Fish Oil and Cyst Formation: Evidence Review
There is no evidence that fish oil supplements cause cyst formation. Fish oil supplements are generally safe at standard doses up to 5 g/day and do not appear to cause cysts in the body 1, 2.
Safety Profile of Fish Oil Supplements
Fish oil supplements containing omega-3 fatty acids (EPA and DHA) have been extensively studied for their safety profile:
- The European Food Safety Authority (EFSA) has concluded that long-term supplemental intakes of EPA and DHA combined up to about 5 g/day do not increase the risk of adverse effects 1, 2
- Supplemental intakes of EPA alone up to 1.8 g/day are considered safe 2
- The most common side effects of fish oil supplements are mild gastrointestinal effects, fishy aftertaste, or fish belching 1, 2
Specific Findings Related to Cysts
The available evidence does not establish any causal relationship between fish oil consumption and cyst formation:
- None of the major guidelines or research studies on fish oil supplementation report cyst formation as an adverse effect 1, 2
- While there is a case report of a ruptured giant oil cyst in the breast 3, this was related to trauma from a car accident and not to fish oil supplementation
- Studies examining fish oil in various populations, including those with cystic fibrosis, have not reported development of cysts as an adverse effect 4, 5
Potential Health Benefits of Fish Oil
Rather than causing harm, fish oil has been associated with several potential health benefits:
- May reduce inflammation in certain conditions 4
- May have cardiovascular benefits by affecting extracellular vesicles and reducing thrombogenic capacity 6
- May improve skin quality and reduce erythema (a marker of inflammation) 7
Special Considerations
While fish oil doesn't cause cysts, there are some specific situations where caution is advised:
- Patients receiving ibrutinib (for chronic lymphocytic lymphoma) should avoid fish oil supplements due to increased risk of epistaxis 2
- Patients on anticoagulants should be aware that fish oil has mild antiplatelet effects, though standard doses are generally considered safe even with anticoagulants 2
- Quality matters - supplements should be free of contaminants such as mercury, dioxins, and polychlorinated biphenyls (PCBs) 2
Conclusion
Based on the available evidence, fish oil supplements do not cause cyst formation. The American Cancer Society and other major health organizations do not list cyst formation as a potential adverse effect of fish oil consumption 1. Fish oil supplements are generally safe at recommended doses and may offer various health benefits.