Everything You Need to Know About Fish Oil & Omega-3 Fatty Acids

Everything You Need to Know About Fish Oil & Omega-3 Fatty Acids

February 18, 2020 15 min read

Salmon on a counter next to omega-3 supplements

In the supplement space, few topics are more researched, debated and scrutinized than Omega 3 fatty acids. While doctors have long been recommending fatty fish and other healthy food sources of omega-3s as a critical part of cardiovascular health, there are a lot of skeptics who believe that omega 3 supplements have little to no health benefits.

The story of healthy fats is a complex one that can be (and has been) explored in volumes of books, but here you’ll find a relatively comprehensive overview of omega-3 that spans a broad array of topics, from omega-3 research and its loose affiliation with Spam, to the deliberate removal of omega-3 fatty acids from food in America.

Omega 3 research has evolved rapidly in recent years, with huge studies like the VITAL Study and REDUCE-IT illuminating both the usefulness and limitations of supplementation. But despite new research and a paradigm shift towards environmentally responsible practices by some supplement companies, problems still persist—not just with omega 3 supplements, but with fish farms, pollution, toxins and the general imbalance of fats in the American diet.

What are Omega-3s?

Omega-3 fatty acids are found in various foods and dietary supplements. There are three main omega 3s: Alpha-linolenic acid (ALA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).

Omega-3 acids are considered “essential fatty acids” because they are not naturally made in the body. So the only way for us to get these vital nutrients is through food and supplementation. Omega 3s are important for proper human cellular function, and we’ll discuss the importance of a balanced fat composition in the cell membranes later in this article. But as a component of cellular structure, omega-3 acids provide a vital role and help the function of the cardiovascular, nervous, respiratory, immune and endocrine systems.

Alpha-Linolenic Acid (ALA):This is the most common omega-3. Found mainly in plants, the majority of ALA that we consume is stored in the body to be used as energy later like any other fat in our diets. A small percentage of ALA is converted into EPA and DHA (this is important to note as DHA and EPA are considered the omega 3s that have the most beneficial properties); the conversion from ALA into DHA and EPA in the body is inefficient. Estrogen allows women to turn dietary ALA into EPA and DHAmuch more effectivelythan men, and genetic differences also impact the body’s ability to synthesize ALA. But for the most part, people have to consume a huge quantity of ALA for it to convert into a useful amount of EPA and DHA in the body.

Eicosapentaenoic Acid (EPA):In regard to omega-3 benefits, EPA is the specific fatty acid that has a positive impact on the body’s inflammatory response, helping with ailments like arthritis.EPA may also bethe most important of the three main omega 3s in relation to mood and depression.

Docosahexaenoic Acid (DHA):DHA is the omega 3 that correlates to the healthy function of the eyes and brain. Deficiency of DHA early in life can lead to brain-related issues later on like Alzheimer’s, learning disabilities, ADHD and more. DHA is themost important omega-3 in relation to blood pressure and cholesterol.

Omega-3s in the Diet

On average, adults in the United States are not getting enough omega-3 in their diets. The American Heart Association recommends getting at least two 3.5 oz. servings of oily fish per week. While fish consumption per-capita hasincreased steadilysince the ‘60s, the United States still lags far behind countries like China, Japan, Korea and France (all of which have some of the lowest rates of heart disease in the world).

In the bookThe Queen of Fats, Susan Allport discusses the idea that the lack of omega-3 in the Western diet isn’t just a lack of fish consumption, but a deliberate removal of omega 3 acids in food. Canola oil, which is thought of as a healthier alternative to other types of cooking oils, may have been solely responsible for the uptick in American omega 3 consumption for many years. But the susceptibility of oxidation in products with natural ALA, like canola oil, has prompted corporations to develop strains of rapeseed (the plants used to make canola oil) that are lower in ALA to increase shelf life. The same idea is being put into practice in soybeans—food that once provided Americans with healthy omega-3 fatty acids are being modified to reduce fatty acids and increase shelf life.

A whale in the ocean

Inuit Genetics and Fatty Acids

While certain countries consume more fish, and in turn see a lower incidence of heart disease, researchers in the 1970s were fascinated by one group of people in particular: The Inuit. Despite historically having a diet that would be considered unhealthy by today’s standards—whales, seals, fish, and other fatty meats—the Intuit had a very low rate of heart disease. It was the landmark findings of the research conducted in the 1970s—when Jorn Dyerberg and his team collected 130 blood samples from Inuit people in Greenland— that led doctors to start recommending that people eat more fish. The levels of omega 3 in the Inuit samples led Dyerberg to the conclusion that fish and seafood had protective properties regarding the cardiovascular system.

In 2015,a study was publishedthat helped researchers further understand why the Inuit population, in particular, seemed to benefit from fish in the diet. The reason is that Inuit ancestors (maybe as long as 20,000 years ago) evolved genetically, and it changed the way their bodies used omega 3 and other fatty acids. Because their diet lacked other kinds of nutrition (vegetables and lean meats were sparse), an evolutionary genetic mutation occurred so that the fats in their cells wouldn't overwhelm their bodies.

This genetic mutation resulted in the production of enzymes that help regulate different kinds of fats on the body, and researchers discovered that this specific mutation was found in the DNA of almost every Inuit person in the study. To put it in perspective, only about 25% of Chinese people had the genetic mutation, and only about 2% of European-descended people in the study had it.

This genetic anomaly was also discovered to have adirect impact on height and weight, with the average Inuit person measuring about an inch shorter and 10 lbs. lighter than those without the gene. Studies had been done on height and weight genetics before, but the critical fat-metabolizing gene was missed because most of the studies focused on people of European ancestry. When this research was published, scientists conducted follow-up studies and discovered that the small percentage of European-descended people who did have the fat-metabolizing gene were, in fact, shorter and lighter.

The research done in Greenland in the '70s was important for several reasons, but it was especially important because scientists hypothesized that the Inuit diet would soon be “Westernized.” This made the 130 blood samples that Jorn Dyerberg and his team obtained extremely valuable. As predicted, the Inuit dietdid become more Westernized, so it was great foresight at the time to treat the samples accordingly.

So, although the modern Inuit diet aligns more closely with typical Western diets, the gene within them still acts as a way to balance fats in the body. This balance is important as it may be the imbalance of fats in the cell membrane that’s responsible for heart disease, obesity and other ailments.

How Do Omega-3s Work in Your Body?

The reason that “fat balance” is so important for health is becausecell membranes will fill upwith whatever fats are available in the body. In “The Queen of Fats,” Allport discusses the problem with vilifying certain fats, like trans fats. Just because trans fats are banned from products doesn’t mean that companies are replacing trans fats with healthy fats—it could just be another saturated fat that's equally (or more) unhealthy. This is dangerous, because when our cell membranes are filled with fats of an under-researched mechanism, there could be unexpected health consequences in the long-term. Fats are vital for cell function and the function of our body’s systems, and it’s important to ensure the cell membranes are filled with a diverse array of fats, including (and especially) omega-3 fatty acids.

Omega-3s perform important communication roles from cell to cell. In addition, omega-3 fatty acidsact as direct competition to arachidonic acidin the cell membrane. Arachidonic acid is what enables cells like monocytes to create inflammation in the body. So omega 3 acids help keep the body’s inflammatory response in check to mitigate tissue damage and prevent arthritis.

Researchalso shows that the several cell-related proteins, like the retinal protein rhodopsin, change and respond to light much more efficiently when the membranes are full of omega-3 fatty acids. This light response is the mechanism responsible for the positive effect omega 3 acids can have on vision.

The impact ALA, EPA and DHA have on the cardiovascular system are still being researched, but we do know that omega-3s can protect the heart in some capacity. Within the cellular membrane, sodium and calcium channels control the “voltage-gated sodium and calcium currents.” In other words, they are responsible for the bioelectrical currents that pass between cells and control the function of the heart. When a cell is enriched with omega-3 acids, the cardiac-ion activity is inhibited, which is believed to be partly responsible for the heart-protective properties of omega 3.

What Do Omega-3s Have to do with Spam?

To be fair, the association between Spam and omega-3 research is pretty loose, but it does put an entertaining spin on the research. One of the most important discoveries in fatty acid research occurred when Jorn Dyerberg and Ralph Holman worked together at the Hormel Institute (makers of Spam). Dyerberg was part of the team that discovered that the level of fish in the Inuit diet correlated to a low incidence of heart disease. Holman, who then worked at the Hormel Institute, was the leading fatty acid analyst of the time.

Working together,the two were able to synthesize their researchand determine that the unidentified fatty acid "spikes" in Dyerberg’s Inuit blood samples were EPA and DHA. Dyerberg had never heard of DHA and EPA, and Holman—perhaps distracted by the persistent, wafting smell of Spam in the air—hadn’t yet made the connection that these essential fatty acids had protective properties in the body’s systems. This was a key foundational event in the advancement of omega-3s; it ushered in a new era of research into the possible benefits of fatty acids and sparked more interest in the actual content of omega 3 fatty acids in fish and other types of foods.

Red snapper in the refrigerator at a market

Foods Rich in Omega-3s

Since the discovery of the protective qualities of omega 3 fatty acids, doctors and dieticians have been recommending that every person eat two or three servings of fish per week. But it’s also important to keep in mind the kind of fish you’re eating, where it comes from and your own health risks.

Fish High in Omega-3s (per 100-gram portion)

In general, eating 2-3 (or more) servings of fish, seafood or plant-based foods with omega 3 will be beneficial, and the amount of mercury in the fish will not be a concern. But some kinds offish are high in mercuryand should be avoided by people who are pregnant, or who have compromised immune systems or other health issues. As a rule of thumb, the smaller the animal, the less mercury will be present. Here’s a quick breakdown of the omega-3 content in commonly eaten fish, seafood and plant-based foods—most of which also have low mercury content (the exception being tuna).

  • Herring - 1300-1800 mg
  • Salmon - 1000-1500 mg
  • Bass - 300- 800 mg
  • Sardines - ~1500 mg
  • Trout - 600-2000 mg
  • Halibut - 500-900 mg
  • Tuna - 500-1600 mg
  • Anchovies - ~1400 mg

Other Seafood

  • Oysters - 400-600 mg
  • Shrimp - 200-500 mg
  • Squid - 300-600 mg
  • Mussels - 300-500 mg
  • Crab - 300-400 mg

Vegetarian and Vegan Sources of Omega-3s (per 100-gram portion)

Although plant-based omega-3 options have a lot of nutritional value, they aren’t as effective for getting EPA and DHA since most of the omega-3 listed below is in the form of ALA (recalling that ALA does not convert into EPA or DHA efficiently within the body).

  • Chia Seeds - 1750 mg
  • Flaxseeds - 2280 mg
  • Walnuts - 900 mg
  • Soybeans - 1241 mg

Omega-3 Supplements

The debate about the efficacy of omega-3 supplements is ongoing. One side argues that none of the human studies done on omega 3 supplementation so far can prove there are any benefits to taking fish oil, krill oil, or plant oils in supplement form. The other side argues that omega-3 supplements are an effective alternative for people who don’t like the taste of fish or seafood. While there are logical arguments for both sides, new research that has emerged in the past two years, along with the approval of prescription omega 3 drugs, is showing a lean in support of supplements as an effective alternative to eating fish—particularly those with heart conditions or high cholesterol.

Fish Oil

Traditionally, an omega-3 supplement will come in theform of fish oil. Fish oil is exactly what it sounds like—oil from the tissue of fish. Even though (until recently) there was limited evidence that omega-3 supplements were a reasonable substitute for actual dietary omega-3s, many people take omega-3 fish oil supplements for health. This is helpful for people who just don’t like the taste of fish (even though a lot of fish oils have a fishy aftertaste).

Cod Liver Oil

Cod liver oilmight conjure up some unpleasant memories from childhood, depending on your generation or parents’ view on the reported health benefits of cod liver oil. CLO seems a bit "old school," but the supplements are still popular. CLO varies slightly from fish oil in that it (obviously) comes from the liver of the fish, but it also has vitamin A and D in it. But it is most bioavailable (absorbed by the body) in liquid form, and anyone who’s tried it knows how hard it can be to get past the taste.

Vegetarian and Vegan Omega-3 Supplements

There are a lot of omega-3s without fish on the market, including flaxseed oil, perilla oil and algal oil. While these supplements do provide ALA, they are different from marine-based omega-3s and do not generally provide EPA and DHA. Algal oil is probably the most researched of the vegetarian omega-3 supplements, whereas perilla oil has very little supporting evidence. As vegetarian and vegan omega-3 options become more popular, more variants and larger studies will likely be conducted.

Proponents of vegetarian and vegan sources of omega-3 are quick to claim that ALA is the only type of omega-3 that the body needs. And while the healthy fats and ALA contained in vegan omega 3 supplements are beneficial, the body is still limited in how much ALA it can convert into EPA and DHA. Another potential benefit of vegetarian and vegan supplements is there could be less of an impact on marine ecosystems around the world.

Krill in the ocean

Krill Oil

Krill oil is not new, but its surge in popularity is fairly recent. Krill oil comes from the oil of small, shrimp-like crustaceans called krill. Because it doesn’t come from fish, krill oil solves a problem that a lot of people have with fish oil supplements, which is its fishy aftertaste. Krill oil has many of the same benefits of fish oil, but maybe more potentand allow for smaller doses.

Another benefit of krill oil is that its DHA and EPA content usually comes in theform of phospholipids, which means it generally has a higher bioavailability than fish oil. Krill oil that is harvested responsibly from the Southern Ocean also tends to be purer since the waters are nearly unpolluted and there's less chance of having mercury or other toxins in the oil.

Prescription Omega-3s

In addition to dietary supplements, which are considered food and aren't evaluated for efficacy by the FDA, some pharmaceutical companies are attempting to use large-scale clinical trials to get omega 3-based prescription drugs approved for a more broad population of people.

Big Pharma company AstraZeneca was on the verge of getting prescription omega 3 fish oil drug, Epanova, approved by the FDA for a broader range of patients than its current use (which is solely for people who have very high levels of triglycerides).

The trials of the drug were discontinued, however, when an independent committee determined, in a clinical trial calledSTRENGTH, that the difference between the patients in the placebo group and the patients taking Epanova was insignificant as it pertained to cardiovascular events.

Conversely, the drug Vascepa from Amarinwas given the broader FDA approvalthe AstraZeneca was seeking. Their drug is approved for its original purpose—people with high triglyceride counts—but it is also approved as a supplemental therapy for patients already taking statin drugs (drugs intended for lowering cholesterol).

Why Vascepa was given approval and Epanova was not could be related to the purity of the omega-3 compounds in each drug, concentration of the beneficial elements in the given dosage, or the addition of DHA in Epanova (whereas Vascepa only contains EPA and may be a higher purity).

While clinical trials often contradict each other, the science behind why omega 3 fatty acids help the body is fairly uniform and sound (fatty acids in the cell membranes help improve important systemic functions). So if so many people can agree that fish is healthy and the oils and fats from fish are good for the brain, heart, skin and eyes, why is it hard to find consistent data among research studies?

Omega-3 Clinical Research


TheVITAL (VITamin D and Omega-3 TriAL) Study was a very large study conducted over several years with25,871adults. It is an ongoing study, with initial results posted in November of 2018. It is the largest study of its kind to study omega-3 supplementation (vs. food-derived omega-3s). The study found that omega-3s did reduce the risk of heart attack by28%, and it also reduced the risk of all major cardiovascular events by19%of people who didn’t already regularly consume fish (regularly=1.5 servings or more).


While the VITAL study focused on average, healthy people, the REDUCE-IT (Reduction ofCardiovascularEvents with EPA-InterventionTrial) studied 8,000 middle-aged and older adults with elevated triglyceride levels and were at risk for a cardiovascular event (heart attack, stroke, etc.) or had already experienced an event.

The study found that omega-3 supplements reduce the chance of a cardiovascular event (including death) by25%.

Both of these studies were presented in anarticle by Harvard Medical School, which generally takes a skeptical lean when it comes to supplements. But legitimate, large and well-conducted studies like VITAL and REDUCE-IT are the kinds of studies needed to propel supplement research into the future.


Prior to the published results of the VITAL study, alarge meta-analysisof almost 80 clinical trials was conducted that examined randomized studies that focused on omega-3 capsules. With 112,059 cumulative subjects, this meta-analysis provided a convincing argument that omega-3 supplementation had little benefit on heart health. The studies did not show any conclusive evidence that supplements could benefit the heart or prevent stroke or any other heart-related death.

One of the possible reasons for this contradiction, apart from the fact that the meta-analysis didn’t include the results of the VITAL study, is that environmental, purity, and other factors can influence the effectiveness of a supplement. Additionally, not all studies consider the other factors of health that impact patients’ cholesterol and heart health (exercise, genetics, etc.).

So while the newest emerging research does seem to show that most populations can benefit from omega-3 supplements, it’s always a good reminder that supplements are just that—supplements. They don’t replace exercise and a balanced diet. But when used properly in conjunction with other good health practices, omega-3 can benefit just about every system in the body.

Problems in the Omega-3 Supplement Industry

Apart from inconsistent research, other problems exist in the omega-3 supplement industry that can influence a product’s efficacy, safety and bioavailability. Additionally, some fishing practices can be detrimental to the marine ecosystem from which a particular product originates.

A problem with fish oil supplements in general is that fish may come from water that’s been polluted to levels that affect the marine life internally. So unless a fish (or fish supplement) has been tested for purity, there’s no guarantee that consumers aren’t putting these toxins in their body.

Mercury is another concern. Fish don’t naturally contain mercury, and neither do the oceans...but the plants that fish feed on retain mercury, and larger fish that eat smaller fish will have higher levels of mercury as well. In general, the smaller the organism, the less mercury will be present.

For environmentalists, the most pressing issue for the omega-3 industry is overfishing. According to an article published inThe Guardian, the so-called “reduction industry” (industries that take marine life and reduce them to oils) remove 20-25 million tons each year from the ocean. Though some supplement companies have turned to more environmentally friendly practices, that’s far from becoming an industry standard.

One example of a company that uses sustainable practices with traceability isAker BioMarine. The krill that they harvest for their Superba and Superba2 krill oil products are fished from the Southern Ocean, which is a nearly unpolluted body of water near Antarctica. Krill are small, not nearly as susceptible to mercury, and according to Aker’s website, they use eco-harvesting practices that are “below the limits outlined by the Commission for the Conservation of Antarctic Marine Living Resources.” The company also received a fourth consecutive “A” rating for its fishing practices from the Sustainable Fisheries Partnership.

Key takeaways

Omega 3 supplement research is no longer in its infancy, but it’s only recently that large-scale studies on the usefulness of supplements specifically are being conducted. The VITAL study is an ongoing study and it aims to look at some of the other benefits of omega-3 aside from its impact on heart health. Since the study is so large (over 28,000 participants), the results take a while to compile, so if you’re interested in knowing what else the study reveals, check back on their website atvitalstudy.org.

Whichever side you take when it comes to supplement science, it seems you would have enough information to prove your case either way. But modern research does seem to be in a significant transitional phase, where we’re starting to understand that supplements can be useful in treating certain conditions—in conjunction with other drugs and lifestyle changes—and there’s more to the story of omega-3 fatty acids in the Western diet than we've considered in the past.

When you understand the biological mechanisms of fat and fatty acids, it makes a lot more sense to see how a fat balance within the cell membranes makes an impact on all of the body’s systems. So while omega-3s only tell part of the story of human health, they’re a part that can’t be ignored. Using supplements in conjunction with lifestyle changes will have a synergistic effect on health, and wellbeing itself is always multifaceted by nature.

Seth Garland - Content Writer, Physician's Choice

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