, which are found in fish, like anchovies, salmon, mackerel, tuna, herring, and sardines, and other seafood. "However, fish are not the primary producers of EPA and DHA. Like us, fish must get them from their food," explains Dana Ellis Hunnes, Ph.D., MPH, R.D., senior dietitian at RR-UCLA Medical Center and author of Recipe for Survival: What You Can Do To Live a Healthier and More Environmentally Friendly Life. "The primary producers are actually algae, which produce plant-based omega-3 DHA; some make EPA as well." The algae are then eaten by plankton and small fish, which are then eaten by bigger fish, and so the amount of omega-3s accumulates as you go up the food chain.

Why do these omega-3s matter? mbg's director of scientific affairs Ashley Jordan Ferira, Ph.D., RDN, shares these insights: "In addition to conferring fluidity to our cellular membranes—which has major implications for everything from normal cellular signaling and combating oxidative stress, to gene expression—these marine omega-3s deliver an array of meaningful health benefits."*

And other dietitians agree. "EPA has anti-inflammatory properties and supports cardiovascular health, specifically healthy triglyceride levels and blood pressure,"* says nutritionist Keri Gans, R.D., author of The Small Change Diet. Research also suggests that EPA is the omega-3 for supporting a balanced mood7, although both are certainly at play, and DHA is known to be highly concentrated in the brain (when it's consumed!).*

"DHA also has anti-inflammatory properties and is associated with heart health but is also known to aid in brain development during pregnancy and early childhood," Gans adds. It's a must-have for eye development and function8, too, and you'll find it especially concentrated in the retina.*

The U.S. Dietary Guidelines for Americans and the American Heart Association (AHA)9 recommend healthy adults consume at least two servings of fish a week, which nets out to roughly 250 to 500 milligrams of EPA and DHA per day. However, most of us don't get that much—and, according to Harris, it probably wouldn't be enough even if we did. "Typical intakes of EPA and DHA in the U.S. (a low fish-eating country) are about 100 to 150 milligrams per day on average," he says.

And honestly, Harris is being generous because nationally representative data10 indicates the average EPA plus DHA intake of Americans is only 86 milligrams per day.

"In a country like Japan or Korea, where fish is eaten nearly every day, intakes are between 750 and 1,000 milligrams [and up] per day. The latter is way better than the former in terms of health,"* shares Harris. And the AHA agrees with him.

As Ferira explains, "Hundreds of research studies, including epidemiological and interventional clinical trials, led the cardiology experts of the AHA to recommend 1,000 milligrams (i.e., 1 gram) and higher of EPA plus DHA daily for incremental cardioprotective health support. It's a dose-response relationship. More is more in this case."*

She goes on to say that she considers the two servings of fish a week (500 mg of EPA + DHA daily) recommendation a baseline, "but in reality, it's the higher levels like 1 gram and up of these marine omega-3s that deliver significant heart health and other whole-body benefits over life."*

Since we can technically produce EPA and DHA from ALA—more on that shortly—there's no official daily requirement issued from the national organizations for these two omegas; though many health experts think there should be. This marine omega-3 pair are certainly "conditionally essential."

Ferira concludes, "Whether 'essential' or 'conditionally essential,' those are just semantics created by humans. The bottom line is you cannot rely on ALA conversion for clinically useful levels of EPA and DHA on the daily. So yes, these marine omega-3s have all the makings of an essential nutrient. I'm not anti-ALA. I'm pro ALA, EPA, and DHA!"

What to know about plant-based omega-3s.

Speaking of ALA, this is the type of omega-3 you'll find in plant-based foods, particularly flaxseeds, walnuts, chia seeds, and hemp seeds. As mentioned a few times already, the body has the variable ability (different between women and men and as we age) to technically produce EPA and DHA from ALA in the liver. Again, that conversion rate is quite low (like 0.3 to 20%5), so we can't rely on ALA alone for meaningful levels of EPA and DHA.

But, as Ferira says, "Just because ALA is not a reliable starter compound for EPA and DHA doesn't mean this plant-origin omega-3 isn't awesome in its own right. It's actually indispensable, so think of ALA for its unique benefits, one of which is helping us achieve a healthy balance of omega-3s (versus omega-6s) each day."*

Since we can't produce any ALA on our own endogenously, the National Academy of Medicine has set specific daily requirements for the omega-3, recommending that most adult men strive for 1.6 grams of ALA per day, while adult women aim for 1.1 grams. Those numbers are a little higher for pregnant people (1.4 grams) and those who are breastfeeding (1.3 grams). 

In addition to allowing for the production of EPA and DHA, ALA also has a slew of health benefits all its own11, including supporting heart health (specifically by promoting healthy cholesterol and blood pressure levels) and brain health, as well as offering anti-inflammatory properties, says Hunnes.*

Are marine omega-3s better than plant omega-3s? 

Considering the body converts some ALA into EPA and DHA, it's easy to assume that EPA and DHA (which we traditionally get from marine food sources) are more valuable.

This is where things get a little complicated. EPA and DHA certainly are important, which is why it's recommended that we regularly eat fish. However, there are environmental and health reasons not to go this route, in Hunnes' opinion. "Many fish eat plastic and have chemical residues in them that attach to fats, such as omega-3s," she says. "Plus, many fish are overfished, and it simply is not sustainable to keep catching fish at the levels that we do." 

Other experts, though, disagree. According to Ferira, "While concerns about mercury levels, plastics, sustainability, and the like are warranted for people consuming high levels of fish meat, I don't believe those whole-fish concerns should be extrapolated to high-quality, purified, and sustainably sourced fish oils."

Functional medicine doctor Mark Hyman, M.D., takes a similar stance. Unless you're a strict vegan or vegetarian who excludes fish, he recommends prioritizing fish known to be lower in heavy metals—sardines, mackerel, anchovies, salmon, and herring, also known as SMASH—to ensure you're getting ample amounts of EPA and DHA.

The researchers behind Oregon State University's Linus Pauling Institute12, meanwhile, remind us that because of the low conversion rates of ALA into EPA and DHA in the body, we should not depend on it alone to fulfill those nutrient needs. So, they suggest seeking out additional sources of these two omega-3s.

Harris agrees: "Making EPA and DHA from ALA is possible but very inefficient, and achieving optimal omega-3 levels is nearly impossible with only ALA," he says. (Much less those 1-gram-plus doses for your heart health.)*

However, Harris also takes things a step further, suggesting that we shouldn't really be pitting plant- and seafood-based omega-3s against each other at all. "They are simply different chemical compounds with different biological actions," he urges.

How to approach the omega-3s in your diet.

Since many experts recommend consuming ample sources of ALA, EPA, and DHA, a combination of both foods and supplements may be helpful to meet our needs. This is especially true for people who follow a dietary pattern that excludes seafood or other sources of omega-3s.

To get the recommended 1.1 to 1.6 grams of ALA on a daily basis, turn to foods like flaxseeds and walnuts (both of which provide well over 2 grams of omega-3 per serving13). The leafy green vegetable purslane is another surprisingly good option, offering around five to seven times14 as much ALA as other greens, such as spinach.

As for EPA and DHA, stick to Hyman's SMASH recommendation if you eat seafood and want to do so as healthfully and sustainably as possible. However, if eating seafood just isn't in the cards for you, research suggests that eating seaweed and algae, which can provide DHA (and smaller amounts of EPA), boosts DHA levels in your blood15 more than other omega-3-containing plant foods.

Also worth noting: Since almost all Americans (seriously, 90% of us16) don't consume those recommended two servings of fish per week (and that's just the starting point), a high-quality, pure supplement sourced from sustainably sourced wild-caught, cold-water fish can be a game-changing tool in helping us provide our body with a consistent supply and effective dose of EPA and DHA.*

The takeaway.

Omega-3 fatty acids are an invaluable part of your overall health—and incorporating a variety of sources of ALA, EPA, and DHA into your daily diet is the ideal move for ensuring your body has a steady input of these beneficial fats. However, since various dietary restrictions and eating patterns may affect whether you incorporate only plant-based sources of omega-3s or marine-based sources, as well, a high-quality supplement can play a key role in helping you meet your needs.*

If you are pregnant, breastfeeding, or taking medications, consult with your doctor before starting a supplement routine. It is always optimal to consult with a health care provider when considering what supplements are right for you.