If you do not get enough omega-3s in your diet from fatty fish, you may choose to get some of these essential fatty acids from a supplement. These come in different forms, like fish oil and algal oil.
Omega-3 fatty acids are important for health and help support essential body functions, such as brain health.
The best way to get enough is to eat whole foods rich in omega-3s, like fatty fish. But if you don’t eat a lot of fatty fish, taking a supplement may help.
While different omega-3 supplements are available, not all have the same health benefits.
This detailed guide explains everything you need to know about omega-3 supplements.
Fish oil comes in both natural and processed forms.
Processing can affect the form of the fatty acids. This is important because the body absorbs some forms better than others.
Fish: In whole fish, omega-3 fatty acids are present as free fatty acids, phospholipids, and triglycerides.
Fish oil: In conventional fish oils, omega-3 fatty acids are mostly present as triglycerides.
Processed fish oil: When fish oils are refined, food chemists often convert the triglycerides into ethyl esters, allowing them to adjust the concentration of DHA and EPA in the oil.
Reformed triglycerides: The ethyl esters in processed fish oils can be converted back into triglycerides, which are then termed “reformed†triglycerides.
All of these forms have health benefits, but research suggests the absorption of omega-3 from ethyl esters is not as good as from the other forms, although they all increase EPA and DHA in the bloodstream.
Research also suggests that many health benefits of eating fatty fish do not necessarily extend to supplements.
This is the oil that comes from the tissue of oily fish, mainly in the form of triglycerides. It’s the closest thing you can get to real fish.
Natural fish oil contains several important nutrients.
While the amount may vary between fish species, 1,000 mg of fish oil often contains about 180 mg EPA and 120 mg DHA. Natural fish oil also contains vitamins A and D.
Sources of natural fish oil typically include fish high in omega-3 fatty acids, such as:
Processed fish oil is purified, concentrated, or both. It consists of ethyl esters or triglycerides.
Purification removes contaminants such as mercury and PCBs from the oil. Concentrating the oil can also increase EPA and DHA levels.
Processed fish oils make up most of the fish oil market, as they’re cheap and usually come in capsules.
However, your body doesn’t absorb processed or natural fish oil in the ethyl ester form. Some manufacturers process the oil even further to convert it back into a synthetic triglyceride form, which is well absorbed.
These oils are referred to as reformed (or re-esterified) triglycerides. Although they’re the most expensive fish oil supplements, they only make up a small percentage of the market.
Ethyl esters may also be more prone to oxidation and rancidity than triglycerides. However, manufacturers can take steps to improve the stability of processed fish oils, including limiting the amount of oxygen in the product and its packaging.
Krill oil is extracted from Antarctic krill, a small shrimp-like animal. Krill oil contains omega-3s in both triglyceride and phospholipid form.
Numerous studies have shown that omega-3 is absorbed just as well from the phospholipids in krill oil as from the triglycerides in fish oil, and sometimes better.
Krill oil is highly resistant to oxidation, as it naturally contains a potent antioxidant called astaxanthin.
Additionally, krill are very small and have a short life span, so they don’t accumulate many contaminants like mercury during their lifetime. Their oil doesn’t need to be purified and is rarely found in the ethyl ester form.
The green-lipped mussel is native to New Zealand, and its oil is usually triglycerides or free fatty acids.
In addition to EPA and DHA, it also contains trace amounts of eicosatetraenoic acid (ETA). This rare omega-3 fatty acid may also help reduce inflammation.
Consuming green-lipped mussel oil is also considered to be environmentally friendly.
Your body can convert ALA into EPA or DHA, but this process is inefficient. According to the National Institutes of Health Office of Dietary Supplements, the best way to get EPA and DHA is to consume them directly, whether from food or supplements.
Most plant oils also contain more omega-6s than omega-3s.
Marine algae, particularly microalgae, are another triglyceride source of EPA and DHA.
The EPA and DHA in fish originate in algae. Smaller fish eat the algae, and it moves up the food chain from there.
Algal oil can be a particularly good source of DHA and EPA for vegetarians and vegans.
It may also contain important minerals like iodine.
Furthermore, algal oil is considered environmentally friendly. It doesn’t contain any contaminants, such as heavy metals, which makes it a sustainable, healthy option.
A regular fish oil supplement is probably the best choice for most people looking to improve their well-being.
However, remember that natural fish oil usually consists of no more than 30% EPA and DHA, which means 70% is other fats.
You can also buy supplements that contain a higher concentration of omega-3s. EPA and DHA can be as high as 90%. For best results, look for brands that contain omega-3s as free fatty acids. Triglycerides or phospholipids are good as well.
Omega-3 capsules are usually made from a soft layer of gelatin, and many manufacturers also use an enteric coating to keep the capsule from dissolving until it reaches your small intestine. This is common in fish oil capsules, as it prevents fishy-tasting burps.
However, it can also mask the foul smell of rancid fish oil. If you take omega-3 capsules, it may be a good idea to open one occasionally and smell it to ensure it hasn’t gone rancid.
When shopping for an omega-3 supplement, always read the label carefully and choose a variety that has undergone third-party testing.
The FDA does not monitor the contents of supplements like they do medications. Over time, independent research has found that some supplements may not contain the ingredients or amounts indicated on the label. Research from 2015 found that omega-3 fatty acid supplements were no exception. The researchers found that only 70% of the supplements tested contained what they said they did on the label.
When reading the level, look for the following:
Type of omega-3: Many omega-3 supplements often contain little, if any, EPA and DHA, the most important types of omega-3s. Make sure your supplement contains these.
Amount of omega-3: A supplement may say on the front that it contains 1,000 mg of fish oil per capsule. However, on the back, you’ll read that EPA and DHA are only 320 mg.
Form of omega-3: For better absorption, look for FFA (free fatty acids), TG, rTG (triglycerides and reformed triglycerides), and PLs (phospholipids) rather than EE (ethyl esters).
Purity and authenticity: Try to buy products that have a third-party seal. These labels show that they’re safe and contain what they say they do.
Freshness: Omega-3s are prone to going rancid. Once they go bad, they’ll have a foul smell and become less potent or even harmful. Always check the date, smell the product, and see if it contains an antioxidant like vitamin E.
Sustainability: Try to buy fish oil certified by the MSC, the Environmental Defense Fund, or a similar organization. Small fish with short lifespans tend to be more sustainable.
The FDA recommends that your daily intake of omega-3 fatty acids not exceed 3 grams (3000 mg) of EPA and DHA combined, with no more than 2 grams (2000 mg) deriving from supplements.
A regular fish oil supplement is probably sufficient for most people who do not get enough fatty fish in their diet. However, according to the National Center for Complementary and Integrative Health (NCCIH), eating seafood, particularly fatty fish, may have more health benefits than taking fish oil or other supplements.
However, make sure the supplement contains what it says it does, and pay special attention to the EPA and DHA content. EPA and DHA are most often found in animal-based omega-3 products. Vegetarian options are available, but they usually only contain ALA. One exception is algal oil, which provides an excellent source of quality omega-3s and is suitable for everyone, including vegans.
It’s best to take these supplements with a meal that contains fat, as fat increases your absorption of omega-3s.
Finally, omega-3s are perishable, just like fish, so avoid buying them in bulk.
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Kleiner AC, et al. (2015). A comparison of actual versus stated label amounts of EPA and DHA in commercial omega-3 dietary supplements in the United States. https://pubmed.ncbi.nlm.nih.gov/25044306/
Lu FSH, et al. (2014). Effect of temperature towards lipid oxidation and non-enzymatic browning reactions in krill oil upon storage. https://pubmed.ncbi.nlm.nih.gov/24679797/
Yi M, et al. (2023). Highly valuable fish oil: Formation process, enrichment, subsequent utilization, and storage of eicosapentaenoic acid ethyl esters. https://pmc.ncbi.nlm.nih.gov/articles/PMC9865908/
