Omega-3 Fatty Acids (EPA, DHA): Safety Assessment

Individuals who have an increased tendency to bleed, such as from medications, should exercise greater caution. The risk group of sensitive individuals with an increased tendency to bleed includes people taking anticoagulants (anticoagulants) of the coumarin type (e.g., Marcumar). Omega-3 fatty acids may enhance the effect of anticoagulants through a vitamin K-independent effect.

The long-chain omega-3 fatty acids EPA and DHA are generally recognized as safe (GRAS status, generally recognized as safe) and the study evidence shows that daily intake of up to 3 g EPA and DHA is highly unlikely to increase the tendency to bleed. Serious adverse reactions have not been reported regarding omega-3 fatty acids (EPA, DHA) from dietary supplements. The most common adverse reactions are limited to a fishy aftertaste, belching, and occasionally heartburn. High doses may cause nausea and soft stools.

Adverse effects of high intake of long-chain omega-3 fatty acids (EPA and DHA) have been discussed as prolongation of bleeding time, suppression of the immune system, and elevation of LDL cholesterol levels.

Prolongation of bleeding time: the potential of high doses of omega-3 fatty acids, particularly EPA and DHA, to prolong bleeding time has now been well studied. This effect may play a role in the cardioprotective effect (protective function for the cardiovascular system) of omega-3 fatty acids. The Eskimos of Greenland have been found to have excessively long bleeding times and also an increased incidence (frequency) of cerebral hemorrhage, probably due to their intake of very high doses of omega-3 fatty acids (about 6.5 g per day) in the diet. However, it is not known whether omega-3 fatty acids are the only reason for this. In a study of adolescents and young adults with hypercholesterolemia (elevated blood cholesterol levels), 1.5 g of omega-3 fatty acids taken over several months resulted in increased nosebleeds. In another study, a prolonged bleeding time was measured after administration of 2 g EPA (eicosapentaenoic acid), taken over 12 weeks. Suppression of the immune system: Omega-3 fatty acids have an anti-inflammatory (anti-inflammatory) effect and can be used therapeutically for corresponding diseases. Anti-inflammatory (anti-inflammatory) doses of omega-3 fatty acids may be able to reduce the effects of the immune system. In vitro studies have shown that this can occur at doses as low as 0.9 g/day for EPA and 0.6 g/day for DHA. In a human study of 48 healthy subjects, intake of fish oil capsules (720 mg EPA + 280 mg DHA) over a 12-week period resulted in both decreased natural killer cell activity by 48% and decreased proliferation (growth and multiplication) of T lymphocytes by up to 65%. These effects are usually interpreted positively as anti-inflammatory, but they also imply a weakening of the immune response to pathogens. For the healthy and especially the elderly population, suppression of the specific as well as the non-specific immune defense is not desirable and involves a risk. Increase in LDL cholesterol levels: Almost all studies on omega-3 fatty acids also found an increase in LDL cholesterol levels (cholesterol-containing low-density lipoproteins). One study showed that the increase in LDL cholesterol was higher with amounts of 2.4 g of DHA and EPA per day (26% increase) than with very large amounts of DHA and EPA of over 4 g per day (11% increase). In another study, as little as 700 mg of DHA taken for 3 months resulted in a slight 7% increase in LDL cholesterol.