Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In

Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In


Disease Prevention

The Omega Divide

Think all omegas-3s are the same? We’re breaking down the differences between fish- and plant-based oils, helping you select the right one for your needs.

Heading out the door? Read this article on the new Outside+ app available now on iOS devices for members! Download the app.

Think all omegas-3s are the same? We’re breaking down the differences between fish- and plant-based oils, helping you select the right one for your needs.

Being mindful of your omega-3 intake may be one of the simplest, most effective things you can do for your health. After all, it’s a potent anti-inflammatory that can positively impact arthritis, cardiovascular conditions, neurodegenerative disorders and even traumatic brain injuries.

“Omega-3s are the most scientifically researched supplement you can take,” explains William Sears, MD, author of The Omega-3 Effect (Little Brown and Company, 2012). “There are over 22,000 medical journal articles on the health benefits of omega-3s.”

A component of your cell membranes, these fatty acids are often referred to as essential because the body can’t make them on its own, and you need to get them from food or supplements. They’re found in a number of sources, both plant and marine, but they aren’t all processed the same way in the body. Here, we highlight some of the key differences plus our top product picks for each type.

Plant Versus Fish Oils

Alpha-linolenic acid (ALA) — sometimes referred to as a shorter-chain fatty acid because it has 18 carbons in its chain — comes from plant sources like flax, walnuts and chia seeds. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) — both considered long-chain fatty acids with 20 and 22 carbons in their chains respectively — come from marine sources such as fish, krill and algae.

Dr. Sears refers to them as the “short” and the “tall” guys. “The brain only uses the tall guys, the 20- to 22-carbon atoms,” he says. “EPA and DHA are the top omega-3s in the brain. The only place those are found is in the sea.”

So what happens when you eat ALA sources like flax oil? Your body sends the oil to the liver, where it has to tack on additional carbon atoms so it can be converted to the longer-chain fatty acids EPA and DHA and then used as such. The only caveat is that some people are better at converting than others. Women tend to be better converters than men, for example, but it varies from person to person.

The only plant-based source of DHA is algae, a sea plant such as chlorella or spirulina. In fact, algae is the original source of omega-3s, as fish and krill get their omega-3s from eating phytoplankton that contains it.

How Much to Take

Dr. Sears suggests a simple way to remember the dosage: 1 gram of DHA a day for general health. Alternatively, you can look at the combined EPA and DHA (simply add up those two numbers) to get to 1 gram. For inflammatory conditions, Dr. Sears says you may need to take more, as much as 3 grams, but he suggests working with your health-care practitioner in such cases. If you’re taking plant oils such as flax oil that contain ALAs, you might consider getting your levels tested to see if you’re converting enough.

Can you get enough from food without supplementing? You can, according to Dr. Sears. Wild Alaskan salmon, or small fatty fish such as anchovies or sardines, are all rich in omega-3s, though he prefers salmon because it’s rich in other nutrients such as selenium, choline and vitamin D. He recommends this rule of thumb, which works for any age: “If you don’t eat a minimum of two fistfuls of wild Alaskan salmon per week, then you should take a supplement.”

Are You Getting Enough?

A simple finger-prick test will give you the answer.

The optimal dosage of omega-3s can vary from person to person – depending on diet, the type of supplement you choose and your level of absorption. The most accurate way to know if you’re getting enough is to get tested. Some companies offer a home test kit, such as the Vital Omega-3/6 HUFA test from Vital Choice, which measures your omega-3 index (the amount of EPA and DHA in your red blood cell membranes), as well as other measures, like your omega-6/omega-3 ratio.

According to Dr. Sears, if your score on the omega-3 index is lower than 8%, then you need to adjust your diet or supplement regimen to get more for optimal health and disease prevention. This can be particularly helpful for plant-based eaters taking flax oil, he says, as you’ll be able to see if you’re converting enough to the EPA and DHA forms. $100,


Dr. Mercola Antarctic Krill Oil

Dr. Mercola Antarctic Krill Oil Preliminary research, although limited, is showing that the oil from krill, a crustacean that feeds on phytoplankton, may actually be more bioavailable than the oils from fish. Krill also contains astaxanthin, an antioxidant that helps prevent the delicate oils from oxidizing (and in larger quantities may also help protect vision health). When choosing krill oil, ensure the product is certified by a third party, such as the Marine Stewardship Council (MSC). $30,


iWi Algae-Based Omega-3 EPA + DHA

iWi Algae-Based Omega-3 EPA + DHA This company grows the Northern Atlantic algae strain Nannochloropsis sustainably in open ponds in the southwest United States. Typically, algae contains DHA, but this company is unique in that it has varieties that contain both EPA and DHA, and the company combines them in specific ratios depending on the product. iWi’s algae strains also contain protein, chlorophyll, carotenoids and other antioxidants. $30, 


Udo’s Oil DHA 3•6•9 Blend

Udo’s Oil DHA 3•6•9 Blend This plant-based blend of flax, sunflower, sesame and evening primrose oil was specifically designed in a 2:1 ratio of omega- 3s to omega-6s by researcher Udo Erasmus, PhD. Flax oil contains ALA, a precursor to anti-inflammatory EPA and brain-supportive DHA, although the conversion rate varies from person to person. “The general consensus from existing research is that about 5 to 10% of ALA can be converted to EPA and 2 to 5% to DHA,” explains Robert Dadd, product information supervisor at Flora Health. “These percentages sound small, but if you consider just 15 milliliters of Udo’s Oil has 6 grams of ALA, it can still potentially be a significant amount of EPA/DHA produced.” ALA has a number of other benefits – it’s anti-inflammatory and it supports gut health by helping to protect the delicate intestinal lining. This blend also contains a boost of DHA from algae oil, which is particularly helpful for men since they tend to be poorer converters of ALA to DHA. The oils are all organic, unrefined and tested for pesticides, heavy metals and fatty-acid content. $38,


Nordic Naturals Ultimate Omega 2x

Nordic Naturals Ultimate Omega 2x This potent fish oil blend from a combination of small fish (anchovies and sardines) provides about 1 gram per softgel of combined EPA and DHA – the minimum daily dosage Dr. Sears recommends for general health. As with most fish oil blends, this product is naturally higher in the fatty acid EPA, which is often used for inflammatory conditions such as arthritis, and it can also play a role in preventing both Alzheimer’s and depression, according to a 2018 study in the Journal of Lipid Research. $50,


Carlson Cod Liver Oil Gems, Super 1,000 mg

Carlson Cod Liver Oil Gems, Super 1,000 mg Cod liver oil tends to be naturally higher in DHA than other fish oils. Remember that DHA supports neurological function, so it’s not surprising that cod liver oil tends to be used for overall brain-health support and brain development in children. It also contains vitamin A, a boon for vision health, as well as vitamin D to support immunity. This product received five stars on the International Fish Oil Standards Program (IFOS) product database, a third-party rating system that measures product quality through parameters such as fatty-acid content, heavy metals and oxidization. $33,