Fish oil is a widely consumed dietary supplement that comes from the oil of fatty fish such as tuna, mackerel, salmon, herring, trout, anchovies, and tilapia. Fish oils contain the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). There is another omega-3 called alpha-linolenic acid (ALA) that comes from walnuts, seeds, and certain vegetable oils. Sometimes fish oil is produced from the livers of other fish, such as cod. Cod liver oil contains fat-soluble vitamins A and D in addition to omega-3 fatty acids.
The body cannot make omega-3 fatty acids on its own, relying instead on food in order to get the omega-3s it needs. The American Heart Association recommends that every adult eat at least two servings of (preferably fatty) fish each week. The majority of people do not. Fish oil is widely used to supplement that gap in omega-3s.
Fish oils are commonly sold as over-the-counter supplements, though they are also available in prescription strength from a physician. The two should not be used interchangeably.
When taking fish oil supplements, it is best to do so with a meal that includes healthy fats in order to maximize absorption and minimize possible side effects. Though very safe, it is not uncommon for people taking fish oil to experience occasional fishy burps, bad breath, indigestion, or other potential digestive symptoms. The symptoms are usually remedied by taking fish oil with food, altering the schedule of dosage, or, sometimes, just letting your body adapt to them.
There is clinical evidence to suggest that EPA and DHA help to promote cardiovascular health and maintain cognitive health. DHA specifically has been shown to support memory and reaction time in healthy adults from findings in this study.
There is evidence to indicate that fish oil may support eye health. This randomized, double-blind clinical trial found that oral consumption of omega-3 fatty acids (EPA and DHA) twice daily for 30 days is positively associated with a decrease in the rate of tear evaporation, an improvement in dry eye symptoms, and an increase in tear secretion.
Flaxseed is the dried, ripened seeds of the flax plant, which was originally grown in ancient Egypt and China. It is a nutrient-rich antioxidant that is also high in fiber. It is currently available in tablets, powder, seeds, flour, capsules, and oil.
Flaxseed oil is produced by cold pressing the seeds, which then release the oil, a rich source of the plant-based omega-3 alpha-linolenic acid (ALA). While other foods such as walnuts, canola oil, and soybean oil contain ALA, flaxseed oil is by far the richest source.
Cold pressing also enables the oil to retain its antioxidant properties, though it does not contain any of the dietary fiber that is available from the flaxseed.
While flaxseed oil is very high in the omega-3 fatty acid ALA, it is not a good substitute for the omega-3s in fish oil because ALA does not effectively convert to EPA and DHA. The problem is that ALA must be converted by a limited supply of enzymes into EPA and DHA. As a result, only a small percentage of it (10-15% at best) converts into EPA and DHA. The bulk of it (85-90%) is either burned up as energy or is metabolized in other ways in the body.
Flaxseed oil can be used in your kitchen as a replacement for less healthy oils. It can be part of your salad dressing or used as a sauce in your favorite recipe. It is also a perfect, healthy addition to a smoothie or any blended drink. It does not, however, have a high smoke content, so do not use it for cooking.
Both flaxseed oil and fish oil contain an abundance of omega-3 fatty acids, which are essential fats. You must get your essential fats from your food since your body does not have the ability to make them. The omega-3s in fatty fish like trout, mackerel, tuna, tilapia, herring, and salmon have an abundance of DHA and EPA. The omega-3s in flaxseed oil are even more abundant, though they have to be converted into DHA and EPA through a process that ends up converting a mere 10-15%, which is inefficient at best.
Flaxseed oil supports skin health. This study found that supplementing with flaxseed oil for 12 weeks led to improvements in both skin smoothness and hydration, while skin sensitivity to irritation and roughness had decreased. Preliminary research shows potential skin health benefits regarding UV-B rays with fish oil supplementation. However, more studies are needed. Research is more supportive for collagen and ceramide supplementation to support skin health. In general, healthy omega 3 levels are important for overall skin health.
This report confirms that omega-3 fatty acids DHA and EPA are cardioprotective in the setting of secondary prevention and that they benefit multiple cardiometabolic risk factors. They also contend that a more practical way than supplementation to increase omega-3 fatty acid intake is to incorporate fish as part of a healthy diet with increased fruit and vegetables. There are several lifestyle factors that can promote heart health, as well, including exercise, adequate sleep, and consuming nutrient- and antioxidant-rich foods.
While fish oil and flaxseed oil each have a number of benefits, neither is really better than the other. It all depends on what you are looking for. In terms of shared benefits, fish oil is a better option if you are looking for bioavailable EPA and DHA. If you are looking to increase your intake of ALA, flaxseed oil is a better choice. If you are vegan, vegetarian, or have fish allergies, ALA might seem like the better choice, but given the constraints of its conversion into EPA and DHA you might look for another vegan source, such as algae oil.
The decision between fish oil or flaxseed oil is pretty much based on what you are looking for. If it’s the best supplement to increase your EPA and DHA, then it’s fish oil – unless, of course, you’re a vegan, vegetarian, or have fish allergies, in which case you’ll want flax seed or something else.
It is an individual decision based on your specific needs. Get all the facts and consult your physician or a registered dietician before you begin a new supplementation regimen.
Care/of has an excellent article, How Much Fish Oil Should I Take, that is an invaluable resource if you are thinking about supplementing with fish oil.