CMAJ Fact Sheet: Fish oil and omega-3 fatty acids
Omega-3 Fatty Acids: Fish Oil Benefits for Heart Health
Omega-3 fatty acids are key for normal development and growth. Lack of dietary intake of omega-3 fatty acids and too much intake of omega-6 fatty acids is believed to be a significant contributing factor to many diseases. Since the human body cannot make omega-3 fatty acids, we have to get them from our diet. Omega-3 supplements have become one of the most popular supplements in the U.S. They're used to help prevent and treat a number of serious diseases.
Why do people take omega-3 fatty acids? Studies show that omega-3 fatty acids from fish oil is associated with a decreased risk of high blood pressure and triglyceride levels. There's also some evidence that diets high in omega-3 fatty acids help with rheumatoid arthritis. Past evidence pointed to omega-3 fatty acids reducing risk of heart attacks, strokes, and death from heart disease, but recent research has refuted some of these findings. More specific research is needed to sort this out. Omega-3 fatty acids have been studied in many other conditions. They include asthma, cancer, depression, psoriasis, and inflammatory bowel diseases such as Crohn's disease and ulcerative colitis. While some of these studies have been promising, they're still inconclusive.
The different types of omega-3 fatty acids can be confusing. There are the fish oils, which contain docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Then there are the plant sources with alpha-linolenic acid (ALA), which is converted into omega-3 fatty acids in the body. Studies have generally used fish oils as the source for omega-3 fatty acids. While plant sources with ALA may have the same benefits, less is known about them. For now, fish oils with DHA and EPA have the more established benefit.
Cod Liver Oil or Omega 3?
Cod Liver Oil or Omega 3?
Which is more valuable - Cod Liver Oil or Omega 3?
Both omega 3 fish oils and cod liver oil contain beneficial levels of essential omega 3 fatty acids. The main difference between the two is that cod liver oil also contains vitamins A and D. Many people believe that fats are unhealthy but this is not always the case. Omega 3’s are healthy fats.
The essential fatty acids found in fish oils are polyunsaturated and play important roles in the function of the body. They are vital for the health of every cell and are required for the formation of cell membranes. Two of the most important omega 3 fatty acids are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
Our bodies can not manufacture essential fatty acids and so they need to be consumed in our diet. Fish oil supplements can offer a simple and affordable way to help top up the body's supply and to boost overall health.
Cod Liver Oil
Cod liver oil is produced from the livers of fish belonging to the cod family. The oils in these fish tend to build up in the liver and as a result, the oil is also high in vitamins A and D. Vitamin A is vital for the maintenance of healthy skin and the immune system. Vitamin D is important for the body’s absorption and use of calcium, and as a result, helps to maintain healthy bones and teeth. The body naturally manufactures vitamin D when exposed to the suns rays. Many people choose to take cod liver oil supplements during the winter months, when natural sunlight and vitamin D may be in short supply.
These vitamins offer further benefits when combined with the EPA and DHA in fish oils. However, cod liver oil often contains a lower concentration of omega 3’s when compared to omega 3 fish oil.
Oily fish such as mackerel and herring tend to accumulate oil in fatty layers of flesh rather than the liver. This results in more highly concentrated levels of EPA and DHA. As these oils are not taken from the liver, they do not contain vitamin A or D.
Benefits of Omega 3 Fatty Acids
Over the years many different health benefits have been discovered for omega 3’s . These include:
Healthy Heart – Omega 3 fatty acids can reduce cholesterol and triglyceride levels. Studies also indicate that they can help to reduce high blood pressure and therefore improve heart health.
– Omega 3 fatty acids can reduce cholesterol and triglyceride levels. Studies also indicate that they can help to reduce high blood pressure and therefore improve heart health. Joint Pain and Mobility – Numerous studies findings show that EPA may offer anti-inflammatory benefits and therefore contribute to healthy joints and reduce pain such as from arthritis.
– Numerous studies findings show that EPA may offer anti-inflammatory benefits and therefore contribute to healthy joints and reduce pain such as from arthritis. Stroke – Omega 3’s can help to promote healthy blood circulation which can improve the health of arteries by reducing the build-up of plaque and blood clots and reduce the risk of a stroke.
– Omega 3’s can help to promote healthy blood circulation which can improve the health of arteries by reducing the build-up of plaque and blood clots and reduce the risk of a stroke. Brain Function – EPA and DHA can help to insulate nerve cells in the brain, which improves their ability to communicate with each other effectively. As a result, they are often referred to as ‘brain food’.
– EPA and DHA can help to insulate nerve cells in the brain, which improves their ability to communicate with each other effectively. As a result, they are often referred to as ‘brain food’. Depression and Mood – Numerous studies have looked in detail at the relationship between omega 3's and depression. Results have found that higher levels of EPA and DHA may help to reduce feelings of anxiety and irritability.
– Numerous studies have looked in detail at the relationship between omega 3's and depression. Results have found that higher levels of EPA and DHA may help to reduce feelings of anxiety and irritability. Hormonal Balance – Omega 3’s are integral for the production of hormones. As a result, they can help to regulate hormone production and offer relief from menstrual cramps or menopausal symptoms.
– Omega 3’s are integral for the production of hormones. As a result, they can help to regulate hormone production and offer relief from menstrual cramps or menopausal symptoms. Skin Conditions – If you are deficient in omega 3’s then you may find that your skin is dry and cracked. Omega 3’s may provide anti-inflammatory properties that can be useful in preventing or treating skin conditions such as rosacea, psoriasis and eczema.
How Much Omega 3 Should I Take?
The current government recommendation for fish intake is two portions of fresh fish each week. Any more could potentially be dangerous, due to the toxins and pollutants that can be found in fresh fish. Fish oil supplements can be taken in higher doses because the oils undergo a distillation process, which ensures all toxins and pollutants are filtered out of the oil. Omega 3 fatty acids are beneficial for both adults and children, although different dosages are recommended:
Children between 5 to 14 years – take 500mg each day.
– take 500mg each day. Adults under the age of 40 years - if you are under the age 40 years old and fit with no health problems then you may only need around 1000mg each day.
- if you are under the age 40 years old and fit with no health problems then you may only need around 1000mg each day. Adults over the age of 40 years – if you are over 40 or have a higher risk of heart disease or arthritis then you will require a higher dose of 2000mg per day.
– if you are over 40 or have a higher risk of heart disease or arthritis then you will require a higher dose of 2000mg per day. Cod liver oil should not be taken in doses above 2000mg due to its vitamin A content. Vitamin A can be toxic when taken in high doses.
Use the infographic above to learn about the key differences between so that you can decide which best suits your needs.
CMAJ Fact Sheet: Fish oil and omega-3 fatty acids
What are omega-3 fatty acids? Omega-3 fatty acids are polyunsaturated fatty acids found in certain foods. The term “omega-3” refers to their chemical structure. Omega-3 fatty acids cannot be made in the body and must be obtained from food; thus, they are essential fatty acids. There are many forms of omega-3 fatty acids, each with a different length and chemical structure.
Where are omega-3 fatty acids found? The shortest omega-3 fatty acid, α-linolenic acid, is found in plants and plant oils, including leafy vegetables, walnuts, mustard seed oil, soy bean oil, canola oil and flaxseed oil (which is made up of 50% α-linolenic acid). The longer omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are found in algae, which are eaten by fish and baleen whales. We obtain these fatty acids by eating fish (e.g., salmon). Eicosapentaenoic acid and docosahexaenoic acid are often referred to as being from marine or fish sources.
Are plant omega-3 fatty acids the same as fish omega-3 fatty acids? Not quite. Although their chemical structures are similar, they have important differences, which affect their metabolism in the body.
Can our bodies convert plant omega-3 fatty acids to fish omega-3 fatty acids? Not well. Although our bodies can convert about 5% of α-linolenic acid to eicosapentaenoic acid, the level of eicosapentaenoic acid in blood does not rise when we eat α-linolenic acid.
What do omega-3 fatty acids do? Both omega-3 fatty acids from fish and plants appear to reduce the risk of some types of heart disease. However, the results of all studies have not been consistent. Some suggest that fish oil may reduce mortality among patients with coronary heart disease, possibly by stabilizing the heart's rhythm and by reducing blood clotting. We don't know as much about the effects of plant omega-3 fatty acids, but they appear to have similar actions in reducing coronary heart disease events.
What are the benefits of taking fish-oil supplements? It is usually stated that omega-3 fatty acids from fish may reduce cardiac deaths, inflammatory disease, including rheumatoid arthritis and ulcerative colitis, and promote brain development and mental function. Evidence for a benefit for fish oils in preventing coronary artery restenosis after angioplasty and rhythm abnormalities is less clear.
Are there risks from taking fish-oil supplements? In general, no. However, at least 1 study has suggested a negative effect among patients with implantable cardioverter defibrillators (to treat a heart-rhythm problem) who were not taking antiarrhythmic medications. There also may be negative effects among men with angina in terms of coronary heart disease. Again, these adverse events were reported among men who were not taking medication to reduce their blood pressure and stabilize their heart rhythm.
Are fish-oil supplements recommended for specific conditions? Some doctors recommend fish-oil supplements to prevent or treat cardiovascular disease. Although fish oil does not reduce LDL cholesterol, it may be recommended to lower serum triglycerides. In addition, infant formula is supplemented with docosahexaenoic acid in Europe to enhance development of the central nervous system because the rapidly growing brain requires large amounts of this fatty acid.
Are fish oils essential for human health? Many people believe this to be true, but officials are still divided. Vegetarians, who do not have an obvious source of fish oil in their diet, seem to have a low incidence of coronary heart disease. For certain functions, α-linolenic acid from vegetable sources may be able to substitute for longer fatty acids, either directly or after partial conversion to eicosapentaenoic acid.
Are there other sources of fish omega-3 fatty acids? As mentioned, α-linolenic acid may substitute for eicosapentaenoic acid. Docosahexaenoic acid used in infant formula comes from algae. With globally declining fish stocks and post-Kyoto awareness of the size of the human footprint, studies that involve plant-derived omega-3 fatty acids (e.g., α-linolenic acid or docosahexaenoic acid, or both) are needed to see if they also produce the desired benefits. David J.A. Jenkins MD PhD Andrea R. Josse MSc From the Department of Medicine, Divisions of Endocrinology and Metabolism (Jenkins) and the Clinical Nutrition and Risk Factor Modification Centre (Josse), St. Michael's Hospital, Toronto, Ont.; and the Department of Nutritional Sciences (Jenkins, Josse), University of Toronto, Toronto, Ont.