Because they perform important physiological functions and the body cannot make them, both omega-6 and omega-3 polyunsaturated fatty acids [PUFAs] are considered to be essential nutrients: A person must consume them in order to maintain basic health.
Omega-3 PUFAs are found in some plant-based foods and many kinds of fish. However, Docosahexaenoic Acid (DHA) and Eicosapentaenoic acid (EPA), the two types of omega-3 fatty acids that have been associated with positive mental and physical health outcomes, are only obtained from fatty fish or supplements.
Heart disease prevention and improved outcomes usually top the list, but emerging evidence also links fish intake to optimal fetal development and eye health as well as lower rates of depression, anxiety, weight-related and inflammatory disorders. Many Americans do not eat fish on a weekly basis, even with compelling research and strong recommendations. This review of omega-3 sources, mercury concerns, and supplements may help you evaluate your own intake and find ways to improve, if needed.
Food sources of Omega-3 DHA and EPA
In our food supply, DHA and EPA are found in fatty fish—primarily salmon, sardines, mackerel, herring, tuna, and trout. While flax seeds, chia, walnuts, and canola oil contain omega-3, it is in the form of alpha-linolenic acid, which does not convert effectively to DHA and EPA.
Adults should aim for 1-2 servings of fish each week for a goal of at least 8 ounces.
Fish and mercury:
Mercury can enter our bodies of fresh and salt water from burning coal (more on this at Dartmouth’s Toxic Metals Superfund Research website). The heavy metal eventually makes its way into some seafood in the form of methyl mercury.
Although mercury is toxic to humans and should be avoided when possible, experts agree that the benefits of consuming non-predatory fish far outweigh any potential risk. Seafood choices higher in EPA and DHA but lower in methyl mercury are encouraged—common varieties that meet these criteria include:
salmon, anchovies, herring, shad, sardines, anchovies, Pacific oysters, trout, and Atlantic and Pacific mackerel.
Pregnant women should follow consumption recommendations closely and speak to their doctors with concerns.
Eating a variety of different foods is advisable to protect against any toxin.
What to buy?
Consider fish first, as supplements can only attempt to re-create all the healthy components of fish, which is a lean protein containing several types of healthy fatty acids, vitamins and minerals.
Most research relating omega-3 DHA and EPA to improved health is based on fish consumption, not supplements. However, supplements containing DHA and EPA may have similar health benefits, and is probably beneficial for most adults who do not consume fish on a regular basis. Always consult your physician before starting a new herb, supplement, or medication.
The recommended intake for supplements varies from 250mg – 1,000 mg DHA / EPA per day. Why such a big range? Experts disagree on the levels needed to prevent or improve disease outcomes. The lower end of the range may be considered to prevent a deficiency, although there is no official daily intake recommendation.
- Fish oil (salmon, sardine, or cod liver oils). This would be your supplement option most similar to fish, making it the most “natural” choice. However, only 30% of the oil is DHA and EPA, so this option comes with some added calories and a potentially higher cost. Because this type of supplement most closely replicates fish, absorption of DHA and EPA may be higher, even if present in smaller quantities than the concentrated versions.
Buy un-processed oils from a reputable source, as minimal processing means there is no opportunity to adjust purity or quality. These oils may have a shorter shelf-life than concentrated or purified options, so only buy in quantities you will use fairly quickly.
- Concentrated fish oils (often labeled as omega-3, rather than fish oil). Most products labeled as Omega-3 contain purified and/or concentrated fish oils. Benefits of this form include a lower chance of toxins and a longer shelf life. However, most products come in the ethyl ester form of the fatty acid, which is not the naturally occurring form.
There is no reliable evidence to know if this format is any better or worse than the triglyceride form, and many supplements are sold as ethyl esters. If you are on a budget, these are a good choice. Some brands, such as Nordic Naturals, offer concentrated options as reformed triglycerides, which are more easily absorbed, but are usually pricier.
- Omega 3/6/9. As previously mentioned, omega-6 PUFAs are abundant in most peoples’ diets. Besides being a potential waste of money, there are some studies that suggest the proper ratio of omega 3 to omega 6 within the body yields benefits—so to add more omega-6 to what we’re already getting would negate some of the benefit of adding omega-3, of which we don’t usually get enough. I have seen little evidence to support the use of a 3/6/9 supplement in the case of healthy adults.
- Krill oil. Krill oil not only contains Omega-3 DHA and EPA, but also the antioxidant carotenoid astaxanthin. This oil is absorbed well into the body, may have fewer toxins than are present in larger fish, and has an antioxidant bonus. However, less is known about krill oil than fish oil, so pregnant women and other high-risk groups may want to stick with fish oil until more research is conducted.
- Algal oil. Great for vegetarians and non-vegetarians alike, as this oil is unlikely to contain contaminants, is in triglyceride form, and is more environmentally friendly than fish. Algae is the original source of omega-3 for fish, so it makes sense that this would be a good source for humans as well.
In summary: If you can’t eat fish, look for fish oil or omega-3 supplements in triglyceride form that contains at least 250 mg of DHA / EPA per serving.
For an economical approach, concentrated or ethyl ester products are also safe and effective as far as we know.
A few more things:
- Gummies: A nice format for kiddos or if you’re averse to swallowing large capsules. However, you generally need to take more gummies to get the recommended dose, which can make them expensive. Besides the cost, with 1-2 grams of sugar per serving, taking 6-10 will stick you with a lot of sugar! There is also the potential to take too much DHA and EPA because gummies are so yummy, you may be tempted to treat them like a snack. As a last resort, gummies can be used to consume DHA and EPA, but doses are likely to be less consistent and contain needless sugar.
Additionally, While DHA is important for pregnant and breast-feeding women and has also become ubiquitous in infant formula, there are very few studies to support DHA supplementation for toddlers and children (the usual target of gummy marketing). Just like adults, parents should aim to feed their children (smaller portions of) fish once or twice a week. Consult your pediatrician for further guidance and be aware that companies will try to market to parents of toddlers using cognitive claims that are not supported by scientific evidence.
- Cost-saving opportunity: Purchase fish oil in its oil format- rather than capsules or gummies- to save money per serving. As this is less appetizing to most people than swallowing capsules, you may need to be creative with how you consume the oil. Try adding to salad dressings and yogurt or follow a quick spoonful with strong flavors like lemon or kombucha.