Inhaltsstoff-Glossar

Fish Oil

What Is Fish Oil?

Fish oil contains long-chain unsaturated fatty acids—known as omega-3 fatty acids—that are essential for human health. In everyday language, fish oil or omega-3 fish oil is often used synonymously with the two omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). DHA and EPA are important for regulating inflammatory processes, supporting brain function, and influencing various metabolic signaling pathways. Fish oil is one of the most popular dietary supplements on the market.

Where Does Fish Oil Naturally Occur?

Fish oil is obtained from oily fish species. DHA and EPA are found primarily in fish and, in very small amounts, in other animal-derived foods. However, the original source of these two marine omega-3 fatty acids is microscopic algae, commonly referred to as microalgae, which consist of countless microscopic single-celled organisms, unlike visible macroalgae. It is only through the food chain that omega-3 fatty acids accumulate in fish. Commercial omega-3 algae oil is commonly produced using species of the microalgae genus Schizochytrium.

To meet the body's DHA and EPA requirements, humans can convert the omega-3 fatty acid alpha-linolenic acid (ALA) into EPA and DHA. ALA is found exclusively in plant-based foods, particularly rapeseed oil, walnuts, and flaxseed. However, the efficiency of this conversion depends on various environmental and physiological factors such as age, stress, illness, and diet. Depending on the circumstances, conversion rates range from approximately 0.1% to 10%.

Because the same enzyme is involved both in converting the omega-3 fatty acid ALA and in several metabolic steps involving omega-6 fatty acids, ALA and omega-6 fatty acids compete for this enzyme. When the diet contains a substantial excess of omega-6 fatty acids, the conversion of ALA into EPA and DHA approaches zero. To ensure sufficient endogenous production of EPA and DHA from ALA, researchers recommend maintaining an omega-6 to omega-3 ratio in the diet of no more than 4–6:1.

What Is the Primary Function of Fish Oil in the Body?

Due to their chemical structure (spatial configuration) with multiple double bonds, omega-3 fatty acids are highly susceptible to oxidation. However, this structural flexibility also makes these molecules particularly valuable for the human body. DHA contains six double bonds, making it the most flexible of the major omega-3 fatty acids, and it is an integral component of nerve cell membranes. DHA accounts for nearly all omega-3 fatty acids found in the brain and the optic nerve. If the mother develops a DHA deficiency during pregnancy, there is a risk of developmental abnormalities, particularly in these tissues.

EPA serves as the precursor for the synthesis of DHA and eicosanoids, which are important signaling molecules. Eicosanoids regulate blood pressure, heart rate, the entire cardiovascular system, inflammatory responses, and pain perception.

A deficiency of DHA and EPA is associated with an increased risk of developmental disorders in unborn children. However, no universally accepted threshold values are currently known below which the functions of the nervous system or immune system become impaired.

Benefits

May help maintain normal heart function
May help prevent cardiovascular disease

What Are the Benefits of Fish Oil Supplementation?

Fish oil is one of the most widely used dietary supplements because numerous studies have demonstrated beneficial effects of omega-3 supplementation. Based on robust evidence in several areas of application, the European Food Safety Authority (EFSA) has approved a number of health claims. Among these is the finding that a daily intake of 2–4 g of DHA and EPA helps lower blood pressure and triglyceride levels. A daily intake of 250 mg of omega-3 fatty acids is considered sufficient to help maintain normal heart function and contribute to the prevention of cardiovascular disease. An EFSA expert panel has concluded that a combined daily intake of up to 5 g of DHA and EPA is safe.

Consistent with the biological effects of omega-3 fatty acids, numerous research areas have produced further promising findings regarding fish oil supplementation. Meta-analyses have reported positive effects of fish oil on mood, muscle recovery and inflammatory markers in athletes, insulin sensitivity in individuals with metabolic disorders, and the rate of age-related cognitive decline. DHA and EPA often exert different, yet complementary, physiological effects.