The essential omega-3 fatty acids and their effects
The body needs fats, that much is certain. But not all fats are created equal. Unhealthy saturated and trans fatty acids have given the whole group of fats a bad reputation, but omega-3 fatty acids - and especially those from fish - have a variety of positive properties in the body. The National Consumption Study showed that on average only half of the recommended amount of fish is consumed; 16% of Germans eat no fish at all [1].
Here you will learn why it is so important to ensure you have an adequate omega-3 intake and what options there are other than fish to meet your needs.
Table of contents:
- What are omega-3 fatty acids?
- Does the body need omega-3 fatty acids?
- Health effects
- Overdose & Side Effects
- What dosage is recommended?
- Omega-3 rich foods
- The main thing is to eat fish?
- How omega-3 fatty acids are enriched in fish...
- How do the omega-3 fatty acids from food reach their active sites in the body?
- When does a nutritional supplement make sense?
- Important criteria when buying Omega-3 supplements
- Conclusion
- Sources
What are omega-3 fatty acids?
Omega-3 fatty acids are a component of various dietary fats such as linseed oil and fatty sea fish. Chemically speaking, they belong to the group of unsaturated fatty acids . The omega-3 fatty acids alpha-linolenic acid (ALA), eicosahexaenoic acid (EPA) and docasahexaenoic acid (DHA) are particularly well researched and relevant for human nutrition.
Figure 1: Structural formula of omega-3 fatty acids
Knowledge box: The name Omega-3
The name Omega-3 is derived from the molecular structure. The end of a fatty acid chain is always designated as Omega (the last letter of the Greek alphabet). The position of the last double bond in the molecule determines the number that appears after Omega in the name. In the case of Omega-3 fatty acids, this can be found on the third-to-last carbon atom in the chain. [2]
Does the body need omega-3 fatty acids?
ALA, EPA and DHA must be supplied to the body through food, as the body can in principle produce fatty acids, but not omega-3 fatty acids. The necessary enzymes are missing for this. Strictly speaking, only ALA of the above fatty acids is essential (must be taken in through the diet) because ALA can be converted into EPA and DHA in the body. Since the conversion is only 5% for EPA and 0.5% for DHA, these fatty acids are also essential. [3, 4].
Health effects
The EFSA (European Food Safety Authority) confirmed, based on clear evidence, that EPA and DHA contribute to the normal functioning of the heart and that DHA also supports the maintenance of normal vision and brain function . [4, 5]
Pregnant women should ensure that they consume sufficient DHA to reduce the risk of premature birth. In addition, the child needs sufficient DHA for brain and vision development, especially in the last trimester of pregnancy and in the first few months after birth. [4, 6].
Figure 2: The effect of Omega-3 on the body
Omega-3 for the heart
The mechanism of the cardioprotective effects of omega-3 fatty acids is not yet fully understood. Omega-3 fatty acids inhibit the conversion of arachidonic acid into pro-inflammatory eicosanoids by converting them themselves instead. Among the metabolites produced enzymatically from omega-3 are anti-inflammatory substances. Endo and Arita write that these substances could be involved in the positive effects on coronary heart disease [7].
Omega-3 for the eyes
The retina in the eye is particularly rich in DHA. In membranes (in the eye), this long-chain unsaturated fatty acid ensures sufficient membrane fluidity due to its physical properties. The mechanisms behind maintaining normal vision have not been fully clarified either. According to Bazan, docosanoids, which are formed in the body from DHA, could play a role in various eye diseases [8].
Omega-3 for the brain
In addition to the membranes in the eye, DHA is also found in large quantities in the brain. Data from cell and animal studies indicate that DHA influences brain function, the growth and differentiation of neuronal cells, and signal transmission. Recent studies show that the effect of DHA can vary depending on gender and genetic predispositions involved in the body's own DHA synthesis. It is therefore difficult to obtain clear and consistent results from studies on humans [9]. An American research team writes in its 2017 paper that neurotransmitters derived from DHA can protect nerve cells and counteract disorders [10]. Neuroprotectin D1, for example, can support the survival and repair of brain cells [11].
Overdose & Side Effects
Excessive intake of omega-3 fatty acids, for example, can change the flow properties of the blood , thereby prolonging bleeding times . As with all nutrients, the rule of thumb is not: more is better; instead, a moderate intake should be chosen that corresponds to the recognized recommendations [12].
If you have an infectious disease or are taking medication regularly, you should only take omega-3 products after consulting a doctor [12]. When buying a dietary supplement, you should always make sure that the dosage is safe and in accordance with current recommendations.
Figure 4: Omega-3 consumption is below the recommendation in all population groups
Overall, however, the negative effects mentioned rarely occur. In the population, as nutrition reports regularly show, an omega-3 deficiency is more typical. [3] Anyone who follows the intake recommendations of experts is in no danger of consuming too much (or too little) omega-3.
How much Omega-3 should you consume?
The table summarizes the EFSA's intake recommendations for different population groups. There are no gender-specific recommendations for men and women. The desirable ALA intake does not change over the course of life, whereas EPA and DHA fluctuate depending on requirements. [13]
Figure 5: Recommended intake of omega-3 fatty acids
Meeting the recommendations is not always easy, as many food groups do not contain any omega-3 fatty acids.
Omega-3 rich foods
ALA is found primarily in some vegetable oils, seeds and nuts . Marine products (e.g. salmon and herring) are the only food sources of EPA and DHA . However, many people eat little or no fish for a variety of reasons. If an adequate supply of EPA or DHA is at risk, fish oil supplements or purely vegetable oils from algae can supplement the diet. The table below provides an overview of the omega-3 content of some relevant sources. [3]
Figure 6: Vegetarian and vegan foods with omega-3 content in descending order
Figure 7: Animal foods with omega-3 content in descending order [14]
The main thing is to eat fish?
Different types of fish vary greatly in terms of their omega-3 fatty acid content. Low-fat fish such as cod or pollock provide between 280 and 840 mg of EPA and DHA per 100 g. Better than nothing, but still not much compared to a herring, which contains just under 3000 mg of EPA and DHA. Freshwater fish (eg trout) have similar omega-3 contents to low-fat saltwater fish [1].
Tuna and other fatty predatory fish that live in salt water are rich in Omega-3, but they also often contain high levels of pollutants, which is why they should be consumed in moderation (especially during pregnancy). The DGE recommends 1-2 fish meals per week [1].
How omega-3 fatty acids are enriched in fish...
Fish ingest tiny algae and crustaceans through their diet, which produce DHA and EPA. As with humans, the fatty acids accumulate in membranes and fatty tissue. This is particularly important for cold-water fish, as the membranes remain flexible even at low temperatures and do not solidify. For this reason, these fish species contain comparatively large amounts of omega-3. [15]
Figure 8: Enrichment of Omega-3 in the food chain
How do the omega-3 fatty acids from food reach their active sites in the body?
Omega-3 fatty acids are usually more than 95% absorbed in the small intestine; from there they are transported to various parts of the body bound to transport molecules. The first steps in fat digestion are mixing with saliva and breaking down the fat droplets in the stomach. Enzymes break down the fats in the stomach and small intestine into small fragments: glycerin and fatty acids.
Short fatty acids can then be absorbed simply as they are, while long-chain fatty acids such as omega-3 fatty acids are not very soluble in water due to their chemical structure and are therefore absorbed with the help of micelles . In this composition, the components move to a membrane where the fat components are absorbed into the small intestinal cell . From there, they can be transported to the sites of action in the body by transport molecules. [16, 17]
Knowledge box: Micelles
Micelles can be imagined as spherical structures that serve to transport water-insoluble substances. The outer layer, which is in contact with the aqueous environment of the human body, is made up of water-soluble components (including bile salts), while the core of the micelle contains the water-insoluble substances (including fat-soluble vitamins) [17].
Figure 9: Micelles support the absorption of Omega-3 in the body
When does a nutritional supplement make sense?
Since a large part of the population is undersupplied with omega-3 fatty acids [3], supplementation can be useful in all phases of life . There is also a special increased daily requirement for pregnant and breastfeeding women . The reason for this is to cover the body's own needs and those of the fetus/newborn, which is primarily dependent on DHA for brain and eye development. Cardiological societies also recommend an increased intake of omega-3 for people with diseases that affect the heart and blood vessels . [18]
If you are unsure, you can determine your Omega-3 supply status using the Omega-3 index . This indicates the proportion of EPA and DHA in the total fatty acids in the erythrocytes.
Important criteria when buying Omega-3 supplements
- Freshness: The TOTOX value indicates the degree of oxidation of a fat and thus its freshness. Fish oils with a low value are therefore particularly fresh and high quality.
- Contaminant levels: When buying fish oil or algae oil, it is important to check the contaminant levels before making a purchase; there are big differences between manufacturers. Only a few manufacturers manage to undercut the EU requirements for contaminants. Certificates can be an additional indication of a high level of safety.
- Dosage & ingredients: As with all nutritional supplements, correct and safe dosage is important. The purity of the fish oil should also be a priority. Long ingredient lists with lots of additives should not inspire your trust.
- Intake: Capsules make it easier to take the right dosage. A taste-neutral shell makes consumption particularly pleasant. Compared to oil in bottles, capsules offer the decisive advantage that the oil, which is susceptible to oxidation, is protected from reacting with atmospheric oxygen and thus stays fresh longer.
Conclusion
Omega-3 fatty acids help maintain brain and heart function as well as eyesight and are important components of cell membranes in the body. They are therefore very important in the diet. ALA is found in plant-based foods, but the more biologically active fatty acids EPA and DHA are found almost exclusively in fish. In order to ensure that you are adequately supplied with omega-3 fatty acids, dietary supplements can help. Be careful when buying them, as supplements from different manufacturers vary greatly in terms of quality and dosage. The rule of thumb is not: more is better. Instead, the recognized recommendations for the amount of omega-3 contained should be used as a basis so that an oversupply can be avoided.
