Omega-3 fatty acids are vital for us humans. We need to take them in through food – such as vegetable oils and sea fish – to maintain important functions of our organism. But do polyunsaturated fatty acids actually have a preventive effect against cardiovascular diseases? Or is an increased intake of the fats even harmful to health? In the following, we answer all questions about omega-3 fatty acids.
What are omega-3 fatty acids?
Omega-3 fatty acids are essential fatty acids. Essential means that we need to get them from food because the human body cannot make them by itself. Omega-3 fatty acids are among the polyunsaturated fatty acids. This means that there are several double bonds in their molecular structures. This is the difference to saturated fatty acids, which do not have double bonds. Contained omega-3 fatty acids are mainly in vegetable oils and fatty sea fish.
Omega-3 and omega-6 fatty acids
Omega-3 fatty acids can be divided into different types of fatty acids. The relevant acids are called:
- Α-linolenic acid (alpha-linolenic acid, ALA).
- Eicosapentaenoic acid (EPA)
- Docosahexaenoic acid (DHA)
EPA and DHA can be formed by our organism from α-linolenic acid, so only this can be considered truly essential for adults. How effectively this synthesis takes place depends on the intake of omega-6 fatty acids. These are also unsaturated fatty acids that are essential for life. However, there is a complicated relationship between omega-3 and omega-6 fatty acids. In the human body, both types of fatty acids are processed in the same enzyme system. If there is a disproportion between the different types, disorders can occur. Ideally, there should be a 5:1 ratio of omega-6 to omega-3 fatty acids. However, we tend to consume too much omega-6.
What is omega-3 good for?
The human body needs omega-3 fatty acids to build cell membranes. These should be adaptable and – for the right substances – permeable. Some omega-3 fatty acids have an anti-inflammatory effect, serve as precursors to hormones or contribute to normal brain function and the maintenance of vision. In addition, research shows that omega-3 fatty acids most likely have a positive effect on blood triglyceride levels. This is a specific type of dietary fat. Triglyceride levels are part of the complex also known as “cholesterol levels.” These are three individual values. In addition to the triglyceride level, they include the HDL and LDL levels. Simply put, HDL is “good” cholesterol and LDL is “bad” cholesterol. Therefore, it is important that HDL cholesterol is sufficiently present in the body relative to LDL. Unfavorable cholesterol levels are considered a risk factor for the development of atherosclerosis and cardiovascular disease.
Omega-3 fatty acids: increased intake not advisable
For a long time, omega-3 fatty acids were considered a true miracle cure that would help against just about any disease. A positive influence on depression, the function of the kidneys in diabetics and an effect against pain were discussed. Above all, however, the fats were considered to protect against serious cardiovascular diseases such as a heart attack or stroke. The so-called Cochrane Review from 2018 has brought disillusionment with regard to the latter aspect. This review is a meta-study for which 79 randomized studies with a total of over 110,000 participants were evaluated. The question was: Does an increased intake of omega-3 fatty acids bring benefits for heart health? The answer was clearly no. Although a minimal preventive effect against cardiac arrhythmias was found, the scientists believe that the small effect makes it negligible. And not only that: too high an intake of omega-3 fatty acids can actually harm us. High doses can increase the risk of bleeding, cause nausea and vomiting. The preventive effect against cardiac arrhythmias then ceases to exist; rather, such disorders can be triggered in the first place and, in addition, LDL concentrations can be increased. Diabetics may experience problems with blood sugar and the immune system may be weakened.For these reasons, the German Federal Office for Risk Assessment has recommended for many years that a recommended upper limit for daily omega-3 intake be established.
How healthy are omega-3 fatty acids?
However, these study results do not prove that omega-3 fatty acids are unhealthy and that we should avoid their intake. In fact, the opposite is true. Because – we remember – omega-3 fatty acids are essential, that is, necessary for life. The research presented has only shown that increased intake beyond the daily requirement most likely has little or no benefits for heart health. That doesn’t change the fact that we need to get omega-3 fatty acids every day from food or, failing that, from a dietary supplement. What omega-3 fatty acids are also good for has not yet been conclusively determined. Whether they can actually help treat depression, protect against dementia or have other effects on health, for example, is still being researched in studies.
Who needs omega-3 – and how much?
It is recommended that daily intake of omega-3 fatty acids should be 0.5 percent of calories. For an adult with a daily consumption of 2,400 kilocalories (kcal), this is equivalent to 1.3 g of omega-3 fatty acids per day, or about one tablespoon of canola oil. During pregnancy, the need is slightly increased because the fatty acids are important for the neurological development of the child and its vision. If you are pregnant and want to know if you need an omega-3 supplement such as fish oil capsules or fortified foods, it is best to discuss this with your health care provider. Infants cannot yet make EPA and DHA from α-linolenic acid. Therefore, they must also ingest EPA and DHA. Usually, an adequate supply for infants comes from breast milk.
Omega-3 deficiency: who is at risk?
Omega-3 deficiency is very rare. Symptoms tend to be nonspecific, so they do not clearly indicate an omega-3 deficiency. Possible signs include:
- Problems with vision and eyes
- Concentration problems
- Fatigue
Diagnosed such a deficiency with the help of a blood test. If a visit to the doctor is not an option, you can use a test kit for home. Here you take a small blood sample yourself and send it to a laboratory, where it is evaluated. People who eat a balanced and healthy diet do not need to take omega-3 supplements, as their needs are covered by the food they eat. If fish is not consumed, for example as part of a vegetarian or vegan diet, compensation may need to be provided.
Food supplements: what to look out for?
Because of their double bonds, omega-3 fatty acids are very reactive and therefore oxidize quickly, meaning that they undergo chemical reactions with oxygen. To prevent this, antioxidants are added to most supplements containing omega-3. Capsules containing omega-3 with vitamin D or coenzyme Q10 are also available. If supplements are taken that combine omega-3 with vitamins, again, caution should be exercised with regard to daily requirements: If the recommended maximum daily intake of certain vitamins is significantly exceeded, there is a risk of serious health risks in some cases. Anyone who wants to buy omega-3 capsules should also take a look at the list of ingredients: Fish oil capsules are often also obtained from krill. However, whales, seals and penguins, for example, depend – either directly or indirectly – on sufficient krill stocks. More environmentally friendly and also suitable for vegans are therefore omega-3 supplements from microalgae.
Where is the most omega-3 contained?
Foods with omega-3 fatty acids are on the one hand fatty sea fish such as salmon and tuna, on the other hand vegetable oils such as linseed oil, walnut oil and rapeseed oil. Nuts, avocados and green leafy vegetables are also suitable sources of omega-3s. Olive oil also contains omega-3 fatty acids, but the ratio to omega-6 is rather unfavorable. To optimize the utilization of omega-3 fatty acids from vegetable oils or fish, it is advisable to pay attention to the correct ratio to the consumption of foods containing omega-6 fatty acids. A lot of omega-6 is contained in safflower and sunflower oil, for example. In principle, it is recommended not to take omega-3 capsules without medical advice.Instead, it is better to eat a portion of (fatty) sea fish once or twice a week, prefer to use omega-3-rich vegetable oils, and reduce the consumption of meat and sausage whenever possible.
How much omega-3 fatty acids are in fish?
The amount of omega-3 fatty acids varies greatly depending on the type of fish. The following table shows the types of fish that contain the most omega-3, as well as the respective content of the omega-3 fatty acid eicosapentaenoic acid (values may vary, depending on the fat content of the fish and the feeding method).
| Fish / 100 g edible portion | Omega-3 fatty acid |
|---|---|
| Herring | 2,040 mg |
| Tuna | 1,380 mg |
| Salmon | 750 mg |
| Mackerel | 630 mg |
| Eel | 260 mg |
| Carp | 190 mg |
| Halibut | 140 mg |
| Trout | 140 mg |
| Haddock | 90 mg |
| Cod | 70 mg |