Can fish oil help with anergia (lack of energy) or fatigue in the absence of other psychological symptoms?

Fish Oil for Anergia/Fatigue Without Other Psychological Symptoms

Fish oil supplementation may help reduce fatigue in specific populations, but there is insufficient evidence to recommend it broadly for anergia/fatigue in the absence of other psychological symptoms.

Evidence in Specific Populations

Cancer Patients

• Fish oil (2.2 g/day EPA) has shown benefits in reducing fatigue symptoms specifically in cancer patients undergoing chemotherapy 1
• In the largest trial with cancer patients, those receiving fish oil supplements maintained better body weight and reported less fatigue compared to control groups 1
• ESPEN guidelines suggest using long-chain N-3 fatty acids or fish oil supplementation in patients with advanced cancer undergoing chemotherapy to improve various symptoms including fatigue (weak recommendation, low evidence) 1

Cardiovascular Disease with Depression

• A recent randomized controlled trial (2023) found that omega-3 supplementation (2g EPA + 1g DHA daily) improved fatigue symptoms in patients with cardiovascular disease comorbid with major depressive disorder, with significant improvements seen at week 4 2
• The effects were more pronounced in older patients (≥55 years) for fatigue reduction 2

Mechanisms of Action

• Fish oil contains omega-3 fatty acids (EPA and DHA) that have anti-inflammatory properties 1
• Omega-3 fatty acids decrease production of inflammatory mediators including interleukin-1 and tumor necrosis factor 3
• Reduced inflammation may be a possible mechanism for addressing fatigue symptoms 3
• EPA is a competitive antagonist of N-6 arachidonic acid, which produces pro-inflammatory eicosanoids 1

Dosage Considerations

• For potential clinical benefits, at least 2 g/day of omega-3 fatty acids appears to be required 1
• Most studies showing benefits for fatigue used doses between 2-3 g/day 1, 2
• Fish oil is generally well-tolerated at doses up to 5 g/day 1

Limitations of Evidence

• Most positive evidence comes from studies in specific populations (cancer patients, cardiovascular disease with depression) 1, 2
• There is limited direct evidence for fish oil's effectiveness for fatigue/anergia as a primary symptom in otherwise healthy individuals 4
• A randomized trial in men with angina found no significant effect of increased fish intake on mood or anxiety 4

Safety Considerations

• Fish oil supplementation is generally well-tolerated with minimal side effects 1
• Common side effects include mild gastrointestinal effects, fishy aftertaste, or fish-scented belching 1
• Despite theoretical concerns, long-term supplementation with EPA and DHA up to 5 g/day does not appear to increase bleeding risk 1

Clinical Application

• Consider fish oil supplementation (2-3 g/day) for fatigue in patients with cancer undergoing chemotherapy 1
• Consider fish oil (2g EPA + 1g DHA daily) for patients with cardiovascular disease who also experience fatigue 2
• For general health benefits, consuming fish as part of a healthy diet (2-3 servings/week) is recommended by the American Heart Association 1, 5
• Fish oil supplementation may be considered as an adjunct to fish intake for those who do not consume fish regularly 1

Pitfalls and Caveats

• Benefits for fatigue may be limited to specific patient populations and may not generalize to all cases of anergia/fatigue 1, 2
• Effects may take several weeks to become apparent (improvements in fatigue were noted at week 4 in the cardiovascular disease study) 2
• Quality and source of fish oil supplements vary; oily fish (dark meat fish) contain up to 10-fold higher omega-3 fatty acids than white meat fish 1
• Potential contaminants in fish (mercury, persistent organic pollutants) should be considered, especially for pregnant women 1