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Aceite de Pescado

Also known as: Aceite de Pescado, Fish oil, marine oil, EPA, DHA, eicosapentaenoic acid, docosahexaenoic acid, Omega-3 Fatty Acids

Overview

Fish oil is a nutritional supplement derived from the tissues of oily fish such as salmon, mackerel, sardines, and anchovies. It is primarily valued for its high concentration of long-chain omega-3 polyunsaturated fatty acids (PUFAs), specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These essential fatty acids are not efficiently synthesized by the human body and must be obtained through diet or supplementation. Fish oil is widely used to support cardiovascular health, cognitive function, and metabolic health, and is also investigated for its anti-inflammatory properties and neuroprotective effects. Research on fish oil is extensive, with numerous high-quality randomized controlled trials, systematic reviews, and meta-analyses supporting its various applications.

Benefits

Fish oil offers several evidence-based benefits. For metabolic health, a 2025 systematic review and meta-analysis of RCTs demonstrated significant improvements in metabolic parameters in individuals with metabolic dysfunction-associated steatotic liver disease (MASLD) with fish oil supplementation. Regarding cognitive and neurotrophic effects, a 2024 meta-analysis of 12 RCTs involving 587 subjects found that omega-3 supplementation significantly increased serum brain-derived neurotrophic factor (BDNF) levels, suggesting neuroprotective and cognitive benefits. However, the evidence for cardiovascular health is more mixed; a 2024 meta-analysis of 15 RCTs indicated inconsistent effects on major cardiovascular events, myocardial infarction, and other cardiovascular outcomes, suggesting that while some benefits exist, fish oil may not be a standalone preventative measure for heart disease. Benefits appear more pronounced in populations with existing metabolic disorders or at risk for cognitive decline. Secondary effects include potential anti-inflammatory actions, improvements in lipid profiles, and mood stabilization, though these require further confirmation.

How it works

Fish oil exerts its effects primarily through the incorporation of EPA and DHA into cell membranes, which alters membrane fluidity and receptor function. This integration modulates the synthesis of eicosanoids, leading to a reduction in inflammatory responses. Omega-3 fatty acids also influence gene expression related to lipid metabolism and neurotrophic factors. In the cardiovascular system, they exhibit anti-atherogenic and anti-arrhythmic properties. In the nervous system, they promote neuroprotection, partly by elevating brain-derived neurotrophic factor (BDNF) levels. They interact with nuclear receptors like PPARs, inflammatory cytokines, and ion channels in cardiac tissue. Fish oil is absorbed in the small intestine, with bioavailability enhanced by co-ingestion with fat and by triglyceride forms over ethyl esters.

Side effects

Fish oil is generally considered safe and well-tolerated at recommended doses. The most common side effects, affecting more than 5% of users, are mild gastrointestinal symptoms such as a fishy aftertaste, nausea, and diarrhea. Uncommon side effects, occurring in 1-5% of individuals, include a tendency for increased bleeding, particularly at higher doses, and mild allergic reactions. Rare side effects, affecting less than 1% of users, can include severe bleeding events, especially when combined with anticoagulant medications. Fish oil may potentiate the effects of anticoagulants and antiplatelet drugs, thereby increasing the risk of bleeding. It is contraindicated or should be used with caution in patients with bleeding disorders or those on blood-thinning medications. For special populations, fish oil is generally considered safe during pregnancy and lactation, though dosing adjustments may be necessary.

Dosage

For general health maintenance, a minimum effective dose of 250–500 mg of combined EPA and DHA per day is typically recommended. For specific conditions, such as metabolic dysfunction-associated steatotic liver disease (MASLD) or to achieve cognitive benefits, studies have investigated optimal dosage ranges up to 2000 mg/day of combined EPA and DHA. The maximum safe dose is generally considered to be up to 3000 mg/day; however, higher doses should only be taken under medical supervision due to increased risk of side effects. Fish oil supplements should ideally be taken daily with meals to enhance absorption. Triglyceride forms of fish oil are generally considered to have better bioavailability compared to ethyl ester forms. No specific cofactors are required for its efficacy, but overall nutritional status can influence outcomes.

FAQs

Is fish oil supplementation safe long-term?

Yes, long-term use of fish oil at recommended doses is generally considered safe with minimal side effects. Regular monitoring may be advised for very high doses.

When will I see benefits?

Cognitive and metabolic benefits may become noticeable within weeks to a few months. Cardiovascular benefits, if they occur, may require several months to years of consistent supplementation.

Can fish oil prevent heart disease?

Evidence is mixed; while fish oil may reduce some cardiovascular risk factors, it is not a standalone preventative measure for heart disease and its effects on major cardiovascular events are inconsistent.

Does fish oil cause bleeding?

At high doses, fish oil can slightly increase the risk of bleeding, especially when taken concurrently with anticoagulant or antiplatelet medications. Consult a doctor if on blood thinners.

Is fish oil better than plant-based omega-3?

Fish oil directly provides EPA and DHA, which have more potent biological effects. Plant-based omega-3 (ALA) needs to be converted to EPA and DHA, a process that is often inefficient in the body.

Research Sources

https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2025.1524830/full – This systematic review and meta-analysis of RCTs found that fish oil supplementation significantly improved metabolic parameters in patients with metabolic dysfunction-associated steatotic liver disease (MASLD). The study used random-effects models and subgroup analyses to assess the impact of dose and duration, highlighting the efficacy of fish oil in this population.
https://pubmed.ncbi.nlm.nih.gov/36103100/ – This meta-analysis of 15 randomized controlled trials investigated the effects of omega-3 supplementation on major cardiovascular events. It concluded that omega-3 supplementation showed variable and inconsistent effects on cardiovascular outcomes, suggesting insufficient evidence to conclusively confirm prevention benefits due to heterogeneity in results and populations studied.
https://pubmed.ncbi.nlm.nih.gov/37589276/ – This meta-analysis of 12 RCTs (n=587) demonstrated that omega-3 supplementation significantly increased serum brain-derived neurotrophic factor (BDNF) levels. This finding suggests potential neuroprotective and cognitive benefits associated with omega-3 intake, despite some heterogeneity observed across the included studies.